(OV/4-1) Overview of HL-2A Experiment Results

Qingwei Yang1), Yong Liu1), X.T. Ding1), L.W. Yan1), D.Q. Liu1), W.M. Xuan1), L.Y. Chen1), J. Rao1), X.M. Song1), Z. Cao1), J.H. Zhang1), X.R. Duan1), W.C. Mao1), C.P. Zhou1), X.D. Li1), S.J. Wang1), M.N. Bu1), Y.H. Chen1), C.H. Cui1), Z.Y. Cui1), Z.C. Deng1), J.Q. Dong1), B.B. Feng1), Q.D. Gao1), W.Y. Hong1), H.T. Hu1), Y. Huang1), Z.H. Kang1), T. Lan2), B. Li1), G.S. Li1), H.J. Li1), Qiang Li1), Qing Li1), W. Li1), Y.G. Li1), Z.J. Li1), Yi Liu1), Z.T. Liu1), C.W. Luo1), X.H. Mao1), Y.D. Pan1), J.F. Peng1), K. Shao1), Z.B. Shi1), X.Y. Song1), A.K. Wang1), H. Wang1), M.X. Wang1), Q.M. Wang1), Y.Q. Wang1), Z.G. Xiao1), Y.F. Xie1), L.H. Yao1), L.Y. Yao1), C.X. Yu2), B.S. Yuan1), K.J. Zhao1), Y.Z. Zheng1), G.W. Zhong1), H.Y. Zhou1), Y. Zhou1), J.C. Yan1), C.H. Pan1)
 
1) Southwestern Instiyute of Physics, Chengdu, China
2) Department of modern Physics, University of Science and Technology of China, Hefei, China

Abstract.  The recent experiment results of the HL-2A tokamak are presented in this paper. Up to now, the stable and reproducible discharges with divertor configuration have been obtained, under the main plasma parameters of IP = 400 kA, BT = 2.65 T, Ne  6.01019 m-3 and the discharge duration  3.0 s, using the reliable feedback control. Siliconization is the normal wall conditioning method on HL-2A and after that, the impurity concentration and radiated power can be obviously suppressed after siliconization. Advanced scenario with weak positive/negative current shear, calculated by TRANSP codes using experimental data, is achieved by the central fuelling of the pellet injection. The supersonic molecular beam injection (SMBI) with liquid nitrogen temperature gas is used. It is proved that the low temperature SMBI can form the hydrogen cluster and penetrate into plasma more deeply and efficiently. The particle diffusion coefficient is obtained as 0.5 1.5m2/s at plasma peripheral area. The symmetries (m = 0 1, n = 0) of the directly measured low frequency (7 9 kHz) electric potential and field are simultaneously observed for the first time by a novel designed Langmuir probe system. The impurity diffusion coefficient and convection velocity are determined by using laser blow-off system and transport code. In disruption studies, a new criterion for disruption prediction is given according to the MHD activity features and statistic analysis, and the plasma current quench time increases from about 5 ms to 20 ms with noble gas injection. The sawtooth character in on-axis ECRH experiment is investigated, and a persistent m=1 oscillation induced by SMBI and pellet injection is found to be a thermal fluctuation instead of magnetic island. The detachment characteristics of HL-2A divertor are numerically and experimentally studied using code SOLPS5.0 and measured data. The long divertor legs and thin divertor throats in HL-2A pose MHD shaping problems resulting in momentum losses even at low densities and strongly enhanced main chamber losses.

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