Hoshino, Kazuo

写真a

Affiliation

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

Position

Associate Professor

Related Websites

External Links
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Career 【 Display / hide 】

  • 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

  • 2016.07
    -
    2018.03

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

  • 2018.04
    -
    Present

    Keio University, Faculty of Science and Technology, Associate Professor

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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 】

  • Study of plasma meniscus including surface produce negative ions by using PIC-MCC simulation

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

    Journal of Instrumentation （Journal of Instrumentation)  18 （ 6 ）  2023.06

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

    　View Summary

    In general, a quality of negative ion beam optics is determined by the shape of the plasma meniscus, which is an ion emitting surface. In this study, the key parameters to control the plasma meniscus and relevant physical structure in the electronegative plasma including the surface produced H- ions is investigated by using PIC-MCC simulation. The region from the source plasma up to the accelerator is modeled for a single aperture, and thus, the plasma meniscus can be obtained self-consistently. Parameter survey for the net flux of surface produced H- ion is conducted by varing the numbers of the surface produced H- ion super-particles per timestep in order to investigate the effcet of the electronegativity, that is, the ratio of the negative ion density to the electron density. It is shown that the effective distance d eff, between the plasma meniscus and the extraction grid depends on the electronegativity as well as the plasma density. Especially, the effective distance d eff, decreases with the increase of the electronegativity under the constant plasma density, which means that the shape of the plasma meniscus becomes flat or convex rather than concave. Moreover, it is also verified that the electronegativity affects the H- ion trajectories extracted from near the edge of plasma meniscus through the shape of plasma meniscus.

  • Recent progress of plasma exhaust concepts and divertor designs for tokamak DEMO reactors

    Asakura N., Hoshino K., Kakudate S., Subba F., You J.H., Wiesen S., Rognlien T.D., Ding R., Kwon S.

    Nuclear Materials and Energy （Nuclear Materials and Energy)  35 2023.06

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

    　View Summary

    The power exhaust concept and an appropriate divertor design are common critical issues for tokamak DEMO design activities which have been carried out in Europe, Japan, China, Korea and the USA. Conventional divertor concepts and power exhaust studies for recent DEMO designs (Pfusion = 1 – 2 GW, Rp = 7 – 9 m) are reviewed from the viewpoints of the plasma physics issues and the divertor engineering design. Radiative cooling is a common approach for the power fusion scenario. Requirements on the main plasma radiation fraction (fradmain = Pradmain/Pheat) and the plasma performance constrain the divertor design concept. Different challenges contribute to optimizing the future DEMO designs: for example, (i) increasing the main plasma radiation fraction for ITER-level Psep/Rp designs and simplifying the divertor geometry, and (ii) extending ITER divertor geometry with increasing divertor radiation (Praddiv) for larger Psep/Rp ≥ 25MWm−1 designs. Power exhaust simulations with large Psep = 150 – 300 MW have been performed using integrated divertor codes considering an ITER-based divertor geometry with longer leg length (1.6 – 1.7 m), as in a common baseline design. Geometry effects (ITER like geometry or more open one without baffle) on the plasma detachment profile and the required divertor radiation fraction (fraddiv = Praddiv/Psep) were key aspects of these studies. All simulations showed that the divertor plasma detachment were extended widely across the target plate with a reduction in the peak heat load of qtarget ≤ 10 MWm−2 for the large fraddiv = 0.7 – 0.8, while the peak qtarget location and value were noticeably different in the partially detached divertor. Simulation results also demonstrated that radial diffusion coefficients of the heat and particle fluxes were critical parameters for DEMO divertor design, and that effects of plasma drifts on outboard-enhanced asymmetry of the heat flux, suggested the need for longer divertor leg to ensure the existence of a detached divertor operation with qtarget ≤ 10 MWm−2. Integrated design of the water cooled divertor target, cassette body (CB) and cooling pipe routing has been developed for each DEMO concept, based on the ITER-like tungsten monoblock (W-MB) with Cu-alloy cooling pipes. Engineering design adequate under higher neutron irradiation condition was required. Therefore, inlet coolant temperature (Tcool) was increased. In current designs, it still shows a large potential variation between 70 °C and 200 °C. The influence of thermal softening on the Cu-alloy (CuCrZr) pipe was fostered near the strike-point when the high qtarget of ∼10 MWm−2 was studied. Improved technologies for high heat flux components based on the ITER W-MB unit have been developed for EU-DEMO. Different coolant conditions (low- and high-Tcool) were provided for Cu-alloy and reduced activation ferritic martensitic (RAFM) steel heat sink units, respectively. The high-Tcool coolant was also considered for the CB and supporting structures. Appropriate conditions for the high-Tcool coolant, i.e. 180 °C/ 5 MPa (EU-DEMO) and 290 °C/ 15 MPa (JA-DEMO, CFETR and K-DEMO), will be determined in the future optimizations of the divertor and DEMO design.

  • Transient analysis of high-Z impurity screening by additional injection of low-Z impurity using integrated divertor code SONIC

    Yamoto S., Hoshino K., Homma Y., Nakano T., Hayashi N.

    Nuclear Fusion （Nuclear Fusion)  63 （ 7 ）  2023.04

    Research paper (scientific journal), Joint Work, Accepted,  ISSN  00295515

    　View Summary

    The dynamics of the screening effect of Ar impurity by the injection of additional Ne has been studied through time-dependent analysis with the integrated divertor code SONIC. In the preceding study (Yamoto et al 2020 Plasma Phys. Control. Fusion 62 045006), the predictive simulation of JT-60SA plasma by SONIC has shown that the injection of additional Ne into Ar-seeded plasma results in lower Ar density and radiation power in the SOL and core edge than in the Ar-only seeded case. The results have demonstrated that the mixed impurity seeding of Ar and Ne may be advantageous for maintaining a high core plasma performance with a low divertor heat load. It was found that the friction force induced by the high D+ flow in the SOL towards the inner divertor (ID) region in the Ar + Ne seeded case pushes Ar impurities to the ID. However, the dynamics of D+ flow acceleration cannot be interpreted in the previous study because SONIC was a steady state code. In this study, we have developed the time-dependent version of SONIC and applied it to the transient analysis of the injection of additional Ne into Ar-seeded plasma in JT-60SA. When additional Ne is injected, Ne ions stay in the ID plasma near the X-point. As a result, the Ne radiation power increases near the X-point. The electron pressure then decreases due to the radiation cooling and the D+ flow is accelerated by the electron pressure gradient. The ion pressure also decreases due to the convection by the accelerated D+ flow by electron pressure gradient. The resulting ion pressure gradient further accelerates the D+ flow velocity towards the ID. The results suggest that both the high-performance core plasma and the low divertor heat load can be achieved by the Ar + Ne mixed impurity seeding.

  • Effect of Surface Produced H<sup>- </sup>Ion on the Plasma Meniscus in Negative Hydrogen Ion Sources

    HAYASHI Katsuya, HOSHINO Kazuo, HATAYAMA Akiyoshi, MIYAMOTO Kenji, LETTRY Jacques

    Plasma and Fusion Research （The Japan Society of Plasma Science and Nuclear Fusion Research)  18 （ 0 ） 1401008 - 1401008 2023.03

    Research paper (scientific journal), Joint Work, Accepted

    　View Summary

    <p>To extract intense ion beams with good beam optics from ion sources, controlling the distance <i>d</i><sub>eff </sub>between the plasma meniscus (i.e., beam emission surface) and the beam extraction grid is important. This study conducts a novel investigation into the dependence of the effective distance <i>d</i><sub>eff </sub>on the amount of surface H<sup>- </sup>production <i>S</i><sub>H-</sub>. For this purpose, a 3D PIC (three dimensional Particle-in-Cell) simulation is conducted to obtain a model geometry of the extraction region for a H<sup>- </sup>ion source with <i>S</i><sub>H- </sub>as a parameter. Based on results, <i>d</i><sub>eff </sub>significantly depends on <i>S</i><sub>H- </sub>and the H<sup>-</sup>-electron density ratio (α = <i>n</i><sub>H</sub>-/<i>n<sub>e</sub></i>) in front of the extraction aperture for the same plasma density; as <i>S</i><sub>H- </sub>increases, <i>d</i><sub>eff </sub>decreases. The results suggest that <i>S</i><sub>H- </sub>is critical for controlling <i>d</i><sub>eff </sub>and the resultant beam optics extracted from the negative ion source.</p>

  • The development of a zero-dimensional collisional-radiative model for interpreting plasma emission in low temperature divertor plasmas in tokamaks

    Fox-Widdows E., Bowden M.D., Hoshino K., Hatayama A., Osawa R., Tsubotani Y.

    Frontiers in Physics （Frontiers in Physics)  11 2023

    Research paper (scientific journal), Joint Work, Accepted

    　View Summary

    Collisional-radiative models are commonly used to analyse atomic and molecular processes in low temperature plasmas by determining the distribution functions of excited states as functions of various plasma parameters. This paper outlines the improvements to a zero-dimensional collisional-radiative model, developed at Keio University, for purposes relevant to the analysis of emission measurements in low temperature hydrogen plasmas. The extension of this 0D model centres on the inclusion of additional molecular species and reactions, a calculation of emission intensity in order to directly compare with experimental work, and the addition of a simple wall model to allow for a deeper understanding of recycling of atoms and molecules in low temperature plasmas close to plasma facing components in fusion machines. Results from the improved model are then compared with both an existing CR model for benchmarking and experimental emission spectroscopy data from an inductively-coupled plasma device at the University of Liverpool. These results show how the developments to the model have increased the relevance to experimental plasmas, such as those in the power exhaust regions of fusion machines, with the ratio of the Hβ/Hα line intensities outputted from the improved CR model mirroring more closely the emission measured experimentally in the ICP device.

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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

    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

  • 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 】

  • ダイバータプラズマにおける大角度散乱による粒子輸送 磁力線ピッチ角と中性粒子流速の影響

    梅崎大介、松浦秀明、星野一生

    第39回プラズマ・核融合学会年会, 

    2022.11
    , 

    Poster presentation

  • 原型炉プラズマ対向壁の燃料インベントリー評価とヘリウム照射効果

    大宅諒、星野一生、朝倉伸幸、坂本宜照、大野哲靖、花田和明

    第39回プラズマ・核融合学会年会, 

    2022.11
    , 

    Oral presentation (general)

  • トロイダルリップル及びRMPコイルパリティ差異に着目したJT-60SA周辺プラズマ輸送シミュレーション

    榎本昇悟、田中宏彦、河村学思、松永剛、鈴木康浩、小林政弘、星野一生、梶田信、大野哲靖

    第39回プラズマ・核融合学会年会, 

    2022.11
    , 

    Poster presentation

  • PICシミュレーションによる非接触ダイバータプラズマ解析

    星野一生、櫻井陽都、吉田旬汰

    第39回プラズマ・核融合学会年会, 

    2022.11
    , 

    Poster presentation

  • 分子の振動・回転状態を区別した水素および重水素の中性粒子輸送コードの開発

    土居健志、西分久弘、佐藤優作、上田朝陽、澤田圭司、河村思、齋藤誠紀、中村浩章、星野一生

    第39回プラズマ・核融合学会年会, 

    2022.11
    , 

    Poster presentation

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

  • 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。

  • 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
    -
    2022.03

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

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    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
    -
    2022.03

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

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    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。

  • Kinetic Modeling of Fusion Edge Plasma and Dynamic Characteristics of Detachemnt Plasmas

    2015.04
    -
    2018.03

    Keio University, Hatayama Akiyoshi, Sawada Keiji, Tsumori Katuyoshi, Kojima Atsushi, Murakami Izumi, Nakamura Hiroaki, Nakashima Yousuke, Lettry Jacques, Grant-in-Aid for Scientific Research (B), Research grant, Coinvestigator(s)

    　View Summary

    The final goal of this study is to develop a new kinetic simulation tool of plasmas, neutrals, and impurities in fusion edge plasmas. Taking into account the non-equilibrium and non-steady characteristics of electron energy distribution function (EEDF), we have done a dynamic simulation of the ELM (Edge Localized Mode). The effect of the ELM on the plasma detachment has been studied. Especially. the effects of the ELM on the MAR (Molecular Activated Recombination) has been analyzed. The results show that the vibrational excited molecules, which play a key for MAR, are effectively produced during the ELM heat pulse. Due to this enhancement, MAR rate is possibly enhanced after the ELM pulse. In addition, a new kinetic impurity transport model has been successfully developed. The model includes neo-classical transport effects of impurities, which becomes important under the steep density/temperature gradient in the core pedestal region before and after the ELM pulse.

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Courses Taught 【 Display / hide 】

  • SPECIAL TOPICS IN APPLIED PHYSICS AND PHYSICO-INFORMATICS

    2023

  • SCIENCE OF ATOMIC ENERGY

    2023

  • PRESENTATION TECHNIQUE

    2023

  • PLASMA PHYSICS

    2023

  • PLASMA PHYSICS

    2023

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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 】

  • 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

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