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为了揭示螺旋波等离子体推力器中的等离子体源功率耦合机理,针对气体工质电离后被射频加热的稳态过程,考虑等离子体密度非均匀分布条件,采用三参数压力函数(fa,sp,tp)和温度函数(f_a,s_t,t_t)表示柱状等离子体内压力和温度的径向分布,分析了径向压力梯度、温度梯度对螺旋波等离子体内功率沉积、波电场、波磁场和电流密度的影响。考虑梯度为正,梯度为负和梯度为零三种梯度类型。结果发现:压力梯度为正时,螺旋波在等离子体临近壁面处的功率沉积减弱,但射频波透入深度增加,原因是靠近管壁处等离子体密度较低,RF波径向单位长度衰减较少,透入深度增加。温度梯度为负时,柱状等离子体中心处能量沉积变强,原因是管中心位置等离子体密度较大,电子温度较高,与RF波能量耦合增强;横向截面的电磁场、电流密度分布在不同压力和温度梯度下基本不变,证明了m=1模式的稳定性。
In order to reveal the power coupling mechanism of plasma source in helical wave plasma thruster, a three-parameter pressure function (fa, sp, tp) and temperature function (f_a, s_t, t_t) represent the radial distribution of pressure and temperature in the columnar plasma. The effect of radial pressure gradient and temperature gradient on the power deposition, wave electric field, magnetic field and current density in spiral plasma influences. Consider gradient positive, gradient negative and gradient zero three gradient types. The results show that when the pressure gradient is positive, the power deposition of the spiral wave near the plasma wall is weakened, but the penetration depth of the radio frequency wave is increased due to the lower density of the plasma near the wall and the attenuation of the RF wave length to the unit length Less, penetration depth increases. When the temperature gradient is negative, the energy deposition becomes stronger at the center of the columnar plasma due to the larger plasma density and higher electron temperature at the center of the tube, which increases the energy coupling with the RF wave energy. The transverse cross-section of the electromagnetic field and the current density are distributed at different pressures And the temperature gradient is basically unchanged, proving the stability of m = 1 mode.