AC operation and runaway electron behaviour in HT-7 tokamak

doi:10.1088/1674-1056/19/6/065201

Abstract 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 (\sim MeV) are found to circulate predominantly in the opposite direction to the plasma current, while the number of low energy runaway electrons (\sim 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.

Keywords: runaway electron alternating current (AC) discharge lower hybrid current drive loop voltage

Received: 04 September 2009
Accepted manuscript online:

PACS:	52.55.Fa	(Tokamaks, spherical tokamaks)
	28.52.Cx	(Fueling, heating and ignition)
	52.50.Jm	(Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.))
	52.25.Jm	(Ionization of plasmas)
	52.35.Hr	(Electromagnetic waves (e.g., electron-cyclotron, Whistler, Bernstein, upper hybrid, lower hybrid))
	52.55.Wq	(Current drive; helicity injection)

Fund: Project supported by the National Natural Science Foundation of China (Grant Nos.~10935004 and 10775041).

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Lu Hong-Wei(卢洪伟), Hu Li-Qun(胡立群), Zhou Rui-Jie(周瑞杰), Lin Shi-Yao(林士耀), Zhong Guo-Qiang(钟国强), Wang Shao-Feng(王少锋), Chen Kai-Yun(陈开云), Xu Ping(许平), Zhang Ji-Zong(张继宗) Ling Bi-Li(凌必利), Mao Song-Tao(毛松涛), Duan Yan-Min(段艳敏), and HT-7 Team AC operation and runaway electron behaviour in HT-7 tokamak 2010 Chin. Phys. B 19 065201

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AC operation and runaway electron behaviour in HT-7 tokamak

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