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中国物理学会期刊

螺旋波等离子体中螺旋波与Trivelpiece-Gould波模式耦合及线性能量沉积特性参量分析

CSTR: 32037.14.aps.69.20200062

Parametric analysis of mode coupling and liner energy deposition properties of helicon and Trivelpiece-Gould waves in helicon plasma

CSTR: 32037.14.aps.69.20200062
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  • 采用有限温度等离子体介电张量模型, 在考虑粒子热效应情形下, 通过求解传导边界条件下等离子体柱中本征模的色散关系, 分析了螺旋波等离子体中典型参量条件下螺旋波与Trivelpiece-Gould (TG) 波的耦合特性及线性能量沉积特性. 在ω/(2π) = 13.56 MHz和TeV,i = 0.1TeV,e参量条件下计算结果表明: 对于螺旋波, 存在截止静磁场B0,H,cutoff与截止等离子体密度n0,H,cutoff, 在B0 > B0,H,cutoffn0 < n0,H,cutoff条件下, 螺旋波变为消逝波; 在ω/ωce ∈ (0.01, 0.10)范围内, 对于m = 0 角向模, TG波Landau阻尼致使的能量沉积占主导地位, 而对于m = 1角向模, 螺旋波Landau阻尼或TG波Landau阻尼致使的能量沉积哪个占据主导地位则取决于B0的大小; 在ωpe/ωce ∈ (3, 100)范围内, TG波Landau阻尼致使的能量沉积占主导地位; 在整体能量沉积过程中, 对于m = 0模和m = 1模, Landau阻尼致使的能量沉积均占据主导地位.

     

    Based on the finite temperature plasma dielectric tensor model which contains the particle thermal effect, by numerically solving the eigenmode dispersion relation of electromagnetic waves propagating in radially uniform and magnetized warm plasma column which is surrounded by conducting boundary, the mode coupling characteristic and liner damping mechanism induced wave power deposition properties of helicon and Trivelpiece-Gould (TG) waves are parametrically analyzed. The detailed investigations show as follows. Under typical helicon plasma parameter conditions, i.e. wave frequency ω/(2π) = 13.56 MHz, ion temperature is much smaller than electron temperature, for the helicon wave, there exist a cut-off magnetic field B0,H,cutoff and a cut-off plasma density n0,H,cutoff, for which under the conditions of B0 > B0,H,cutoff or n0 < n0,H,cutoff, the helicon wave becomes an evanescent wave. When the magnetic field intensity changes from 48.4 to 484 G, i.e., ω/ωce ranges from 0.01 to 0.1, for the power deposition intensity, Landau damping of TG wave dominates for the m = 0 mode, meanwhile, for the m = 1 mode, which wave, i.e. helicon wave or TG wave, plays a major role in power deposition mainly depends on the magnitude of the magnetic field. On the other hand, for a given magnetic field B0 = 100 G, when ωpe/ωce changes from 3 to 100, for both the m = 0 mode and the m = 1 mode, the power deposition induced by Landau damping of TG wave plays a major role, further, one may notice that the power deposition of TG wave decreases while the power deposition of the helicon wave increases as plasma density increases. Finally, for both the m = 0 mode and the m = 1 mode, the power deposition due to the Landau damping plays a dominant role. All these conclusions provide us with some useful clues to better understanding the high ionization mechanism of helicon wave discharges.

     

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