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Sasaki Koichi
| Faculty of Engineering Applied Quantum Science and Engineering Quantum Engineering for Materials | Professor |
Researcher basic information
■ Degree■ URL
researchmap URLホームページURL■ Various IDs
J-Global ID■ Research Keywords and Fields
Research KeywordResearch Field
- Nanotechnology/Materials, Optical engineering and photon science
- Nanotechnology/Materials, Thin film/surface and interfacial physical properties
- Energy Engineering, Fundamental plasma
- Energy Engineering, Applied plasma science
- Bachelor's degree program, School of Engineering
- Master's degree program, Graduate School of Engineering
- Doctoral (PhD) degree program, Graduate School of Engineering
Research activity information
■ Awards- Sep. 2023, 静電気学会, 論文賞
- Mar. 2018, 応用物理学会, プラズマエレクトロニクス賞
- Jan. 2018, 日本学術振興会第153委員会, プラズマ材料科学賞(基礎部門賞)
- Sep. 2017, 応用物理学会, ポスター発表賞
- Oct. 2014, 応用物理学会, ポスター発表賞
- 2008, The most outstanding oral presenter in the Nanoscience and Nanotechnology International Conference 2008
- 2008, 永井科学技術財団賞
Japan - 2008, The most outstanding oral presenter in the Nanoscience and Nanotechnology International Conference 2008
- 2007, Outstanding Preposter-Poster Award
Japan - 2007, JJAP編集貢献賞
Japan - 2007, Outstanding Preposter-Poster Award
- 1993, 井上研究奨励賞
Japan - 1992, 電気学会論文発表賞
Japan
- One-step conversion of benzene to phenol in plasma-irradiated benzene solution
Y. Inagaki; Y. R. Hayashi; K. Sasaki; S. Takakusagi; K. Okamoto; A. Nagaki; N. Shirai
Journal of Applied Physics, 138, 11, 113301, 113301, AIP Publishing, 15 Sep. 2025, [Peer-reviewed]
Scientific journal, One-step synthesis of phenol was achieved in aqueous benzene solutions irradiated with atmospheric-pressure air and helium plasmas. We prepared the plasma-irradiated benzene solution by two experimental procedures: (1) mixture solution of benzene and NaCl was irradiated with the plasma and (2) benzene was admixed with the NaCl solution irradiated with the plasma. We observed the synthesis of phenol in both the methods except in procedure (2) using the helium plasma. When we used air for discharge, we observed the continuous production of phenol for at least 300 h after the irradiation of the plasma or mixing benzene with plasma-irradiated NaCl solution. The synthesis of phenol is attributed to the substitution reaction of hydroxyl radical (∙OH) with a hydrogen in benzene, which has been confirmed by the relationship between the synthesis rate of phenol and the concentration of a scavenger (2-propanol) for ∙OH. The apparent long lifetime of ∙OH is owing to its continuous production in the solution by homolytic splitting of ONOOH, which is produced from H2O2 and NO2−. - Importance of highly excited vibrational states of molecular nitrogen in ammonia synthesis using low-pressure nitrogen–hydrogen plasma
Masahiro Yamazaki; Koichi Sasaki
Physics of Plasmas, 32, 8, 084501, 084501, AIP Publishing, 01 Aug. 2025, [Peer-reviewed]
Scientific journal, In a previous work using an atmospheric-pressure plasma, we observed the contribution of vibrationally excited molecular nitrogen in the synthesis of ammonia, while in another previous work using a low-pressure plasma, the synthesis rate was dominated by atomic nitrogen. In this work, we examined the synthesis of ammonia in a low-pressure nitrogen–hydrogen mixture plasma where the vibrational temperature of molecular nitrogen was as high as 4500 K. No specific catalysts were employed, and ammonia was produced on the surface of a stainless-steel vacuum chamber. As a result, we observed an insufficient correlation between the densities of atomic nitrogen and synthesized ammonia, whereas a better correlation was observed between the ammonia density and the vibrational temperature. The experimental result suggests that vibrationally excited molecular nitrogen contributes to ammonia synthesis even in a low-pressure plasma if the vibrational temperature is higher than 3000 K. - Populations of n=2 states of atomic hydrogen in low-density hydrogen plasma: temperature and metastability of 2s2S1/2
Shusuke Nishiyama; Koichi Sasaki
Plasma Sources Science and Technology, 34, 4, 045006, 045006, IOP Publishing, 01 Apr. 2025, [Peer-reviewed]
Scientific journal, Abstract
The populations of the 2s , 2p , and 2p states of atomic hydrogen were examined in a low-density inductively coupled hydrogen plasma using diode laser absorption spectroscopy at the Balmer-α line. The Doppler broadened absorption spectra were not fitted with the theoretical spectra under the assumption that the population distribution of the three states followed the statistical weights. The fitting accuracy improved when the population ratio was allowed to deviate from the statistical weights; however, the improvement remained insufficient, especially for spectra observed at low electron densities and low hydrogen pressures. A reasonable fit was achieved only when a high-temperature component was introduced into the velocity distribution function of the 2s state. It was considered that the high-temperature component was produced via the electron-impact dissociative excitation of molecular hydrogen, because the population of the high-temperature component was proportional to the electron density. The experimental results clearly indicated a decrease in the population of high-temperature 2s with increasing electron density and hydrogen pressure. This trend is qualitatively reasonable considering the collisional transfer from the 2s to the 2p and 2p states. However, the cross-sections of the collisional transfer were insufficiently small to explain the experimental observations quantitatively. In addition, the experimental results suggest lower metastability of low-temperature 2s than that of the high-temperature component, which cannot be explained by collision cross-sections. Thus, a more sophisticated model should be investigated in future studies to obtain a deeper understanding of the kinetics governing the 2s , 2p , and 2p states. - Rate limiting step in ammonia synthesis using low-pressure nitrogen–hydrogen mixture plasma
Shogo Uebayashi; Koichi Sasaki
Japanese Journal of Applied Physics, 64, 3, 036001, 036001, IOP Publishing, 01 Mar. 2025, [Peer-reviewed]
Scientific journal, Abstract
The contributions of atomic nitrogen, atomic hydrogen, and vibrational excited molecular nitrogen were compared in the synthesis of ammonia using low-pressure nitrogen–hydrogen mixture plasma. No specific catalysts were employed, and ammonia was synthesized via reactions on the surface of a stainless-steel chamber. It was found that the number of nitrogen atoms transported to the chamber wall per unit time approximately coincided with the synthesis rate of ammonia. On the other hand, the synthesis rate of ammonia was saturated with the number of transported hydrogen atoms. In addition, we observed no correlation between the synthesis rate of ammonia and the number of vibrational excited nitrogen molecules. The experimental results indicate that the adsorption of atomic nitrogen is the rate limiting step in the synthesis process of ammonia in the present experimental condition, where the flux of atomic nitrogen was 103 times lower than the flux of vibrational excited molecular nitrogen. - Influence of atomic hydrogen, physical properties, and surface impurity film on droplet ejection from liquid metals interacting with inductively coupled hydrogen plasma
Yuki Hamana; Koichi Sasaki
Japanese Journal of Applied Physics, 64, 2, 028003, 028003, IOP Publishing, 01 Feb. 2025, [Peer-reviewed]
Scientific journal, Abstract
This paper reports characteristics of droplet ejection from liquid metals interacting with inductively coupled hydrogen plasma. It was observed that the ejection frequency was independent of the flux of atomic hydrogen, whereas it increased with the ion flux. The ejection frequency was dependent on the physical properties of liquid metals, and the transport height of droplets was shortened by the impurity film formation on the liquid metal surface. These results gave us an insight into a method to avoid the transport of droplets to the core plasma, when we apply liquid metals to divertor materials in nuclear fusion reactors. - Plasma-Derived Atomic Hydrogen Enables Eley–Rideal-Type CO2 Methanation at Low Temperatures
DAE-YEONG KIM; Yoshinobu Inagaki; Tsukasa Yamakawa; Bang Lu; Yoshiaki Sato; Naoki Shirai; Shinya Furukawa; Hyun-Ha Kim; Satoru Takakusagi; Koichi Sasaki; Tomohiro Nozaki
JACS Au, 5, 1, 169, 177, 18 Nov. 2024, [Peer-reviewed]
English, Scientific journal - Correlation between temperature distribution and changes in self-organized luminous pattern in an atmospheric pressure DC glow discharge with sheath gas flow
Toshiaki Miyazaki; Koichi Sasaki; Naoki Shirai
Plasma Sources Science and Technology, 33, 11, 115007, 115007, 01 Nov. 2024, [Peer-reviewed]
Scientific journal - Contribution of vibrational excited molecular nitrogen to ammonia synthesis using an atmospheric-pressure plasma jet
Atsufumi Miyake; Naoki Shirai; Koichi Sasaki
Journal of Applied Physics, 135, 21, 213301, 213301, 07 Jun. 2024, [Peer-reviewed]
Scientific journal - Synthesis of core–shell nanoparticles with liquid core using magnetron sputtering and capacitively coupled dusty plasmas
Munaswamy Murugesh; Koichi Sasaki
Japanese Journal of Applied Physics, 63, 5, 056003, 056003, IOP Publishing, 01 May 2024, [Peer-reviewed]
Scientific journal, Abstract
We succeeded in depositing amorphous carbon films around tin nanodroplets retained in a capacitively coupled plasma (CCP). High-pressure magnetron sputtering was used for synthesizing tin nanoparticles at the top of a vacuum chamber. Tin nanoparticles were transported to CCP at the bottom of the chamber, and they were trapped in the sheath above an rf electrode. Tin nanoparticles were heated above the mp by ion bombardment in CCP. We introduced methane into CCP to deposit amorphous carbon films around melted tin nanoparticles. The transmission electron microscope (TEM) images of core–shell nanoparticles showed completely spherical cores. We observed the melting of cores at the melting point of metal tin when we heated core–shell nanoparticles in TEM, suggesting that the amorphous carbon films protected cores from the oxidation. In addition, the amorphous carbon films were robust against the volume expansion of the cores due to melting. - Detection of negative ions in streamer discharge in air by transient cavity ringdown spectroscopy
Kimika Fushimi; Naoki Shirai; Koichi Sasaki
Plasma Sources Science and Technology, 33, 2, 02LT01, 02LT01, 01 Feb. 2024, [Peer-reviewed]
Scientific journal - Catalyst-free synthesis of ammonia using dc-driven atmospheric-pressure plasma in contact with water
Mary Ramoy; Naoki Shirai; Koichi Sasaki
Journal of Physics D: Applied Physics, 57, 1, 01LT01, 01LT01, 05 Jan. 2024, [Peer-reviewed]
Scientific journal - Production rates and destruction frequencies of ammonia in inductively coupled H2O/N2 and H2/N2 plasmas
Jin Takahashi; Koichi Sasaki
Contributions to Plasma Physics, 64, 3, e202300167, e202300167, Wiley, 28 Dec. 2023, [Peer-reviewed]
Scientific journal, Abstract
We compared the production rates and the destruction frequencies of ammonia in inductively coupled H2O/N2 and H2/N2 plasmas. We observed that the production rates of ammonia ranged between 4 and 7 μmol/s both in the H2O/N2 and H2/N2 plasmas generated at rf powers between 100 and 160 W, corresponding to the energy cost of 23–25 mol/MJ. Almost the same production rates suggest the usefulness of H2O as the resource for hydrogenation of atomic nitrogen adsorbed on surfaces. On the other hand, the destruction frequency was 2–4 times higher in the H2O/N2 than H2/N2 plasmas. Although the H2O/N2 plasma has a drawback in the destruction frequency, the present work shows its potential for the direct synthesis of ammonia from water with skipping the production of hydrogen. - Mechanism of droplet ejection from liquid gallium interacting with inductively coupled hydrogen plasma
Yuki Hamana; Naoki Shirai; Koichi Sasaki
Journal of Physics D: Applied Physics, 56, 47, 475204, 475204, 23 Nov. 2023, [Peer-reviewed]
Scientific journal - Saturated cavity ringdown spectroscopy at Balmer-α line of atomic hydrogen for estimating sheath electric field in plasma
Kimika Fushimi; Shusuke Nishiyama; Satoshi Tomioka; Koichi Sasaki
Journal of Instrumentation, 18, 10, C10002, C10002, IOP Publishing, 01 Oct. 2023
Scientific journal, Abstract
We applied saturated cavity ringdown spectroscopy (CRDS) to the measurement of the Doppler-free absorption spectrum of the Balmer-α line of atomic hydrogen in an inductively coupled hydrogen plasma. The spectrum was used for estimating the electric field in the sheath region in the vicinity to a biased electrode. The absorption frequency (the absorption coefficient multiplied by the speed of light) and the saturation parameter were estimated by fitting the experimental ringdown curve with the theory reported by Giusfredi and coworkers (Phys. Rev. Lett. 104 (2010) 110801). We detected the Lamb dip corresponding to the 2p 2 P o 3/2 - 3d 2 D 5/2 transition in the absorption spectrum in the field-free condition. We observed the change in the Lamb dip spectrum when we repeated the measurement in the sheath, and we succeeded in estimating the sheath electric field of 220–230 V/cm at a distance of 1.8 mm from the electrode which was biased at -100 V with respect to the ground potential. The experimental results indicate the potential of saturated CRDS for the measurement of sheath electric fields in plasmas. - Synthesis of Metal Nanoparticles Induced by Plasma-Assisted Electrolysis
Naoki Shirai; Koichi Sasaki
High-Energy Chemistry and Processing in Liquids, 57, 72, Springer Nature Singapore, 05 Feb. 2022, [Peer-reviewed]
In book - Effect of atmospheric-pressure plasma irradiation on the surface tension of water
Naoki Shirai; Takuma Kaneko; Yuto Takamura; Koichi Sasaki
Journal of Physics D: Applied Physics, 55, 15, 15LT01, 15LT01, 06 Jan. 2022, [Peer-reviewed]
Scientific journal - Efficient production and transport of OH radicals in spatial afterglow of atmospheric-pressure DC glow discharge using intersecting helium flows
Naoki Shirai; Hiroki Owada; Koichi Sasaki
Plasma Sources Science and Technology, 30, 12, 125012, 125012, IOP Publishing, 01 Dec. 2021, [Peer-reviewed]
Scientific journal, Abstract
An efficient method for generating OH radicals in the spatial afterglow of atmospheric-pressure plasma was investigated. The method employed a DC glow discharge along two intersecting helium flows in air. Tiny helium flows were ejected from two metal nozzles with inner diameters of 0.5 mm, and they intersected at a distance of 3–5 mm from the nozzles. A stable glow discharge was formed along the intersecting helium flows by applying a DC high voltage between the two nozzles. It was shown by laser-induced fluorescence spectroscopy that an origin of OH radicals was water vapor admixed into the intersection point of the two helium flows from ambient air. OH radicals were transported from the intersection toward the spatial afterglow along the coalesced helium flow. This is a distinctive feature of the present plasma source, by which we can obtain the stream of OH radicals in the outside of the active plasma zone even though we employ the DC discharge. In addition, we observed the production of OH radicals in the spatial afterglow. We presume that the production process of OH radicals in the spatial afterglow is dissociative electron attachment to H2O2. - Reaction frequency of solvated electrons in water interacting with atmospheric-pressure helium plasma jet
Yoshinobu Inagaki; Koichi Sasaki
Japanese Journal of Applied Physics, 60, 9, 096001, 096001, IOP Publishing, 11 Aug. 2021, [Peer-reviewed]
Scientific journal - Estimation of sheath electric field in inductively coupled hydrogen plasma on the basis of Doppler-broadened absorption spectrum of hydrogen Balmer-α line
Shusuke Nishiyama; Kosuke Takada; Koichi Sasaki
Japanese Journal of Applied Physics, 60, 7, 076001, 076001, IOP Publishing, 01 Jul. 2021, [Peer-reviewed]
Scientific journal - Comparison among translational temperatures of He(1P1o) , He(3S1) , and Ar(4s[3/2]2o) in inductively coupled plasmas
Kosuke Takada; Shusuke Nishiyama; Koichi Sasaki
Japanese Journal of Applied Physics, 60, 6, 066003, 066003, IOP Publishing, 01 Jun. 2021, [Peer-reviewed]
Scientific journal - Single-phase CZTS thin film prepared by high power impulse magnetron sputtering (HiPIMS): A first attempt
Siti Noryasmin Jaffar; Nafarizal Nayan; Zulkifli Azman; Amaliyana Raship; Mohd Khairul Ahmad; Soon Ching Fhong; Saidur Rahman; Mohd Yazid Ahmad; Koichi Sasaki
International Journal of Nanoelectronics and Materials, 14, 2, 195, 208, Apr. 2021, [Peer-reviewed] - Synthesis mechanism of cuprous oxide nanoparticles by atmospheric-pressure plasma electrolysis
Jiandi Liu; Naoki Shirai; Koichi Sasaki
Journal of Physics D: Applied Physics, 54, 10, 105201, 105201, IOP Publishing, 11 Mar. 2021, [Peer-reviewed]
Scientific journal - Synthesis and characterisation of nanoparticles by pulse laser ablation at solid-solid interface
Munaswamy Murugesh; Sasaki Koichi; G.L. Samuel
International Journal of Precision Technology, 10, 1, 74, 74, Inderscience Publishers, 2021, [Peer-reviewed]
Scientific journal - Rate Coefficient of CO2 Splitting via Vibrational Excited States in Recombining Plasmas with Ultralow Electron Temperatures
Koichi SASAKI; Masahiro YAMAZAKI
Vacuum and Surface Science, 63, 12, 635, 640, Surface Science Society Japan, 10 Dec. 2020, [Peer-reviewed]
Scientific journal - Effect of discharge tube temperature on N2(A3Σu+) and N(4So) densities in remote nitrogen plasma
Masaharu Shimabayashi; Koichi Sasaki
Japanese Journal of Applied Physics, 59, 9, 098002, 098002, Sep. 2020, [Peer-reviewed] - Rate coefficient of CO2 splitting in recombining H2 and He plasmas with ultralow electron temperatures
Masahiro Yamazaki; Shusuke Nishiyama; Koichi Sasaki
Plasma Sources Science and Technology, 29, 11, 115016, 115016, IOP Publishing, 17 Jul. 2020, [Peer-reviewed]
Scientific journal - Negative ion species in atmospheric-pressure helium dc glow discharge produced in ambient air
Koichi Sasaki; Ryohei Hosoda; Naoki Shirai
Plasma Sources Science and Technology, 29, 8, 085012, 085012, IOP Publishing, 16 Jul. 2020, [Peer-reviewed]
Scientific journal - Observation of 1D −1S forbidden optical emission of atomic oxygen in atmospheric-pressure N2 /O2 plasma jet
Koichi Sasaki; Shusuke Nishiyama; Naoki Shirai
Contributions to Plasma Physics, 60, e202000061, e202000061, Wiley, 07 Jul. 2020, [Peer-reviewed]
Scientific journal - Nitriding of 4H-SiC by irradiation of fourth harmonics of Nd:YAG laser pulses in liquid nitrogen
Masaharu Shimabayashi; Takuma Kaneko; Koichi Sasaki
SN Applied Sciences, 2, 7, 1167, 1167, Springer Science and Business Media LLC, Jul. 2020, [Peer-reviewed]
Scientific journal - Reactivity of solvated electrons in ionic liquid interacting with low-pressure plasmas
Yoshinobu Inagaki; Koichi Sasaki
Japanese Journal of Applied Physics, 59, 6, 066001, 066001, IOP Publishing, 01 Jun. 2020, [Peer-reviewed]
Scientific journal - Mechanism of droplet generation and optical emission of metal atoms in atmospheric-pressure dc glow discharge employing liquid cathode
Naoki Shirai; Goju Suga; Koichi Sasaki
Plasma Sources Science and Technology, 29, 2, 025007, 025007, IOP Publishing, 11 Feb. 2020, [Peer-reviewed]
English, Scientific journal - Detection of OH radicals in atmospheric-pressure plasma jet by evanescent-wave laser-induced fluorescence spectroscopy
K. Sasaki; Y. Hishida; N. Sadeghi
Journal of Instrumentation, 14, 11, C11016, C11016, IOP Publishing, 18 Nov. 2019, [Peer-reviewed]
Scientific journal - Correlation between gas-phase OH density and intensity of luminol chemiluminescence in liquid interacting with atmospheric-pressure plasma
N. Shirai; G. Suga; K. Sasaki
J. Phys. D: Appl. Phys., 52, 39, 39LT02, 39LT02, Jul. 2019, [Peer-reviewed] - Effective species for ignition of premixed burner flame in effluent of dielectric barrier discharge
Koichi Sasaki; Yusei Deguchi
Japanese Journal of Applied Physics, 57, 9, 096102, 096102, IOP Publishing, 07 Aug. 2018, [Peer-reviewed]
Scientific journal - Decomposition of carbon dioxide by recombining hydrogen plasma with ultralow electron temperature
Masahiro Yamazaki; Shusuke Nishiyama; Koichi Sasaki
Applied Physics Express, 11, 6, 066202, 066202, Japan Society of Applied Physics, 01 Jun. 2018, [Peer-reviewed]
English, Scientific journal - Suppression of carbon desorption from 4H-SiC by irradiating a remote nitrogen plasma at a low temperature
Masaharu Shimabayashi; Kazuaki Kurihara; Koichi Sasaki
Japanese Journal of Applied Physics, 57, 5, 056201, 056201, Japan Society of Applied Physics, 01 May 2018, [Peer-reviewed]
English, Scientific journal - Magnetron sputtering of liquid tin: Comparison with solid tin
Koichi Sasaki; Hiroshi Koyama
Applied Physics Express, 11, 3, 036201, 036201, Japan Society of Applied Physics, 01 Mar. 2018, [Peer-reviewed]
English, Scientific journal - Visualization of short-lived reactive species in liquid in contact with atmospheric-pressure plasma by chemiluminescence of luminol
Naoki Shirai; Yutaka Matsuda; Koichi Sasaki
Applied Physics Express, 11, 2, 026201, 026201, Japan Society of Applied Physics, 01 Feb. 2018, [Peer-reviewed]
English, Scientific journal - Physics-based investigation of negative ion behavior in a negative-ion-rich plasma using integrated diagnostics
K. Tsumori; K. Tsumori; Y. Takeiri; Y. Takeiri; K. Ikeda; H. Nakano; H. Nakano; S. Geng; M. Kisaki; K. Nagaoka; K. Nagaoka; T. Tokuzawa; M. Wada; K. Sasaki; S. Nishiyama; M. Goto; M. Goto; M. Osakabe; M. Osakabe
AIP Conference Proceedings, 1869, 030001, 030001, Aug. 2017, [Peer-reviewed]
English, Scientific journal - Discharge phenomena in a cavitation bubble induced by liquid-phase laser ablation
Koichi Sasaki; Yuta Takahashi
JOURNAL OF PHYSICS D-APPLIED PHYSICS, 50, 32, 325202, 325202, Aug. 2017, [Peer-reviewed]
English, Scientific journal - Stark spectroscopy at Balmer-alpha line of atomic hydrogen for measuring sheath electric field in a hydrogen plasma
Shusuke Nishiyama; Haruhisa Nakano; Motoshi Goto; Koichi Sasaki
JOURNAL OF PHYSICS D-APPLIED PHYSICS, 50, 23, 234003, 234003, Jun. 2017, [Peer-reviewed]
English, Scientific journal - Excitation of cavitation bubbles in low-temperature liquid nitrogen
Koichi Sasaki; Shingo Harada
JAPANESE JOURNAL OF APPLIED PHYSICS, 56, 6, 068002, 068002, Jun. 2017, [Peer-reviewed]
English, Scientific journal - Laser-Induced Cavitation Bubble and its Role in Syntheses of Nanomaterials
佐々木 浩一
レーザー研究 = The review of laser engineering : レーザー学会誌, 45, 5, 267, 272, レーザー学会, May 2017, [Peer-reviewed], [Invited]
Japanese - Influence of condensation coefficient on spherical bubble collapse with evaporation and condensation
森川 昌太郎; 立藏 祐樹; 小林 一道; 藤井 宏之; 渡部 正夫; 佐々木 浩一
ながれ : 日本流体力学会誌 = Nagare : journal of Japan Society of Fluid Mechanics, 36, 2, 105, 108, 日本流体力学会, Apr. 2017
Japanese - Performance of sheath electric field measurement by saturation spectroscopy in Balmer-alpha line of atomic hydrogen
Shusuke Nishiyama; Kento Katayama; Haruhisa Nakano; Motoshi Goto; Koichi Sasaki
APPLIED PHYSICS EXPRESS, 10, 3, 036101, 036101, Mar. 2017, [Peer-reviewed]
English, Scientific journal - Transient change in the shape of premixed burner flame with the superposition of pulsed dielectric barrier discharge
Kazunori Zaima; Koichi Sasaki
JAPANESE JOURNAL OF APPLIED PHYSICS, 55, 8, 086201, 086201, Aug. 2016, [Peer-reviewed]
English, Scientific journal - Absolute densities of Cu, Zn, Sn, and S atoms in magnetron sputtering plasmas employing a Cu2ZnSnS4 target
Nayan Nafarizal; Koichi Sasaki
JAPANESE JOURNAL OF APPLIED PHYSICS, 55, 7, 07LC02, 07LC02, Jul. 2016, [Peer-reviewed]
English, Scientific journal - Nickel nanoparticles generated by pulsed laser ablation in liquid CO2
Mardiansyah Mardis; Noriharu Takada; Siti Machmudah; Wahyudiono; Koichi Sasaki; Hideki Kanda; Motonobu Goto
RESEARCH ON CHEMICAL INTERMEDIATES, 42, 5, 4581, 4590, May 2016, [Peer-reviewed]
English, Scientific journal - Spectrum of laser light scattered by nanoparticles in an ablation-induced cavitation bubble
Masato Takeuchi; Koichi Sasaki
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING, 122, 4, 312, 312, Apr. 2016, [Peer-reviewed]
English, Scientific journal - Nitriding characteristics of 4H-SiC irradiated with remote nitrogen plasmas
Masaharu Shimabayashi; Kazuaki Kurihara; Yoshimine Horikawa; Koichi Sasaki
JAPANESE JOURNAL OF APPLIED PHYSICS, 55, 3, 036503, 036503, Mar. 2016, [Peer-reviewed]
English, Scientific journal - Measurements of absolute Cu, Zn and Sn metastable densities in CZTS sputtering plasmas measured using UVAS technique
Nayan Nafarizal; Koichi Sasaki
2016 IEEE INTERNATIONAL CONFERENCE ON SEMICONDUCTOR ELECTRONICS (ICSE) PROCEEDINGS, 252, 255, 2016, [Peer-reviewed]
English, International conference proceedings - Origin of activated combustion in steady-state premixed burner flame with superposition of dielectric barrier discharge
Kazunori Zaima; Haruaki Akashi; Koichi Sasaki
JAPANESE JOURNAL OF APPLIED PHYSICS, 55, 1, 016201, 016201, Jan. 2016, [Peer-reviewed]
English, Scientific journal - An Attempt to Produce Electrical Discharges in Acoustic Cavitation Bubbles
TAKADA Noriharu; HAYASHI Yui; GOTO Motonobu; SASAKI Koichi
Plasma and Fusion Research, 11, 0, 1406113, 1406113, The Japan Society of Plasma Science and Nuclear Fusion Research, 2016, [Peer-reviewed]
English, <p>It is widely known that cavitation bubbles are not static bubbles but have the dynamics of the expansion, the shrinkage, and the collapse. In this work, we produced electrical discharges in acoustic cavitation bubbles for the first time with the intension of enhancing the reactivity of sonochemical processes. Glow-like discharges were observed in cavitation bubbles on the bottom surface of the cylindrical electrode which was connected to a pulsed high-voltage power supply. Bright optical emission was observed from the region corresponding to the cloud of expanded cavitation bubbles, while we also observed electrical discharges even in the shrinking phase of cavitation bubbles. If discharge-produced reactive species have lifetimes that are longer than the interval between the discharge and the collapse of the cavitation bubble, the species composition in the collapsed cavitation bubble becomes different from that in conventional cavitation bubble, which may result in the enhancement of reactivity in sonochemical processes.</p> - Sticking probabilities of Cu, Zn, Sn, and S atoms in magnetron sputtering plasmas employing a Cu2ZnSnS4 stoichiometric target
Nayan Nafarizal; Shunya Kikuchi; Koichi Sasaki
VACUUM, 121, 26, 31, Nov. 2015, [Peer-reviewed]
English, Scientific journal - Self-absorption-calibrated vacuum ultraviolet absorption spectroscopy for absolute oxygen atomic density measurement
Xiaoli Yang; Koichi Sasaki; Masaaki Nagatsu
PLASMA SOURCES SCIENCE & TECHNOLOGY, 24, 5, 055019,1-8, Oct. 2015, [Peer-reviewed]
English, Scientific journal - Electron Temperatures and Electron Densities in Microwave Helium Discharges with Pressures Higher than 0.1 MPa
K. Sasaki; S. Soma; H. Akashi; M. ElSabbagh; Y. Ikeda
CONTRIBUTIONS TO PLASMA PHYSICS, 55, 8, 563, 569, Sep. 2015, [Peer-reviewed]
English, Scientific journal - Influence of mirror size on ringdown frequency in cavity-ringdown spectroscopy of slender premixed burner flame
Kazunori Zaima; Satoshi Tomioka; Koichi Sasaki
JAPANESE JOURNAL OF APPLIED PHYSICS, 54, 8, 088005, 088005, Aug. 2015, [Peer-reviewed]
English, Scientific journal - Density distributions of OH, Na, water vapor, and water mist in atmospheric-pressure dc helium glow plasmas in contact with NaCl solution
Koichi Sasaki; Hiroaki Ishigame; Shusuke Nishiyama
EUROPEAN PHYSICAL JOURNAL-APPLIED PHYSICS, 71, 2, 20807, 20807, Aug. 2015, [Peer-reviewed]
English, Scientific journal - Oxygen atomic density measured with a self-absorption calibrated vacuum ultraviolet absorption spectroscopy and its effect on spore etching in N-2/O-2 surface-wave plasma
Xiaoli Yang; Xijiang Chang; Reitou Tei; Koichi Sasaki; Masaaki Nagatsu
JAPANESE JOURNAL OF APPLIED PHYSICS, 54, 7, 070308, 070308, Jul. 2015, [Peer-reviewed]
English, Scientific journal - Spatial distribution of OH radical density in atmospheric-pressure dc helium glow plasma in contact with electrolyte solution
Hiroaki Ishigame; Shusuke Nishiyama; Koichi Sasaki
JAPANESE JOURNAL OF APPLIED PHYSICS, 54, 1, 01AF02, 01AF02, Jan. 2015, [Peer-reviewed]
English, Scientific journal - Plasma Diagnostics by Cavity Ringdown Absorption Spectroscopy
SASAKI Koichi
プラズマ・核融合学会誌, 91, 1, 2, 9, プラズマ・核融合学会, Jan. 2015, [Peer-reviewed]
Japanese, キャビティリングダウン吸収分光法は,主に気体中の微量原子/分子等を高感度に検出し,その密度を求める方法として,様々な分野で広く用いられている.一対の高反射率ミラーからなるキャビティの内部に測定対象を置き,キャビティ内でレーザー光を多数回往復させるという単純とも思われる工夫により,通常のレーザー吸収分光法の104倍以上の高感度が容易に得られ,反応性の高さ故にプラズマ中で低密度となる反応中間種の密度計測,および,遷移確率が小さいために通常の吸収分光法では検出が困難なラジカル種の密度計測などにおいて威力を発揮する.本解説では,キャビティリングダウン吸収分光法の原理について基礎的事項を含めて述べた後,キャビティリングダウン吸収分光法を用いたプラズマ計測について,主に我が国における取り組みを紹介する. - Responses of OH (x(2)n) and OH (A(2)Sigma(+)) to high-energy electrons of dielectric barrier discharge in plasma-assisted burner flame
Kazunori Zaima; Koichi Sasaki
JAPANESE JOURNAL OF APPLIED PHYSICS, 53, 11, 110309.1-110309.4, Nov. 2014
English, Scientific journal - Control of burning velocity in premixed burner flame by high-energy electrons of dielectric barrier discharge
Kazunori Zaima; Koichi Sasaki
JAPANESE JOURNAL OF APPLIED PHYSICS, 53, 6, 066202.1-066202.5, Jun. 2014
English, Scientific journal - In-laboratory sensitivity calibration of an optical emission spectroscopy system in vacuum ultraviolet wavelength range
Shuntaro Soma; Kazuaki Kurihara; Koichi Sasaki
JAPANESE JOURNAL OF APPLIED PHYSICS, 53, 4, 048001.1-048001.3, Apr. 2014
English, Scientific journal - Characteristics of optical emission intensities and bubblelike phenomena induced by laser ablation in supercritical fluids
Noriharu Takada; Siti Machmudah; Hiroshi Goto; Wahyudiono; Motonobu Goto; Koichi Sasaki
JAPANESE JOURNAL OF APPLIED PHYSICS, 53, 1, 010213.1-010213.7, Jan. 2014
English, Scientific journal - Acoustic Cavitation and Plasmas
SASAKI Koichi
Journal of the Society of Mechanical Engineers, 117, 1148, 449, 452, The Japan Society of Mechanical Engineers, 2014
Japanese - Decomposition of methyl orange using pulsed discharge plasma at atmospheric pressure: Effect of different electrodes
Yui Hayashi; Wahyudiono; Siti Machmudah; Noriharu Takada; Hideki Kanda; Koichi Sasaki; Motonobu Goto
JAPANESE JOURNAL OF APPLIED PHYSICS, 53, 1, Jan. 2014
English, Scientific journal - LIF imaging of OH radicals in atmospheric DC glow discharge using miniature gas flow and electrolyte cathode
Shusuke Nishiyama; Hiroaki Ishigame; Tomoki Komori; Koichi Sasaki
International Journal of Asian Studies, 1598, 2, Cambridge University Press, 10 Dec. 2013, [Peer-reviewed]
English, Scientific journal - A Simple Method for Efficient Generation of Standing Cavitation Bubbles
Yushi Iwata; Noriharu Takada; Koichi Sasaki
APPLIED PHYSICS EXPRESS, 6, 12, 127301, 127301-4, Dec. 2013
English, Scientific journal - Removal of Water Pollutants by Pulsed Discharge Plasma and Observation of Its Optical Emission Intensity at Atmospheric Pressure
Yui Hayashi; Wahyudiono; Siti Machmudah; Hideki Kanda; Noriharu Takada; Koichi Sasaki; Motonobu Goto
JAPANESE JOURNAL OF APPLIED PHYSICS, 52, 11, 11NE02, 11NE02-6, Nov. 2013
English, Scientific journal - Effects of Nonequilibrium Plasmas on Steady-State Premixed Bunner Flame
UESUGI Yoshihiko; SASAKI Koichi
プラズマ・核融合学会誌 = Journal of plasma and fusion research, 89, 4, 225, 228, プラズマ・核融合学会, 25 Apr. 2013
Japanese, プラズマ支援燃焼は,プラズマ支援着火・点火に関する研究と,すでに燃焼状態にある火炎に対するプラズマ支援効果に関する研究に大別される.本章では,定常燃焼状態にある火炎に対するプラズマ支援効果に関する研究例として,予混合バーナー火炎に静電放電を重畳し燃焼速度を増加させた実験を紹介する.また,パルス化したマイクロ波を予混合バーナー火炎に照射したときに生じる過渡現象を調べた実験を紹介する.定常状態予混合バーナー火炎を用いた実験がプラズマ支援燃焼の素過程を調べるための基礎実験として重要であることを示す. - Effect of ultrasonic wave on the syntheses of Au and ZnO nanoparticles by laser ablation in water
N. Takada; A. Fujikawa; N. Koshizaki; K. Sasaki
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING, 110, 4, 835, 839, Mar. 2013
English, Scientific journal - Structure and size control of ZnO nanoparticles by applying high pressure to ambient liquid in liquid-phase laser ablation
W. Soliman; N. Takada; N. Koshizaki; K. Sasaki
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING, 110, 4, 779, 783, Mar. 2013
English, Scientific journal - LIF imaging of OH radicals in atmospheric DC Glow discharge using miniature gas flow and electrolyte cathode
Shusuke Nishiyama; Hiroaki Ishigame; Tomoki Komori; Koichi Sasaki
Materials Research Society Symposium Proceedings, 1598, Materials Research Society, 2013, [Peer-reviewed]
English, International conference proceedings - Transport characteristics of N-2(A(3)Sigma(+)(u)), N(S-4(o)), and N(D-2(o)) in a remote nitrogen plasma source
Y. Horikawa; T. Hayashi; K. Sasaki
11TH APCPST (ASIA PACIFIC CONFERENCE ON PLASMA SCIENCE AND TECHNOLOGY) AND 25TH SPSM (SYMPOSIUM ON PLASMA SCIENCE FOR MATERIALS), 441, 2013
English, International conference proceedings - Synthesis characteristics of Cu particulates in high-pressure magnetron sputtering plasmas studied by in situ laser-light scattering
N. Nafarizal; K. Sasaki
JOURNAL OF PHYSICS D-APPLIED PHYSICS, 45, 50, Dec. 2012
English, Scientific journal - Lifetime of Molecular Nitrogen at Metastable A(3)Sigma(+)(u) State in Afterglow of Inductively-Coupled Nitrogen Plasma
Yoshimine Horikawa; Toshio Hayashi; Koichi Sasaki
JAPANESE JOURNAL OF APPLIED PHYSICS, 51, 12, 126301, 1-5, Dec. 2012
English, Scientific journal - 水中・音響 重畳超音波が及ぼす水中レーザアブレーション反応場への影響 : 超音波によるナノ粒子生成プロセス制御
高田 昇治; 佐々木 浩一
超音波techno, 24, 6, 67, 70, 日本工業出版, Nov. 2012
Japanese - Transition from equilibrium to nonequilibrium combustion of premixed burner flame by microwave irradiation
Koichi Sasaki; Koji Shinohara
JOURNAL OF PHYSICS D-APPLIED PHYSICS, 45, 45, Nov. 2012
English, Scientific journal - Optical Emission of Molecular Hydrogen in a Recombining Hydrogen Plasma
K. Sasaki; R. Asakawa
CONTRIBUTIONS TO PLASMA PHYSICS, 52, 8, 676, 681, Sep. 2012
English, Scientific journal - Evaluation of Absolute Flux of Vacuum Ultraviolet Photons in an Electron Cyclotron Resonance Hydrogen Plasma: Comparison with Ion Flux
Kazunori Zaima; Kazuaki Kurihara; Koichi Sasaki
JAPANESE JOURNAL OF APPLIED PHYSICS, 51, 8, 08HC02, 08HC02-5, Aug. 2012
English, Scientific journal - Characteristics of saturation spectroscopy at the Balmer-alpha line of atomic hydrogen in a linear magnetized plasma source
R. Asakawa; M. Goto; N. Sadeghi; K. Sasaki
JOURNAL OF INSTRUMENTATION, 7, Jan. 2012
English, Scientific journal - Control of Plasma and Cavitation Bubble in Liquid-Phase Laser Ablation Using Supersonic Waves
Noriharu Takada; Akinori Fujikawa; Koichi Sasaki
JAPANESE JOURNAL OF APPLIED PHYSICS, 50, 12, 126201, 126201-4, Dec. 2011
English, Scientific journal - Effect of Water Pressure on Size of Nanoparticles in Liquid-Phase Laser Ablation
Wafaa Soliman; Noriharu Takada; Koichi Sasaki
JAPANESE JOURNAL OF APPLIED PHYSICS, 50, 10, 108003, 108003-2, Oct. 2011
English, Scientific journal - Effective Species in Inductively Coupled Nitrogen Plasma for Silicon Nitriding
Yoshimine Horikawa; Kazuaki Kurihara; Koichi Sasaki
APPLIED PHYSICS EXPRESS, 4, 8, 86201, 1〜3, Aug. 2011
English, Scientific journal - Magnetron Sputtering Deposition of Conductive Diamond-Like Carbon Films with Embedded Nanoparticles
Koichi Sasaki; Takahiko Tsutsumi; Noriharu Takada
JAPANESE JOURNAL OF APPLIED PHYSICS, 50, 8, 08KE05, 08KE05-4, Aug. 2011
English, Scientific journal - Estimations of Electron Temperature and Electron Density in Argon-Containing Reactive Plasma Based on Diode Laser Absorption Spectroscopy
Koichi Sasaki; Ryota Asaoka
JAPANESE JOURNAL OF APPLIED PHYSICS, 50, 8, 08JB02, 08JB02-5, Aug. 2011
English, Scientific journal - Measurements of Rotational Temperature and Density of Molecular Nitrogen in Spark-Plug Assisted Atmospheric-Pressure Microwave Discharges by Rotational Raman Scattering
Mansour ElSabbagh; Shinichiro Kado; Yuji Ikeda; Koichi Sasaki
JAPANESE JOURNAL OF APPLIED PHYSICS, 50, 7, 76101, 076101-6, Jul. 2011
English, Scientific journal - Formation of cavitation-induced pits on target surface in liquid-phase laser ablation
N. Takada; T. Nakano; K. Sasaki
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING, 101, 2, 255, 258, Nov. 2010, [Peer-reviewed]
English, Scientific journal - Modification of Rayleigh-Plesset Theory for Reproducing Dynamics of Cavitation Bubbles in Liquid-Phase Laser Ablation
Wafaa Soliman; Tetsutaro Nakano; Noriharu Takada; Koichi Sasaki
JAPANESE JOURNAL OF APPLIED PHYSICS, 49, 11, 116202, 116202-6, Nov. 2010
English, Scientific journal - レーザーアブレーションによるナノ粒子生成場の特徴
佐々木 浩一
レーザー加工学会誌, 17, 18, 23, Jul. 2010 - Enhancement of Ti+ density in high-pressure magnetron sputtering plasmas
K. Sasaki; N. Nafarizal
JOURNAL OF PHYSICS D-APPLIED PHYSICS, 43, 12, 124012,1-9, Mar. 2010
English, Scientific journal - Liquid-phase laser ablation and supercritical-fluid technologies
佐々木 浩一
Jasco report, 52, 0, 28, 33, ジャスコレポート社, Mar. 2010
Japanese - Temporally-Resolved Measurements on Growth Processes of Nanoparticles in Laser Ablation
SASAKI Koichi
The Review of Laser Engineering, 38, 2, 113, 119, The Laser Society of Japan, 15 Feb. 2010
Japanese, This review article reports the growth processes of nanoparticles in laser ablation processes. The growth - Precise analysis of sputtering plasmas diagnostics by laser-induced fluorescence
Koichi Sasaki
Journal of the Vacuum Society of Japan, 53, 8, 473, 479, The Vacuum Society of Japan, 2010
Japanese - Enhancement of Crystal Growth in Si Thin-Film Deposition by H-Radical-Assisted Magnetron Sputtering
Kota Fukaya; Akimori Tabata; Koichi Sasaki
JAPANESE JOURNAL OF APPLIED PHYSICS, 49, 1, 15501, 015501-5, 2010
English, Scientific journal - Absolute Densities of N-2(A(3)Sigma(+)(u)), N(S-4(o)), and N(D-2(o)) in an Inductively Coupled Nitrogen Plasma Source
Yoshimine Horikawa; Kazuaki Kurihara; Koichi Sasaki
JAPANESE JOURNAL OF APPLIED PHYSICS, 49, 2, 2010, [Peer-reviewed]
English, Scientific journal - Effect of Water Pressure on the Size of Nanoparticles in Liquid-Phase Laser Ablation
Wafaa Soliman; Noriharu Takada; Koichi Sasaki
TENCON 2010: 2010 IEEE REGION 10 CONFERENCE, 154, 157, 2010, [Peer-reviewed]
English, International conference proceedings - Diode laser cavity-ringdown absorption spectroscopy for measuring N-2(A(3)Sigma(+)(u)) density in plasmas
Y. Horikawa; K. Kurihara; K. Sasaki
14TH INTERNATIONAL SYMPOSIUM ON LASER-AIDED PLASMA DIAGNOSTICS (LAPD14), 227, 012012, 2010
English, International conference proceedings - Liquid-phase laser ablation
Koichi Sasaki; Noriharu Takada
Pure and Applied Chemistry, 82, 6, 1317, 1327, 2010
English, International conference proceedings - Growth Processes of Nanoparticles in Liquid-Phase Laser Ablation Studied by Laser-Light Scattering
Wafaa Soliman; Noriharu Takada; Koichi Sasaki
APPLIED PHYSICS EXPRESS, 3, 3, 35201, 035201-3, 2010
English, Scientific journal - Investigations of Production Processes of Ti+ in High-Pressure Magnetron Sputtering Plasmas
Nayan Nafarizal; Noriharu Takada; Koichi Sasaki
JAPANESE JOURNAL OF APPLIED PHYSICS, 48, 12, 126003, 126003-7, Dec. 2009
English, Scientific journal - Modification of Fluorinated Al2O3 Surface by Irradiating H-2 and O-2 Plasmas
Kazuhiro Miwa; Kenji Usami; Noriharu Takada; Koichi Sasaki
JAPANESE JOURNAL OF APPLIED PHYSICS, 48, 12, 126002, 126002-5, Dec. 2009
English, Scientific journal - Merging Plasma Science into Combustion Science : Plasma-Assisted Combustion
SASAKI Koichi; UESUGI Yoshihiko; OHNO Noriyasu; OSAKA Yugo
Journal of the Combustion Society of Japan, 51, 158, 259, 267, 日本燃焼学会, 15 Nov. 2009
Japanese - Influence of additional external pressure on optical emission intensity in liquid-phase laser ablation
N. Takada; T. Nakano; K. Sasaki
APPLIED SURFACE SCIENCE, 255, 24, 9572, 9575, Sep. 2009
English, Scientific journal - Enhancement of burning velocity in premixed burner flame by irradiating microwave power
K. Shinohara; N. Takada; K. Sasaki
JOURNAL OF PHYSICS D-APPLIED PHYSICS, 42, 18, 182008, Sep. 2009
English, Scientific journal - Fluorination mechanisms of Al2O3 and Y2O3 surfaces irradiated by high-density CF4/O-2 and SF6/O-2 plasmas
Kazuhiro Miwa; Noriharu Takada; Koichi Sasaki
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A, 27, 4, 831, 835, Jul. 2009
English, Scientific journal - Effect of Pressurization on the Dynamics of a Cavitation Bubble Induced by Liquid-Phase Laser Ablation
Koichi Sasaki; Tetsutaro Nakano; Wafaa Soliman; Noriharu Takada
APPLIED PHYSICS EXPRESS, 2, 4, 046501, Apr. 2009
English, Scientific journal - Mechanism of Hydrogenated Microcrystal line Si Film Deposition by Magnetron Sputtering Employing a Si Target and H-2/Ar Gas Mixture
Kota Fukaya; Akimori Tabata; Koichi Sasaki
JAPANESE JOURNAL OF APPLIED PHYSICS, 48, 3, 035507, Mar. 2009
English, Scientific journal - Analysis of precursors for crystal growth of YBaCuO thin films in magnetron sputtering deposition
Kota Fukaya; Koichi Sasaki; Junsi Gao; Taishi Kimura; Mitsuhiro Watanabe; Masumi Inoue; Akira Fujimaki; Hideo Sugai
THIN SOLID FILMS, 517, 8, 2762, 2766, Feb. 2009
English, Scientific journal - Laser-Aided Diagnostics of Atoms and Particulates in Magnetron Sputtering Plasmas
N. Nafarizal; N. Takada; K. Sasaki
FRONTIERS IN PHYSICS-BOOK, 1150, 174, +, 2009
English, International conference proceedings - Absorption line profile of the 5So2 - 5P1 transition of atomic oxygen and its application to plasma monitoring
Int J. Spectroscopy, 2010, 627571, 2009 - Synthesis of crystalline TiN and Si particles by laser ablation in liquid nitrogen
N. Takada; T. Sasaki; K. Sasaki
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING, 93, 4, 833, 836, Dec. 2008
English, Scientific journal - Are dominant sputtering products from metal targets really monatomic?
K. Sasaki; N. Nafarizal; J. -S. Gao; K. Shibagaki
VACUUM, 83, 3, 463, 466, Oct. 2008
English, Scientific journal - Negative ion densities in high-density, low-temperature recombining hydrogen plasmas
K. Shibagaki; K. Sasaki
JOURNAL OF PHYSICS D-APPLIED PHYSICS, 41, 19, 195204, Oct. 2008
English, Scientific journal - Temporal variation of two-dimensional temperature in a laser-ablation plume produced from a graphite target
Koichi Sasaki; Satoshi Aoki
APPLIED PHYSICS EXPRESS, 1, 8, 086001, Aug. 2008
English, Scientific journal - Production of Ar metastable atoms in the late afterglow of pulse-modulated rf magnetron sputtering plasmas
N. Nafarizal; N. Takada; K. Sasaki
JOURNAL OF PHYSICS D-APPLIED PHYSICS, 41, 3, 035206, Feb. 2008
English, Scientific journal - Temporal and Spatial Variations in Electron Density and Blackbody Temperature in the Initial Phase of a Laser Ablation BN Plasma
SASAKI Koichi; YASUDA Shin; TAKADA Noriharu
Plasma and Fusion Research, 3, 023, 23, The Japan Society of Plasma Science and Nuclear Fusion Research, 2008
English, Optical emission spectroscopy was used for examining the temporal variations in the spatial distributions of the blackbody temperature and electron density of plasmas produced by laser ablation of a BN target in ambient nitrogen gas. The blackbody temperature was estimated by fitting the continuum component in the optical emission spectrum using the Planck's law of radiation, and the electron density was evaluated from the Stark broadening of a line emission of a B atom. The blackbody temperature was evaluated to be close to 104 K and the electron density was on the order of 1017- 1018 cm-3, immediately after the irradiation of the laser pulse on the target. The dynamics of the blackbody temperature and the electron density were understood by considering plasma expansion and the confinement effect of ambient gas. - プラズマ発光分光計測法の基礎
Plasma Electronics, 48, 15, 2008 - Dramatic Enhancement of OH(A2Σ+) Density in a Recombining Hydrogen Plasma
SHIBAGAKI Kanji; ASAKAWA Renge; HAYASHI Daiyu; SASAKI Koichi
Plasma and Fusion Research, 3, 055, 55, The Japan Society of Plasma Science and Nuclear Fusion Research, 2008
English, Optical emission spectra in the wavelength range of molecular hydrogen were observed in both ionizing and recombining plasma modes of hydrogen discharges. The optical emission spectrum from the ionizing plasma was dominated by the Fulcher-α system (a3Σg+ - d3Πu-) of molecular hydrogen. On the other hand, the optical emission spectrum from the recombining plasma was composed of many lines, and was completely different from the spectrum of the ionizing plasma. The many peaks observed from the recombining plasma were assigned to the X2Π - A2Σ+ transition of OH. The OH(A2Σ+) is thought to originate from the chemical etching of a glass discharge tube by atomic hydrogen. This is analogous to the interaction between a detached divertor plasma and a graphite plate, and a possible process for the enhancement of OH(A2Σ+) density in a recombining plasma is discussed with this analogy in mind. - Experimental study of stark effects in argon high Rydberg states
Kazuki Takizawa; Koichi Sasaki
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS, 46, 10A, 6822, 6827, Oct. 2007
English, Scientific journal - Sticking probability of Ti atoms in magnetron sputtering deposition evaluated from the spatial distribution of Ti atom density
N. Nafarizal; K. Sasaki
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A, 25, 2, 308, 311, Mar. 2007
English, Scientific journal - Distribution of electric field in the sheath of an electronegative plasma
K. Takizawa; A. Kono; K. Sasaki
APPLIED PHYSICS LETTERS, 90, 1, 011503, Jan. 2007
English, Scientific journal - 最新レーザー技術を用いたプロセスプラズマ診断
プラズマ・核融合学会誌, 83, 573, 2007 - Plasma Diagnostics by Spectroscopic Methods
SASAKI Koichi
Bunko Kenkyu, 56, 5, 224, 236, The Spectroscopical Society of Japan, 2007
Japanese, Plasma diagnostics by spectroscopic methods are reviewed with the emphasis on measurements of radical densities in reactive plasmas used for material processing. A brief introduction on the radiation equilibrium of plasmas will be given on the basis of a collisional-radiative model. Optical emission spectroscopy (OES) is an economical diagnostic method, but simple OES is not useful for estimating radical densities. An improved OES method is actinometry, which is widely used in reactive plasma experiments. Active spectroscopic methods such as absorption spectroscopy and laser-induced fluorescence are more reliable for measuring radical densities. Various types of absorption spectroscopy using various light sources will be introduced after a brief description of the fundamentals of optical absorption. The advantages of laser-induced fluorescence are the compatibility with imaging spectroscopy and the applicability to measurements of various quantities in plasmas. - Ultra-sensitive measurement of sheath electric field by laser-induced fluorescence-dip spectroscopy
J. Plasma Fusion Res., 83, 215, 2007 - Measurement of Cu atom density in a magnetron sputtering plasma source using an YBaCuO target by laser-induced fluorescence imaging spectroscopy
Junsi Gao; Nayan Nafarizal; Koichi Sasaki
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A, 24, 6, 2100, 2104, Nov. 2006
English, Scientific journal - Deposition profile of Ti film inside a trench and its correlation with gas-phase ionization in high-pressure magnetron sputtering
N. Nafarizal; N. Takada; K. Nakamura; Y. Sago; K. Sasaki
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A, 24, 6, 2206, 2211, Nov. 2006
English, Scientific journal - Temporal variations in distributions of NO and NO2 densities in streamer corona discharges
Hiroshi Kurakane; Mitsutoshi Aramaki; Koichi Sasaki
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS, 45, 10B, 8264, 8269, Oct. 2006
English, Scientific journal - Temporal variations in densities of Y, Ba, and Cu atoms in magnetron sputtering plasmas with YBaCuO target
Junsi Gao; Koichi Sasaki
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS, 45, 10B, 8113, 8117, Oct. 2006
English, Scientific journal - Absolute densities and kinetics of H atoms and CFx radicals in low-pressure, high-density CHF3 plasmas
K Sasaki; M Okamoto
THIN SOLID FILMS, 506, 705, 709, May 2006
English, Scientific journal - Dynamics of laser-ablation plume and ambient gas visualized by laser-induced fluorescence imaging spectroscopy
K Sasaki; H Watarai
JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS, 45, 12-16, L447, L449, Apr. 2006
English, Scientific journal - Spectroscopic studies on impurity transport of core and edge plasmas in LHD
Shigeru Morita; Motoshi Goto; Sadatsugu Muto; Ryuji Katai; Hisamichi Yamazaki; Hideaki Nozato; Atsushi Iwamae; Makoto Atake; Takashi Fujimoto; Atsushi Sakaue; Hiroaki Nishimura; Ikuya Sakurai; Chiho Matsumoto; Akihiro Furuzawa; Yuzuru Tawara; Mitsutoshi Aramaki; Yuji Okumura; Koichi Sasaki; Xianzu Gong; Jiangang Li; Baonian Wan; Zhengying Cui
PLASMA SCIENCE & TECHNOLOGY, 8, 1, 55, 60, Jan. 2006
English, Scientific journal - Production of radicals and particulates by interaction between high-density hydrogen plasma and graphite plate
K Sasaki; T Maeda; N Takada; M Aramaki; M Goto; S Muto; S Morita
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS, 44, 10, 7614, 7618, Oct. 2005
English, Scientific journal - Measurements of gas temperature in high-density helicon-wave H-2 plasmas by diode laser absorption spectroscopy
M Aramaki; Y Okumura; M Goto; S Muto; S Morita; K Sasaki
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS, 44, 9A, 6759, 6763, Sep. 2005
English, Scientific journal - Spatial distribution of the velocity distribution function of Fe atoms in a magnetron sputtering plasma source
K. Shibagaki; N. Nafarizal; K. Sasaki
Journal of Applied Physics, 98, 4, 043310, 15 Aug. 2005
English, Scientific journal - Measurement of absolute Cu atom density in magnetron sputtering plasmas
Trans.Mater.Res.Soc.Jpn, 30, 291, 294, 2005 - Absolute densities of Ti atoms and Ti+ ions in magnetron sputtering plasmas measured by laser-induced fluorescence
Trans.Mater.Res.Soc.Jpn., 30, 299, 302, 2005 - Two-dimensional distributions of Ti and Ti+ densities in high-pressure magnetron sputtering discharges
N Nafarizal; N Takada; K Shibagaki; K Nakamura; Y Sago; K Sasaki
JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS, 44, 20-23, L737, L739, 2005
English, Scientific journal - Enhancement of the synthesis efficiency of carbon cluster ions by the irradiation of two laser pulses to polymers in vacuum
K Shibagaki; Y Kamiya; K Sasaki
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING, 79, 4-6, 1161, 1163, Sep. 2004
English, Scientific journal - Synthesis of anatase-type TiO2 films by reactive laser ablation of a metallic Ti target in ambient O-2 gas
H Ito; N Takada; K Sasaki
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING, 79, 4-6, 1327, 1329, Sep. 2004
English, Scientific journal - Chemical bonds of fluorocarbon films which can be a source of CFx radicals
N Takada; T Iida; K Shibagaki; K Sasaki
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A, 22, 2, 413, 418, Mar. 2004
English, Scientific journal - Development of a compact divertor simulator excited by helicon-wave discharge
M Aramaki; K Kato; M Goto; S Muto; S Morita; K Sasaki
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS, 43, 3, 1164, 1165, Mar. 2004
English, Scientific journal - Sensitive measurements of electric field distributions in low-pressure Ar plasmas by laser-induced fluorescence-dip spectroscopy
K Takizawa; K Sasaki; A Kono
APPLIED PHYSICS LETTERS, 84, 2, 185, 187, Jan. 2004
English, Scientific journal - Observation of the electric field structure in the sheath of electronegative plasmas by laser-induced fluorescence-dip spectroscopy
TAKIZAWA Kazuki; SASAKI Koichi
J. Plasma Fusion Res., 80, 1, 3, 4, The Japan Society of Plasma Science and Nuclear Fusion Research, 2004
English, We have measured the distribution of the electric field in the sheath formed between electronegative Ar⁄SF6 plasmas and a biased electrode by laser-induced fluorescence-dip spectroscopy. It has been found for the first time that the electric field in the sheath of an electronegative plasma has a multistage structure, which may be due to the reflections of negative ions and electrons at different distances from the electrode surface. - Experimental Techniques of Laser Ablation with Emphasis on Diagnostics
SASAKI Koichi
Kakuyūgō kenkyū, 79, 12, 1269, 1277, The Japan Society of Plasma Science and Nuclear Fusion Research, 25 Dec. 2003
Japanese, Experimental techniques of laser ablation are reviewed with the emphasis on diagnostic methods. The current trend of laser sources for ablation experiments is the use of short-wavelength lasers and femtosecond lasers. In addition, several innovations have been tried in the selection of ambient medium of laser ablation. Because of significant spatial distributions with transient properties, the diagnostics of laser ablation plasmas are more difficult than those of discharge plasmas. It is shown that visualized diagnostics are especially useful for the diagnostics of laser ablation plasmas. - Composition of positive ions in high-density H-2 plasmas measured by time-of-flight mass spectrometry
H Yamaguchi; S Sobhanian; M Goto; S Morita; K Kawahata; K Sasaki
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS, 42, 11, 7080, 7085, Nov. 2003
English, Scientific journal - Kinetics of hydrogen atoms in high-density CF4/H-2 plasmas studied by (2+1)-photon laser-induced fluorescence spectroscopy
K Sasaki; M Okamoto
APPLIED PHYSICS LETTERS, 83, 10, 1935, 1937, Sep. 2003
English, Scientific journal - Estimation of carbon fluxes interchanging between chamber wall and gas phase in fluorocarbon plasmas
N Takada; K Sasaki; T Iida; K Shibagaki; K Kadota
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS, 42, 7A, 4510, 4512, Jul. 2003
English, Scientific journal - Laser desorption time-of-flight mass spectrometry of fluorocarbon films synthesized by C4F8/H-2 plasmas
K Shibagaki; T Maeda; N Takada; K Sasaki; K Kadota
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A, 21, 4, 866, 873, Jul. 2003
English, Scientific journal - エレクトロニクスとプラズマ（ナノテクとプラズマ）
プラズマ・核融合学会誌, 79, 6, 561, 564, 2003 - Synthetic characteristics of large carbon cluster ions by laser ablation of polymers in vacuum
K Shibagaki; N Takada; K Sasaki; K Kadota
JOURNAL OF APPLIED PHYSICS, 93, 1, 655, 661, Jan. 2003
English, Scientific journal - Dynamics of laser-ablation Ti plasmas studied by laser-induced fluorescence imaging spectroscopy
K Sasaki; S Matsui; H Ito; K Kadota
JOURNAL OF APPLIED PHYSICS, 92, 11, 6471, 6476, Dec. 2002
English, Scientific journal - Observation of stark spectra of argon high Rydberg states in well-defined electric fields by laser-induced fluorescence-dip spectroscopy
K Takizawa; K Sasaki; K Kadota
JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS, 41, 11B, L1285, L1287, Nov. 2002
English, Scientific journal - Collisional quenching of C-2(d(3) Pi(g)) and C-3((A)over-tilde(1) Pi(u)) and its application to the estimation of absolute particle density in laser-ablation carbon plumes
T Wakasaki; K Sasaki; K Kadota
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS, 41, 9, 5792, 5796, Sep. 2002
English, Scientific journal - Observation of continuum optical emission from laser-ablation carbon plumes
K Sasaki; T Wakasaki; K Kadota
APPLIED SURFACE SCIENCE, 197, 197, 201, Sep. 2002
English, Scientific journal - Synthesis efficiency of heavy carbon clusters from ETFE ablated by different numbers of laser pulse in vacuum
K Shibagaki; N Takada; K Sasaki; K Kadota
APPLIED SURFACE SCIENCE, 197, 598, 602, Sep. 2002
English, Scientific journal - Visual diagnostics of laser-ablation plasmas by laser-induced fluorescence imaging spectroscopy
SASAKI Koichi; ITO Hirokazu; WATARAI Hiroshi; KADOTA Kiyoshi
ITE Technical Report, 26, 39, 7, 12, The Institute of Image Information and Television Engineers, 17 Jun. 2002
Japanese, Since laser-ablation plasmas have significant spatial distributions with transient properties, the diagnostic techniques should have temporal and spatial resolutions. Laser-induced fluorescence (LIF) imaging spectroscopy, which can visualize the distributions of particle densities in plasmas, is a suitable method for the diagnostics of laser ablation plasmas. This report describes our system of LIF imaging spectroscopy. Although LIF imaging spectroscopy is an excellent diagnostic technique, in this report, we dare to discuss some problems of LIF imaging spectroscopy to clarify the limitations in the application to laser-ablation plasmas. - Distributions of C-2 and C-3 radical densities in laser-ablation carbon plumes measured by laser-induced fluorescence imaging spectroscopy
K Sasaki; T Wakasaki; S Matsui; K Kadota
JOURNAL OF APPLIED PHYSICS, 91, 7, 4033, 4039, Apr. 2002
English, Scientific journal - Production of carbon clusters by laser ablation of polymers in vacuum
K. Shibagaki; N. Takada; K. Sasaki; K. Kadota
Journal of Applied Physics, 91, 3, 2449, 2454, 01 Feb. 2002
English, Scientific journal - Synthesis of heavy carbon clusters by laser ablation in vacuum
K Shibagaki; K Sasaki; N Takada; K Kadota
JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS, 40, 8B, L851, L853, Aug. 2001
English, Scientific journal - Correlation between metastable and ground-state fluorine atom densities measured by laser-induced fluorescence and vacuum ultraviolet absorption spectroscopies
K Takizawa; K Sasaki; K Kadota
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS, 40, 8, 5130, 5133, Aug. 2001
English, Scientific journal - Spatial distribution of H atom density in high-density, helicon-wave H-2 plasmas measured by laser-induced fluorescence
M Nakamoto; K Sasaki; K Kadota
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS, 40, 5A, 3431, 3432, May 2001
English, Scientific journal - A measurement method of absolute hydrogen atom density in plasmas by (2+1)-photon laser-induced fluorescence spectroscopy
K Sasaki; M Nakamoto; K Kadota
REVIEW OF SCIENTIFIC INSTRUMENTS, 72, 5, 2298, 2304, May 2001
English, Scientific journal - Development of a compact nitrogen radical source by helicon-wave discharge employing a permanent magnet
K Sasaki; H Kokubu; D Hayashi; K Kadota
THIN SOLID FILMS, 386, 2, 243, 247, May 2001
English, Scientific journal - Analysis of the molecular structure of fluorocarbon deposits produced by C4F8 and C4F8-H-2 plasmas
N Takada; K Shibagaki; K Sasaki; K Kadota; KI Oyama
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS, 19, 2, 689, 692, Mar. 2001
English, Scientific journal - Rate coefficient for self-association reaction of CF2 radicals determined in the afterglow of low-pressure C4F8 plasmas
C Suzuki; K Sasaki; K Kadota
PLASMA CHEMISTRY AND PLASMA PROCESSING, 21, 1, 139, 147, Mar. 2001
English, Scientific journal - Gas-phase and surface kinetics of radicals in a low-pressure, high-density fluorocarbon plasma device
Recent Res. Devel. Appl. Phys, 4, 223, 240, 2001 - Characteristics of C-3 radicals in high-density C4F8 plasmas studied by laser-induced fluorescence spectroscopy
K Takizawa; K Sasaki; K Kadota
JOURNAL OF APPLIED PHYSICS, 88, 11, 6201, 6206, Dec. 2000
English, Scientific journal - Surface production of CF, CF2, and C-2 radicals in high-density CF4/H-2 plasmas
K Sasaki; H Furukawa; K Kadota; C Suzuki
JOURNAL OF APPLIED PHYSICS, 88, 10, 5585, 5591, Nov. 2000
English, Scientific journal - Correlation between CF2 and CxFy densities in C4F8 plasmas
K Sasaki; K Takizawa; N Takada; K Kadota
THIN SOLID FILMS, 374, 2, 249, 255, Oct. 2000
English, Scientific journal - Formation of positive and negative carbon cluster ions in the initial phase of laser ablation in vacuum
K Shibagaki; T Kawashima; K Sasaki; K Kadota
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS, 39, 8, 4959, 4963, Aug. 2000
English, Scientific journal - Etching efficiency for Si and SiO2 by CFx+F+, and C+ ion beams extracted from CF4 plasmas
T Yamaguchi; K Sasaki; K Kadota
PLASMA CHEMISTRY AND PLASMA PROCESSING, 20, 1, 145, 157, Mar. 2000
English, Scientific journal - Absolute density and reaction kinetics of fluorine atoms in fluorocarbon plasmas studied by vacuum ultraviolet absorption spectroscopy
K Sasaki; K Kadota
PLASMA ETCHING PROCESSES FOR SUB-QUARTER MICRON DEVICES, PROCEEDINGS, 99, 30, 73, 84, 2000, [Peer-reviewed]
English, International conference proceedings - レーザーアブレーションチタンプラズマのレーザー誘起蛍光分光計測
プラズマ・核融合学会誌, 76, 11, 1165, 1174, 2000 - Diagnostics of laser-ablated Ti plasmas by laser-induced fluorescence spectroscopy
Journal of Plasma and Fusion Research, 76, 11, 1165, 1174, 2000 - Formation of C-2 radicals in high-density C4F8 plasmas studied by laser-induced fluorescence
C Suzuki; K Sasaki; K Kadota
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS, 38, 12A, 6896, 6901, Dec. 1999
English, Scientific journal - Diagnostics of laser-ablated carbon plumes by photoionization using a tunable laser
T Kawashima; K Sasaki; T Wakasaki; K Kadota
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING, 69, S767, S770, Dec. 1999
English, Scientific journal - Role of reaction products in F- production in low-pressure, high-density CF4 plasmas
D Hayashi; M Nakamoto; N Takada; K Sasaki; K Kadota
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS, 38, 10, 6084, 6089, Oct. 1999
English, Scientific journal - Enhancement of surface productions of CFx radicals by the addition of H-2 into CF4 plasmas
K Sasaki; H Furukawa; C Suzuki; K Kadota
JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS, 38, 8B, L954, L957, Aug. 1999
English, Scientific journal - Loss processes of F atoms in low-pressure, high-density CF4 plasmas with the admixture of H-2
K Usui; K Sasaki; C Suzuki; K Kadota
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS, 38, 7B, 4373, 4376, Jul. 1999
English, Scientific journal - Decay processes of electrons in the afterglow of high-density CF4, c-C4F8 and CF4-H-2 plasmas
K Sasaki; K Kadota
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS, 38, 7B, 4383, 4388, Jul. 1999
English, Scientific journal - Observation of self-association reaction of CF2 radicals in late afterglow of low-pressure C4F8 plasmas
C Suzuki; K Sasaki; K Kadota
INTERNATIONAL CONFERENCE ON PHENOMENA IN IONIZED GAS, VOL I, PROCEEDINGS, 85, 86, 1999, [Peer-reviewed]
English, International conference proceedings - Measurements of H atom and HF molecule densities in high-density CF4-H-2 plasmas
K Sasaki; K Usui; K Kadota
INTERNATIONAL CONFERENCE ON PHENOMENA IN IONIZED GAS, VOL I, PROCEEDINGS, 75, 76, 1999, [Peer-reviewed]
English, International conference proceedings - Production and Loss Processes of Negative Ions
SASAKI Koichi; KONO Akihiro; KADOTA Kiyoshi
Kakuyūgō kenkyū, 75, 7, 792, 799, The Japan Society of Plasma Science and Nuclear Fusion Research, 1999
Japanese, Negative ions strongly affect the transport and chemical reactions in fluorocarbon plasmas. In this article, a review is given of elementary processes concerning negative ions in fluorocarbon plasmas. Typical behaviors of negative fluorine ions in low-density and high-density plasmas are briefly described. - Determination of fluorine atom density in reactive plasmas by vacuum ultraviolet absorption spectroscopy at 95.85 nm
K Sasaki; Y Kawai; K Kadota
REVIEW OF SCIENTIFIC INSTRUMENTS, 70, 1, 76, 81, Jan. 1999
English, Scientific journal - Surface kinetics of CFx radicals and fluorine atoms in the afterglow of high-density C4F8 plasmas
C Suzuki; K Sasaki; K Kadota
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS, 37, 10, 5763, 5766, Oct. 1998
English, Scientific journal - Lifetime measurements of CFx radicals and H atoms in afterglow of CF4/H-2 plasmas
K Sasaki; K Usui; H Furukawa; C Suzuki; K Kadota
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS, 37, 9A, 5047, 5048, Sep. 1998
English, Scientific journal - Surface productions of CF and CF2 radicals in high-density fluorocarbon plasmas
C Suzuki; K Sasaki; K Kadota
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS, 16, 4, 2222, 2226, Jul. 1998
English, Scientific journal - Absolute density and reaction kinetics of fluorine atoms in high-density c-C4F8 plasmas
K Sasaki; Y Kawai; C Suzuki; K Kadota
JOURNAL OF APPLIED PHYSICS, 83, 12, 7482, 7487, Jun. 1998
English, Scientific journal - Determination of negative ion density with optical emission spectroscopy in oxygen afterglow plasmas
T Ishikawa; D Hayashi; K Sasaki; K Kadota
APPLIED PHYSICS LETTERS, 72, 19, 2391, 2393, May 1998
English, Scientific journal - Measurements of electron density in helicon-wave excited high-density reactive plasmas by vacuum ultraviolet emission spectroscopy
Y Kawai; K Sasaki; K Kadota
PLASMA SOURCES SCIENCE & TECHNOLOGY, 7, 1, 36, 40, Feb. 1998
English, Scientific journal - Efficient production of H- in high-density helicon plasmas
D Hayashi; K Sasaki; K Kadota; Y Oka; K Tsumori; O Kaneko
PRODUCTION AND NEUTRALIZATION OF NEGATIVE IONS AND BEAMS / PRODUCTION AND APPLICATION OF LIGHT NEGATIVE IONS, 439, 123, 132, 1998, [Peer-reviewed]
English, International conference proceedings - 反応性プラズマ計測用加熱プローブの開発
プラズマ・核融合学会誌, 74, 7, 758, 1998 - プラズマ科学の将来展望
電気学会論文誌, 118-A, 602, 603, 1998 - Development of a heated probe for diagnostics of reactive plasmas
J. Plasama Fusion Res., 74, 7, 758, 1998 - Spatial and temporal variations of CF and CF2 radical densities in high-density CF4 plasmas studied by laser-induced fluorescence
C Suzuki; K Sasaki; K Kadota
JOURNAL OF APPLIED PHYSICS, 82, 11, 5321, 5326, Dec. 1997
English, Scientific journal - Kinetics of fluorine atoms in high-density carbon-tetrafluoride plasmas
K Sasaki; Y Kawai; C Suzuki; K Kadota
JOURNAL OF APPLIED PHYSICS, 82, 12, 5938, 5943, Dec. 1997
English, Scientific journal - Diagnostics of fluorine negative ions by laser photodetachment combined with a heated probe in high-density CF4 plasmas
N Takada; D Hayashi; K Sasaki; K Kadota
JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS, 36, 12B, L1702, L1705, Dec. 1997
English, Scientific journal - Comparison of the fluorine atom density measured by actinometry and vacuum ultraviolet absorption spectroscopy
Y Kawai; K Sasaki; K Kadota
JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS, 36, 9AB, L1261, L1264, Sep. 1997
English, Scientific journal - Dynamic variation of the sticking coefficient of oxygen atoms helicon-wave excited high-density oxygen plasmas
J Matsushita; K Sasaki; K Kadota
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS, 36, 7B, 4747, 4751, Jul. 1997
English, Scientific journal - Loss processes of CF and CF2 radicals in the afterglow of high-density CF4 plasmas
C Suzuki; K Sasaki; K Kadota
JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS, 36, 6B, L824, L826, Jun. 1997
English, Scientific journal - Time-of-flight mass spectrometry of positive ions in helicon-wave excited high-density CF4 and C4F8 plasmas
K Sasaki; K Ura; K Suzuki; K Kadota
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS, 36, 3A, 1282, 1286, Mar. 1997
English, Scientific journal - Vacuum ultraviolet absorption spectroscopy for absolute density measurements of fluorine atoms in fluorocarbon plasmas
K Sasaki; Y Kawai; K Kadota
APPLIED PHYSICS LETTERS, 70, 11, 1375, 1377, Mar. 1997
English, Scientific journal - Numerical study of an optically pumped multimode D2O laser
K Sasaki; T Tsukishima
JOURNAL OF APPLIED PHYSICS, 81, 1, 30, 37, Jan. 1997
English, Scientific journal - Basic experiments on in-situ magnetized boronization by electron cyclotron resonance discharges
H Kokura; K Sasaki; H Toyoda; T Mizuuchi; K Kondo; F Sano; T Obiki; H Sugai
JOURNAL OF NUCLEAR MATERIALS, 241, 1217, 1221, 1997
English, Scientific journal - Development of a Plasma Shutter for Fast Truncation of CO_2 Laser Beams
SASAKI Koichi
rle, 24, 5, 596, 601, The Laser Society of Japan, 31 May 1996
Japanese, A plasma shutter having two ZnSe lenses has been developed with the intention of applying it to the generation of ultrashort pulses in the far-infrared and millimeter wavelength range. A fast truncation time of about 1.5 ns was obtained by the plasma shutter, which is approximately the same as the response time of the measurement system. It was found experimentally that truncation waveforms were dependent on both the detection location in the laser beam cross section and the N2 gas pressure inside the shutter chamber. A physical explanation for the above experimental results is given briefly. - Self-mode locking of a hybrid CO2 laser with two transversely excited atmosphere sections
K Sasaki
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS, 35, 5A, 2692, 2693, May 1996
English, Scientific journal - Characteristics of Fluorine Negative lons in Helicon-Wave Excited High-Density Carbon-Tetrafluoride Plasmas
URA Kenichiro; SASAKI Koichi; KADOTA Kiyoshi
Journal of plasma and fusion research, 72, 11, 1204, 1212, プラズマ・核融合学会, 1996
English, Negative ion behavior in helicon-wave excited high-density carbon-tetrafluoride (CF_4) plasmas was examined with a time-of-flight mass spectrometer. As a result of mass spectrum measurements, only fluorine negative ions (F^-) were observed ,in afterglow plasmas as the negative ion species. The F^- density increased immediately after the termination of the rf power into the plasma. During this period, the electron density decreased rapidly with a decay time constant of less than 20 μs. The experimental results of the relation between the F^- and electron densities showed several inconsistencies with the assumption that F^- was mainly produced by dissociative electron attachment to CF_4. In the present study, dissociative electron attachment to CF_3 radicals is proposed as a production process of F^- in low-temperature afterglow plasmas. In addition, pulse modulation of the rf power was tried to enhance the production of F^-. Negative ions were obtained in each afterglow phase in the pulse-modulated plasma, resulting in the increase of the sum total of F^- during the entire discharge duration. - INJECTION SEEDING FOR SINGLE-MODE OPERATION IN AN OPTICALLY PUMPED HIGH-POWER D2O LASER
K SASAKI; O TAKAHASHI; N TAKADA; M NAGATSU; T TSUKISHIMA; T OKADA; S OKAJIMA; Y TSUNAWAKI; S SUDO; KN SATO; K KONDO; H ARIMOTO; KI SATO
INTERNATIONAL JOURNAL OF INFRARED AND MILLIMETER WAVES, 16, 12, 2133, 2146, Dec. 1995
English, Scientific journal - SPECTRAL NARROWING OF AN OPTICALLY PUMPED HIGH-POWER D2O LASER USING THE OSCILLATOR-AMPLIFIER SYSTEM
K SASAKI; N TAKADA; O TAKAHASHI; M NAGATSU; T TSUKISHIMA; T OKADA; S OKAJIMA; Y TSUNAWAKI; S SUDO; KN SATO; K KONDO; H ARIMOTO; KI SATO
JOURNAL OF APPLIED PHYSICS, 77, 4, 1378, 1384, Feb. 1995
English, Scientific journal - HIGH-RESOLUTION SPECTRAL MEASUREMENTS OF THE STIMULATED RAMAN EMISSION FROM OPTICALLY-PUMPED D2O VAPOR
K SASAKI; O TAKAHASHI; N TAKADA; M NAGATSU; T TSUKISHIMA; T OKADA; S OKAJIMA; Y TSUNAWAKI; S SUDO; KN SATO; K KONDO; H ARIMOTO; KI SATO
OPTICS COMMUNICATIONS, 113, 4-6, 535, 540, Jan. 1995
English - COMPUTER-SIMULATION OF AN OPTICALLY PUMPED 385-MU-M D2O LASER-BASED ON THE SEMICLASSICAL LASER THEORY
K SASAKI; M NAGATSU; T TSUKISHIMA
OPTICS LETTERS, 19, 22, 1846, 1848, Nov. 1994
English, Scientific journal - 2-LONGITUDINAL-MODE OSCILLATION IN A HYBRID TEA CO2-LASER WITH THE CW SECTION ABOVE THE LASING THRESHOLD
K SASAKI; M NAGATSU; T TSUKISHIMA
OPTICS COMMUNICATIONS, 107, 5-6, 378, 382, May 1994
English, Scientific journal - Single-Mode Operation of a Compact D_2O Laser for Injection Locking and Oscillator-Amplifier Systems
TAKADA Noriharu; SASAKI Koichi; TAKAHASHI Osamu; NAGATSU Masaaki; TSUKISHIMA Takashige
The Transactions of the Institute of Electronics,Information and Communication Engineers. C-(0xF9C1), J77-C-1, 6, 408, 411, The Institute of Electronics, Information and Communication Engineers, 1994
Japanese, 共振器長800mmの小形D_2Oレーザにおいて,単一モード発振が得られる条件を2種類の共振器について明らかにした.また,得られた単一モード出力のスペクトル幅が極めて狭帯域(約3MHz)であることを確認し,本レーザが増幅および注入ロック実験におけるマスタ発振器として十合な性能を有することを示した. - Single-mode operation of a compact D2O laser for injection locking and oscillator-amplifier system
TAKADA Noriharu; SASAKI Koichi; TAKAHASHI Osamu; NAGATSU Masaaki; TSUKISHIMA Takashige
The Transactions of the Institute of Electronics,Information and Communication Engineers. C-(0xF9C1), J77-C-1, 6, 408, 411, The Institute of Electronics, Information and Communication Engineers, 1994
Japanese, 共振器長800mmの小形D_2Oレーザにおいて,単一モード発振が得られる条件を2種類の共振器について明らかにした.また,得られた単一モード出力のスペクトル幅が極めて狭帯域(約3MHz)であることを確認し,本レーザが増幅および注入ロック実験におけるマスタ発振器として十合な性能を有することを示した. - ON THE POSSIBILITY OF DETERMINING ACCURATE ION TEMPERATURE FROM MULTIMODE FAR-INFRARED LASER SCATTERING
T TSUKISHIMA; M NAGATSU; N TAKADA; K SASAKI
PLASMA PHYSICS AND CONTROLLED FUSION, 35, 9, 1229, 1241, Sep. 1993
English, Scientific journal - EXCITATION OF ELECTROSTATIC ION-CYCLOTRON WAVES BY A POWER-MODULATED TRANSVERSELY EXCITED ATMOSPHERE (TEA) CO2-LASER
K SASAKI; T FUJII; K TAKAHASHI; M NAGATSU; T TSUKISHIMA
PHYSICS OF FLUIDS B-PLASMA PHYSICS, 5, 4, 1154, 1159, Apr. 1993
English, Scientific journal - Theoretical Analysis and Computer Simulation of the Amplitude of Electrostatic Plasma Waves Excited by a Power-Modulated Laser Beam
Sasaki Koichi; Takahashi Kouichi; Nagatsu Masaaki; Tsukishima Takashige
Journal of plasma and fusion research, 69, 7, 822, 832, プラズマ・核融合学会, 1993
Japanese, The amplitude of electrostatic ion cyclotron waves excited by a power-modulated laser beam is compared with those predicted by theoretical analysis and computer simulation. It is shown that the wave amplitude obtained experimentally roughly agrees with the theoretical value within an order of magnitude, while the amplitude in the computer simulation is consistent with the theoretical value within a factor of 1.5. - Theoretical analysis and computer simulation of the amplitude of electrostatic plasma waves excited by a power-modulated laser beam
Sasaki Koichi; Takahashi Kouichi; Nagatsu Masaaki; Tsukishima Takashige
Journal of Plasma and Fusion Research, 69, 7, 822, 832, プラズマ・核融合学会, 1993
Japanese, The amplitude of electrostatic ion cyclotron waves excited by a power-modulated laser beam is compared with those predicted by theoretical analysis and computer simulation. It is shown that the wave amplitude obtained experimentally roughly agrees with the theoretical value within an order of magnitude, while the amplitude in the computer simulation is consistent with the theoretical value within a factor of 1.5. - EXPERIMENTAL-STUDY OF THE SPECTRAL CHARACTERISTICS OF A HIGH-POWER, PULSED D2O LASER FOR APPLICATION TO PLASMA DIAGNOSTICS
M NAGATSU; Y TSUBOUCHI; N TAKADA; K SASAKI; T TSUKISHIMA; T OKADA; S OKAJIMA; K SATO; S SUDO; Y TSUNAWAKI
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS, 31, 12A, 3873, 3881, Dec. 1992
English, Scientific journal - NUMERICAL STUDY ON MODE STRUCTURE OF AN OPTICALLY-PUMPED 385 MU-M D2O LASER
K SASAKI; K MATSUOKA; M NAGATSU; T TSUKISHIMA
JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS, 31, 11A, L1556, L1559, Nov. 1992
English, Scientific journal - Computer Simulation for Evaluating Ion Temperature by Means of Collective Thomson Scattering Using a High Power, Multi-Mode D2O Laser.
Nagatsu Masaaki; Tsubouchi Yuichi; Takada Noriharu; Sasaki Koichi; Tsukishima Takashige
Journal of Plasma and Fusion Research, 68, 3, 279, 297, The Japan Society of Plasma Science and Nuclear Fusion Research, 1992
Japanese, Computer simulation has been carried out with the Monte Carlo method to assess the accuracy of ion temperature measurement by means of the collective Thomson scattering for the Heliotron E using a high power, multi-mode D2O laser.Knowing the fine spectral structure of a pulsed D2O laser emission which has been simultaneously measured using a highly frequency-resolved heterodyne detection system, we can evaluate the ion temperature with almost the same accuracy as that obtained in the conventional single-mode laser scattering. - A high-power, power-modulated TEA CO2 laser system as a driving source of electrostatic plasma waves
SASAKI K; TAKAHASHI K; FUJII T; NAGATSU M; TSUKISHIMA T
Rev. Sci. Instrum., 63, 9, 4086, 4091, 1992 - Development of power-modulated TEA CO2 laser system with long-pulse duration
Koichi SASAKI; Takashige TSUKISHIMA
Rev. Laser Eng., 20, 7, 475, 487, The Laser Society of Japan, 1992
Japanese, After a brief historical review on injection locking of TEA CO2 lasers, it is shown that the in-jection locking scheme with a pulsed injection source is a useful method to obtain monochromatic or power-modulated high-power outputs with long pulse durations (-μs). Details of the newly developed laser system are presented together with experimental results and computer simulations. Various feedback loops are incorporated in the laser system to assure reliable operation. Some applications of the laser outputs so obtained are also mentioned. - Numerical study of an optically-pumped 385μm-D2O laser for the single-mode operation
K. Sasaki; K. Matsuoka; Y. Tsubouchi; N. Takada; M. Nagatsu; T. Tsukishima; T. Okada; S. Okajima; Y. Tsunawaki; S. Sudo; K. N. Sato
Proceedings of SPIE - The International Society for Optical Engineering, 1576, SPIE, 1991
English, International conference proceedings - Frequency-resolved spectral measurement of a high power D2O laser
M. Nagatsu; K. Sasaki; N. Takada; Y. Tsubouchi; T. Tsukishima; T. Okada; S. Okajima; K. Mizuno; K. N. Sato; S. Sudo; Y. Tsunawaki
Proceedings of SPIE - The International Society for Optical Engineering, 1576, SPIE, 1991
English, International conference proceedings - レーザーでプラズマをゆする
パリティ, 6, 10, 49, 52, 1991 - Excitation of plasma waves by lasers
6, 10, 49, 52, 1991 - PULSE INJECTION-LOCKED TEA CO2-LASER FOR LONG PULSE OPERATION WITH FEEDBACK STABILIZATION
K SASAKI; H OHNO; T TSUKISHIMA
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS, 29, 8, 1459, 1465, Aug. 1990
English, Scientific journal - NUMERICAL-SIMULATION OF ELONGATING THE PULSE DURATION OF A TEA CO2-LASER
K SASAKI; T TSUKISHIMA
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS, 29, 2, 277, 283, Feb. 1990
English, Scientific journal - THEORETICAL-MODEL AND NUMERICAL-SIMULATION OF 2-LONGITUDINAL-MODE OSCILLATION IN AN INJECTION-LOCKED TEA CO2-LASER
K SASAKI; H OHNO; T TSUKISHIMA
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS, 29, 2, 284, 293, Feb. 1990
English, Scientific journal - Two-frequency operation of a hybrid tea co2 laser and its application to two-frequency pulse injection locking
Koichi Saski; Hirotaka Ohno; Takaharu Fujii; T Akashige Tsukishima
Japanese Journal of Applied Physics, 29, 12, 2226, 2228, 1990
English, Scientific journal - Negative ion production and beam extraction processes in a large ion source
K. Tsumori; K. Ikeda; H. Nakano; M. Kisaki; S. Geng; M. Wada; K. Sasaki; S. Nishiyama; M. Goto; G. Serianni; P. Agostinetti; E. Sartori; M. Brombin; P. Veltri; C. Wimmer; K. Nagaoka; M. Osakabe; Y. Takeiri; O. Kaneko
Review of Scientific Instruments, 87
- Effects of gas temperature and neutral particle density on self-organized luminous pattern formation in atmospheric-pressure DC glow discharge
宮崎俊明; 白井直機; 佐々木浩一, 応用物理学会春季学術講演会講演予稿集(CD-ROM), 71st, 2024 - Species and amounts of gases produced by atmospheric pressure plasma-induced electrolysis
白土宏太郎; 白井直機; 佐々木浩一, 応用物理学会春季学術講演会講演予稿集(CD-ROM), 71st, 2024 - Dependence of phenol formation concentration using plasma-irradiated water and benzene on 2-propanol concentration
林ロバート勇斗; 稲垣慶修; 白井直機; 高草木達; 佐々木浩一, 応用物理学会春季学術講演会講演予稿集(CD-ROM), 71st, 2024 - Dependence of synthesized phenol concentration on working gas species in benzene-phenol conversion using atmospheric-pressure plasma-liquid interaction
林ロバート勇斗; 稲垣慶修; 高草木達; 佐々木浩一; 白井直機, 応用物理学会秋季学術講演会講演予稿集(CD-ROM), 85th, 2024 - The role of oxygen gas in self-organized luminous pattern formation in atmospheric-pressure DC glow discharge
宮崎俊明; 佐々木浩一; 白井直機, 応用物理学会秋季学術講演会講演予稿集(CD-ROM), 85th, 2024 - Influence of pH on gases generated by atmospheric-pressure plasma-induced electrolysis
白土宏太郎; 佐々木浩一; 白井直機, 応用物理学会秋季学術講演会講演予稿集(CD-ROM), 85th, 2024 - 大気圧プラズマ液体相互作用を利用した物質変換プロセス
白井直機; 稲垣慶修; 佐々木浩一, 化学工学会秋季大会研究発表講演要旨集(CD-ROM), 55th, 2024 - Correlation between self-organized luminous pattern and luminol chemiluminescence in atmospheric-pressure DC glow discharge
宮崎俊明; 白井直機; 佐々木浩一, 応用物理学会秋季学術講演会講演予稿集(CD-ROM), 84th, 2023 - Ammonia Synthesis Using Atmospheric Pressure DC Discharge and Water Interaction
白井直機; RAMOY Mary; 佐々木浩一, 応用物理学会秋季学術講演会講演予稿集(CD-ROM), 84th, 2023 - Propagation of large plasma bullet in atmospheric-pressure dielectric barrier discharges produced in sealed gas
曽我悠太; 白井直機; 佐々木浩一, 応用物理学会秋季学術講演会講演予稿集(CD-ROM), 84th, 2023 - Control of self-organized luminous pattern formation in atmospheric-pressure DC glow discharge using external electric field
宮崎俊明; 白井直機; 佐々木浩一, 応用物理学会春季学術講演会講演予稿集(CD-ROM), 70th, 2023 - Propagation of plasma bullet in large-scale atmospheric-pressure dielectric barrier discharge
曽我悠太; 白井直機; 佐々木浩一, 応用物理学会春季学術講演会講演予稿集(CD-ROM), 70th, 2023 - Relationship between the amount of dissolved gas and droplet emission from liquid gallium interacting with inductively coupled plasma
濱名優輝; 白井直機; 佐々木浩一, 応用物理学会春季学術講演会講演予稿集(CD-ROM), 70th, 2023 - Effect of anode structure on self-organized luminous pattern formation in atmospheric-pressure DC glow discharge
宮崎俊明; 白井直機; 佐々木浩一, 応用物理学会秋季学術講演会講演予稿集(CD-ROM), 83rd, 2022 - Influence of dissolved gas on the mechanism of droplet ejection in the interaction of inductively coupled plasma and liquid gallium
濱名優輝; 白井直機; 佐々木浩一, 応用物理学会秋季学術講演会講演予稿集(CD-ROM), 83rd, 2022 - Large-scale atmospheric-pressure dielectric barrier discharge with helium gas flow
曽我悠太; 白井直機; 佐々木浩一, 応用物理学会秋季学術講演会講演予稿集(CD-ROM), 83rd, 2022 - Relationship between characteristic values of liquid and droplet emission in atmospheric-pressure dc glow discharge with a liquid electrode
高村祐仁; 白井直機; 佐々木浩一, 応用物理学会秋季学術講演会講演予稿集(CD-ROM), 83rd, 2022 - Relation between Optical Emission and Surface Tension of Liquid in Atmospheric-Pressure Glow Discharge with Liquid Electrode
高村祐仁; 白井直機; 佐々木浩一, 応用物理学会春季学術講演会講演予稿集(CD-ROM), 69th, 2022 - Effect of negative ions on self-organized pattern formation in atmospheric-pressure DC glow discharge
宮崎俊明; 白井直機; 佐々木浩一, 応用物理学会春季学術講演会講演予稿集(CD-ROM), 69th, 2022 - Production of large-scale dielectric barrier discharge atmospheric-pressure plasmas with helium flows
曽我悠太; 白井直機; 佐々木浩一, 日本原子力学会北海道支部研究発表会・プラズマ・核融合学会北海道地区研究連絡会研究会講演予稿集(CD-ROM), 39th-25th, 2022 - Detection of Short-lived Reactive Species Induced by Plasma-liquid Interaction Using Luminol Chemiluminescence
白井直機; 佐々木浩一, 静電気学会誌, 45, 4, 2021 - Mechanism of OH radicals induced by atmospheric pressure DC glow discharge using crossed gas flow
白井直機; 大和田裕樹; 佐々木浩一, 応用物理学会秋季学術講演会講演予稿集(CD-ROM), 82nd, 2021 - Measurements of vibrational temperature of molecular nitrogen and density of atomic nitrogen in atmospheric-pressure dielectric barrier discharge nitrogen plasma jet
三宅淳文; 白井直機; 佐々木浩一, 応用物理学会秋季学術講演会講演予稿集(CD-ROM), 82nd, 2021 - Synthesis of ammonia using atmospheric-pressure direct current glow discharge with mixture of nitrogen and water vapor
今井拓哉; 白井直機; 佐々木浩一, 応用物理学会秋季学術講演会講演予稿集(CD-ROM), 82nd, 2021 - Droplet ejection from liquid gallium interacting with inductively coupled plasmas: influence of gas solubility
濱名優輝; 白井直機; 佐々木浩一, 応用物理学会春季学術講演会講演予稿集(CD-ROM), 68th, 2021 - Measurement of vibrational temperature in atmospheric-pressure dielectric barrier discharge nitrogen plasma jet by vibrational Raman scattering
三宅淳文; 白井直機; 佐々木浩一, 応用物理学会春季学術講演会講演予稿集(CD-ROM), 68th, 2021 - Correlation between gas-phase radicals induced by atmospheric-pressure gas-liquid interfacial plasma and chemiluminescence in liquid
宮崎俊明; 白井直機; 佐々木浩一, 日本原子力学会北海道支部研究発表会・プラズマ・核融合学会北海道地区研究連絡会研究会講演予稿集(CD-ROM), 38th-24th, 2021 - Simplified analysis of mineral elements in dairy products by laser-induced breakdown spectroscopy and DC glow discharge using liquid electrode
丸山一沙; 白井直機; 佐々木浩一, 応用物理学会秋季学術講演会講演予稿集(CD-ROM), 81st, 2020 - Optimization of OH radical production in direct-current atmospheric-pressure plasma using crossed gas flow
大和田裕樹; 白井直機; 佐々木浩一, 応用物理学会秋季学術講演会講演予稿集(CD-ROM), 81st, 2020 - Plasma-liquid interaction induced by atmospheric pressure plasma
白井直機; 佐々木浩一, 日本物理学会講演概要集(CD-ROM), 75, 1, 2020 - Distribution of OH radical density in direct-current atmospheric-pressure plasma using crossed gas flow
大和田裕樹; 白井直機; 佐々木浩一, 応用物理学会春季学術講演会講演予稿集(CD-ROM), 67th, 2020 - Influence temperature on droplet ejection from liquid gallium interacting with inductively coupled plasmas
濱名優輝; 白井直機; 佐々木浩一, 応用物理学会春季学術講演会講演予稿集(CD-ROM), 67th, 2020 - Relationship between OH density distribution and change in surface tension induced by spatial afterglow of an atmospheric-pressure plasma
金子拓真; 白井直機; 佐々木浩一, 応用物理学会春季学術講演会講演予稿集(CD-ROM), 67th, 2020 - 誘導結合プラズマと相互作用する液体金属からの液滴放出現象
濱名優輝; 白井直機; 佐々木浩一, プラズマ・核融合学会年会(Web), 36th, 2019 - 3P4-11 Sonoluminescence observed in a generator of standing acoustic cavitation with the help of a punching metal plate(Poster Session)
Sasaki Koichi; Iwata Yushi; Nishiyama Shusuke; Tomioka Satoshi; Takada Noriharu, Proceedings of Symposium on Ultrasonic Electronics, 35, 477, 478, 03 Dec. 2014
Steering committee of symposium on ultrasonic electronics, English - 3P4-25 Generation mechanism of standing acoustic cavitation with the help of a punching metal plate(Poster Session)
Sasaki Koichi; Iwata Yushi; Nishiyama Shusuke; Tomioka Satoshi; Takada Noriharu, Proceedings of Symposium on Ultrasonic Electronics, 34, 479, 480, 20 Nov. 2013
Steering committee of symposium on ultrasonic electronics, English - Summary and Prospects
SASAKI Koichi, プラズマ・核融合学会誌 = Journal of plasma and fusion research, 89, 4, 242, 242, 25 Apr. 2013
プラズマ・核融合学会, Japanese - 3Pa4-4 Development of an efficient method for producing standing cavitation bubbles(Poster Session)
Sasaki Koichi; Iwata Yushi; Nishiyama Shusuke; Tomioka Satoshi; Takada Noriharu, Proceedings of Symposium on Ultrasonic Electronics, 33, 361, 362, 13 Nov. 2012
Steering committee of symposium on ultrasonic electronics, English - 2Pa4-12 Influence of changing frequency of superposed ultrasonic wave on reaction fields induced by laser ablation in water(Poster Session)
Takada Noriharu; Sasaki Koichi, Proceedings of Symposium on Ultrasonic Electronics, 32, 131, 132, 08 Nov. 2011
Steering committee of symposium on ultrasonic electronics, English - Multiphase Plasmas Produced by Liquid-Phase Laser Ablation
SASAKI Koichi, Journal of plasma and fusion research, 86, 6, 324, 327, 25 Jun. 2010
液体中に設置した固体ターゲットをレーザーアブレーションすると,固相(ターゲット),液相(アブレーション媒質),気相(アブレーション誘起キャビテーションバブル),および,超臨界相(レーザーアブレーションプラズマ)が混在する特異な反応場が形成される.一方,アブレーション媒質の温度と密度を高めることによりアブレーション媒質を超臨界流体化し,超臨界流体中でレーザーアブレーションプラズマを生成することも可能である.本稿では,液相レーザーアブレーションプラズマの密度と温度の概略評価,アブレーション誘起キャビテーションバブルのダイナミックス,超臨界水中でのレーザーアブレーション装置,および,超臨界水中でのレーザーアブレーション現象に関する初期的結果について報告する., プラズマ・核融合学会, Japanese - 22aZB-7 Laser-aided spectroscopic diagnostics of plasmas
Sasaki Koichi, Meeting abstracts of the Physical Society of Japan, 63, 2, 173, 173, 25 Aug. 2008
The Physical Society of Japan (JPS), Japanese - 名古屋大学大学院工学研究科附属プラズマナノ工学研究センター
佐々木 浩一, 電気学会論文誌. A, 基礎・材料・共通部門誌 = The transactions of the Institute of Electrical Engineers of Japan. A, A publication of Fundamentals and Materials Society, 127, 10, 664, 664, 01 Oct. 2007
Japanese - Diagnostics of liquid-phase laser ablation plasmas by spectroscopic methods
H. Ushida; N. Takada; K. Sasaki, COLA'05: 8TH INTERNATIONAL CONFERENCE ON LASER ABLATION, 59, 563, +, 2007
English - Reaction between laser ablation plume and ambient gas studied by laser-induced fluorescence imaging spectroscopy
K. Sasaki; H. Watarai, COLA'05: 8TH INTERNATIONAL CONFERENCE ON LASER ABLATION, 59, 60, +, 2007
English - Nitridation of titanium surface by the irradiation of YAG laser pulses in N-2/O-2 gas mixture and liquid nitrogen
N. Takada; H. Ushida; K. Sasaki, COLA'05: 8TH INTERNATIONAL CONFERENCE ON LASER ABLATION, 59, 40, +, 2007
English - 発光分光計測技術およびLIF計測技術
第１回名古屋大学プラズマナノ工学スクール「先端プラズマ計測の基礎と応用」テキスト, 1, 1, 25, 2007 - VII-1 Importance of high-temperature, high-pressure reaction environment produced by laser ablation plasma
Sasaki K., プラズマ・核融合学会年会予稿集, 23, 39, 39, 2006
プラズマ・核融合学会, Japanese - 28aB43P Detection of negative hydrogen ions in high-density recombining hydrogen plasmas with ultralow electron temperatures
Shibagaki Kanji; Sasaki Koichi, プラズマ・核融合学会年会予稿集, 23, 86, 86, 2006
プラズマ・核融合学会, Japanese - Production processes and production mechanisms of radicals and particulates by the irradiation of high-density hydrogen plasmas onto a graphite plate
SASAKI Koichi; MAEDA Toshiki; TAKADA Noriharu; ARAMAKI Mitsutoshi; GOTO Motoshi; MUTO Sadatsugu; MORITA Shigeru, 電気学会研究会資料. PST, プラズマ研究会, 2005, 37, 29, 33, 30 Jun. 2005
Japanese - 01pC16P Measurements of electron temperature and electron density in recombining hydrogen plasmas by optical emission spectroscopy
Shibagaki Kanji; Sasaki Koichi, プラズマ・核融合学会年会予稿集, 22, 211, 211, 2005
プラズマ・核融合学会, Japanese - 29aB06P Laser-desoprtion time-of-flight mass spectrometry of graphite plate irradiated by high-density hydrogen plasma
Shibagaki Kanji; Takada Noriharu; Aramaki Mitsutoshi; Goto Motoshi; Muto Sadatsugu; Morita Shigeru; Sasaki Koichi, プラズマ・核融合学会年会予稿集, 22, 73, 73, 2005
プラズマ・核融合学会, Japanese - KS-2 Close interaction between academic and application studies on ablation plasmas
Sasaki K., プラズマ・核融合学会年会予稿集, 22, 46, 46, 2005
プラズマ・核融合学会, Japanese - 12pXB-6 Visualization of laser ablation plumes by laser-induced fluorescence imaging spectroscopy
Sasaki Koichi, Meeting abstracts of the Physical Society of Japan, 59, 2, 154, 154, 25 Aug. 2004
The Physical Society of Japan (JPS), Japanese - 25pA43P Basic experiments on the interaction between high-density hydrogen plasmas and a carbon material
Sasaki K.; Maeda T.; Takada N.; Aramaki M.; Goto M.; Muto S.; Morita S., プラズマ・核融合学会年会予稿集, 21, 204, 204, 2004
プラズマ・核融合学会, Japanese - 25pA14P Heating mechanism of H atom in a compact divertor simulator with helicon-wave discharge
OKUMURA Yuji; ARAMAKI Mitsutoshi; SASAKI Koichi; GOTO Motoshi; MUTO Sadatsugu; MORITA Sigeru, プラズマ・核融合学会年会予稿集, 21, 190, 190, 2004
プラズマ・核融合学会, Japanese - Development of Droplet-Free Plasma Source for Copper Metal Ion Process
NAKAMURA Keiji; IKEZAWA Shunjiro; SASAKI Koichi; YOSHIDA Tatsuhiko, 電気学会研究会資料. ED, 放電研究会, 2003, 239, 35, 40, 12 Dec. 2003
Japanese - 26aB38P Experiments on the interaction between a carbon material and the hydrogen plasmas produced by divetor simulator of helicon wave electron discharge type
Maeda T.; Aramaki M.; Sasaki K.; Goto M.; Muto S.; Morita S., プラズマ・核融合学会年会予稿集, 20, 144, 144, 2003
プラズマ・核融合学会, Japanese - 28aB51P Measurement of H atom temperature in the divertor simulation by absorption spectroscopy using diode laser
Okumura Y.; Aramaki M.; Sasaki K.; Goto M.; Muto S.; Morita S., プラズマ・核融合学会年会予稿集, 20, 263, 263, 2003
プラズマ・核融合学会, Japanese - Visual diagnostics of laser-ablation plasmas by laser-induced fluorescence imaging spectroscopy
SASAKI Koichi; ITO Hirokazu; WATARAI Hiroshi; KADOTA Kiyoshi, IEICE technical report. Electronic information displays, 102, 121, 7, 12, 10 Jun. 2002
Since laser-ablation plasmas have significant spatial distributions with transient properties, the diagnostic techniques should have temporal and spatial resolutions. Laser-induced fluorescence (LIF) imaging spectroscopy, which can visualize the distributions of particle densities in plasmas, is a suitable method for the diagnostics of laser ablation plasmas. This report describes our system of LIF imaging spectroscopy. Although LIF imaging spectroscopy is an excellent diagnostic technique, in this report, we dare to discuss some problems of LIF imaging spectroscopy to clarify the limitations in the application to laser-ablation plasmas., The Institute of Electronics, Information and Communication Engineers, Japanese - 27aC21P Diagnostics of CH radicals generated by the interaction between hydrogen plasmas and a carbon material
Maeda T.; Aramaki M.; Sasaki K.; Kadota K.; Goto M.; Muto S.; Morita S., プラズマ・核融合学会年会予稿集, 19, 128, 128, 2002
プラズマ・核融合学会, Japanese - 27aC20P Measurements of electron and hydrogen atom temperature in helicon-wave hydrogen plasmas
Kato K.; Aramaki M.; Sasaki K.; Kadota K.; Goto M.; Muto S.; Morita S., プラズマ・核融合学会年会予稿集, 19, 127, 127, 2002
プラズマ・核融合学会, Japanese - 27aC19P Production mechanism of large carbon clusters by laser ablation in vacuum
Kamiya Y.; Shibagaki K.; Sasaki K.; Kadota K., プラズマ・核融合学会年会予稿集, 19, 127, 127, 2002
プラズマ・核融合学会, Japanese - 28pB20P In-situ measurements of NO and N0_2 densities in Streamer Corona Discharges by Laser-Induced Fluorescence Spectroscopy
Kurakane H.; Aramaki M.; Sasaki K.; Kadota K., プラズマ・核融合学会年会予稿集, 19, 168, 168, 2002
プラズマ・核融合学会, Japanese - 28pB19P Distribution of the Rotational Temperature of C_2 in Laser-Ablated Carbon Plasmas measured by Laser-Induced Fluorescence
Aoki S.; Sasaki K.; Kadota K., プラズマ・核融合学会年会予稿集, 19, 167, 167, 2002
プラズマ・核融合学会, Japanese - 28pB17P Measurements of density distributions of Ti,Ti^+,and TiO in laser-ablation Ti plumes by laser-induced fluorescence imaging spectroscopy
Ito H.; Sasaki K.; Kadota K., プラズマ・核融合学会年会予稿集, 19, 166, 166, 2002
プラズマ・核融合学会, Japanese - 28pB22P Spatial distributions of absolute C_2 and C_3 densities in C_4F_8 plasmas
Kobayashi M.; Aramaki M.; Sasaki K.; Kadota K., プラズマ・核融合学会年会予稿集, 19, 169, 169, 2002
プラズマ・核融合学会, Japanese - 29aB14 Laser desorption time-of-flight mass spectrometry for analyzing chemical composition of films deposietd on chamber wall
Shibagaki Kanji; Maeda Toshiki; Takada Noriharu; Sasaki Koichi; Kadota Kiyoshi, プラズマ・核融合学会年会予稿集, 19, 202, 202, 2002
プラズマ・核融合学会, Japanese - 28pB18P Visual diagnostics of laser-ablation plumes and ambient gas by laser-induced fluorescence imaging spectroscopy
Watarai H.; Sasaki K.; Kadota K., プラズマ・核融合学会年会予稿集, 19, 167, 167, 2002
プラズマ・核融合学会, Japanese - 28pB21P Laser Stark spectroscopy of Ar for highly-sensitive measurement of sheath electric field
TAKIZAWA Kazuki; SASAKI Koichi; KADOTA Kiyoshi; GAVRILENKO valeri, プラズマ・核融合学会年会予稿集, 19, 168, 168, 2002
プラズマ・核融合学会, Japanese - Diagnostics of reactive plasmas by laser spectroscopy
Sasaki Koichi, プラズマ・核融合学会年会予稿集, 19, 35, 35, 2002
プラズマ・核融合学会, Japanese - 26pA06 Temporal variation of recombination radiation in the afterglow of helicon-wave high-density hydrogen plasmas
Aramaki M.; Kato K.; Sasaki K.; Kadota K.; Goto M.; Muto S.; Morita S., プラズマ・核融合学会年会予稿集, 19, 85, 85, 2002
プラズマ・核融合学会, Japanese - Introductory Talk : Growth of laser ablation research and its applicatiions
Sasaki Koichi, プラズマ・核融合学会年会予稿集, 19, 31, 31, 2002
プラズマ・核融合学会, Japanese - 30pA29P Measurement of Hydrogen Atom Temperature in High Density Hydrogen Plasma
Aramaki M.; Kato K.; Sasaki K.; Kadota K., プラズマ・核融合学会年会予稿集, 18, 188, 188, 2001
プラズマ・核融合学会, Japanese - 30pA15P Mutual neutralization between H^+ and H^- in high-density hydrogen plasmas
佐々木 浩一; 山口 弘晃; 門田 清; 後藤 基志; 森田 繁; 川端 一男, プラズマ・核融合学会年会予稿集, 17, 216, 216, 2000
プラズマ・核融合学会, Japanese - Photoionization measurements of laser ablation C and Si Plumes
SASAKI K.; KAWASHIMA T.; KADOTA K., レーザー学会学術講演会年次大会講演予稿集 = Annual meeting, of the Laser Society of Japan digest of technical papers, 19, 85, 85, 01 Jan. 1999
Japanese - Composition of positive ion species in high-density D_2 plasmas measured by time-of-flight mass spectrometry
佐々木 浩一; 山口 弘晃; 門田 清; 後藤 基志; 森田 繁; 川端 一男, プラズマ・核融合学会年会予稿集, 16, 114, 114, 1999
プラズマ・核融合学会, Japanese - Balmer Line Emission by Mutual Neutralization with H^- and H^+ in a High-Density Hydrogen Plasma
HAYASHI D.; SASAKI K.; KADOTA K., Meeting abstracts of the Physical Society of Japan, 53, 1, 839, 839, 10 Mar. 1998
The Physical Society of Japan (JPS), Japanese - Dissociative Electron Attachment of a Slow Electron to a Highly-Excited Metastable Oxygen Molecule O_2(A^3*^+_u, A'^3Δ_u, c^1*_u)
HAYASHI Daiyu; SASAKI Koichi; KADOTA Kiyoshi, 電気学会研究会資料. PST, プラズマ研究会, 1997, 62, 47, 54, 18 Nov. 1997
Japanese - 飛行時間型質量分析法によるCF_4プラズマの診断
浦 賢一郎; 林 大雄; 佐々木 浩一; 門田 清, 電気学会研究会資料. EP, プラズマ研究会, 1995, 107, 79, 87, 27 Nov. 1995
Japanese - Excitation of Electrostatic Plasma Waves by a Power-Modulated Laser Beam
Sasaki K.; Ohno H.; Fujii T.; Nagai T.; Nagatsu M.; Tsukishima T., 年会講演予稿集, 45, 4, 196, 196, 16 Mar. 1990
The Physical Society of Japan (JPS), Japanese - 注入ロックモ-ドビ-ト法によるTEA CO2レ-ザ-光のパワ-変調の安定化
佐々木 浩一; 吉岡 政信; 築島 隆繁, レ-ザ-研究, 16, 10, p681, 690, Oct. 1988
レ-ザ-学会, Japanese - 6p-F6-10 TEA CO_2レーザーにおける注入ロックによる2モード同時発振の動作解析
佐々木 浩一; 大野 裕孝; 築島 隆繁, 秋の分科会講演予稿集, 1988, 4, 225, 225, 16 Sep. 1988
一般社団法人日本物理学会, Japanese
- プラズマ診断の基礎と応用
コロナ社, 2006 - Plasma etching processes for sub-quarter micron devices
The Electrochemical Society Inc.,, 2000 - Plasma etching processes for sub-quarter micron devices
The Electrochemical Society Inc.,, 2000
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- 光エレクトロニクス特論, 2024年, 修士課程, 工学院
- 光エレクトロニクス特論, 2024年, 博士後期課程, 工学院
- 光エレクトロニクス特論, 2024年, 博士後期課程, 工学院
- 制御・電気工学演習, 2024年, 学士課程, 工学部
- 応用電子工学, 2024年, 学士課程, 工学部
- プラズマ物理, 2024年, 学士課程, 工学部
- 電気・電子回路, 2024年, 学士課程, 工学部
■ Works
- 非平衡プラズマ超燃焼技術の基礎研究
2009 - 2009 - 炭素ナノコンポジット膜のスッパタ成膜技術の開発と燃料電池セパレータへの応用
2009 - 2009 - レーザー生成多相混在プラズマの科学と応用創出
2009 - ドップラーフリー分光計測に基づくエルゴディック層内粒子輸送の研究
2009 - プラズマとナノ界面の相互作用に関する総括研究
2009 - 超音波支援液相レーザーアブレーションによる高効率ナノ粒子創製技術の開発
2009 - プラズマ診断のためのドップラーフリー分光計測技術の開発
2009 - 低電子温度再結合プラズマにおける水素分子分光
2007 - 2007 - マイクロ波励起による超高密度マイクロプラズマの生成とその極短波長光源への応用
2003 - 2007 - 加圧液体中でのレーザーアブレーションによる新規材料合成技術の開発
2006 - 2006 - レーザー誘起蛍光減光法によるプラズマ電界計測の高機能化および低コスト化
2004 - 2006 - プラズマ電子温度及び電子密度の非接触モニタリング技術の開発
2005 - 2005 - n=2状態水素原子診断のための半導体レーザー吸収分光計測技術の開発
2005 - 2005 - 高密度水素プラズマ・壁相互作用の基礎過程解明とその診断法開発
2001 - 2004 - レーザー誘起蛍光減光法による高感度電場計測法の開発
2003 - 2003 - 真空中でのレーザーアブレーションによる炭素クラスター生成
2002 - 2002 - レーザー誘起減光分光法による負性プラズマのシース電場測定
2001 - 2002 - ヘリコン波放電型コンパクト窒素ラジカル源の開発と高性能化
2000 - 2000 - レーザーアブレーションプラズマを光源とする真空紫外吸収分光計測システムの開発
1999 - 2000 - 可視分光によるプラズマ中の水素負イオン及び正・負イオン相互中性化過程の測定
1998 - 2000 - フロロカーボン系正・負反応性イオンとシリコン系基板との反応基礎過程
1997 - 1997 - ヘリコン波放電型酸素・フッ素負イオン源の開発
1995 - 1997 - パルス変調フッ化炭素プラズマにおけるフッ素原子およびフッ素負イオンの高信頼性診断
1996 - 1996 - 高速マイクロ波干渉計による負イオン・プラズマ診断
1995 - 1995 - 真空紫外吸収分光法によるプロセス・プラズマ診断
1995 - 1995 - ミリ波・サブミリ波領域における極短パルス光の発生
1994 - 1994 - ミリ波およびサブミリ波領域における極短パルス光の発生
1994 - 1994 - プラズマ計測用大出力光励起遠赤外レーザーの単一モード化
1993 - 1993
- 大気圧直流グロー放電生成時に観測される発光の自己組織化メカニズムの解明
科学研究費助成事業
01 Apr. 2023 - 31 Mar. 2027
白井 直機; 佐々木 浩一; 富田 健太郎
大気圧中で直流電圧駆動の放電プラズマを生成するとある条件において、陽極表面上で自己組織化された発光が観測されるが、その生成因子を実験的アプローチにより調査した。自己組織化パターン形成には、負性ガスである酸素の有無が重要であること、数学的に自己組織化形状が得られる反応拡散系ではある反応物質の密度が増減しながら拡散して模様を形成することを考慮すると、プラズマによるパターン形成は負イオンの有無と電界による輸送が重要であると予想される。2023年度はレーザー光脱離法による負イオン種の同定、レーザー誘起蛍光法による窒素イオン密度の計測、OHラジカルの密度分布・回転温度の計測パターン構造の外部電場制御を行った。その結果パターン構造が生じた際にOH-等の負イオンは確かに観測されるものの、液体陽極の場合と金属陽極の場合で観測される負イオン種の比率が異なっていてもパターン構造が観測されることから負イオンは直接的な生成因子でないことが示唆された。一方、レーザー誘起蛍光法によるOHラジカルの密度ならびに回転温度の空間分布の結果からパターン形成が観測されているときに放電プラズマ領域の温度が高くなっていることが観測された。これは温度の上昇によりプラズマ領域の密度分布が低くなっていることを示唆している。計算シミュレーションや低気圧環境でのプラズマにおいては希ガスのみでも
パターン形成が得られていることから、大気圧直流放電によるパターン形成においても負イオンよりも温度上昇による密度の低下或いは、空間密度分布の変化が重要である可能性が見出された。
日本学術振興会, 基盤研究(B), 北海道大学, 23K26083 - 大気圧直流グロー放電生成時に観測される発光の自己組織化メカニズムの解明
科学研究費助成事業
01 Apr. 2023 - 31 Mar. 2027
白井 直機; 佐々木 浩一; 富田 健太郎
日本学術振興会, 基盤研究(B), 北海道大学, 23H01388 - ナノ秒パルス放電プラズマ中の非平衡反応過程に関する光学診断技術を駆使した研究
科学研究費助成事業
23 Apr. 2024 - 31 Mar. 2026
佐々木 浩一; KUHFELD JAN
日本学術振興会, 特別研究員奨励費, 北海道大学, 24KF0003 - 水と空気からアンモニアを合成するプラズマ反応プロセスの学術基盤構築
科学研究費助成事業
01 Apr. 2023 - 31 Mar. 2026
佐々木 浩一
本計画の初年度に当たる2023年度の研究実績は以下のとおりである。
予備実験で用いた装置とは別に，本計画専用の誘導結合プラズマ発生装置を整備した。新たに整備したプラズマ発生装置では，水蒸気のガス流量を自在に制御するために，水蒸気に適応するマスフローコントローラを採用した。この装置を用いて，予備実験における実験条件よりもはるかに広いプラズマ生成条件においてアンモニアの合成特性を調べた。このとき，四重極質量分析器を用いた独自の方法により，アンモニアの生成レートと生成したアンモニアのプラズマ中での損失周波数を別々に求めた。その結果，予備実験と同様のプラズマ生成条件では予備実験と同様のアンモニア合成特性が得られ，予備実験の結果は装置に依存しない結果であることが確認できた。
しかしながら，予備実験よりも放電電力が高い場合や水蒸気ガス圧が高い場合には，予備実験と比較してアンモニアの合成特性が悪化することが見出された。放電電力が高い場合の合成特性の悪化（特に生成レートの低下）は，計画時点で予測していなかった結果であった。放電電力が高いときにアンモニアの生成レートが低下する理由は，水蒸気の電子衝突解離によって生成されるOHラジカルが本実験において触媒として作用するステンレス製真空容器の表面をより強く酸化するためであると推測した。
OHラジカルは生成したアンモニアのプラズマ中での損失にも関与すると考えられるため，連続波長光源を用いた吸収分光法により，プラズマ中のOHラジカル密度の絶対値を実測した。測定により求まったOHラジカル密度は，窒素／水蒸気プラズマと窒素／水素プラズマにおけるアンモニアの損失周波数の違いを説明することができない程度に低密度であり，プラズマ中での反応過程についての再考が必要である可能性が示唆された。
日本学術振興会, 基盤研究(B), 北海道大学, 23K25860 - Understanding scientific principle of plasma-liquid interface
Grants-in-Aid for Scientific Research
01 Apr. 2020 - 31 Mar. 2023
Sasaki Koichi
The uniqueness of plasma-liquid interaction, in comparison with conventional liquid-phase chemistry, originates in short-lived species located in the vicinity of the liquid surface. In this work, we succeeded in the experimental investigation of the vicinity of the plasma-water interface by detecting OH radicals using luminol chemiluminescence, by measuring the surface tenson of water interacting with a plasma, by observing redox reactions at the water surface interacting with a plasma, and by detecting hydrated electrons at the plasma-liquid interface using laser-indued desolvation.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Hokkaido University, 20H00135 - Detection of solvated electrons and challenge to their kinetics in liquids interacting with plasmas
Grants-in-Aid for Scientific Research
28 Jun. 2019 - 31 Mar. 2021
Sasaki Koichi
We developed two methods for detecting solvated electrons in liquids interacting with plasmas. One was the CTTS (Charge Transfer to Solvent) transition. This is a kind of photo-excited process to produce solvated electrons, and we can examine the reaction frequency of solvated electrons in liquids interacting with plasmas. The other method was the production of free electrons by laser-induced desolvation. The free electrons produced by the desolvation were transported to and detected in the plasma. We have shown experimentally that these two methods works effectively for investigating solvated electrons in liquids interacting with plasmas.
Japan Society for the Promotion of Science, Grant-in-Aid for Challenging Research (Exploratory), Hokkaido University, 19K21861 - Construction of Scientific Principle in Plasma-Liquid Interaction
Grants-in-Aid for Scientific Research
01 Apr. 2016 - 31 Mar. 2020
Sasaki Koichi
We carried out fundamental investigation which contributes to the academic progress of plasma-liquid interaction. We proposed 1) distortion in the shape of liquid surface in strong electric field, 2) reaction between liquid and nanoparticle of alkali metal, and 3) the formation of gas in liquid after the neutralization of irradiated ions as the production mechanisms of droplets from liquid surfaces interacting with plasmas. We observed the production of metal atoms from droplets when they were evaporated in plasma. We have shown that the chemiluminescence of luminol can be utilized for the detection of OH radicals in liquid. In addition, we examined the reaction frequency of solvated electrons in liquids interacting with plasmas using CTTS transition and transient absorption spectroscopy.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Hokkaido University, 16H02121 - Pioneering novel plasma reaction processes utilizing nonequilibrium vibrational temperature
Grants-in-Aid for Scientific Research
30 Jun. 2017 - 31 Mar. 2019
Sasaki Koichi; Nishiyama Shusuke
We have demonstrated the conversion of carbon dioxide via vibrational excited states by experiments using recombining plasmas with ultralow electron temperatures of 0.1-0.3 eV for the first time. We have shown that the overall reaction rate coefficient of the CO2 dissociation decreases with the electron temperature in the temperature range above 0.1 eV. The demonstration of the production of formic acid by reaction between atomic hydrogen and vibrationally excited carbon dioxide was not successful. However, it can be said that this research opens novel plasma reaction processes utilizing nonequilibrium vibrational temperature.
Japan Society for the Promotion of Science, Grant-in-Aid for Challenging Research (Exploratory), Hokkaido University, 17K18767 - Challenge of diagnostic methods for plasma-liquid interaction
Grants-in-Aid for Scientific Research
01 Apr. 2015 - 31 Mar. 2018
Shusuke Nishiyama; SASAKI Koichi; SHIRAI Naoki
We investigated diagnostic methods which can be used for fundamental studies of plasma-liquid interaction. We confirmed that two-dimensional laser-induced fluorescence kept its sensitivity at the vicinity to the interface between plasma and solid (or liquid). It was impossible to observe the region with high densities of liquid-phase reactive species, which are transported from plasma, by laser-induced fluorescence of phenol and the color reaction of titanium sulfate. On the other hand, we observed blue chemiluminescence from alkaline solutions with the addition of luminol. The region with the chemiluminescence was very thin, and was located just below the plasma-irradiated interface. It has been suggested that the chemiluminescence of luminol is useful for the detection of plasma-induced short-lived reactive species in liquids.
Japan Society for the Promotion of Science, Grant-in-Aid for Challenging Exploratory Research, Hokkaido University, 15K13388 - Construction of a model for plasma-assisted nonequilibrium combustion chemistry
Grants-in-Aid for Scientific Research
01 Apr. 2013 - 31 Mar. 2016
Sasaki Koichi; AKASHI Haruaki; AKAMATSU Fumiteru
The objective of the present work is to obtain the microscopic understanding on plasma-assisted combustion by experiments and simulation. It has been understood that the production of atomic oxygen via collision between molecular oxygen and high-energy electron, which is produced in the plasma, in the premixed zone of the flame is the origin of activated combustion reactions. In the case with the addition of water vapor, it has been suggested that OH radical, which is produced by electron impact dissociation of H2O, is the origin of activated combustion reactions.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 25286078 - Thermal Management of Smart Combustion with Non-equilibrium Plasma
Grants-in-Aid for Scientific Research
01 Apr. 2013 - 31 Mar. 2016
Tomita Eiji; SASAKI Koichi; AKAMATSU Fumiteru; IKEDA Yuji; KAWAHARA Nobuyuki
We propose plasma-assisted combustion that is different from conventional combustion to reduce harmful exhaust emissions as well as carbon dioxide in this study. The purpose of this study is to investigate the relation between ignition and combustion and non-equilibrium plasma under the conditions from room temperature and atmospheric pressure to high temperature and pressure both physically and chemically. And then, fundamental phenomena were revealed to create a new research field of smart combustion and these findings were applied to heat power engines. The effect of microwave plasma on radical density and combustion, radical behavior and combustion characteristics in the process of laser ignition superimposed with non-equilibrium plasma, and the effect of microwave on wet ethanol combustion and chemical reaction were investigated. A propagating flame could be controlled spatially and temporally with microwave. As a result, the possibility of new combustion with microwave was found.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Okayama University, 25249015 - Development of a method for the efficient production of sonoplasmas
Grants-in-Aid for Scientific Research
01 Apr. 2012 - 31 Mar. 2015
SASAKI Koichi; TOMIOKA Satoshi; NISHIYAMA Shusuke; TAKADA Noriharu
In this work, we have proposed the mechanism by which the efficient production of sonoplasmas is achieved in a sonoplasma production system with the help of a punching metal plate. Small bubbles are produced at the sharp edges of holes on the punching metal plate. They are transported by the primary Bjerknes force toward the bottom side of the vessel, and are trapped at the dip in the distribution of the ultrasonic pressure. These processes result in standing cavitation bubbles with a high density. The present method is unique as a method for producing liquid-phase plasmas without using high voltages. It can be utilized for enhancing the rates of various sonochemistry processes.
Japan Society for the Promotion of Science, Grant-in-Aid for Challenging Exploratory Research, Hokkaido University, 24654185 - Development of high sensitivity electric field measurement method in plasmas by saturation spectroscopy using a diode laser
Grants-in-Aid for Scientific Research
01 Apr. 2012 - 31 Mar. 2015
NISHIYAMA Shusuke; SASAKI Koichi; GOTO Motoshi; TAKIZAWA Kazuki; NAKANO Haruhisa
Conventional methods of high sensitivity electric field measurement in plasmas are Stark spectroscopy with a high power tunable laser. In this work, we applied saturation spectroscopy, which is high resolution Doppler-free spectroscopy, to Stark spectroscopy in plasmas with a tunable diode laser. Direct detection of Stark effect in sheath region is achieved for atomic hydrogen Balmer-alpha line with absorption sensitivity enhancement method.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, 24540529 - Science and applications of laser-induced multiphase plasmas
Grants-in-Aid for Scientific Research
23 Jul. 2009 - 31 Mar. 2014
SASAKI Koichi; KOSHIZAKI Naoto
We investigated the reaction field induced by liquid-phase laser ablation, which was treated as a method for producing a multiphase plasma consisting of solid (the target), liquid (the ambient liquid), gas (the cavitation bubble), and supercritical fluid (the ablation plasma). We focused on the growth processes of nanoparticles in liquid-phase laser ablation. We have found that atomic and molecular species ejected into the liquid are transported toward the inside of the cavitation bubble, and the growth of nanoparticles occurs inside the cavitation bubble. We have shown that the structure of nanoparticles is affected by the control of the dynamics of the cavitation bubble. Regarding application sides, we synthesized brookite-type titania and submicron-size spherical particles by laser irradiation in liquids.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area), 21110004 - Frontier science of interactions between plasmas and nano-interfaces
Grants-in-Aid for Scientific Research
23 Jul. 2009 - 31 Mar. 2014
SHIRATANI Masaharu; TERASHIMA Kazuo; SHIRAFUJI Tatsuru; SASAKI Kouichi; ITO Masafumi; TOCHIKUBO Fumiyoshi; ONO Kouichi; GOTO Motonobu; NAGATSU Masaaki; KOMATSU Shojiro; UCHIDA Satoshi; OTA Takayuki; KOGA Kazunori
本取り纏め研究では、プラズマとナノ界面の相互作用ゆらぎに関する学術的成果を統合・発展させて、より汎用性のある学術大系に結びつけることを目的としている。計画研究代表者を研究分担者として、各計画研究における研究成果を取り纏めるとともに、領域内連携により表れた３つの研究項目に共通する基本原理を統合して体系化する。基本原理の体系化に際しては、すべての研究に関する議論を一度に行うと議論が発散する可能性があるため、ゆらぎ・多相界面・バイオというテーマを設定した個別の研究会を開催し研究分担者が成果を統合した後、シンポジウム等で領域全体での成果統合を行った。平成26年度に取りまとめた、平成21-25年度に新学術領域で得られた成果の概要は以下の様に要約される。これらの成果を成果報告書およびホームページで公開した。
ゆらぎに関しては、超高精度トップダウンプロセスの確立（ゆらぎの制御）について、エッチングプラズマに関する実験とシミュレーションの研究グループが連携して、エッチング表面形状揺らぎの機構を解明した。ここでは、揺らぎ抑制法について、従来の物理量を一定にする方法から、物理量に制御した揺らぎを与えて抑制する方法へのパラダイムシフトを起こす事に成功した。また、高精度ボトムアッププロセスの確立（ゆらぎの利用）では、超臨界プラズマに関する実験とモデリングの研究グループの連携により、超臨界プラズマにおける密度ゆらぎ機構を解明し、従来法では得る事ができない高次ダイアモンドイドの合成に成功した。
予想以上の顕著な成果として、気液プラズマに関する実験とモデリングの研究グループの連携により気液界面プラズマにおいてナノ界面が存在することを発見した（多相界面プラズマ）。また、高いインパクトを持つ成果として、バイオ応用プラズマ関連の研究グループの連携により、大気圧プラズマ反応系の世界標準を確立することに成功した。
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area), Kyushu University, 21110001 - Control of combustion chemistry with the help of nonequilibrium plasma
Grants-in-Aid for Scientific Research
2010 - 2012
SASAKI Koichi; AKASHI Haruaki
We have realized nonequilibrium combustion chemistry with the help of nonequilibrium plasmas, where the temperature of electrons is much higher than the temperatures of atomic/molecular species. We used the irradiation of microwave and the superposition of dielectric barrier discharge onto a premixed gas burner flame for realizing the nonequilibrium combustion states.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 22340170 - Investigation of ignition and combustion processes of ultra-combustion heat system with containing water due to nonequilibrium plasma
Grants-in-Aid for Scientific Research
2010 - 2012
TOMITA Eiji; SASAKI Koichi; AKAMATSU Fumiteru; IKEDA Yuji; KAWAHARA Nobuyuki; AKASHI Haruaki
The properties of plasma produced by microwave were investigated and this plasma was applied to the ignition in a premixed burner and in spark-ignition engines. At first, the plasma made by magnetron was used at first and the power supply was changed to semiconductor type, so that stable plasma was produced. It is found that the ignition system utilizing microwave plasma is very useful for the fuel such as ethanol containing water. Furthermore, when ethanol with water is used, ignition is promoted due to the plasma produced by laser induced breakdown.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Okayama University, 22246025 - Study of particle transport in the ergodic layer based on the Doppler-free spectroscopy
Grants-in-Aid for Scientific Research
2009 - 2012
GOTO Motoshi; SASAKI Koichi; MORITA Shigeru
We have developed the technique of absorption spectroscopy for a hydrogen atom line with diode laser aiming at determination of the ionization location of hydrogen atoms in fusion plasma. An ultra-high wavelength resolution that is never available with usual emission spectroscopy technique has been realized with a relatively simple measurement system. Furthermore, we have observed several interesting phenomena like unexpected large tail components and anomalous crossover signals that could be related to the momentum relaxation mechanism of particles in plasma.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), National Institute for Fusion Science, 21340174 - Development of high efficient synthesis technologies by liquid-phase laser ablation with superposing ultrasonic wave.
Grants-in-Aid for Scientific Research
2009 - 2011
TAKADA Noriharu; SASAKI Koichi
We examined the effects of superposing an ultrasonic wave on laser-induced plasma and cavitation bubble in liquid-phase laser ablation. The integrated optical emission intensity form ablation plasma was enhanced at negative phase of the wave. The repetitive formation and collapse of the cavitation bubbles was driven at the same frequency as the ultrasonic wave. Additionally, we revealed that the production rate and the crystallinity of nanoparticles were enhanced by superposing the ultrasonic wave.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Nagoya University, 21510114 - 大気圧マイクロ波プラズマにより自動車エンジン燃焼改善
科学研究費助成事業
2008 - 2009
佐々木 浩一; 池田 浩一
研究分担者の所属機関において実際に自動車エンジンの燃費改善に用いられているのと同様の放電方式で得られるマイクロ波プラズマの電子温度,電子密度,ガス温度,および,ガス密度を測定するため,YAGレーザーを光源に用いたトムソン散乱/ラマン散乱計測システムを整備した。東京大学より借用した2重回折格子分光器を用いた本システムでは,迷光レベルが大きく,トムソン散乱信号を得ることができなかったが,窒素分子の回転ラマン散乱信号が明瞭に観測された。
窒素分子の回転ラマン散乱信号の解析から,本大気圧マイクロ波プラズマに関して,平成20年度の発光分光計測では把握できなかった以下の特性が確認された。まず,プラズマ中のガス温度(窒素分子温度)は放電開始後の時間に比例して増加するが,放電開始後1msの時点においては,プラズマ中心部に近い領域におけるガス温度は500K未満と低い。プラズマの中心から離れた領域でのガス温度の増加は緩やかであり,放電開始後3msが経過した時点でも450K程度である。したがって,放電をパルス化してその持続時間を1ms以下とすれば,ほとんどのプラズマ領域でガス温度の上昇を抑制でき,自動車エンジンへの適用に際して窒素酸化物の発生を防止できる。一方,ガス密度(窒素分子密度)の測定では,放電開始後の時間経過に従ってガス密度が低下することが観測された。プラズマの中心に近い領域では,ガス密度とガス温度の積は時間的に一定値を示し,ガス密度の低下がガス温度の増加によるものであると理解できる。しかし,プラズマの中心から離れた領域では,ガス温度の低下が顕著でないにも関わらずガス密度の低下が顕著であり,低温度下における窒素分子の顕著な解離を示している。このことは,プラズマの中心から離れた領域では電子温度の高い非平衡プラズマが得られており,ラジカルの生成が活発であることを示唆するものである。
日本学術振興会, 挑戦的萌芽研究, 名古屋大学, 20654056 - Production of high-density microplasma by microwave excitation and its application to ultra-short-wavelength light
Grants-in-Aid for Scientific Research
2003 - 2007
KONO Akihiro; SASAKI Koichi; ARAMAKI Mitsutoshi
Research was carried out to inject microwave power into small space and thereby to produce a high-density microplasma continuously, aiming at applying the plasma to a high-brightness ultra-short-wavelength light source. The effect of microwave frequency on the plasma production was also studied. Two types of plasmas were studied: one is "microgap plasma" produced around atmospheric pressure in the microgap (100 μm wide) between two knife-edge electrodes and the other is "micro ECR plasma" produced at low pressures (〜1 Pa) in a microwave stripline with the aid of magnetic field. To study the fundamental properties of plasmas produced, a laser Thomson scattering technique for measuring electron temperature and density in small space was developed. For Ar microgap plasma, a plasma with an electron temperature of 1.2 eV and a high density of 3x10^<14>cm^<-3> was realized with a gas temperature as low as near room temperature. The density of metastable Ar atoms, which are the precursor of VUV light emitting Ar_2 excimer, was measure using laser absorption spectroscopy and the effect of plasma conditions on the Ar_2 excimer formation was clarified; this gives a guide into optimization of the plasma as a VUV excimer light source. Experiments on producing microgap plasma using 10-GHz microwave excitation indicated that reducing the microwave radiation loss is crucial for increasing the electron density, though increasing electron density is expected on the theoretical basis. For micro ECR plasma, 10-GHz excitation showed better plasma localization characteristics, and most measurements were carried out using 10-GHz excitation. Strong Ar^+ emission as well as He^+ emission was observed, indicating the existence of high-energy electrons in the plasma. To increase the plasma density and thereby to obtain variety of short-wavelength emissions from multiply ionized species, improvement of microwave power injection scheme is necessary and is in progress.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research on Priority Areas, Nagoya University, 15075205 - Cost reduction and performance improvement of electric field measurement in plasmas by laser-induced fluorescence-dip spectroscopy
Grants-in-Aid for Scientific Research
2004 - 2006
SASAKI Koichi; SUGAI Hideo; KONO Akihiro
The objective of this project is to reduce the equipment cost and to improve the data acquisition efficiency of the electric field measurement by laser-induced fluorescence-dip spectroscopy. The research results are summarized as follows. 1) We proposed excitation-observation schemes which are compatible with the use of diode lasers. 2) We analyzed the proposed scheme by rate equations. We found that the intensity of laser-induced fluorescence (LIF) was reduced temporally even when cw diode lasers were used for excitation. We examined the reduction ratio and the duration of the temporal reduction of LIF. 3) We demonstrated a two-step excitation scheme using a pulsed tunable laser and a diode laser. 4) To realize the excitation scheme using two diode lasers, we constructed a spectroscopy system employing a photon counter and an acoustic-optical modulator. 5) We showed the possibility that the less significant reduction LIF in the two-step excitation was attributed to the cascade transition from the laser-excited state. 6) We proposed a two-route scheme as an alternative excitation-observation scheme. We demonstrated the reduction of LIF by the two-route scheme. 7) We proposed an excitation-observation scheme employing a two-step excitation and cavity-ringdown absorption spectroscopy. 8) We demonstrated the enhancement of the data acquisition efficiency by employing a two-dimensional LIF spectroscopy system. 9) We compared the experimentally observed structure of sheathe electric field in an electronegative plasma with a theory based on a fluid model. We summarized the agreement and the discrepancy between the experimental and theoretical results.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Nagoya University, 16340181 - プラズマの環境技術への応用
2005
Competitive research funding - Plasma-aided environmental technologies
2005
Competitive research funding - Measurement of sheath electric field in electronegative plasm as by laser-induced fluorescence-dip spectroscopy
Grants-in-Aid for Scientific Research
2001 - 2003
SASAKI Koichi; ARAMAKI Mitsutoshi
The purpose of this project is the development of a sensitive diagnostic technique for measuring electric fields in plasmas. The method is a kind of laser Stark spectroscopy. We adopted laser-induced fluorescence-dip spectroscopy to argon, in order to carry out the electric field measurement in various plasmas including electronegative plasmas. We measured Stark spectra of argon high Rydberg states in well-defined electric fields, and the electric fields in plasmas were determined by comparing the spectra observed in plasmas with the reference spectra observed in well-defined electric fields. We achieved sensitive detection limit of 3 V/cm, which is the champion sensitivity in the world. We carried out the electric field measurement in an inductively-coupled plasma source. We measured the distribution of electric field in the sheath region in front of a metal electrode inserted in the plasma. Owing to the sensitive detection limit, we succeeded in measuring the electric field in the presheath region, where we observed uniform electric field due to the inicrofield. We repeated the electric field measurement in Ar/SF_6 electronegative plasmas. We have found for the first time that the sheath electric field of electronegative plasmas has multistage structure.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Nagoya University, 13480124 - レーザーアブレーションプラズマを光源とする真空紫外吸収分光計測システムの開発
科学研究費助成事業
1999 - 2000
佐々木 浩一
本研究は,レーザーアブレーションプラズマを光源とする真空紫外吸収分光法により反応性プラズマ中の原子状ラジカル密度を測定する方法を確立することを目的としている。昨年は,アブレーションプラズマの発光スペクトル分布を飛行時間発光分光計測により推定し,その結果を元に永久磁石型ヘリコン波ラジカル源中の窒素ラジカル密度を決定した。本年度は,イメージインテンシファイアつきCCDカメラを用いてアブレーションプラズマの画像計測を行い,発光スペクトル分布を推定した。
本年度の実験では,アブレーションターゲットにポリエチレンを採用し,アブレーションプラズマからのH_α発光空間分布をイメージインテンシファイア付のCCDカメラで撮影した。イメージインテンシファイアは50nsの時間幅でゲート動作しており,アブレーション後ある時間経過した後にゲート撮影された発光空間分布を元にアブレーション粒子の運動速度分布を算出できる。その結果から,アブレーションプラズマの発光スペクトル分布を求めた。実験の結果,アブレーションプラズマ中の水素原子の速度分布は空間的に等方的であることがわかり,レーザーアブレーションのメカニズムを解明する観点からも有用な情報が得られた。このようにして発光スペクトル分布が推定されたレーザーアブレーションプラズマを永久磁石型ヘリコン波ラジカル源に取り付けた。ラジカル源で水素プラズマを生成し,得られる水素ラジカルの絶対密度を算出した。真空紫外吸収分光法で信頼性の高いラジカル密度測定を行うには,光源の発光スペクトル分布の評価が最も重要である。本研究により,光源にレーザーアブレーションプラズマを用いれば,光源の発光スペクトル分布が推定可能であり,信頼性の高い測定が可能であることが実証された。
日本学術振興会, 奨励研究(A), 名古屋大学, 11780346 - Measurements of negative hydrogen ions and mutual neutralization process by optical emission spectroscopy
Grants-in-Aid for Scientific Research
1998 - 2000
KADOTA Kiyoshi; SASAKI Koichi
The purpose of the present project is to develop a novel diagnostic method for monitoring negative hydrogen ion density in plasmas. The principle of the diagnostics is based on mutual neutralization between positive and negative hydrogen ions. Hydrogen atoms at excited states are yielded by this reaction. Negative hydrogen ions are detected by measuring visible optical emission from excited hydrogen atoms produced by mutual neutralization. To achieve the goal, we have investigated the following items : 1) the measurement of the ion composition by time-of-flight mass spectrometry, 2) the measurement of the negative ion density by laser photodetachment, 3) the detection of optical emission due to mutual neutralization, 4) the measurement of the hydrogen atom density by laser-induced fluorescence, and 5) the rate-equation analysis of hydrogen plasmas. The intensities of Hα and Hβ emissions observed in the afterglow of high-density hydrogen plasmas had tail components with long decay time constants. The temporal variation of the emission intensity was consistent with the product of the positive and negative hydrogen ion densities, indicating that the visible optical emissions are originated from mutual neutralization between positive and negative hydrogen ions. Therefore, it has been shown by the present project that simple optical emission spectroscopy can be used for monitoring negative hydrogen ions in plasmas.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B)., Nagoya University, 10480107 - Development of Negative Oxygen and Fluorine Ion Sources with Helicon-Wave Discharge
Grants-in-Aid for Scientific Research
1995 - 1997
KADOTA Kiyoshi; MATSUNAGA Kouzi; SASAKI Koichi; SHOJI Tatsuo
In this work, efficient negative oxygen and fluorine ion sources for materials processing have been developed.
A helicon-wave discharge device for the production of negative ions was constructed. High-density oxygen and CF_4 plasmas of 10^<12>-10^<13> cm^<-3> were produced. Two kinds of plasma phases were formed in the high-density plasmas for the efficient negative ion production, namely a high-density and high-temperature plasma of 5-6 eV in the discharge-ON phase, and a high-density and low-temperature plasma of about 1 eV in the discharge-OFF phase. It was confirmed by time-of flight mass spectrometry and laser photodetachment that negative ions were produced efficiently in the afterglow of the discharge-OFF ohase. Negative ions were also efficiently produced in the outer low-temperature region of a sheet plasma, which was formed by controlling plasma parameters spatially.
The dominant negative ion species in the high-density oxygen and CF_4 plasmas were atomic negative ions, O^- and F^-, respectively. The atomic negative ions increased with increase in electron density.
The main production process of negative ions was dissociative attachment of slow electrons to excited molecules or molecular radicals, and the dominant decay process was mutual neutralization between negative and positive ions.
Efficient negative ion production can be realized by forming a high-density and high-temperature plasma, and a low-temperature and high-density plasma. The plasmas with the two phases or regions can be formed by controlling parameters of high-density oxygen and fluorine plasmas temporally and spatially. A guiding principle of the design for efficient negative ion sources has been obtained by this work.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Nagoya University, 07558178 - パルス変調フッ化炭素プラズマにおけるフッ素原子およびフッ素負イオンの高信頼性診断
科学研究費助成事業
1996 - 1996
佐々木 浩一
本研究は,大規模集積回路の製造工程(ドライエッチング)において広く利用されているフッ化炭素プラズマ中のフッ素原子(F)およびフッ素負イオン(F^-)の絶対密度測定法を開発し,高密度プラズマにおけるそれらの粒子の物理・化学過程に関する知見を得ることを目的としている。本年度は,研究計画書および交付申請書に記載した研究計画に従い,以下の項目を実施した。
1.ECR放電圧力CF_4プラズマを光源とする真空紫外吸収分光計測システムを開発した。これをヘリコン波放電高密度CF_4プラズマに適用し,F原子密度の絶対値を求めることにはじめて成功した。
2.F原子密度の絶対値をでんし密度と親ガス密度の積に対して生理し,高密度プラズマにおけるF原子の消滅過程が他の中性粒子との反応によるものであることを明らかにした。アフタ-グロー(初期)におけるF原子密度の減衰の様子からも,F原子の消滅過程が反応であることを支持する結果が得られた。
3.パルス偏重CF_4プラズマのアフタ-グロー(後期)におけるF原子密度の減衰時定数から,真空容器壁(主としてSiO_2)におけるF原子の付着確率を評価した。
4.真空紫外吸収分光法の結果を従来のアクチノメトリー法と比較し,アクチノメトリー法の信頼性を評価した。
5.フッ化炭素プラズマにおいても使用可能な加熱型ラングミュアプローブを開発した。これをエキシマレーザーを用いたレーザー光脱離法と組み合わせることにより,ヘリコン波CF_4プラズマにおけるF^-の絶対密度をはじめて求めた。
6.アフタ-グローにおけるF^-密度の時間変化を加熱プローブによる電子密度,正イオン密度,および電子温度の時間変化と比較し,F^-の生成・消滅過程に関して検討した。
日本学術振興会, 奨励研究(A), 名古屋大学, 08780448 - 高速マイクロ波干渉計による負イオン・プラズマ診断
科学研究費助成事業
1995 - 1995
佐々木 浩一
半導体集積回路などの製造工程において,電気的陰性(負性)の強いガスを用いたプラズマプロセスが広く利用されている。最近では,エッチングにおける基板損傷などを低減する観点から,負性プラズマ中での負イオンの振る舞いが特に注目されている。本研究は,高速マイクロ波干渉計を用いて,材料プロセス用プラズマ中の負イオンの挙動を詳しく診断することを目的としている。本年度は,研究計画調書および交付申請書に記載した研究計画に従い,以下の項目を実施した。
1.ヘリコン波放電高密度CF_4プラズマ発生装置に35GH_Zマイクロ波干渉計を設置した。CF_4プラズマでは,プローブ・チップ表面への絶縁膜の堆積のために,静電プローブによる電子密度測定が困難である。そこで,先ず,設置したマイクロ波干渉計により電子密度の時間変化を高時間分解で測定した。
2.ヘリコン波放電CF_4プラズマでは,放電rf電力が遮断された直後のアフタ-グローにおいて,F^-が効率的に発生する。飛行時間型質量分析器によりF^-を測定し,それと同時にマイクロ波干渉計で電子密度の時間変化を詳しく測定した。実験結果は電子が中性ラジカル等に解離性付着する過程を如実に示しており,これをもとにF^-の生成過程についての検討を進めた。
3.同上のCF_4プラズマにパルス変調を施した場合のF^-と電子密度の時間変化を同時測定し,負イオン生成にとって最適な条件を明らかにした。
4.ヘリコン波放電酸素プラズマ発生装置にマイクロ波干渉計を設置した。 CF_4プラズマの場合と同様に,電子密度と負イオン(O^-)密度の時間変化を測定し,検討を加えた。
5.以上により,レーザー光脱離法とマイクロ波干渉計を組み合わせた方法による負イオン密度の絶対値測定の準備が整った。最終的な実験に間もなく取りかかる予定で,有意な結果が得られるものと期待される。
日本学術振興会, 奨励研究(A), 名古屋大学, 07780416 - Novel First-Wall Conditioning in Stationary Reactor Studies
Grants-in-Aid for Scientific Research
1994 - 1995
SUGAI Hideo; SASAKI Kohichi; NAKAMURA Keiji; TOYODA Hirotaka
Studies on stationary rectors with use of superconducting magnets have recently become more important. In this situation, conventional dc glow plasmas under no magnetic field is useless and, instead of them, magnetized plasmas such as ECR microwave plasmas have to be used. Furthemore, such techniques as lithium pellet injection will be promising for in situ wall conditioning without interrupting fusion plasmas. Most of this study was devoted to lithium coating and ECR-based boronization as follows :
(1) Boron coating
Two methods for new boronization in stationary reactors were proposed. One is injection of decaborane pellet injection and the other is boronization based on ECR microwave discharge under magnetic field. The basic experiment of ECR boronization showed a neutral radical deposition localized near the gas inlet and wider deposition of ionic radicals transported along magnetic lines of force, thus making a large vessel coating possible.
(3) Lithium coating
It was found for the first time that a lithium layr has a storong gettering effect on various molecules such as O_2, H_2O,CO and CH_4 while it absorbs a hydrogen atom per a lithium atom. Moreover, studies on the temperature dependence of hydrogen desorption and on hydrogen state in lithium layr. In future, lithium pellet injection could be a powerful tool of conditioning walls without interrupting a fusion plasma.
Japan Society for the Promotion of Science, Grant-in-Aid for General Scientific Research (B), Nagoya University, 06452419 - レーザーアブレーション
1995
Competitive research funding - 反応性プラズマ計測法の開発
1995
Competitive research funding - 高密度プラズマ源の開発と材料プロセスへの応用
1995
Competitive research funding - Laser ablation
1995
Competitive research funding - Development of diagnostics technologies for reactive plasmas
1995
Competitive research funding - Development of high-density plasma sources and their applications to material processing
1995
Competitive research funding - ミリ波・サブミリ波領域における極短パルス光の発生
科学研究費助成事業
1994 - 1994
佐々木 浩一
本研究は,ミリ波・サブミリ波の波長域における極短パルス光の実現を目指したものである.本年度は,先に提出した研究計画調書および交付申請書に記載した研究計画に従い,以下の項目を実施した.
1.ハイブリッド型TEA CO_2レーザー,トリプル・パス増幅器,遠赤外レーザー・セル(本補助金により試作)からなる実験装置全体の組立・調整を行った.増幅器から得られるCO_2レーザー光のパワーは5MW以上に達した.
2.CO_2レーザーパルスをパルス途中で遮断するためのプラズマ・シャッターを整備した.レンズ間隔の微調整により,シャッターを通過したあとのビームの発散を抑制した.
3.マルチモードのCO_2レーザー光でD_2Oガスを励起する実験を行った.CO_2レーザーにモードロックなどの短パルス化措置が施されていないのにもかかわらず,D_2Oガスの圧力を6Torr以上と高めに設定した場合,パルス幅約3ns(約1kW,波長385μm)の短パルス列が遠赤外レーザー・セルから発生した.レーザーガスにNH_3を用いた場合にも,2nsを割る程度の短パルス出力(波長2.14mmのミリ波を含む)が得られた.
4.プラズマ・シャッターにより,単一モードまたは2モード化されたCO_2レーザー光をパルス途中で遮断し,それにより,遠赤外レーザー・セルを励起した.その結果,数ショットで,遮断CO_2レーザーパルスの立ち下がり時刻に呼応した短パルス出力が得られた.
5.2台のTEA CO_2レーザーを一つの共振器内に直列に並べた新しいハイブリッドCO_2レーザーにより,自発的(受動的)なモードロッキングを引き起こすことに成功した.モードロックされたCO_2レーザーパルスにより遠赤外レーザー・セルを励起すれば,単なるマルチモード・パルスを光励起に用いた場合よりもパルス幅が短いサブミリ波出力が得られるものと期待される.
日本学術振興会, 奨励研究(A), 名古屋大学, 06750049 - プラズマ計測用大出力光励起遠赤外レーザーの単一モード化
科学研究費助成事業
1993 - 1993
佐々木 浩一
本研究は,協同トムソン散乱法による核融合プラズマのイオン温度計測において,プラズマへの入射光源となる大出力光励起D_2Oレーザーの単一モード化を目的とする。従来のD_2Oレーザーの多モード発振出力は,イオン温度の測定結果に重大な誤差を与えることが示されており,これを単一モード化する技術の確立が必要となっていた。
本研究では,小出力の単一モード発振・小型D_2Oレーザーを用い,その出力を大型D_2Oレーザー増幅器で増幅する「増幅方式」と,小型レーザー出力を大型D_2Oレーザー発振器に入射し,その発振出力を直接単一モード化する「注入ロック方式」の二つの方法を試みた。増幅方式では,大型D_2Oレーザー増幅器のガス圧を4〜6Torrに設定し,小型レーザーの発振周波数をASE(Amplified Spontaneous Emission)放射のピーク周波数より20MHz程低くした場合に,半値幅で10MHzの極めて狭帯域な出力が得られた。出力エネルギーは約50mJである。一方,注入ロック方式では,小型レーザーの発信周波数が大型レーザー発信器の縦モードとよく一致しており,かつ,大型レーザーの発振パルスの生長前に小型レーザー光が入射された場合,注入光と結合したモードが支配的に発振し,半値幅で約5MHzの狭帯域出力が得られた。ただし,この場合には,他のモード成分も僅かながらの振幅で同時発振した。注入ロック方式の出力エネルギーは約110mJである。
本研究で用いた出力規模のD_2Oレーザーで,上記のような狭帯域発振出力が得られたのはこれが初めてである。なお,増幅方式の実験に先立ち,予備実験として,D_2Oレーザー増幅器からのASE放射のスペクトル測定を行ったが,この実験においてもいくつかの新しい知見が得られている。このように,本研究の所期の目的はほぼ100%達成され,大出力光励起遠赤外レーザーの単一モード化の方法を確立することができた。
日本学術振興会, 奨励研究(A), 名古屋大学, 05780354 - Development of a Power-Modulated Laser System with Long Pulse Duration and Its Application to Plasma Diagnostics
Grants-in-Aid for Scientific Research
1990 - 1992
TSUKISHIMA Takashige; SASAKI Koichi; NAGATSU Masaaki
The objective of the present study is to prove the principles of the driven scattering method which has been proposed as a novel scheme for high temperature plasma diagnostics. In the driven scattering, a power-modulated laser beam is injected into the plasma to excite electrostatic waves. Certain plasma parameters can be evaluated from the dispersion character of the excited waves.
In 1990, a power-modulated TEA CO_2 laser system was developed. Two-mode pulse injection locking scheme was adopted and a power-modulated (the modulation frequency of 30MHz, 10J-class outputs with long pulse durations of the order of 1mus were obtained with high probability.
In 1991, electrostatic ion cyclotron waves were excited in a laboratory plasma by making use of the power-modulated laser system developed in 1990. Langmuie probes were used to detect the plasma waves. A newly developed numerical filter having a narrow bandwidth was used to extract the wave signal from noisy background. The dispersion character of the excited waves was consistent with the dispersion relation of the electrostatic ion cyclotron wave.
In 1992, the wave amplitude obtained in the experiment was compared with those predicted by a theoretical analysis and computer simulation. The wave amplitude obtained experimentally roughly agreed with the theoretical value within an order of magnitude, while the simulation result agreed well with the theoretical value.
Japan Society for the Promotion of Science, Grant-in-Aid for General Scientific Research (B), School of Engineering,Nagoya University, 02452272
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Research Profiles
■ Research Profiles- Sonoplasma Generator
Themes: Nanotechnology/Materials
Keywords: In-liquid plasma,ultrasonic waves,sonochemistry
