AC operation and runaway electron behaviour in HT-7 tokamak

• Published in: Chinese physics B Vol. 19; no. 6; pp. 375 - 384
• Main Author: 卢洪伟 胡立群 周瑞杰 林士耀 钟国强 王少锋 陈开云 许平 张继宗 凌必利 毛松涛 段艳敏 HT-7 Team
• Format: Journal Article
• Language: English
• Published: IOP Publishing 01.06.2010
• Subjects: Alternating current; Circulating; Electric potential; Plasma (physics); Plasma currents; Retarding; Tokamak devices; Voltage
• ISSN: 1674-1056; 2058-3834
• DOI: 10.1088/1674-1056/19/6/065201

Operation of HT-7 tokamak in a multicycle alternating square wave plasma current regime is reported. A set of AC operation experiments, including LHW heating to enhance plasma ionization during the current transition and current sustainment, is described. The behaviour of runaway electrons is analysed by four HXR detectors tangentially viewing the plasma in the equatorial plane, within energy ranges 0.3-1.2 MeV and 0.3-7 MeV, separately. High energy runaway electrons （~MeV） axe found to circulate predominantly in the opposite direction to the plasma current, while the number of low energy runaway electrons （~tens to hundreds of keV） circulating along the plasma current is comparable to that in the direction opposite to the plasma current. AC operation with lower hybrid current drive （LHCD） is observed to have an additional benefit of suppressing the runaway electrons if the drop of the loop voltage is large enough.