Studies on impact of electron cyclotron wave injection on the internal transport barriers on JT-60U

JT-60Uにおける電子サイクロトロン波入射の内部輸送障壁への影響に関する研究

井手 俊介; 竹永 秀信; 諌山 明彦; 坂本 宜照; 吉田 麻衣子; Gormezano, C.*; JT-60チーム

Ide, Shunsuke; Takenaga, Hidenobu; Isayama, Akihiko; Sakamoto, Yoshiteru; Yoshida, Maiko; Gormezano, C.*; JT-60 Team

内部輸送障壁(ITB)はITER先進運転や定常トカマク炉を実現するうえで、重要な役割を果たすと考えられる。プラズマ中心での安全係数が1を少し上回る弱磁気シアプラズマはITERのハイブリッド運転等として考えられており、そこでもITBは重要な役割を担う。本論文では弱磁気シアプラズマにおけるイオン温度内部輸送障壁(Ti ITB)への電子サイクロトロン領域波(ECRF)の影響について詳細に調べ、ECRFのTi ITB抑制効果にプラズマ電流等への依存性があることを初めて明らかにした。また、ITB境界付近(0.4a)にECRFを入射した場合にもプラズマ中心付近のイオン温度やトロイダル回転(Vt)に同時に反応が現れることを見いだし、ITB特性の非局在性について新たな知見を得た。

Impact of an electron cyclotron range of frequency (ECRF) wave on the internal transport barriers (ITBs) in a weak shear (WS) plasma has been investigated in JT-60U. It has been observed that the ITB in the ion temperature (Ti ITB) in a WS plasma can be degraded by an EC injection. It is clarified for the first time that the degradation effect depends increasingly on the EC power (PEC) but decreasingly with plasma current (Ip). Moreover it was confirmed that an EC injection affects the toroidal rotation profile (Vt (r)) indirectly and results in flattening of Vt (r) regardless to the direction of the target Vt (r) peaking, co- (relative to the Ip direction) or counter. Furthermore, it was newly found that the central Ti and Vt are affected with no delay from the EC onset even by an off-axis EC injection. These results suggest that an EC injection acts on background mechanism that has special structure, and EC deposition in any location in this structure gives instantaneous effect.