Observation of Parametric Decay Instability on TST-2 Lower Hybrid Wave Driven Plasma

被引：2

作者：

Ko, Yongtae ^{[1
]}

Takase, Yuichi ^{[1
]}

Ejiri, Akira ^{[1
]}

Tsujii, Naoto ^{[1
]}

Watanabe, Osamu ^{[1
]}

Yamazaki, Hibiki ^{[1
]}

Moeller, Charles P. ^{[2
]}

Yoshimura, Yasuo ^{[3
]}

Iwasaki, Kotaro ^{[1
]}

Aoi, Yuki ^{[1
]}

Matsuzaki, Kyohei ^{[1
]}

Rice, James H. P. ^{[1
]}

Peng, Yi ^{[1
]}

Osawa, Yuki ^{[1
]}

机构：

[1] Univ Tokyo, Kashiwa, Chiba 2778561, Japan

[2] Gen Atom, San Diego, CA 92186 USA

[3] Natl Inst Fus Sci, Toki, Gifu 5095292, Japan

来源：

PLASMA AND FUSION RESEARCH | 2020年 / 15卷

关键词：

spherical tokamak; lower hybrid wave; magnetic probe; parametric decay instability;

D O I：

10.1585/pfr.15.2402007

中图分类号：

O35 [流体力学]; O53 [等离子体物理学];

学科分类号：

070204 ; 080103 ; 080704 ;

摘要：

Parametric decay instabilities (PDIs) in lower hybrid (LH) frequency range were observed in TST-2 in a various parameter range. LH wave measurement has been performed using four RF magnetic probes. We have been studied experiments aiming at efficient non-inductive current drive with the outboard and the top antennas installed on the outboard side and the top side of the vacuum vessel, respectively. Since PDIs are believed to deteriorate the current drive efficiency, we investigated conditions to avoid them. Operations with various combination of antennas (outboard, top), toroidal magnetic field strength and direction (CW, CCW B-T), working gas (hydrogen, deuterium) and density (normal, high) were investigated. In the outboard launch case, PDI sideband frequency delta f associated with ion cyclotron quasi-modes was observed with large degree in any B-T strength in both hydrogen and deuterium plasma. On the other hand, no clear such sideband delta f peak was observed only in deuterium plasma with the top launch case. Among various scenarios, the top launch with CW and CCW toroidal field in deuterium plasma seems to be desirable in terms of avoiding PDIs. (C) 2020 The Japan Society of Plasma Science and Nuclear Fusion Research

引用

页数：5

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