Study of particle behaviour at the edge in HT-7 tokamak
Xu Wei (徐伟)ab, Wan Bao-Nian (万宝年)a, Zhou Qian (周倩)a, Wu Zhen-Wei (吴振伟)a, Mao Jiao-Shan (毛剑珊)a, Li Jian-Gang (李建刚)a
a Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China; b Department of Physics, Guangzhou University, Guangzhou 510405, China
Abstract The cross-field diffusion coefficient (D⊥) at the edge in the HT-7 tokamak is close to the Bohm value when the line average electron density ranges from $1.5\times10^{19}$ to $3.0\times10^{19}$m$^{-3}$. The energy profile of the particles is derived directly from the $H_{\alpha}(D_{\alpha}$) line shape; the dissociative excitation of molecules is dominating when the local electron temperature is above 10eV. By means of the Monte Carlo method the $D_{\alpha}$ line shape is also simulated. We find that the molecular dissociation contributes to 57% of neutral atoms and 53% of emission intensity in front of the limiter, and 85% of neutral atoms and 82% of emission intensity in front of the wall. The influence of atomic and molecular processes on the energy balance is discussed for the scrape-off layer (SOL), and the power loss from molecular dissociation is found to be $6\times10^4$kW at the SOL. The ion Bernstein wave (IBW) can effectively suppress the magnetohydrodynamic behaviour, the fluctuation levels and the turbulence; the D⊥ in front of the limiter declines from 0.84 to 0.2m$^2$$\cdot$s$^{-1}$ and the particle confinement time rises from 9 to 12ms.
Received: 24 August 2003
Revised: 26 April 2004
Accepted manuscript online:
Fund: Project supported by the National Natural Science Foundation of China (Grant Nos 19775013 and 10275014).
Cite this article:
Xu Wei (徐伟), Wan Bao-Nian (万宝年), Zhou Qian (周倩), Wu Zhen-Wei (吴振伟), Mao Jiao-Shan (毛剑珊), Li Jian-Gang (李建刚) Study of particle behaviour at the edge in HT-7 tokamak 2004 Chinese Physics 13 1510
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