KEIO RESEARCHERS INFORMATION SYSTEM

Career 【 Display / hide 】

Career 【 Display / hide 】

• 2024.04

  -

  Present

  Keio University, Faculty of Science and Technology, Professor

• 2020.02

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  Present

  National Institutes for Quantum and Radiological Science and Technology, Visiting Researcher

• 2008.04

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  2011.03

  Japan Atomic Energy Agency, Sector of Fusion Research and Development, Postdoctoral Fellow

• 2011.04

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  2016.03

  Japan Atomic Energy Agency, Sector of Fusion Research and Development, Researcher

• 2016.04

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  2016.06

  National Institutes for Quantum and Radiological Science and Technology, Fusion Energy Research and Development Directorate, Senior Researcher

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Academic Background 【 Display / hide 】

Academic Background 【 Display / hide 】

• 1998.04

  -

  2002.03

  Keio University, Faculty of Science and Technology, Department of Applied Physics and Physico-Informatics

  University, Graduated

• 2003.04

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  2005.03

  Keio University, Graduate School of Science and Technology, School of Fundamental Science and Technology

  Graduate School, Completed, Master's course

• 2005.04

  -

  2008.03

  Keio University, Graduate School of Science and Technology, School of Fundamental Science and Technology

  Graduate School, Completed, Doctoral course

Academic Degrees 【 Display / hide 】

Academic Degrees 【 Display / hide 】

• Ph.D (Engineering), Keio University, Coursework, 2008.03

  Study of Flow Structure and Transport Process of Heavy Metal Impurity in Tokamak Edge Plasmas

Research Areas 【 Display / hide 】

Research Areas 【 Display / hide 】

• Energy Engineering / Fundamental plasma

• Energy Engineering / Nuclear fusion

Research Keywords 【 Display / hide 】

Research Keywords 【 Display / hide 】

• Plasma

• Computer Simulation

• Fusion

• Divertor Plasma

• Ion source plasma

Papers 【 Display / hide 】

Papers 【 Display / hide 】

• Numerical study of the plasma meniscus shape and beam optics in RF negative ion sources

  Hayashi K., Hoshino K., Miyamoto K., Hatayama A., Lettry J.

  Journal of Instrumentation 19 （ 4 ） C04031 2024.04

  Research paper (international conference proceedings), Joint Work, Accepted

  　View Summary

  In order to extract intense ion beams with good beam optics from hydrogen negative ion sources, it is important to control the shape of the plasma meniscus (i.e. beam emission surface). Recently, it is suggested experimentally that the degradation of beam optics in the RF negative ion sources may be due to the fluctuation of the distance d eff between the meniscus and the extraction grid caused by the fluctuation of the plasma density np . The purpose of this study is to make clear the dependence of d eff on np in the presence of a large amount of surface produced H- ions in order to understand such fluctuation of beam optics in RF sources For the purpose, 3D electrostatic PIC simulation was conducted taking the bulk plasma density as a parameter, investigating the extraction region of a H- ion source. A large amount of the surface H- production on the PG has been taken into account under the assumption that the H- production rate is proportional to the bulk plasma density. The result shows that the effective distance d eff is proportional to np-1/2 even for a large amount of surface H- production. This dependence suggests that the bulk plasma density np is the key parameters to control d eff and the resultant beam optics extracted from the negative ion source.

  • Access to Document (DOI)

• Hamiltonian simulation using the quantum singular-value transformation: Complexity analysis and application to the linearized Vlasov-Poisson equation

  Toyoizumi K., Yamamoto N., Hoshino K.

  Physical Review A 109 （ 1 ） 01243 2024.01

  Research paper (scientific journal), Joint Work, Accepted,  ISSN  24699926

  　View Summary

  Quantum computing can be used to speed up the simulation time (more precisely, the number of queries of the algorithm) for physical systems; one such promising approach is the Hamiltonian simulation (HS) algorithm. Recently, it was proven that the quantum singular-value transformation (QSVT) achieves the minimum simulation time for HS. An important subroutine of the QSVT-based HS algorithm is the amplitude amplification operation, which can be realized via the oblivious amplitude amplification or the fixed-point amplitude amplification in the QSVT framework. In this work we execute a detailed analysis of the error and number of queries of the QSVT-based HS and show that the oblivious method is better than the fixed-point one in the sense of simulation time. Based on this finding, we apply the QSVT-based HS to the one-dimensional linearized Vlasov-Poisson equation and demonstrate that the linear Landau damping can be successfully simulated.

  • Access to Document (DOI)

• Spatial Distribution Analyses of Axially Long Plasmas under a Multi-Cusp Magnetic Field Using a Kinetic Particle Simulation Code KEIO-MARC

  Nishimura R., Seino T., Yoshimura K., Takahashi H., Matsuyama A., Hoshino K., Oishi T., Tobita K.

  Plasma （Plasma)  7 （ 1 ） 64 - 75 2024.01

  Research paper (scientific journal), Joint Work, Accepted

  　View Summary

  To realize the development of a long plasma source with a uniform electron density distribution in the axial direction, the spatial distribution of plasma under a multi-cusp magnetic field was analyzed using a KEIO-MARC code. Considering a cylindrical plasma source with an axial length of 3000 mm and a cross-sectional diameter of 100 mm, in which the filament electrode was the electron source, the electron density distribution was calculated using the residual magnetic flux density, Bres, and the number of permanent magnets installed at different locations surrounding the device, Nmag, as design parameters. The results show that both Bres and Nmag improved the uniformity of the electron density distribution in the axial direction. The maximum axial electron density decreased with increasing Nmag and increased with increasing Bres. These trends can be explained by considering the nature of the multi-cusp field, where particles are mainly confined to the field-free region (FFR) near the center of the plasma column, and the loss of particles due to radial particle transport. The use of multiple filaments at intervals shorter than the plasma decay length dramatically improved axial uniformity. To further improve axial uniformity, the filament length and FFR must be properly set so that electrons are emitted inside the FFR.

  • Access to Document (DOI)

• Effect of Large-Angle Scattering on Particle Transport and Heat Flux in Advanced Divertor Magnetic Field Configurations

  UMEZAKI Daisuke, MATSUURA Hideaki, HOSHINO Kazuo

  Plasma and Fusion Research （The Japan Society of Plasma Science and Nuclear Fusion Research)  19 （ 0 ） 1403003 - 1403003 2024.01

  Research paper (scientific journal), Joint Work, Accepted

  　View Summary

  <p>Divertor heat loads are one of the most significant issues affecting fusion reactors. Atomic processes play a crucial role in reduction of the divertor heat load. Notably, elastic scattering between ions and neutral particles can be characterized as large-angle scattering. A large fraction of ion energy is transferred to neutral particles, and the ion direction can be significantly changed by a single large-angle scattering event. In abundant neutral particle regions such as divertor plasmas, the large-angle elastic scattering results in additional ion transport perpendicular to magnetic field lines. Effect of the additional ion transport is expected to be significant at low magnetic field strength and long Larmor radii, such as in a case of advanced divertors (e.g., Super-X and Snowflake divertors). In this study, we investigated the effect of the large-angle elastic scattering at low magnetic field strength and long divertor legs with reference to advanced divertor configurations using an orbital calculation. The large-angle elastic scattering transport is seen to cause a spread in density profiles and a reduction of heat flux. The results of this study show that for the short (long) leg divertor configuration like JT-60U (advanced divertor), the peak heat flux is reduced by around 15% (21%) when the magnetic field strength is 0.5 T in comparison to the model that assumes no guiding center movement due to the elastic scattering. It is also shown that the assumption of isotropic elastic scattering with neutral particles leads to excessive suppression of ion flows.</p>

  • Access to Document (DOI)
  • CiNii Research

• Estimation of impact of non-local ion heat flux model on transport simulation for DEMO-relevant scrape-off layer plasma

  Homma Y., Hoshino K., Yamoto S., Tokunaga S., Asakura N., Miyato N.

  Contributions to Plasma Physics  2024

  Research paper (international conference proceedings), Joint Work, Accepted,  ISSN  08631042

  　View Summary

  In a fusion DEMOnstration reactor (DEMO)-relevant scrape-off layer plasma (SOL), whose collisionality is lower than in the SOLs of present-day tokamaks, kinetic effects are predicted to reduce the plasma heat conductivity along the magnetic field below the value obtained with the classical Spitzer–Harm model. As a part of ongoing efforts to improve the predictive capability of SOL heat transport calculations, we have implemented the non-local heat flux model proposed by [Luciani, Mora and Virmont, Phys. Rev. Lett. 51 (1983) 1664–1667] (here referred to as the LMV model) in the integrated SOL–divertor simulation code SONIC in order to account for the kinetic effect on the heat conduction due to the parallel streaming of rapidly moving particles. Our transport simulations for the Japanese demonstration tokamak reactor concept, JA DEMO, show that the LMV model yields a significantly reduced ion parallel conductive heat flux density both on the low- and high-field side of the upstream SOL. The heat flux obtained with the LMV model seems to be consistent with earlier kinetic simulations of tokamak ion transport. As a consequence of the reduced heat flux, a significant increase in the ion temperature and a decrease in the density have also been found over a broad area of the upstream SOL.

  • Access to Document (DOI)

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Papers, etc., Registered in KOARA 【 Display / hide 】

Papers, etc., Registered in KOARA 【 Display / hide 】

• Study of impurity transport in boundary plasma of fusion device

  Hoshino, Kazuo

  学事振興資金研究成果実績報告書 （慶應義塾大学)  2018

• Kinetic modeling of fusion edge plasma and dynamic characteristics of detachment plasmas

  Hoshino, Kazuo

  科学研究費補助金研究成果報告書 2017

Reviews, Commentaries, etc. 【 Display / hide 】

Reviews, Commentaries, etc. 【 Display / hide 】

• イオン源の数値シミュレーション技術の進展と応用

  星野 一生, 宮本 賢治, 畑山 明聖

  プラズマ・核融合学会誌 97   568 - 596 2021

  Article, review, commentary, editorial, etc. (scientific journal), Joint Work

  • CiNii Research

• 小特集統合コードによる磁場閉じ込め核融合プラズマシミュレーションの現状と今後の展望：　２．統合コードを構成する物理モジュール群

  村上定義，本多充，相羽信行，松山顕之，林伸彦，星野一生，藤田隆明，福山淳，横山雅之

  プラズマ・核融合学会誌 95 ( 09 ) 427 - 436 2019.09

  Article, review, commentary, editorial, etc. (scientific journal), Joint Work

• 小特集　原型炉に向けてのダイバータの研究開発課題ー現状と展望ー：　２．日本における原型炉ダイバータ概念の現状と開発課題

  朝倉伸幸、星野一生

  プラズマ・核融合学会誌 92 ( 12 ) 870 - 876 2016.12

  Article, review, commentary, editorial, etc. (scientific journal), Joint Work

• 小特集　原型炉に向けてのダイバータの研究開発課題ー現状と展望ー：3 非接触プラズマと熱・粒子処理に関するダイバータ実験研究およびモデリングの現状と研究開発課題　3.2 ダイバータモデリング研究

  星野一生

  プラズマ・核融合学会誌 92 ( 12 ) 882 - 885 2016.12

  Article, review, commentary, editorial, etc. (scientific journal), Single Work

• 小特集 DEMOに向けた直線型装置を用いた境界プラズマ、プラズマ・壁相互作用研究： １．直線型プラズマ生成装置の現状と原型炉ダイバータ設計における課題

  坂本瑞樹、大野哲靖、朝倉伸幸、星野一生

  プラズマ・核融合学会誌 90 ( 08 ) 473 - 479 2014.08

  Article, review, commentary, editorial, etc. (scientific journal), Joint Work

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Presentations 【 Display / hide 】

Presentations 【 Display / hide 】

• 直線型プラズマ装置NAGDIS-IIを用いた非接触プラズマに関する実験・モデリングの進展と今後の展開

  大野哲靖、田中宏彦、眞野綾二、上松雄太、夏目祥揮、澤田圭司、梶田信、林祐貴、石劼霖、星野一生、荒巻光利

  第15回核融合エネルギー連合講演会 (八戸) , 

  2024.06

  , 

  Poster presentation

• 炉心とSOL・ダイバータとの統合モデリングの進展

  林伸彦、矢本昌平、星野一生

  第15回核融合エネルギー連合講演会 (八戸) , 

  2024.06

  , 

  Poster presentation

• Hydrogen Recycling Model on Tungsten Materials by Machine Learning based on Molecular Dynamics Simulation

  S. Saito, M. Iida, H. Nakamura, K. Sawada, K. Hoshino, M. Kobayashi, M. Hasuo, Y. Homma, S. Yamoto

  the 26th International Conference on Plasma Surface Interaction in Controlled Fusion Devices (Marseille, France) , 

  2024.05

  , 

  Poster presentation

• Simulation studies of power and Helium exhaust in detach divertor and impurity transport for JA-DEMO divertor

  N. Asakura, K. Hoshino, Y. Homma, T. Yamamoto, Y. Sakamoto

  the 26th International Conference on Plasma Surface Interaction in Controlled Fusion Devices (Marseille, France) , 

  2024.05

  , 

  Poster presentation

• Numerical Investigation of Hydrogen Molecule Release in High Rovibrational States from Tungsten Walls

  H. Nakamura, S. Saito, K. Sawada, K. Hoshino, Y. Kojima, T. Doi, M. Kobayashi, M. Hasuo, Y. Homma, S. Yamoto

  the 26th International Conference on Plasma Surface Interaction in Controlled Fusion Devices (Marseille, France) , 

  2024.05

  , 

  Poster presentation

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Research Projects of Competitive Funds, etc. 【 Display / hide 】

Research Projects of Competitive Funds, etc. 【 Display / hide 】

• Understanding energy and momentum losses associated with the generation and transport of excited particles and control of detached recombining plasma

  2024.04

  -

  2028.03

  Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (A), Coinvestigator(s)

  　View Summary

  磁場閉じ込めプラズマ核融合炉の実現のためには，炉心プラズマから周辺領域に流出する膨大な粒子流および熱流を制御し，直接プラズマと接触するプラズマ対向材(ダイバータ板)の損傷を低減することが最重要課題の一つとなっている。熱負荷低減法として，非接触再結合プラズマ（Detached Recombining Plasmas）形成による熱流制御法の確立の重要性が指摘されている。本研究では，直線型高密道プラズマ発生装置を用いた実験と流体コード，中性粒子輸送コードをカップリングした統合コードによる解析により，非接触再結合プラズマの生成機構と制御手法を確立し，核融合発電の早期実現に資する。

• ダイバータ配位プラズマの境界層におけるプラズマ流と不純物輸送へのドリフトの効果

  2022.04

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  2026.03

  Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (B), Coinvestigator(s)

  　View Summary

  内部コイルを用いてダイバータ配位の環状プラズマを生成し、その境界層におけるプラズマ流や不純物イオンの流速などを詳細に計測する。三角形度などプラズマ断面形状を様々に変えた実験を実施し、ダイバータプラズマシミュレーションコードの結果と比較する。これにより、プラズマ流に対するイオンドリフトの効果を明らかにするとともに実験的な裏付けのある不純物輸送モデルを提案する。

• Elucidation and control of the physical and chemical mechanisms governing the spatio-temporal structure of detached recombining plasmas

  2020.04

  -

  2024.03

  Nagoya University, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (A), Research grant, Coinvestigator(s)

  　View Summary

  プラズマプロセッシングや核融合研究において重要な課題となっている気相中で消えるプラズマの物性を明らかにする。電子・イオン再結合（三体再結合，放射再結合）が主要な過程となる再結合プラズマ中の非熱平衡性，電位構造に関連した熱・粒子輸送過程を，直線型高密度プラズマ発生装置を用いた基礎実験とシミュレーションとの相補的な研究により明らかにする。また，振動励起水素分子により駆動される再結合（分子駆動再結合）プラズマ生成に関して，固体壁で生成される振動・回転励起水素分子の影響と同位体効果を明らかにする。さらに，再結合プラズマのパルス応答を高時間分解で調べ，時空間変化を決定する物理・化学過程を明らかにする。

• 重水素負イオン源における同位体効果の物理メカニズムの理論的解明

  2019.04

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  2022.03

  Naruto University of Education, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (C), Coinvestigator(s)

  　View Summary

  本研究は重水素負イオン源について、運動論的粒子モデルに基づく数値計算シミュレーションにより、負イオン源のドライバー領域から引出・加速部までを総括的にモデリングし、「研究の目的」に挙げた同位体効果と呼ばれる水素の場合と異なる物理特性のメカニズムを解明することが目的である。そして得られた知見により、核融合や医療用加速器等において、研究開発が進められている重水素負イオン源の実現に貢献する。

• 運動論的統合モデリングによる非接触ダイバータプラズマの動的応答特性の解明

  2019.04

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  2022.03

  Keio University, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (C), No Setting, Principal investigator

  　View Summary

  核融合原型炉に向けた最重要課題であるダイバータにかかる熱・粒子負荷の低減には、非接触ダイバータプラズマの形成と制御が必須である。本研究課題では、この非接触ダイバータプラズマの物理機構と動的応答特性の解明を目的とする。まず、プラズマPIC(Particle in Cell)モデルと先進的中性粒子輸送コードを用いて、ダイバータプラズマの基本的な動特性の理解を進める。その後、これらのモデルを結合した運動論的統合シミュレーションコードを開発する。開発した統合コードを用いて、非接触ダイバータプラズマの動的応答特性について総合的な理解を進め、その物理機構を明らかにする。

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Courses Taught 【 Display / hide 】

Courses Taught 【 Display / hide 】

• SPECIAL TOPICS IN APPLIED PHYSICS AND PHYSICO-INFORMATICS

  2024

• SCIENCE OF ATOMIC ENERGY

  2024

• PRESENTATION TECHNIQUE

  2024

• PLASMA PHYSICS

  2024

• PLASMA PHYSICS

  2024

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Memberships in Academic Societies 【 Display / hide 】

Memberships in Academic Societies 【 Display / hide 】

• Japan Society for Simulation Technology, 

  2022.07

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  Present

• The Japan Society of Plasma Science and Nuclear Fusion Research, 

  2001.08

  -

  Present

Committee Experiences 【 Display / hide 】

Committee Experiences 【 Display / hide 】

• 2021.09

  -

  Present

  Member of the International Scientific Committee of Plasma Edge Theory in Fusion Devices

• 2019.12

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  Present

  核融合エネルギーフォーラム専門委員

• 2019.07

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  Present

  炉心プラズマ共同企画委員会　理論シミュレーション専門部会　専門委員, 量子科学技術研究開発機構

• 2017.07

  -

  2019.06

  編集委員, プラズマ・核融合学会