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Reference design of the power supply system for the resistive-wall-mode control in JT-60SA

Ferro, A.*; Gaio, E.*; Novello, L.*; 松川 誠; 島田 勝弘; 川俣 陽一; 武智 学

Fusion Engineering and Design, 98-99, p.1053 - 1057, 2015/10

 被引用回数:2 パーセンタイル:19.3(Nuclear Science & Technology)

JT-60SA is the satellite tokamak under construction in Naka, Japan, in the framework of the EU - JA "Broader Approach" Agreement. In JT-60SA, to attain steady-state high-beta plasmas, suppression of Resistive Wall Modes (RWM) is necessary. At this purpose, a passive stabilizing plate (SP) and an active control system based on 18 in-vessel sector coils (SC) are foreseen. This paper firstly reports the main requirements for the RWM control system. Then, the reference design of the RWM-PS is described. It includes an ac/dc conversion system, dc-link capacitor banks and a set of 18 fast inverters. The advantages of the proposed scheme are discussed and the main electrical parameters are shown in detail. The main requirements of the control section are given, with details on possible implementation and interfaces with JT-60SA central control.


Development of magnetic sensors for JT-60SA

武智 学; 松永 剛; 櫻井 真治; 笹島 唯之; 柳生 純一; 星 亨*; 川俣 陽一; 栗原 研一; JT-60SAチーム; Nishikawa, T.*; et al.

Fusion Engineering and Design, 96-97, p.985 - 988, 2015/10

 被引用回数:9 パーセンタイル:59.96(Nuclear Science & Technology)

JT-60SA, which has fully super conducting coils, is under construction in order to demonstrate and develop steady-state high beta operation for supplement ITER toward DEMO. Three types of coils will be installed in the vacuum vessel for resistive wall mode (RWM) control, error field correction and also for edge localized mode (ELM) control. Biaxial magnetic sensors have been developed, because 3D information of magnetic configuration is necessary for these controls. Also, redesigned magnetic sensors for basic information of JT-60SA plasma, e.g. one-turn loop, Rogowski coils, diamagnetic loop and saddle coils have been developed, because manufacture and installation of these sensors are much more difficult for JT-60SA than those for JT-60U. The design and the specification of the magnetic sensors for JT-60SA will be reported from engineering and physics aspects.


In-vessel coils for magnetic error field correction in JT-60SA

松永 剛; 武智 学; 櫻井 真治; 鈴木 康浩*; 井手 俊介; 浦野 創

Fusion Engineering and Design, 98-99, p.1113 - 1117, 2015/10

 被引用回数:13 パーセンタイル:76.47(Nuclear Science & Technology)

JT-60SA is designed and under construction as fully superconducting tokamak under a combined project of the ITER satellite tokamak program of EU-JA (Broader Approach Activities) and the Japanese national program. One of the main purposes of JT-60SA is the steady-state high-beta operation above the ideal no-wall beta limit. To achieve this, we have designed in-vessel coils, thus error filed correction coils (EFCCs) for a correction of magnetic error fields that affect plasma initiation and induce magnetic island locking. We will report the design of the EFCC in JT-60SA from an engineering and a physics points of view.


Estimation of the lifetime of resin insulators against baking temperature for JT-60SA in-vessel coils

助川 篤彦; 村上 陽之; 松永 剛; 櫻井 真治; 武智 学; 吉田 清; 池田 佳隆

Fusion Engineering and Design, 98-99, p.2076 - 2079, 2015/10

 被引用回数:1 パーセンタイル:10.43(Nuclear Science & Technology)

JT-60SA計画は、ITER計画の幅広いアプローチ計画の日欧協力で進められている。JT-60SA容器内コイルは日本で設計・製作を行う。容器内コイル用の樹脂絶縁材には、真空容器のベーキング温度条件(200$$^{circ}$$C, 40000時間)に沿った耐熱性能が要求される。今回、容器内コイル設計に向け、耐熱耐久性の調査を実施し、$$sim$$220$$^{circ}$$C環境で、エポキシ樹脂、シアネートエステル樹脂を母材とする7種類の候補樹脂絶縁材の寿命評価を実施した。高温環境下における化学反応速度はアレニウス法で評価する。耐熱耐久試験では、180$$^{circ}$$C, 200$$^{circ}$$C, 220$$^{circ}$$Cの恒温槽で一定期間保持し、その後、絶縁材の重量減少を測定する。樹脂絶縁材の重量減少率の結果を入力にワイブル解析を実施し、その後、アレニウスプロットにより候補樹脂絶縁材の寿命評価を初めて実施した。この結果、容器内コイルの適用温度は169$$^{circ}$$Cであることが分かった。


Assessment of the accuracy of plasma shape reconstruction by the Cauchy condition surface method in JT-60SA

宮田 良明; 鈴木 隆博; 武智 学; 浦野 創; 井手 俊介

Review of Scientific Instruments, 86(7), p.073511_1 - 073511_13, 2015/07

 被引用回数:5 パーセンタイル:26.06(Instruments & Instrumentation)



Optimization of JT-60SA plasma operational scenario with capabilities of installed actuators

井手 俊介; 相羽 信行; Bolzonella, T.*; Challis, C. D.*; 藤田 隆明; Giruzzi, G.*; Joffrin, E.*; 濱松 清隆; 林 伸彦; 本多 充; et al.

Proceedings of 24th IAEA Fusion Energy Conference (FEC 2012) (CD-ROM), 8 Pages, 2013/03

Assessment of capabilities in controlling key plasma parameters to access and sustain a high normalized pressure plasma in JT-60SA has been carried out using predictive simulations with emphasis on controllability with actuators, including not only heating and current drive but also fueling and pumping system. It is confirmed that the safety factor profile, which is believed to play an important role for confinement improvement, can be prepared appropriately at the plasma current ramp-up phase in a wide extent within capability of the installed ECRF system. At the flat-top of a high pressure and high bootstrap current plasma, it is also confirmed that the installed NB system can modify the safety factor profile and the confinement property within the planned capabilities. It is confirmed that impurity seeding in the SOL and the divertor region can maintain the heat flux within the divertor heat tolerance keeping the separatrix density level acceptable.



武智 学

プラズマ・核融合学会誌, 88(3), p.162 - 167, 2012/03



Electromagnetic analyses on radial field sector coils for JT-60SA

Ferro, A.*; Gaio, E.*; 武智 学; 松川 誠

Fusion Engineering and Design, 86(6-8), p.1527 - 1530, 2011/10

 被引用回数:2 パーセンタイル:19.17(Nuclear Science & Technology)



Core transport properties in JT-60U and JET identity plasmas

Litaudon, X.*; 坂本 宜照; de Vries, P. C.*; Salmi, A.*; Tala, T.*; Angioni, C.*; Benkadda, S.*; Beurskens, M. N. A.*; Bourdelle, C.*; Brix, M.*; et al.

Nuclear Fusion, 51(7), p.073020_1 - 073020_13, 2011/07

 被引用回数:8 パーセンタイル:35.94(Physics, Fluids & Plasmas)



Interactions between MHD instabilities in the wall-stabilized high-$$beta$$ plasmas

松永 剛; 相羽 信行; 篠原 孝司; 坂本 宜照; 武智 学; 鈴木 隆博; 朝倉 伸幸; 諫山 明彦; 大山 直幸; 吉田 麻衣子; et al.

Proceedings of 23rd IAEA Fusion Energy Conference (FEC 2010) (CD-ROM), 8 Pages, 2011/03

In the JT-60U wall-stabilized high-$$beta_mathrm{N}$$ plasmas, interactions between MHD instabilities have been observed. It is observed that an energetic particle driven wall mode (EWM) triggers an edge localized mode (ELM). When the EWM appears, type-I ELM crashes are synchronized with EWM bursts. The EWM-triggered ELMs have a higher frequency and less energy release than those of usual type-I ELMs. This interaction mainly occurs when the EWM with a large amplitude appears. In the SOL region, several measurements indicate ion losses induced by the EWM. Abrupt ion losses through the edge can increase as local pressure gradient at the pedestal that determines the edge stability. Moreover, another interaction that an EWM-triggered ELMs excites marginal resistive (RWM) is observed. Just after the EWM-triggered ELM, an $$n=1$$ distortion appears and decays soon. It is considered that an impact of the induced ELM can excite the marginally stable RWM.


Overcurrent analyses in JT-60SA poloidal circuits due to plasma disruption and quench protection intervention

Novello, L.*; Gaio, E.*; Piovan, R.*; 武智 学; 井手 俊介; 松川 誠

Fusion Engineering and Design, 86(1), p.33 - 40, 2011/01

 被引用回数:10 パーセンタイル:62.85(Nuclear Science & Technology)

The identification of the maximum amplitude of the currents circulating in the circuits is a useful indication for the design both of magnet and power supply components in fusion experiments. This paper evaluates the maximum level of coil overcurrents in the poloidal superconducting magnets of JT-60SA. To derive these information, a complete model capable to take into account all the mutually coupled elements was worked out, including the poloidal superconducting coils, the plasma position control in-vessel coils, the vacuum vessel, the stabilizing plates and the plasma. The model was utilized to analyze plasma disruption and quench protection circuit intervention in a large variety of different conditions to identify the possible overcurrent levels. The paper describes the model and the analyses performed, and presents and discusses the results.



飛田 健次; 西尾 敏*; 榎枝 幹男; 中村 博文; 林 巧; 朝倉 伸幸; 宇藤 裕康; 谷川 博康; 西谷 健夫; 礒野 高明; et al.

JAEA-Research 2010-019, 194 Pages, 2010/08


発電実証だけでなく、最終的には経済性までを一段階で見通しうる核融合原型炉SlimCSの概念設計の成果を報告する。核融合の開発では、これまで、1990年に提案されたSSTR(Steady State Tokamak Reactor)が標準的な原型炉概念とされてきたが、本研究はSSTRより軽量化を図るため小規模な中心ソレノイドを採用して炉全体の小型化と低アスペクト比化を図り、高ベータ及び高楕円度(グリーンワルド密度限界を高めうる)を持つ炉心プラズマにより高出力密度を目指した。主要パラメータは、プラズマ主半径5.5m,アスペクト比2.6,楕円度2.0,規格化ベータ値4.3,核融合出力2.95GW,平均中性子壁負荷3MW/m$$^{2}$$とした。この炉概念の技術的成立性を、プラズマ物理,炉構造,ブランケット,超伝導コイル,保守及び建屋の観点から検討した。


Energetic particle driven instability in wall-stabilized high-$$beta$$ plasmas

松永 剛; 篠原 孝司; 相羽 信行; 坂本 宜照; 諫山 明彦; 朝倉 伸幸; 鈴木 隆博; 武智 学; 大山 直幸; 浦野 創; et al.

Nuclear Fusion, 50(8), p.084003_1 - 084003_8, 2010/08

 被引用回数:30 パーセンタイル:75.58(Physics, Fluids & Plasmas)

We have observed a fishbone like bursting mode in high-$$beta$$ plasmas above the ideal $$beta$$-limit without a conducting wall. The mode frequency is chirping down, and its initial value is close to precession frequency of trapped fast ions produced by perpendicularly injected neutral beams. This mode can often induce the resistive wall mode (RWM) onset. The mode is mainly observed in the high-$$beta_mathrm{N}$$ plasma where ideal kink-ballooning mode (IKBM) and RWM are marginally stable. Since this mode and RWM were simultaneously observed, the mode is attributed to the interaction between the trapped fast ions and a marginally stable IKBM stabilized by conducting wall. From these results, the observed mode was named as "Energetic particle driven Wall Mode (EWM)." Interestingly, the EWM can change edge localized mode (ELM) behavior. Namely, it was observed that ELM was synchronized with the EWM.


Mode rigidity study of RWM on RFX with reduced RWM control coils for JT-60SA RWM stabilization

武智 学; Bolzonella, T.*; Baruzzo, M.*; 井手 俊介; 松永 剛; JT-60SAチーム

Europhysics Conference Abstracts (Internet), 34A, p.P2.192_1 - P2.192_4, 2010/00

To achieve a steady-state high beta plasma, suppression of RWM is necessary. Therefore, the RWM active control system for JT-60SA is being designed. The matter of mode-rigidity is very important for JT-60SA, because the coverage area of plasma surface with coils is very small. There are two issues connected to mode non-rigidity. One is mode deformation and the other is the destabilization of side-band modes which are marginally stable without the control coils. We performed some experiments on the RFX-mod device with reduced sets of coils for mode-rigidity study. The active control system of RFX-mod has 192 coils each with an independent amplifier and successfully controls RWMs. For example, by using only 48 coils in the top poloidal section one can control the RWM. The dependence of mode control efficiency, mode deformation derived by magnetic sensors and amplifier current on coverage area of the coils during mode control will be shown.


Rotational stabilization of resistive wall mode on JT-60U

松永 剛; 武智 学; 相羽 信行; 栗田 源一; 坂本 宜照; 小出 芳彦; 諫山 明彦; 鈴木 隆博; 藤田 隆明; 大山 直幸; et al.

Plasma and Fusion Research (Internet), 4, p.051_1 - 051_7, 2009/11



Development of reversed shear plasmas with high bootstrap current fraction towards reactor relevant regime in JT-60U

坂本 宜照; 松永 剛; 大山 直幸; 鈴木 隆博; 相羽 信行; 竹永 秀信; 諫山 明彦; 篠原 孝司; 吉田 麻衣子; 武智 学; et al.

Nuclear Fusion, 49(9), p.095017_1 - 095017_8, 2009/09

 被引用回数:27 パーセンタイル:71.38(Physics, Fluids & Plasmas)



Plasma rotation effects on magnetic island formation and the trigger of disruptions in reversed shear plasma

石井 康友; Smolyakov, A. I.*; 武智 学

Nuclear Fusion, 49(8), p.085006_1 - 085006_10, 2009/08

 被引用回数:25 パーセンタイル:67.61(Physics, Fluids & Plasmas)



Observation of an energetic-particle-driven instability in the wall-stabilized high-$$beta$$ plasmas in the JT-60U tokamak

松永 剛; 相羽 信行; 篠原 孝司; 坂本 宜照; 諫山 明彦; 武智 学; 鈴木 隆博; 大山 直幸; 朝倉 伸幸; 鎌田 裕; et al.

Physical Review Letters, 103(4), p.045001_1 - 045001_4, 2009/07

 被引用回数:44 パーセンタイル:85.31(Physics, Multidisciplinary)

We have observed bursting modes driven by trapped energetic particles in the high-$$beta$$ plasmas where the resistive wall mode (RWM) is marginally stable by plasma rotation. This mode can directly trigger the RWM despite enough plasma rotation for RWM stabilization. Mode structure is radially extended and mode frequency corresponds to the precession frequency of the trapped particle from the perpendicular neutral beams. We have concluded that the mode is the energetic particle branch as the results of the interaction between the energetic particle and a marginally stable RWM, and then, it is named as "energetic particle driven wall mode (EWM)".


Mock-up test results of monoblock-type CFC divertor armor for JT-60SA

東島 智; 櫻井 真治; 鈴木 哲; 横山 堅二; 柏 好敏; 正木 圭; 芝間 祐介; 武智 学; 柴沼 清; 逆井 章; et al.

Fusion Engineering and Design, 84(2-6), p.949 - 952, 2009/06

 被引用回数:9 パーセンタイル:55(Nuclear Science & Technology)



高ベータの敵; 抵抗性壁モード

武智 学; 松永 剛; 白石 淳也; 徳田 伸二; 飛田 健次

プラズマ・核融合学会誌, 85(4), p.147 - 162, 2009/04


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