Hoshino, Kazuo

写真a

Affiliation

Faculty of Science and Technology, Department of Applied Physics and Physico-Informatics ( Yagami )

Position

Professor

E-mail Address

E-mail address

Related Websites

External Links
Scopus Paper Info  
Paper Count: 126 Citation Count: 1223 h-index: 17

Click to view the Scopus page. The data was downloaded from Scopus API in May 17, 2026, via http://api.elsevier.com and http://www.scopus.com .

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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

  • 2026.04
    -
    2027.03

    九州大学　高温プラズマ理工学研究センター

  • 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

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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

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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

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Research Areas 【 Display / hide 】

  • Energy Engineering / Fundamental plasma

  • Energy Engineering / Nuclear fusion

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Research Keywords 【 Display / hide 】

  • Plasma

  • Computer Simulation

  • Fusion

  • Divertor Plasma

  • Ion source plasma

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Papers 【 Display / hide 】

  • Code-to-code comparison of SOLPS-ITER and SONIC edge transport codes in JT-60SA tokamak plasma conditions

    Rubino G., Yamoto S., Coster D., Falchetto G., Wiesen S., Sozzi C., Hoshino K., Homma Y., Nakano T., Hayashi N., Aiba N.

    Fusion Engineering and Design 228 2026.07

    Research paper (scientific journal), Joint Work,  ISSN  09203796

    　View Summary

    Plasma boundary codes are widely used to interpret and predict SOL/divertor plasmas. The comparison of results obtained by these codes is one of the options to improve the SOL/divertor plasma modelling by defining possible limitations and enhancing the fidelity of future simulations. The aim of this study is to validate the transport models of SOL/divertor transport codes SOLPS-ITER and SONIC by terms-to-terms comparison, from the viewpoint of physical explanation rather than the numerical viewpoint. In this study, the comparison of the results between SOLPS-ITER and SONIC on pure-D plasma conditions with attached and partially detached plasmas in JT-60SA has been performed as a first step of the benchmarking activity. The calculation conditions such as computational grids, boundary conditions, and atomic/molecule database, are set to be as close as possible. In summary, the comparison can be concluded that no substantial difference can be seen although some differences in the plasma parameters have been observed. The main difference can be seen as the higher ratio of pressure drop in SOLPS-ITER than SONIC in front of the divertors in the partially detached case. It was found that the difference can be understood by the following process. The initial difference originated from the electron temperature and ion temperature in the vicinity of divertor plates. The electron temperature in SONIC near outer strike point is slightly higher than that of SOLPS-ITER. The difference in the electron temperature results in broader D+ particle source by ionization of neutrals and higher D+ ion density. Higher D+ ion and neutral densities in SOLPS-ITER leads to a larger momentum loss by charge exchange and thus the plasma loses its pressure. This result suggests that the small difference in the initial plasma parameters can be propagated by the interaction between neutrals, which affects the estimation of degree of detachment.

  • Deep Learning of Hydrogen Trapping Sites in Tungsten for Atomistic Plasma-Wall Simulations

    SAITO Seiki, TAKEUCHI Keisuke, NAKAMURA Hiroaki, ODA Yasuhiro, SAWADA Keiji, HOSHINO Kazuo, HOMMA Yuki, YAMOTO Shohei, UCHIDA Yuki

    Plasma and Fusion Research (The Japan Society of Plasma Science and Nuclear Fusion Research)  21 ( Special_1 ) n/a 2026

    Research paper (scientific journal), Joint Work, Accepted

    　View Summary

    <p>Understanding hydrogen trapping in tungsten is crucial for accurate modeling of plasma-wall interactions in fusion devices. In this study, we developed a deep learning model to predict hydrogen trapping sites, which serve as essential input parameters for kinetic Monte Carlo (kMC) simulations. The model employs a U-Net–based convolutional neural network that directly maps three-dimensional potential energy distributions to trapping site positions. Training data were generated from atomistic calculations using the embedded atom method (EAM) potential, and ground-truth trapping sites were systematically identified by force relaxation. The trained model achieved an F1 score of approximately 0.76, with most predicted sites coinciding with the true minima within ± 1 voxels (1 voxel = 0.1 Å per side). Visual comparisons confirmed the ability of the model to capture both global and local features of the potential energy landscape. In terms of efficiency, the proposed approach reduced prediction time by more than three orders of magnitude compared with conventional force-relaxation searches, enabling predictions in less than one second on a GPU. These results demonstrate that deep learning provides an accurate and computationally efficient method for identifying trapping sites. Future extensions include incorporating more complex defect structures and integrating the model into molecular dynamics-kMC hybrid frameworks for large-scale plasma-wall interaction simulations.</p>

  • Relationship between Surface-Produced H<sup>−</sup> Density and the Potential Structure of an Ion-Ion Plasma near the Extraction Aperture in Negative Hydrogen Ion Sources

    HAYASHI Katsuya, HOSHINO Kazuo, MIYAMOTO Kenji, HATAYAMA Akiyoshi

    Plasma and Fusion Research (The Japan Society of Plasma Science and Nuclear Fusion Research)  21 ( 0 ) n/a 2026

    Research paper (scientific journal), Joint Work, Accepted

    　View Summary

    <p>The so-called “ion-ion” plasma, which consists primarily of negative and positive ions, has been observed near the extraction aperture in negative hydrogen ion (H<sup>−</sup>) sources with a substantial amount of surface-produced negative ions, according to several experiments. In this study, to elucidate the characteristics of ion-ion plasmas with substantial surface H<sup>−</sup> production, the relationship between surface-produced negative ion density and electric potential is investigated using three-dimensional Particle-In-Cell simulations with the KEIO-BFX code. The results reveal that the plasma in a negative ion source can be classified into four distinct regions based on the relationship between H<sup>−</sup> density and electric potential: Region (I), where H<sup>−</sup> follows the Boltzmann relation; Region (II), where H<sup>+</sup> follows the Boltzmann relation; Region (III), a transition region between the plasma region and the beam acceleration region; and Region (IV), the beam acceleration region. In negative ion sources with surface-produced H<sup>−</sup> ions, plotting the H<sup>−</sup> density against the electric potential offers a useful method for identifying the plasma meniscus, which is crucial for optimizing extracted beam quality and ensuring proper operation of beam extraction systems.</p>

  • An Estimation of the Heat Load Distribution on the Divertor Target Using the CSD Model

    Yamada K., Hoshino K., Kawamura G., Si H., Hatayama A.

    Contributions to Plasma Physics  2026

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

    　View Summary

    Handling the heat load on the divertor target is a critical issue in the design of fusion reactors. Estimating the heat load, supported by computationally efficient simulations with varying design parameters, provides valuable input to high-level design discussions and the development of design guidelines. This study aims to estimate the spatial distribution of the heat load on the target at a low computational cost. The Core-SOL-Divertor (CSD) model is employed to provide the integrated heat load on the target. The CSD output forms the basis of an analytical approach to solving the heat transport equation, which yields the spatial distribution of the heat load on the target. The resulting heat load distribution shows good agreement with SOLPS-ITER. The predicted distribution and its dependence on design parameters provide useful guidance for the preliminary design of fusion reactors.

  • Source-term models based on the Boltzmann collision integral for hydrogen-isotope ion-atom collisions in fluid simulations

    Umezaki D., Yamoto S., Hoshino K., Asakura N., Kawamura G.

    Physics of Plasmas 32 ( 12 )  2025.12

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

    　View Summary

    In divertor plasmas, ion–atom collisions critically influence plasma transport and heat flux to divertor targets. Fluid neutral models are widely used in divertor simulations due to their low computational cost and favorable convergence properties. However, source terms representing ion–atom collisions often differ across codes because of variations in the cross section data and in the physical approaches used to model collisions between hydrogen isotope ions and atoms of identical nuclei. This study systematically evaluates these differences and establishes more consistent modeling approaches based on the Boltzmann collision integral (BCI). Using the BCI, we investigate particle transport in velocity space and assess the effect of scattering angles and differential cross sections (DCSs). Several analytical expressions—rarely used in divertor studies—are reviewed. For energy transfer, we derive a new BCI-based expression and validate the analytical expressions by comparing with the direct BCI evaluation. It is also pointed out that the commonly used charge–exchange (CX) cross section data no longer reflect recent experimental and theoretical developments. For deuteron-deuterium atom collisions at T = 10 eV, the CX-based model overestimates the friction force by more than 30% compared with the BCI-based model. For energy transfer between deuterons at T = 20 eV and deuterium atoms at T = 10 eV, the CX-based model overestimates the transferred energy by approximately 25%. The use of DCSs and the analytical expressions introduced in this study is therefore recommended. Implementing them in place of the conventional CX-based model may modify the predicted plasma profiles and the assessment of the detached divertor.

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

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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

  • 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 】

  • 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

    [Domestic presentation]  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

    [Domestic presentation]  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

    [Domestic presentation]  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

    [Domestic presentation]  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

    [Domestic presentation]  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 】

  • 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 】

  • 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

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Courses Taught 【 Display / hide 】

  • BACHELOR'S THESIS

    2026

  • COMPUTATIONAL PHYSICS

    2026

  • APPLIED PHYSICS AND PHYSICO-INFORMATICS LABORATORY C

    2026

  • DOCTORAL RESEARCH ON MATHEMATICAL AND PHYSICAL SCIENCES

    2026

  • INDEPENDENT STUDY ON FUNDAMENTAL SCIENCE AND TECHNOLOGY

    2026

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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
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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
    -
    2025.03

    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

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