Radial Density Profile of Microwave Plasma for Wall Conditioning in a Purely Toroidal Magnetic Field (小特集粒子・熱制御とプラズマ対向材料研究の進展--IEA/TEXTOR共同研究の成果と現状)

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Microwave discharge plasma in a toroidal magnetic field is expected to be used for in-situ wall conditioning of steady-state fusion devices in future. This paper describes a basic study of plasma density profile along major radius for microwave discharge in a purely toroidal B-field. Fluid model analysis shows a significant influence of vertical electric field E induced by ▽B- and curvature drift. The density profile is determined mainly by the parameter P=(E/B)/av_1 which is a ratio of E×B drift time for minor radius a to the ionization frequency v_1. For large values of P(>1), the density distribution is relatively uniform. For smaller P, however, the density dramatically increases along the major radius due to the E×B outward drift. Such behavior was confirmed in the experiment of a simple magnetized torus, TOMAS. Relations between the measured density profile and the electron heating processes at electron cyclotron resonance or upper hybrid resonance are discussed.
社団法人プラズマ・核融合学会の論文
2001-02-25