Papers - KODAMA Naoto

A Proposal for a Detection Method of Short-Gap Arcs Generated in Low Voltage DC Facilities

Mikimasa Iwata, Naoki Nishiyama, Yasunobu Yokomizu, Naoto Kodama, Ayaka Nakamura, Tomoyasu Sakai, Masahiro Tsukahara, Atsushi Miyamoto

Proceeding of IEEJ P&ES – IEEE PES Thailand Joint Symposium 2025 – Advanced Technology in Power Systems –     2025.3

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Interpretation of Transient Arc Resistance Rise Process Using Silicone Resin Based on Arc Diameter Reduction and Thermal Diffusivity of Electric Fuse Arc International journal

Waku Takenaka, Naoto Kodama, Yasunobu Yokomizu, Kanata Nakamura, Koki Kameshima, Mikimasa Iwata, Ayaka

Proceedings of ISPlasma2025/IC-PLANTS2025     2025.3

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Proposal of Emergency Operation and Active Power Dispatch Control Scheme for Bipolar VSC-MTDC System Reviewed International journal Open Access

Nakamura A., Iwata M., Yokomizu Y., Kodama N.

IEEE Access   Vol. 13   page： 31590 - 31602   2025

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In a bipolar voltage source converter-based multi-terminal DC (VSC-MTDC) system, the power flow of the positive and negative pole networks can be controlled independently. This advantage allows bipolar systems to maintain operation with only the healthy pole even in the event of DC faults. However, existing power flow control methods for bipolar systems do not include the optimal mode-switching of each converter’s operation and may not be sufficiently reliable during fault conditions. Thus, this paper proposes a new control scheme considering coordination between the poles and flexibility in power shifting. The proposed method consists of two steps: (a) a mode-switching method of converters to maintain DC voltage stability during converter trips and (b) an active power dispatch control method to enable power shifting from the faulty pole to the healthy pole, mitigating the risk of power surplus and ensuring a robust response to AC grid stability issues. The power assurance coefficient ω mass,i is defined as critical factor for determining the interpolar power dispatch. The simulation results show that an average transmission power outage of approximately 220 MW can be prevented during a single-pole trip while maintaining the operation within the rated VSC capacity when ω mass,i is set to 0.5. This highlights the effectiveness of the proposed method in maintaining the system reliability and stability. Overall, the proposed method enhances the transmission capability by maintaining the operation within the rated capacity, enabling interpolar power shifting, and mitigating the AC grid instability during fault conditions regardless of the bipolar configuration.

DOI： 10.1109/ACCESS.2025.3542740

Open Access

Scopus

Transient Quenching Properties of Vapor Arc Formed in Silica Sand: Contribution of Vaporized SiO₂ Mixture to DC Arc Extinction Performance Reviewed International journal

Kodama, N; Yokomizu, Y; Takenaka, W; Nakamura, K

IEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING   Vol. 19 ( 12 ) page： 1965 - 1975   2024.12

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The current-limiting fuse uses silica (SiO2)-sand as arc quenching medium to increase a current-limiting performance during the DC arc quenching process. In order to increase the current-limiting performance of the fuse, a detailed understanding of an arc resistance (Formula presented.) rise process is necessary. This paper first carried out a 1000 A DC Cu arc quenching experiment using the silica-sand to obtain transient change in (Formula presented.), morphology of the arc, and arc temperature (Formula presented.) during the arc quenching process. As a result, a current decaying increased (Formula presented.). The arc was maintained in the cavity surrounded by the fulgurite during the current decaying process. The temperature of Cu/SiO2 arc was 25–8 kK at a current region of 950–400 A during the arc quenching process. Second, we theoretically calculated an electrical resistivity (Formula presented.), and a thermal diffusivity (Formula presented.) as vapor properties for the Cu/SiO2 vapor mixture. As typical results, the admixing of the SiO2 vapor into the Cu arc less increased (Formula presented.) of the Cu/SiO2 vapor mixture at (Formula presented.) between 25 and 5 kK. The (Formula presented.) of the Cu/SiO2 vapor mixture drastically increased due to only decay in (Formula presented.). In contrast, the admixing of the SiO2 vapor into the Cu arc significantly increased (Formula presented.) at (Formula presented.) between 15 and 8 kK. The present results indicate that an increase in (Formula presented.) and consequent rise in thermal energy dissipation from the arc is the main role of the silica-sand vapor mixed with Cu arc in the DC fuse during the arc quenching process. The increased thermal energy dissipation due to the SiO2 vapor admixing further decreases (Formula presented.) to rapidly rise (Formula presented.) and (Formula presented.) during the arc quenching process. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

DOI： 10.1002/tee.24156

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Scopus

電力ケーブル終端接続部でアークが発生した場合の内部圧力上昇推定手法の開発

富田雄大, 横水康伸, 兒玉直人, 三木栄治, 八木正史

Proceedings of the 14th International Workshop on High Voltage Engineering     2024.11

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EPP-24-078/SP-24-019/HV-24-080

Reaction products and withstanding electric field properties of arc quenching air mixed with CH2O vapor decomposition -Comparison with other polymer vapors-

山本伊織, 横水康伸, 兒玉直人, 大野拓也, 江戸貴広

Proceedings of the 14th International Workshop on High Voltage Engineering     2024.11

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EPP-24-091/SP-24-032/HV-24-093

Simultaneous Estimation of Transient Arc Diameter, Electrical Resistivity and Temperature based on High-Speed Camera Observation for High-Temperature Cu/SiO2 Mixture Arc Generated inside Modeled DC Fuse

    2024.11

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Numerical Calculation of High-Temperature Properties of Hot-Gases and Arc Discharges Formed in Electric Fuse Invited Reviewed

Naoto Kodama

Proceedings of The 8th Annual Conference of the Division of Plasma Physics of the Association of Asia Pacific Physics Society     2024.11

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Optimized sequence control of a fuse-semiconductor hybrid circuit breaker through real-time fuse state estimation Reviewed International journal

SONGAH SHIN, Reon Sasaki, Yusuke Nakano, Shungo Zen, Naoto Kodama, Yasushi Yamano, Yuki Inada, Wataru Ohnishi

Proceedings of the 50th Annual Conference of the IEEE Industrial Electronics Society     2024.11

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DOI： 10.1109/IECON55916.2024.10905360

故障発生時における正極負極間電力配分を考慮した双極多端子直流送電システム制御手法の基礎検討

中村綾花, 岩田幹正, 横水康伸, 兒玉直人

電気学会研究会資料 電力技術/電力系統技術 合同研究会     2024.9

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PE-24-171/PSE-24-171

Additive effect of silicone resin on direct current arc quenching performance of a model electric fuse: electrical resistivity and thermal diffusivity of high-temperature Cu/SiO₂ vapor mixed with C₂H₆SiO vapor decomposition Invited Reviewed International journal Open Access

Takenaka, W; Kodama, N; Yokomizu, Y; Hasegawa, K; Nakamura, K; Iwata, M

JAPANESE JOURNAL OF APPLIED PHYSICS   Vol. 63 ( 9 )   2024.9

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Concerning DC fuses equipped with silica sand (SiO2) as an arc quenching material, the authors have proposed an additive installation of silicone resin (C2H6SiO) on a fuse-element surface to improve the limitation and interruption ability of high DC. This paper describes the additive effect of the silicone resin on the transient resistance of the arc that has formed during the DC interrupting process in a model fuse, based on the measurement result that the arc resistance markedly rises with the silicone mass coated on the fuse element. This phenomenon is subsequently explained as resulting from a thermal diffusivity of high-temperature C2H6SiO/SiO2/Cu vapor. In other words, the mixing of C2H6SiO decomposition vapor into the arc can promote vapor temperature decay through the higher thermal diffusivity, resulting in a rapid increase in the electrical resistivity of the vapor during the DC interrupting process.

DOI： 10.35848/1347-4065/ad7432

Open Access

Web of Science

Scopus

Power Flow Control and Mode-Switching Method Considering Single-Pole Trip for Bipolar MTDC System Reviewed International journal

Nakamura A., Iwata M., Yokomizu Y., Kodama N.

Proceedings of the 2024 International Conference on Sustainable Energy: Energy Transition and Net-Zero Climate Future, ICUE 2024     2024.9

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Due to the advantage of the system operation reliability and flexibility, the bipolar multi-terminal high voltage dc (MTDC) transmission has attracted worldwide attention for the integration of offshore windfarms. However, majority of existing operation methods and dc power flow algorithms are designed to control the monopolar MTDC system. It is difficult to implement the conventional control method for the monopolar system into the bipolar system due to the difference in the characteristics of dc power flow control scheme between the two configurations. Therefore, this paper proposes an operation method of the bipolar MTDC system composed of the dc power flow control scheme and mode-switching method. As a simulation result, the proposed method can realize the power sharing between each VSC and reduce the impact of the active power fluctuation on the AC grid connected to the system even when the single-pole trip occurs in the bipolar MTDC system.

DOI： 10.1109/ICUE63019.2024.10795532

Scopus

直流限流遮断における高分子材配置による効果の出現とアーク抵抗急増域

清水翔太，横水康伸，兒玉直人，岩田幹正，中村綾花，酒井智康，塚原正浩，宮本淳史

電気学会研究会資料 放電・プラズマ・パルスパワー/静止器/開閉保護 合同研究会     2024.8

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EPP-24-067/SA-24-035/SP-24-008

高温ドライエアへの高分子分解蒸気CH2O混入による反応生成物および耐電界特性 --他種高分子分解蒸気との比較--

山本伊織, 横水康伸, 兒玉直人, 大野拓也, 江戸貴広

電気学会研究会資料 放電・プラズマ・パルスパワー/静止器/開閉保護合同研究会     2024.8

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EPP-24-068/SA-24-036/SP-24-009

純水を消弧材とした限流ヒューズの遮断試験

小林泰平，兒玉直人，山田圭矢，山田雄大，野々山颯太，前山光明，山納康，稲田優貴

    2024.8

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EPP-24-063/SA-24-031/SP-24-004

限流ヒューズ内で生じる直流アークの遮断に対するポリイミド樹脂と純水の試適用

兒玉直人，野々山颯太，横水康伸，小林泰平，山田圭矢，山田雄大，前山光明，山納康，稲田優貴

電気学会研究会資料 放電・プラズマ・パルスパワー/静止器/開閉保護合同研究会     2024.8

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EPP-24-064/SA-24-032/SP-24-005

Experimental Validation of Optimized Sequence Control for Fuse Current Under Diverse Conditions

SHIN SONGAH，佐々木怜音，大西亘，稲田優貴 , 山納康，中野 裕介，兒玉直人，全俊豪

電気学会研究会資料 放電・プラズマ・パルスパワー/静止器/開閉保護 合同研究会     2024.8

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EPP-24-066/SA-24-034/SP-24-007

量子化学計算を併用した高温消弧ガス特性の解析 Invited Reviewed

兒玉直人、横水康伸

電気学会誌   Vol. 144 ( 8 ) page： 504 - 507   2024.8

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DOI： 10.1541/ieejjournal.144.504

ヒューズと半導体を併用した限流遮断器による低電圧システムの事故・負荷電流遮断 Reviewed

稲田 優貴, 全 俊豪, 大西 亘, 兒玉 直人, 中野 裕介, 高田 康宏, 佐々木 怜音, 宮岡 優太, 塚本 幸佑, 山田 圭矢, 山納 康

電気学会論文誌Ｄ（産業応用部門誌）   Vol. 144 ( 6 ) page： 502 - 508   2024.6

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DOI： 10.1541/ieejias.144.502

A mixture of Si₃N₄ powder and SiO₂ sand as a novel DC arc quenching medium for improvement of the current-limiting performance of a model electric fuse

Kodama, N; Yokomizu, Y; Takenaka, W

JOURNAL OF PHYSICS D-APPLIED PHYSICS   Vol. 57 ( 22 )   2024.5

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DOI： 10.1088/1361-6463/ad2ab2

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High-temperature properties of dry air used as arc quenching medium and its mixture with vaporized C<inf>2</inf> F<inf>4</inf> : reaction products and critical reduced electric field strength at 300-3000 K

Yokomizu Y., Kodama N., Yamamoto I., Uchiyama S., Sato M., Nakamura Y., Edo T.

Journal of Physics D: Applied Physics   Vol. 57 ( 21 )   2024.5

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Recently, electric power equipment manufacturers released a joint statement with the aim of developing high-voltage electrical equipment completely free of fluorinated gases such as fluoroketones and fluoronitriles, which are considered as alternatives to S F 6 and artificially produced compounds of F. This paper considers air as a typical gas present naturally in the environment to investigate its high-temperature properties, including an air mixture with C 2 F 4 vapor injected from a polytetrafluoroethylene nozzle, for application as an arc-quenching medium in a high-voltage circuit breaker equipped with a nozzle. Chemical composition results for the reaction products at 300-3000 K show that the admixture of C 2 F 4 vapor causes a decrease in the molar number of O 2 contained in the air, owing to the production of O-containing compounds such as C O 2 and C O . Additionally, the results reveal that the admixture of C 2 F 4 vapor lead to the production of C F 4 as the predominant F-containing compound. Furthermore, the boundary condition for O 2 production in terms of O 2 molar number X O 2 and C 2 F 4 molar number X C 2 F 4 is formulated. Such evaluation of the mixture composition enables the determination of a reduced effective collision ionization coefficient α ˉ / N and a critical reduced electric field strength E c r / N , resulting in α ˉ / N = 0. The strength E c r / N for the mixture with 30%-100% C 2 F 4 molar fraction rises to approximately 150 Td (1 Td = 1 × 10 − 21 V m2) over 300-3000 K, which is 20-50 Td higher than that for high-temperature air unmixed with C 2 F 4 vapor. The variation in E c r / N is discussed in terms of predominant electron impact processes and the electron energy distribution function in the mixture.

DOI： 10.1088/1361-6463/ad2a15

Scopus

Development of Electrical Circuit Protection DeviceBased on Gas Properties Analysis of High-Temperature Arc and Hot Gas Invited Reviewed

Naoto Kodama

Proceeding of ISPlasma2024/IC-PLANTS2024/APSPT13     2024.3

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Spatiotemporal evolution of electrical conductivity in current-limiting-fuse arc Reviewed

Inada, Y; Fukai, Y; Takayasu, N; Nakano, Y; Zen, SG; Ohnishi, W; Yamano, Y; Maeyama, M; Kodama, N

JOURNAL OF PHYSICS D-APPLIED PHYSICS   Vol. 56 ( 50 )   2023.12

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To improve the interruption capacity of a current-limiting fuse, a detailed diagnosis of the spatial electrical conductivity distribution inside the fuse arc under the current limiting phase around current zero is required, because this distribution determines the distribution of transient recovery voltage inside the fuse. However, well-established methodologies applicable to fuse arcs are lacking, so the spatial distribution remains unknown. This study presents a borescope-integrated spectroscopic system that simultaneously obtains single-shot recordings of the axial distributions of the electron density and arc temperature in the fuse arc just before extinction. Combining the electron densities and arc temperatures, we can identify the fuse arc composition and hence calculate the axial electrical conductivity distribution under the first Chapman-Enskog approximation. The electrical conductivity provided by this systematic methodology includes no large uncertainties, thus demonstrating its superiority against previous estimation methods of the electrical conductivity.

DOI： 10.1088/1361-6463/acf9b2

Web of Science

Scopus

Direct current arc quenching performance of a model electric fuse equipped with SiO₂ sand and additive silicone resin as an arc quenching medium: the effect of a vaporized silicone decomposition mixture on transient arc resistance Reviewed

Takenaka, W; Kodama, N; Yokomizu, Y; Nakamura, K; Shimizu, H

JOURNAL OF PHYSICS D-APPLIED PHYSICS   Vol. 56 ( 47 )   2023.11

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Most high-power electric fuses installed in DC distributions of automobiles employ silica sand (chemical formula SiO2) as arc quenching material to implement the limitation and subsequent interruption of high direct currents. This paper on arc quenching material describes the effects of the addition of silicone resin (chemical formula C2H6SiO) on SiO2 sand, based on the resistance of an arc discharge in SiO2 vapor mixed with silicone resin vapor. The measurement results obtained for the fuse operation of a model electric fuse show that the addition of silicone resin, e.g. an even coating of silicone resin on the surface of a Cu fuse element, attains a shorter arc quenching time. This phenomenon is subsequently explained based on the rise effect of an arc column resistance achieved by mixing with silicone vapor decomposition. The chemical compositions of high-temperature SiO2 vapor mixed with C2H6SiO vapor decomposition are evaluated to show the predominant chemical species at 30 000 K-5000 K for several C2H6SiO vapor concentrations, X C H . The results obtained for X C H of 10%-50% reveal that a H atom originating from C2H6SiO is present at high molar fractions above 0.1 over a wide temperature range of 12 000 K-5000 K. Further evaluations of the electrical resistivity ρ R for the high-temperature vapor show that mixing with C2H6SiO vapor contributes to a rise in ρ R at temperatures of 10 000 K-6000 K. A contribution analysis of the ρ R reveals that the rise effect of the ρ R is accomplished chiefly by the presence of a H atom that has dissociated from C2H6SiO.

DOI： 10.1088/1361-6463/acee92

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Scopus

高温ドライエアへの高分子分解蒸気混入による反応生成物および耐電界特性 -高分子材C2F4あるいはC6H4S-

山本伊織, 横水康伸, 兒玉直人, 内山隼輔, 佐藤基宗, 中村泰規, 江戸貴広

電気学会研究会資料 放電・プラズマ・パルスパワー/開閉保護/高電圧 合同研究会     2023.11

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SiC-MOSFETを⽤いたモデル低電圧DC遮断器による限流遮断プロセス―電源電圧100～400 V下での測定―

長谷川海渡, 横水康伸, 岩田幹正, 兒玉直人

電気学会研究会資料 放電・プラズマ・パルスパワー/開閉保護/高電圧 合同研究会     2023.11

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珪砂とsilicone樹脂を併用した直流遮断過程で生成されるアークに対する消弧材蒸気濃度の推定―異なる樹脂塗布量に対する検討―

竹中湧, 兒玉直人, 横水康伸, 岩田幹正

電気学会研究会資料 放電・プラズマ・パルスパワー/開閉保護/高電圧 合同研究会     2023.11

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高温CO2/O2アーク消弧ガスへの30%C2F4/10%Cuの2種蒸気混入下におけるCu原子の存在温度域と衝突電離係数への影響-温度4000 K〜300 K-

内山隼輔, 横水康伸, 兒玉直人, 真島周也, 森正, 井上徹

電気学会研究会資料 放電・プラズマ・パルスパワー/開閉保護/高電圧 合同研究会     2023.11

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ヒューズ内で発生する高温Cu/SiO2混合ガスに対する臨界換算電界の決定要因ー温度3000-5000 Kー

兒玉直人, 中村哉太, 横水康伸, 竹中湧, 岩田幹正

電気学会研究会資料 放電・プラズマ・パルスパワー/開閉保護/高電圧 合同研究会     2023.11

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DC Arc Quenching Using Ablation of Polymer Narrow-Section Arranged around Fuse Element Reviewed

Kodama, N; Yokomizu, Y; Takenaka, W; Iwata, M; Danish, MSS

IEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING   Vol. 18 ( 11 ) page： 1837 - 1844   2023.9

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This paper was arranged a polymer cylinder around a Cu fuse-element to increase both an arc resistance (Figure presented.) during a DC arc quenching process and an insulation resistance (Figure presented.) after the DC arc quenching. The used polymer cylinder equips a narrow-section with a width (Figure presented.) made from the polymer. A position of the narrow-section was around an arc-ignition point of the Cu fuse-element. Silica-sand (SiO2-sand) was filled inside the polymer cylinder. Then, a damping DC with a prospective peak of 1000 A was energized to the Cu fuse-element. As an experimental result, (Figure presented.) was successfully increased with (Figure presented.) of the narrow-section. In addition, the rise in (Figure presented.) of the narrow-section also increased (Figure presented.) to more than 10 (Figure presented.) under the DC 1000 V application after the arc quenching. In order to interpret (Figure presented.) rise and high (Figure presented.) under the polymer cylinder arrangement, chemical composition, an electrical resistivity (Figure presented.), and a thermal diffusivity (Figure presented.) of Cu/SiO2/Polymer vapor mixture was also calculated. Based on the experimental result and calculation result, (Figure presented.) rise can be interpreted based on rise in (Figure presented.) and (Figure presented.) due to the polymer vapor admixing into Cu/SiO2 vapor mixture. In addition, increasing (Figure presented.) can also be interpreted by the polymer ablation of the narrow-section of the cylinder. The results are useful to further increase the interruption capacity of the DC fuse. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.

DOI： 10.1002/tee.23911

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Scopus

Estimation of Quenching Medium Vapor Concentration in Arc during DC Interruption using Silicone Polymer and Silica-Sand Reviewed

W. Takenaka, N. Kodama, Y. Yokomizu, M. Iwata, and M.S.S. Danish

Proceedings of the XXIII International Conference of Gas Discharges and their Applications     2023.9

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High DC Arc Quenching Process using Si3N4 or BN powder Mixed with Flattery Silica-Sand- Si3N4 or BN 30wt.% Admixing - Reviewed

Naoto Kodama＊ Yasunobu Yokomizu，Waku Takenaka， Mikimasa Iwata，M. S. S. Danish

Proceedings of the XXIII International Conference of Gas Discharges and their Applications     2023.9

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高温CO2/O2アーク消弧ガスへの30%C2F4/10%Cuの2種蒸気混入下における臨界換算電界

内山隼輔，横水康伸，兒玉直人，真島周也，森正，井上徹

令和5年度 電気・電子・情報関係学会 東海支部連合大会 講演論文集     2023.8

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ドライエア中アーク消弧過程におけるC2F4蒸気混入による高温下の耐電界特性の変化 -混入率50%および100% -

山本伊織，横水康伸，兒玉直人，佐藤基宗，中村泰規，江戸貴広

令和5年度 電気・電子・情報関係学会 東海支部連合大会 講演論文集     2023.8

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低電圧DCシリーズアークの検出手法へのWavelet変換の試適用

西山直希, 岩田幹正, 横水康伸, 兒玉直人

電気学会研究会資料 放電・プラズマ・パルスパワー/静止器/開閉保護 合同研究会     2023.7

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電力ケーブル終端接続部の地絡発生時を模擬した小型容器による地絡模擬実験と圧力挙動解析

富田雄大, 八木正史, 横水康伸, 兒玉直人

電気学会研究会資料 放電・プラズマ・パルスパワー/静止器/開閉保護合同研究会     2023.7

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自然由来系CO2/O2アーク消弧ガスへの10%C2F4/10%Cu蒸気混入下における反応生成物と耐電界特性

内山隼輔, 横水康伸, 兒玉直人, 真島周也, 森正, 井上徹

電気学会研究会資料 放電・プラズマ・パルスパワー/静止器/開閉保護合同研究会     2023.7

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Copper Contact Collaborating with IGBT in Series for Hybrid DCCB in MVDC System

    2023.7

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減衰振動電流の生成によるDC限流遮断―SiC-MOSFET素子を用いた低電圧DC遮断とその基礎検討―

長谷川海渡, 横水康伸, 岩田幹正, 兒玉直人

電気学会研究会資料 放電・プラズマ・パルスパワー/静止器/開閉保護合同研究会     2023.7

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Arc Resistance Rise using Powder Mixture of BN Powder and Silica-Sand during DC Interruption Process Reviewed

Naoto Kodama, Yasunobu Yokomizu, Waku Takenaka, Mikimasa Iwata, M. S. S. Danish

    2023.5

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量子化学計算を併用した高温消弧ガス特性の解析 Invited

兒玉直人・横水康伸

令和5年電気学会全国大会講演論文集     2023.3

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Analysis of Arc Characteristics for Improvement of Power Protection Device Performance Invited Reviewed International journal

Kodama N

Proceeding - ELTICOM 2022: 6th International Conference on Electrical, Telecommunication and Computer Engineering 2022     page： 14 - 17   2023.2

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Power protection devices such as gas circuit breaker and current limiting fuse are key component for safety usage of electric system. During fault current breaking process high temperature arc can be formed inside these devices. The arc breaking is neccessary to achieve current interruption. High temperature gas properties of arc is very important factor to simulate the arc breaking process and to design the protection device. This paper briefly introduces calculation procedure of gas properties and discuss the importance of gas property analysis using the arc inside the limiting fuse as typical example. In addition, it is also introduced the relationship between gas property analysis and the quentum chemical calculation as recent trends.

DOI： 10.1109/ELTICOM57747.2022.10038272

Scopus

Theoretical calculation of current commutation process and residual current during contact sliding movement - Application of High Resistivity Material to Fixed Contact Rear Part-

Hiroumi Kawabata, Yasunobu Yokomizu, Naoto Kodama, Kanta Watanabe, Fukutsuka Takashi

Proceeding of 13th International Workshop on High Voltage Engineering(IWHV2022)     2022.11

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DC Arc Column Resistance Rise with Silicone Resin Painted on Copper Fuse-Element in Silica-sand Filling Space

Waku Takenaka, Naoto Kodama, Kaito Hasegawa, Yasunobu Yokomizu, Hironori Shimizu

Proceeding of 13th International Workshop on High Voltage Engineering(IWHV2022)     2022.11

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Simplified analysis of short-circuit current for hybrid AC/DC delivery system

Mir Sayed Shah Danish, Mikimasa Iwata, Yasunobu Yokomizu, Naoto Kodama

Proceeding of 13th International Workshop on High Voltage Engineering(IWHV2022)     2022.11

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Reaction Products in SF6 Multi Mixture with C2F4-BN and Cu Vapor Decomposition at 300-3000 K: Approach to Dielectric Breakdown Property Evaluation

YOKOMIZU Yasunobu, KODAMA Naoto, URAI Hajime, TERADA Masanao, KURODA Mami

Proceeding of 13th International Workshop on High Voltage Engineering(IWHV2022)     2022.11

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Experiment on DC Arc Quenching using Ablation of Polymer Narrow-Section Arranged around Fuse Element

Kodama Naoto, Yokomizu Yasunobu, Takenaka Waku, Nakamura Kanata, Tozaki Shinsuke, Iwata Mikimasa, Danish M. S. S.

Proceeding of the 13th International Workshop on High Voltage Engineering(IWHV2022)     2022.11

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Arc resistance increasing during DC interruption using SiO2/Si3N4 mixture powder as arc interruption medium Reviewed

Naoto Kodama, Yaunobu Yokomizu, Waku Takenaka, and Kaito Hasegawa

Proceeding of the 75th Annual Gaseous Electronics Conference/11th International Conference on Reactive Plasmas     2022.10

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Trial application of Si3N4 powder as alternative arc interruption medium for DC interruption Reviewed

Naoto Kodama, Yokomizu Yasunobu, Waku Takenaka, and Kaito Hasegawa

Proceeding of the 5th International Union of Materials Research Societies/International Conference of Young Researchers on Advanced Materials     2022.8

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代替ガスを用いたアーク消弧過程で生じる化学種間の相互作用ポテンシャル -量子化学計算を用いた輸送特性の高精度導出に向けて

笠井豪, 兒玉直人, 横水康伸, 杉田武弘, DANISH M. S. S, 岩田幹正

電気学会 研究会資料 放電・プラズマ・パルスパワー/静止器/開閉保護 合同研究会     2022.7

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電気接点の摺動・開離過程における電流転流プロセスおよび残留電流の理論計算 --ブラシ後部への高抵抗材適用による残留電流の低減--

川端大海,　横水康伸,　兒玉直人,　渡邉幹太,　福塚隆司

電気学会研究会資料 放電・プラズマ・パルスパワー/静止器/開閉保護合同研究会     2022.7

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高温CO2/O2/CF3OH混合消弧ガスにおける凝縮相炭素の無生成とO2残存：温度300 Kおよび3000 Kにおける耐電圧特性

兒玉直人, 横水康伸, 杉田武弘, 中村泰規, 佐藤基宗

電気学会研究会資料 放電・プラズマ・パルスパワー/静止器/開閉保護合同研究会     2022.7

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High Temperature Gas Properties for Arc Formed in DC Fuse Using Silica-Sand Reviewed

Naoto Kodama, Yasunobu Yokomizu, Waku Takenaka, Kaito Hasegawa

Proceeding of the International Council on Electrical Engineering Conference 2022     2022.7

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DC Arc Interruption Experiment using Arrangement of Polymer-Narrow Section inside Fuse-Case Filled with Silica-Sand

Naoto Kodama, Yasunobu Yokomizu, Waku Takenaka

Proceeding of the 6th International Conference on Electric Power Equipment -Switching Technology-     2022.3

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Dielectric Breakdown Properties for High Temperature HFO−1234yf/CO2 Gas Mixture with Consideration of Predominant Molecular Products at 300−3000 K

Takehiro Sugita, Yasunobu Yokomizu, Naoto Kodama, Motohiro Sato, Yasunori Nakamura

Proceeding of the 6th International Conference on Electric Power Equipment -Switching Technology-     2022.3

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Arrangement of Silicone Flat Plate in Silica Sand Filling Space for DC Arc Resistance Rise

Waku Takenaka, Naoto Kodama, Yasunobu Yokomizu, Koya Nakamura, Hironori Shimizu

Proceeding of the 6th International Conference on Electric Power Equipment -Switching Technology-     2022.3

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DC Arc Interruption Experiment using Arrangement of Polymer-Narrow Section inside Fuse-Case Filled with Silica-Sand

Kodama, N; Yokomizu, Y; Takenaka, W

2022 6TH INTERNATIONAL CONFERENCE ON ELECTRIC POWER EQUIPMENT - SWITCHING TECHNOLOGY (ICEPE-ST)     page： 28 - 33   2022

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It is strongly desired for DC fuse that a compatibility of high arc resistance(rarc) during a DC arc interruption and high insulation resistance(Rins) after the DC arc interruption. This paper describes a trial experiment of DC arc interruption under following conditions. (1) Copper(Cu)-element arrangement in silica-sand filling space(designated as "S-wo"), (2) Arrangement of a polymer fuse-case filled with the silica-sand around the Cu-element(designated as "S-CaseA"), and (3) Arrangement of a polymer narrow-section around an arc-ignition point of Cu-element in the silica-sand filled fuse-case(designated as "S-CaseB"). The damping DC with a prospective peak of 1000 A was energized to the Cu-element to ignite the DC arc. As a result, the compatibility of high rarc and high Rins was successfully achieved only under the S-CaseB condition. These high rarc and high Rins can be interpreted from the shrinking of arc conductive diameter by the silica-sand filled inside the fuse-case and formation of insulation layer by the ablation of the polymer-narrow section.

DOI： 10.1109/ICEPE-ST51904.2022.9757094

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Scopus

Dielectric Breakdown Properties for High Temperature HFO-1234yf/CO₂ Gas Mixture with Consideration of Predominant Molecular Products at 300-3000 K

Sugita, T; Yokomizu, Y; Kodama, N; Nakamura, Y; Sato, M

2022 6TH INTERNATIONAL CONFERENCE ON ELECTRIC POWER EQUIPMENT - SWITCHING TECHNOLOGY (ICEPE-ST)     page： 88 - 92   2022

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With regard to HFO-1234yf mixed with CO2 as a buffer gas, this paper describes dielectric breakdown properties such as an electron attachment coefficient and a critical reduced electric field strength Ecr/N at 300-3000 K. First, this paper covers predominant molecular products through thermal dissociation and combination reactions for 20%HFO-1234yf/80%CO2 gas mixture. Secondly, dielectric breakdown properties of the mixture in consideration of the predominant gaseous molecular products are described to show that Ecr/N is 87-100 Td at 300-3000 K.

DOI： 10.1109/ICEPE-ST51904.2022.9757102

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Scopus

DC Arc Resistance Rise by PMMA Cylinder Ablation with Arc Shrinking in Silica Sand Filling Space Reviewed

Kodama, N; Nakamura, K; Yokomizu, Y; Takahashi, A; Yamamura, N

IEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING   Vol. 16 ( 12 ) page： 1679 - 1686   2021.12

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Concerning DC arc quenching phenomenon in silica sand filling space, we have proposed a new method for raising an arc column resistance (rcol) by use of polymer-material arrangement. This paper reveals physical factors for rcol rise on the bases of experimental results using the following cylinders made of: (i) Quartz (SiO2) and (ii) PMMA ((C5H8O2)n) with various inner diameters ϕ. For ϕ = 2 mm case, rcol measured for a PMMA cylinder arrangement indicated higher rcol at low current region, while almost same rcol around current peak. For ϕ = 3 mm case, rcol for the PMMA cylinder was lower than rcol for the quartz case at high current region, while almost comparable between these conditions at low current region. For ϕ = 5 mm case, rcol were almost same during the arc quenching process. To discuss the effect of the rcol rise, the followings were also performed: (i) observation of cylinders after arc quenching and (ii) calculation of the electron density of SiO2/Cu or PMMA/SiO2 mixture vapors. It is concluded that, at high current region, rcol can increase due to the shrinking of the arc conductive diameter caused by the cylinder hole and the silica sand filled inside the cylinder hole. On the other hand, the admixing of the PMMA ablation vapor increases rcol at low current region in the present experiment. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

DOI： 10.1002/tee.23462

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Scopus

珪砂を用いた直流アーク消弧過程で生じる高温ガスの特性

兒玉直人，横水康伸，中村晃也，竹中湧，清水宏紀

電気学会研究会資料 放電・プラズマ・パルスパワー/開閉保護/高電圧合同研究会     2021.11

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電気接点の摺動・開離における電流減少プロセスの理論計算―転流回路インダクタンスに対する残留電流の依存性―

川端大海，横水康伸，兒玉直人，渡邉幹太，福塚隆司

電気学会研究会資料 放電・プラズマ・パルスパワー/開閉保護/高電圧合同研究会     2021.11

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珪砂-Silicone材併用時のDCアーク抵抗上昇効果の検討

竹中湧，兒玉直人，中村晃也，横水康伸，山村直希

電気学会研究会資料 放電・プラズマ・パルスパワー/静止器/開閉保護合同研究会     2021.7

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N2/O2/HFO-1336mzz(E)混合ガスにおける衝突電離係数・電子付着係数および臨界電界—温度1500 K，HFO-1336mzz(E)混合率0~20%

杉田武弘，横水康伸，兒玉直人，中村泰規，佐藤基宗

電気学会研究会資料 放電・プラズマ・パルスパワー/静止器/開閉保護合同研究会     2021.7

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SiC-MOSFETの熱インピーダンスの過渡特性を表すCauer型等価熱回路の構築:パワー半導体を用いた低電圧DC遮断器への適用

渡邉幹太，横水康伸，兒玉直人

電気学会研究会資料 放電・プラズマ・パルスパワー/静止器/開閉保護合同研究会     2021.7

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Increasing Arc Column Resistance During DC Arc-Quenching Through Arrangement of Polymer Cylinder in Silica Sand Reviewed

Nakamura, K; Kodama, N; Yokomizu, Y; Takahashi, A; Kondo, Y

IEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING   Vol. 16 ( 6 ) page： 905 - 915   2021.6

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In this study, experiments pertaining to direct current (DC) interruptions are performed in an arc-quenching chamber filled with silica sand. First, the arc column resistance is measured during DC arc-quenching to demonstrate the elementary aspects of the arc in the silica-sand-filled space. Subsequently, an arrangement comprising a polymer cylinder between electrodes in the silica-sand-filled space is proposed to increase the arc column resistance during DC arc-quenching. A polymethyl methacrylate (PMMA) cylinder is used in the experiments. Measurement results indicate that the arrangement of the PMMA cylinder causes the arc column resistance to increase approximately twofold in comparison with the no-PMMA cylinder arrangement. Finally, the effect of increasing the arc column resistance is discussed in terms of PMMA and silica vapor. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

DOI： 10.1002/tee.23368

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Scopus

Predominant reaction products and dielectric breakdown properties of gas mixtures consisting of SF₆ and ablation products of C₂F₄/BN in the temperature range of 300-3000 K Reviewed

Yokomizu, Y; Terada, M; Kodama, N; Ishii, T; Kojima, Y; Kuroda, M; Urai, H

JOURNAL OF PHYSICS D-APPLIED PHYSICS   Vol. 54 ( 16 )   2021.4

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For a high voltage SF6 circuit breaker equipped with a boron nitride (BN)-filled polytetrafluoroethylene ((C2F4)n nozzle, the predominant reaction products in a high-temperature SF6 mixture with vapor decomposition of C2F4 and BN at temperatures of 300-3000 K are determined based on calculations of equilibrium composition. The calculation is performed by considering the molecular products obtained by chemical reactions with boron atoms (e.g. BN, BS, BC, BF, BF2 and BF3), nitrogen atoms (e.g. N2, N3, CN, NS, NF, NF2 and NF3) and carbon atoms (e.g. CS, CS2, C2F4, CF2, CF3 and CF4). The results obtained for the C2F4-BN molar fraction X CFBN of 20%-80% reveal that BF3, N2 and CF4, the molecules originating from the nozzle material, are produced at high molar fractions over a range of 300-3000 K. Such an evaluation of the gas composition allows the derivation of a reduced collision ionization coefficient α/N and a reduced electron attachment coefficient η/N of the gas, considering various electron impact processes such as BF3 + e BF2 + F- and CF4 + e CF3 + F-. The evaluation subsequently enables us to determine a critical reduced electric field strength causing . The results suggest that the decomposed C2F4-BN mixture at XCFBN of 80% causes the reduction of to 110 Td in the range of 1000-2000 K at a gas pressure of 1.0 MPa. This strength is 20 Td lower than that determined separately for the SF6 gas mixture with only 80% C2F4 vapor decomposition, because of the CF4 molar fraction reduction in the SF6/C2F4-BN mixture.

DOI： 10.1088/1361-6463/abda80

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Scopus

Interpretation of Arc Column Resistance Rise on basis of Temperature and Cu Vapor Concentration of DC Arc Established in Silica Sand Filling Space

Kodama Naoto, Yokomizu Yasunobu, Takahashi Asato, Nakamura Koya, Yamamura Naoki

IEEJ Transactions on Power and Energy   Vol. 141 ( 11 ) page： 725 - 733   2021

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<p>DC arc interruptions were carried out under following two conditions: (1) silica sand filling without any cylinder arrangement (designation: Silica), and (2) The silica sand filling with a quartz cylinder arrangement (designation: SilicaQuartz). During these experiments, optical emission spectroscopy (OES) measurements were carried out to investigate an arc column resistance rise by the quartz cylinder arrangement. An arc temperature <i>T</i> and a Cu vapor concentration were evaluated from the OES results. As a result, <i>T</i> were measured to be around 24 kK for the Silica condition and 17kK for the SilicaQuartz condition at a current peak. The Cu vapor concentration under the Silica condition gradually decreased with <i>T</i> decaying. On the other hands, the quartz cylinder arrangement in the silica sand filling space drastically decreased the Cu vapor concentration during an arc-quenching process. This drastic decrease in the Cu vapor concentration is one of key factors to increase <i>r</i>_col under the cylinder arrangement in the silica sand filling space. This verification result can be useful to increase an interruption capacity of fuse.</p>

DOI： 10.1541/ieejpes.141.725

Scopus

CiNii Research

High Temperature Properties of CO₂ Gas Mixture with O₂ and HFO-1234yf Decompositions: Predominant Molecular Products and Critical Electric Field Strength at 300-3000 K

Yokomizu Yasunobu, Kodama Naoto, Sugita Takehiro, Ishii Tatsuya, Sato Motohiro, Nakamura Yasunori

IEEJ Transactions on Power and Energy   Vol. 141 ( 11 ) page： 700 - 711   2021

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<p>The gases used in high voltage electric power equipment are required to withstand against an externally applied electric field strength. It is therefore essential to find out the electrical insulation strength of the gas. However the high temperature gas formed after the current zero through the arc extinction process in a circuit breaker shows different insulation strengths from that at room temperature, because the high temperature gas consists of various molecular products different from the original gas at room temperature. The CF₃CFCH₂ (called as HFO-1234yf) at room temperature is known to have a remarkable electrical insulation property similar to SF₆. After describing the products generated in CO₂ gas mixture with O₂ and HFO-1234yf decompositions at temperatures below 3000K, this paper mentions dielectric breakdown properties of the mixtures in view of the molar fractions of the molecular products. Discussions are furthermore made to compare dielectric breakdown properties of CO₂ gas and CO₂/O₂ gas mixture at high temperatures.</p>

DOI： 10.1541/ieejpes.141.700

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CiNii Research

Characteristic Analysis of Thermal Plasma Formed Inside Power Protection Equipment and Development of DC Protection Device Invited Reviewed

Naoto Kodama

  Vol. 45 ( 3 ) page： 112 - 113   2021

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DC arc resistance rise by PMMA cylinder ablation with arc shrinking in silica-sand filled space

Koya Nakamura,Naoto Kodama,Yasunobu Yokomizu,Naoki Yamamura

The Papers of Technical Meeting, IEEJAPAN　12nd International Workshop on High Voltage Engineering (IWHV2020)     2020.11

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珪砂を用いた直流遮断過程におけるアーク内銅蒸気の二次元分布観測と濃度に関する検討

兒玉直人，横水康伸，中村晃也，高橋明里，山村直希

電気学会研究会資料 放電・プラズマ・パルスパワー/静止器/開閉保護合同研究会     2020.9

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C3H2F4を混合した代替消弧ガスCO2/O2: 8%混合率，温度300-3000 Kにおける衝突電離・電子付着係数および臨界電界

杉田武弘，横水康伸，兒玉直人，石井達也，佐藤基宗，中村秦規

電気学会研究会資料 放電・プラズマ・パルスパワー/静止器/開閉保護合同研究会     2020.9

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Chemical species produced in arc-quenching gas CO2/O-2 mixed with C3H2F4, C4-FN or C5-FK: prevention of condensed-phase carbon formation and its formulation Reviewed International journal

Yokomizu Y, Sato M, Kodama N, Edo T, Kokura K

JOURNAL OF PHYSICS D-APPLIED PHYSICS   Vol. 53 ( 14 )   2020.4

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DOI： 10.1088/1361-6463/ab66d5

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Scopus

珪砂中への円筒設置時における直流アーク温度の測定とアーク電圧上昇機構の検討

兒玉直人，横水康伸，中村晃也，高橋明里，近藤祐介

電気学会研究会資料 放電・プラズマ・パルスパワー/開閉保護/高電圧合同研究会     2019.12

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Approach to Mechanism Interpretation of Arc Voltage Rise by Polymer Cylinder Installation in Silica-Sand Reviewed International journal

Kodama N, Yokomizu Y, Nakamura K, Takahashi A, Kondo Y

Proceedings of the 2019 5th International Conference on Electric Power Equipment - Switching Technology: Frontiers of Switching Technology for a Future Sustainable Power System, ICEPE-ST 2019     page： 243 - 248   2019.10

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Authorship：Lead author,　Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Proceedings of the 2019 5th International Conference on Electric Power Equipment - Switching Technology: Frontiers of Switching Technology for a Future Sustainable Power System, ICEPE-ST 2019  

This report describes experimental results on DC interruption for three experiments: (1) silica-sand filling (designation: Silica), (2) polymer cylinder installation without silica-sand filling (designation: P5-Air), and (3) polymer cylinder installation with silica-sand filling (designation: P5-Silica). The shape of polymer cylinder was fixed at an inner diameter of 5 mm and a length of 15 mm. A damping DC with a peak current of 750 A was supplied to an established experimental system. A current and a voltage between electrodes were measured during the current supplying period. As experimental results, the arc resistance between electrodes were measured to be 0.15 for Silica, 0.20 for P5-Air and 0.56 for P5-Silica at a peak current, respectively. This implies that silica-sand confined in the polymer cylinder effectively contributes to the arc voltage rise at around a peak current. During a current decaying periods, the arc resistance for P5-Air was measured to be almost same value for P5-Silica. This also implies that an interaction between the polymer and the arc rises the arc resistance during the current decaying period.

DOI： 10.1109/ICEPE-ST.2019.8928816

Scopus

Rise Effect of DC Arc Voltage in Silica Sand: Various Interelectrode Distances and Arrangement of PA66-Cylinder

Takahashi A., Kodama N., Yokomizu Y., Kondo Y.

Proceedings of the 2019 5th International Conference on Electric Power Equipment - Switching Technology: Frontiers of Switching Technology for a Future Sustainable Power System, ICEPE-ST 2019     page： 300 - 304   2019.10

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Publisher：Proceedings of the 2019 5th International Conference on Electric Power Equipment - Switching Technology: Frontiers of Switching Technology for a Future Sustainable Power System, ICEPE-ST 2019  

The following three experiments were conducted as an attempt to raise the DC arc voltage during current interrupting process in silica sand. The purpose of the first experiment is to examine the influence of the interelectrode distance of the graphite electrode on the arc length. The three types of interelectrode distance were set in the arc quenching chamber and supplied a damping DC current. As experimental results, voltage between electrodes was not effectively rose with elongation in interelectrode distance in the silica sand. The purpose of the second experiment is to achieve further rise in the arc voltage. In this experiment, PA66-cylinder was arranged between electrodes. As the experiment result, arrangement of PA66-cylinder effectively increases the arc voltage. This may be because the expansion of the arc diameter was restricted to the interaction between the arc and the inner wall of the cylinder. The purpose of the third experiment is to investigate the influence of arc voltage rise effect on the inner diameter of the cylinder. The main factors causing the arc voltage rise are the effect of limiting the arc diameter by the inner diameter and the effect of ablating of silica sand.

DOI： 10.1109/ICEPE-ST.2019.8928782

Scopus

珪砂-高分子円筒併設時の直流アーク抵抗上昇機構に関する検討

中村晃也，兒玉直人，横水康伸，高橋明里，近藤祐介

電気学会研究会資料 放電・プラズマ・パルスパワー/静止器/開閉保護合同研究会     2019.7

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Authorship：Corresponding author   Language：Japanese   Publishing type：Research paper (conference, symposium, etc.)  

Fundamental study on role of silica-sand and polymer cylinder in terms of gas properties during DC interruption Reviewed

Kodama N., Yokomizu Y., Takahashi A., Nakamura K., Kondo Y.

Proceeding of XXXIV International Conference on Phenomena in Ionized Gases/ 10th International Conference on Reactive Plasmas     2019.7

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Efficient modification of Si/SiOz nanoparticles by pulse-modulated plasma flash evaporation for an improved capacity of lithium-ion storage Reviewed International journal

M.Kambara, S.Hamazaki, N. Kodama, Yasunori Tanaka

Journal of Physics D: Applied Physics   Vol. 52 ( 32 ) page： 325502   2019.7

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：{IOP} Publishing  

DOI： 10.1088/1361-6463/ab1c9f

Spatial distribution of Ti vapor admixture ratio in Ar induction thermal plasma torch during Ti feedstock injection Reviewed

Naoto Kodama, Yasunori Tanaka, Yosuke Ishisaka, Kotaro Shimizu, Yoshihiko Uesugi, Tatsuo Ishijima, Shu Watanabe, Shiori Sueyasu, Keitaro Nakamura

Japanese Journal of Applied Physics   Vol. 57 ( 3 )   2018.3

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Applied Physics  

The spatial distribution of the Ti vapor admixture ratio (X Ti) was determined together with Ti excitation temperature () from two-dimensional (2D) optical emission spectroscopy (OES) during Ti feedstock injection into an Ar induction thermal plasma (ICTP) torch for Ti nanoparticle synthesis. The X Ti is one important parameter affecting ICTP properties such as its electrical conductivity. The value of X Ti was estimated from the radiation intensity ratio of the Ar atomic line to the Ti atomic line, and obtained from 2D OES observation. Furthermore the electron density (n e) was also determined from the estimated results of and X Ti through the equilibrium composition. These 2D OES results revealed as 2500-4000 K at around the central axis of the ICTP torch, although it was higher than 4000 K in the off-axis region. In the off-axis region, X Ti and n e were much higher than in the on-axis region.

DOI： 10.7567/JJAP.57.036101

Scopus

High-rate synthesis of Si nanowires using modulated induction thermal plasmas Reviewed

Yosuke Ishisaka, Naoto Kodama, Kentaro Kita, Yasunori Tanaka, Yoshihiko Uesugi, Tatsuo Ishijima, Shiori Sueyasu, Shu Watanabe, Keitaro Nakamura

APPLIED PHYSICS EXPRESS   Vol. 10 ( 9 )   2017.9

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

Using 20kW Ar-H-2 pulse-modulated induction thermal plasma (PMITP) with time-controlled feeding of feedstock (TCFF), numerous Si nanowires were synthesized rapidly at 1,000mgh(-1) without the intentional addition of catalysts. The PMITP + TCFF method is our original method for nanomaterial synthesis. The PMITP periodically provides a unique field including higher-temperature plasma during "on-time" and a lower-temperature plasma during "off-time". For rapid and efficient evaporation, metal-grade Si powder feedstock was intermittently injected synchronously into the generated Ar-H-2 PMITP. The synthesized products were analyzed using various analytical techniques. The synthesized products were Si nanowires 10-30 nm in diameter with a SiOx surface layer. (C) 2017 The Japan Society of Applied Physics

DOI： 10.7567/APEX.10.096201

Web of Science

Spatiotemporal distribution of thermal plasma temperature and nucleation occurrence in a torch during TiO₂ nanopowder synthesis Reviewed

N. Kodama, Y. Tanaka, K Kita, Y Ishisaka, Y. Uesugi, T. Ishijima, S. Sueyasu, K. Nakamura

Plasma Sources Science and Technologies     2017

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1088/1361-6595/aa73ca

Fundamental study of Ti feedstock evaporation and precursor formation process in inductively coupled thermal plasmas during TiO₂ nanopowder synthesis Reviewed

N. Kodama, K. Kita, Y. Ishisaka, Y. Tanaka, Y. Uesugi, T. Ishijima, S. Sueyasu, K. Nakamura

Journal of Physics D: Applied Physics     2016

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DOI： doi:10.1088/0022-3727/49/30/305501

A method for large-scale synthesis of Al-doped TiO₂ nanopowder using pulse-modulated induction thermal plasmas with time-controlled feedstock feeding Reviewed

Naoto Kodama, K. Kita, Y. Tanaka, Y. Uesugi, T. Ishijima, S. Watanabe, K. Nakamura

Journal of Physics D: Applied Physics     2014

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DOI： doi:10.1088/0022-3727/47/19/195304

Two-dimensional spectroscopic observation in the plasma torch for the pulse-modulated induction thermal plasmas for nanopowder synthesis Reviewed

N. Kodama, K. Kita, Y. Tanaka, Y. Uesugi, T. Ishijima, S. Watanabe, K. Nakamura

Journal of Physics: Conference Series     2014

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DOI： doi:10.1088/1742-6596/550/1/012026