(EX/P1-6) Steady-state AC Plasma Current Operation in the HT-7 Tokamak

Jiangang Li1), Jiarong Luo1)2), Shaojie Wang1)3), Peng Fu1), Biao Shen1), Fukun Liu1), B.N. Wan1), Jiafang Shan1), Guosheng Xu1), Juan Huang1), Jun Yu1), J.S. Hu1), Qiping Yuan1), HT-7 Team
 
1) Institue of Plasma Physics, Chinese Academy of Sciences, Hefei, China
2) Donghua university, Shanghai, China
3) Fudan University, Shanghai,China

Abstract.  A steady-state AC operation has been achieved on HT-7 superconducting tokamak with pre-set of 35-second duration. The plasma sustainment through the plasma current zero without lose the ionization was demonstrated under steady-state condition. Efforts are made for several important issues of the steady state AC operation, such as the equilibrium configuration, precisely feedback control of plasma position, current profile, plasma confinement property, plasma wall interaction, and fueling and recycling during the plasma current reversion. The modeling results showed that two equilibrium configurations might exit during the current across zero condition. Configuration one is that there are two oppositely flowing current components on the high field side and low field side. This is coincident with experimental observation in HT-7 by using plasma current ramping rate 1.5 MA/s. The second configuration is that one flowing current component in plasma center and another oppositely flowing current component in plasma edge which can be realized either by fast ramping the current or by lower hybrid current driven in the edge region. This is also partially demonstrated by experiment.

Full paper available (PDF)