KEIO RESEARCHERS INFORMATION SYSTEM

Career 【 Display / hide 】

Career 【 Display / hide 】

• 2024.04

  -

  Present

  Keio University, Faculty of Science and Technology, Professor

• 2020.02

  -

  Present

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

• 2008.04

  -

  2011.03

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

• 2011.04

  -

  2016.03

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

• 2016.04

  -

  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

  -

  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 】

• Machine learning-based hydrogen recycling model for predicting rovibrational distributions of released molecular hydrogen on tungsten materials via molecular dynamics simulations

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

  Nuclear Materials and Energy 43 2025.06

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

  　View Summary

  Understanding the hydrogen recycling process is crucial for comprehending the behavior of detached plasma in nuclear fusion devices. To achieve this, a molecular dynamics (MD) model is being developed to predict the distribution of translational energies and rovibrational states of hydrogen atoms and molecules released from the plasma-facing materials. Neutral transport simulations, utilizing distributions obtained from the MD model as boundary conditions, are also a powerful tool for analyzing the impact of recycled hydrogens on edge plasma. However, the MD model requires significant computational resources to obtain distributions under varying material and irradiation conditions such as material temperature and incident energy. Therefore, developing effective models that seamlessly integrate neutral transport simulation with hydrogen recycling models is crucial. Machine learning techniques are employed to develop predictive models capable of forecasting distributions of energies and rovibrational states of released hydrogen atoms and molecules. Furthermore, a model considering the incident energy distribution (shifted-Maxwellian) is developed by integrating the monochromatic distribution with the shifted-Maxwellian distribution.

  • Access to Document (DOI)

• Improvement of a CSD model toward detached plasma analyses by introducing effective loss factors based on plasma spatial distributions

  Yamada K., Hoshino K., Hatayama A.

  Plasma Physics and Controlled Fusion 67 ( 4 )  2025.03

  Research paper (scientific journal), Joint Work, Accepted,  ISSN  07413335

  　View Summary

  CSD (Core, SOL and Divertor) models sampling a fusion device with three points (Core, SOL and Divertor) aim at understanding fusion plasmas in a wide range of parameter space. Conventional CSD models estimate interactions among plasmas, neutrals and impurities, which are incorporated as loss factors in basic equations in models, with the use of physical quantities of plasmas at three sampled points. Physical quantities are assumed to be uniform in each of the three regions. Neglecting plasma spatial distributions in a divertor prevents the models from accurately evaluating loss factors at low temperatures. This is because loss factors strongly depend on the location-dependent temperature when the temperature is low. Consequently, conventional CSD models have difficulties in reproduction of the detachment. This research increases sampling points for the calculation of loss factors in a divertor. Loss factors at each point are integrated in the volume, then effective loss factors (ELF) for the divertor are obtained. Conventional loss factors in transport equations are replaced with ELFs for an improved CSD model proposed in this study. As a result, the plasma detachment is successfully reproduced in the CSD model without changing the equations. A CSD model for qualitative analyses with low computational costs has been developed to study plasma detachment.

  • Access to Document (DOI)

• DISCOVER: New integrated code to simulate helium detached plasma in a linear device

  Natsume H., Masuda S., Tanaka H., Migita R., Mano R., Sugiura K., Sawada K., Hoshino K., Hayashi Y., Ohno N.

  Physics of Plasmas 32 ( 2 ) 022508 2025.02

  Research paper (scientific journal), Joint Work, Accepted,  ISSN  1070664X

  　View Summary

  A detached plasma integrated simulation code with various elastic/inelastic reactions (DISCOVER) was developed for better understanding of detached helium plasma experiments. DISCOVER, which includes a neutral transport code, fluid code, and collisional radiative code, considers elastic and inelastic collisions between recycling neutrals and bulk particles, as well as the transport of metastable atoms [He( 21S) and He( 23S)]. The code was used for simulating helium plasma in the linear plasma device NAGDIS-II. The transition from attached to detached plasma was demonstrated in the simulation by increasing the upstream electron density through an increase in the gas supply from the plasma source while maintaining a fixed downstream gas injection rate. In addition, similar transition was also observed by introducing neutral particles from downstream, while maintaining a fixed upstream electron density. In the detached plasma, the density of He( 23S) near the end target was approximately seven times higher than that in the attached plasma. Furthermore, it was evident that the transport of He( 23S) enhanced the electron energy rate coefficient and influenced the spatial distribution of the detached plasma.

  • Access to Document (DOI)

• Investigation of spatial distribution characteristics of emission intensity in detachment on the divertor simulator TPDsheet-ICR

  Tonegawa A., Okada N., Miura K., Natume H., Sato K.N., Hoshino K., Hayashi Y., Masuzaki S., Yamoto S.

  Nuclear Materials and Energy 41 2024.12

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

  　View Summary

  For the first time, we have revealed the spatial structure of a detached plasma with electron–ion recombination (EIR) and molecular-activated recombination (MAR) in response to changes in ion temperature (Ti) and gas pressure. This was achieved using high-density sheet plasma generated by a linear divertor simulator (TPDsheet-ICR). The parallel-plate electrodes were positioned above and below the sheet plasma (∼1019 m−3). We varied the Ti from 3 to 7 eV using ion cyclotron resonance heating and investigated the parameters of the detached plasma near the target in the divergent field region. Plasma emission intensities at Balmer series (Hα and Hγ) and Fulcher band wavelengths (610 ± 10 nm) were measured with a high-speed camera equipped with an Arbaa prism. Additionally, a Langmuir probe measured the electron density and temperature of the plasma. Our results show that as the Ti increases, EIR generated near the plasma periphery disappears, while MAR gradually forms near the plasma center during the transition from detached to attached plasma. This transition occurs because the increase in Ti in the detached plasma transfers energy from ions to electrons, raising the high-energy component of the electrons, resulting in EIR disappearance and the onset of MAR.

  • Access to Document (DOI)

• Evaluation of local erosion and deposition on the W-monoblock of JA-DEMO divertor

  Oya M., Hoshino K., Asakura N., Sakamoto Y., Ohno N., Hanada K.

  Nuclear Materials and Energy 41 2024.12

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

  　View Summary

  We developed and performed a 3D Monte-Carlo simulation on local erosion and deposition in outer divertor target of JA-DEMO. The local erosion and deposition were evaluated considering the divertor plasma parameters and the roof shape of W-monoblocks. First, for local erosion simulation, the trajectories of D ions and impurity (He and Ar) ions were traced before irradiating the monoblock surface. The physical sputtering was calculated by these ions irradiation, considering their charge states, incident-energies and -angles. The highest sputtering flux was produced by multiply-charged Ar ions (Ar3+–Ar5+). The sputtering flux strongly depended on the poloidal positions along the divertor target. Although almost no erosion (sputtering) was obtained in low-temperature zone (∼1 eV), the erosion occurred in mid- (∼10 eV) and high-temperature (>10 eV) zone. Second, for local deposition simulation, the trajectories of W atoms emitted from the monoblock surface were traced. After transport (including ionization and recombination) in the plasma, W atoms and ions were deposited on the monoblock surface. The deposition occurred even on the area where plasmas did not irradiate (shadow). This was due to perpendicular diffusion to magnetic field lines, gyro-orbit effects for W ions and straight-line motion for neutral W atoms. The poloidal distribution of the deposition fluxes was similar to that of the sputtering fluxes. In low-temperature zone, no deposition flux occurred due to very low sputtering flux. The deposition flux in mid-temperature zone increased significantly and that in high-temperature zone remained high.

  • 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

  Kenji Miyamoto

  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 】

• シンポジウム　原型炉級ダイバータ模擬プラズマ開発：　原型炉級ダイバータプラズマシミュレーション

  星野一生

  第41回プラズマ・核融合学会年会 (東京都江戸川区) , 

  2024.11

  , 

  Symposium, workshop panel (nominated)

• Simulation of Hydrogen Recycling on Tungsten Wall in Fusion Device

  Seiki Saito, Yuki Kojima, Hiroaki Nakamura, Keiji Sawada, Kazuo Hoshino, Yuki Homma and Shohei Yamoto

  The 43rd JSST Annual International Conference on Simulation Technology & The 23rd Asia Simulation Conference (Kobe, Japan) , 

  2024.11

  , 

  Poster presentation

• 原型炉ダイバータにおけるスパッタ損耗の評価とタングステン不純物の影響

  大宅諒、星野一生、朝倉伸幸、坂本宜照、大野哲靖、花田和明

  第41回プラズマ・核融合学会年会 (東京都江戸川区) , 

  2024.11

  , 

  Poster presentation

• 体積素過程存在下における断熱の式の一般化と磁力線方向流速の音速遷移条件の考察

  東郷訓、滝塚知典、池添竜也、文川優蘭、伊庭野健造、星野一生、江角直道、横山大起、青木史、本間佳史、國井朗光、丸山早瀬、江本一磨、坂本瑞樹

  第41回プラズマ・核融合学会年会 (東京都江戸川区) , 

  2024.11

  , 

  Poster presentation

• JA-DEMOの非接触ダイバータにおける中性粒子間衝突および熱力モデルの熱粒子制御への影響

  朝倉伸幸、星野一生、山本龍人、本間裕貴、 坂本宜照

  第41回プラズマ・核融合学会年会 (東京都江戸川区) , 

  2024.11

  , 

  Oral presentation (general)

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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

  -

  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。

• Theoretical study of the physical mechanism of isotope effects in deuterium negative ion sources

  2019.04

  -

  2022.03

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

  　View Summary

  In this study, the cause of the increase in electron current, which is one of the isotope effects in a deuterium negative ion source, was investigated using both an analysis with a zero-dimensional model that takes into account the atomic and molecular collision processes between hydrogen and deuterium, and a numerical simulation for electron transport analysis (KEIO-MARC code).
  First, for the zero-dimensional model, the results shows that the plasma density is approximately 1.7 times higher for deuterium due to differences in the effective reaction rate coefficients for ionization of hydrogen and deuterium and the transport loss time constant of positive ions. Similar results are also obtained with the KEIO-MARC code. From the above, it is made clear that the increase in electron current due to deuteration is caused by differences in the effective reaction rate coefficients for ionization and the effective confinement time of positive ions.

• Invesigation of dynamic characteristics of the detached divertor plasma by kinetic modeling

  2019.04

  -

  2022.03

  Keio University, Grants-in-Aid for Scientific Research, Hoshino Kazuo, Grant-in-Aid for Scientific Research (C), Research grant, Principal investigator

  　View Summary

  To understand the dynamic characteristics of the detached divertor plasmas in fusion reactors, an integrated model has been developed by coupling a particle-in-cell (PIC) model solving for the plasma transport with a 0-dimensional model solving for the time evolution of the space-averaged atomic and molecular density. The integrated model tentatively reproduced the detached divertor plasma. The time evolution of the divertor plasma after the high energy pulse injection and the energy loss due to the interaction with neutral particles were analysed. The basis of a simulation model was established to clarify the dynamic characteristics of the detached divertor plasma.

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Awards 【 Display / hide 】

Awards 【 Display / hide 】

• 核融合大型計算機利用研究優秀賞

  2024.09, 国立研究開発法人　量子科学技術研究開発機構

  Type of Award： Other

Courses Taught 【 Display / hide 】

Courses Taught 【 Display / hide 】

• SCIENCE OF ATOMIC ENERGY

  2025

• PRESENTATION TECHNIQUE

  2025

• PLASMA PHYSICS

  2025

• PLASMA PHYSICS

  2025

• INDEPENDENT STUDY ON FUNDAMENTAL SCIENCE AND TECHNOLOGY

  2025

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Memberships in Academic Societies 【 Display / hide 】

Memberships in Academic Societies 【 Display / hide 】

• Japan Society for Simulation Technology, 

  2022.07

  -

  Present

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

  2001.08

  -

  Present

Committee Experiences 【 Display / hide 】

Committee Experiences 【 Display / hide 】

• 2024.04

  -

  2026.03

  代議員, 一般社団法人 プラズマ・核融合学会

• 2021.09

  -

  Present

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

• 2019.12

  -

  Present

  核融合エネルギーフォーラム専門委員

• 2019.07

  -

  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