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Line Shape in Front of the Limiter in HT-6M Tokamak /
Current Relaxation and its Roles in Improved Confinement
B. N. Wan, J. Li, J. Luo, J. K. Xie,
Z. W. Wu and HT-6M Group
Institute of Plasma Physics, Chinese Academy of Science, P.O.Box 1126 Hefei, China 230031
Abstract. In this paper H line shape in front of the limiter in HT-6M
tokamak is analyzed by multi-Gaussian fitting. The energy distribution of
neutral hydrogen atoms reveals that H radiation is contributed by
Frank-Condon (FC) atoms, atoms reflected at the limiter surface and charge
exchange. Dissociation of hydrogen molecules and reflection of particles at
the limiter surface are dominante in edge recycling. To lower particle
reflection at the limiter surface is an important issue for controlling edge
recycling. The measured profiles of neutral hydrogen atom density are
reproduced by particle continue equation and a simplified one-dimension
Monte-Carlo simulation code.
Abstract. Effective Low Hybrid wave Current Driving (LHCD) and
improved confinement in higher electron density have been attained in
HT-6M tokamak by
combining with Low Hybrid wave Heating (LHH). Experiments and code simulation
show that off-axis plasma current is driven and sustained by LHW in higher
electron density and relax at the time scale of resistive
diffusion. Sustaining of improved confinement is strongly governed by current
density profile and its relaxation. Relevant issues are also discussed.
IAEA 2001
