热流效应对场向电流确定的影响

给出了任意速度分布函数条件下复频率的介电函数和色散关系的求解方法. 讨论了16矩近似条件下, 场向热流对电子速度分布函数, 介电函数实部与虚部, 以及离子与电子谐振频率和阻尼率的影响, 并与平衡态时麦克斯韦分布等离子体的计算结果进行了比较. 忽略场向热流效应, 正向电子漂移速度条件下, 上行等离子线探测, 会过高估计场向电流; 负向电子漂移速度条件下, 上行等离子线探测会过低估计场向电流. 对上下行等离子线同时探测情况, 忽略热流效应同样会过高估计场向电流. 

Effect of the Heating Flow on the Determination of the Field-aligned Currents

The detection of the filed-aligned currents is an important scientific subject for the Europe Incoherent SCATter radar association (EISCAT). Using the different channels, the ion line and the plasma line can be observed synchronously by the incoherent scatter radar, which can be used to deduce the resonance frequency of the ions and electrons, and the filed-aligned current can be determined by these frequencies. The method is reasonable for the plasma with the Maxwellian distribution. However, the heat flow can be caused by the drift velocity in the velocity phase space. The 16-moment distribution function is used to describe the heat flow effect. On this basis, the solutions of the dielectric function and dispersion relation with a complex frequency are presented for an arbitrary velocity distribution, and the results are compared with those of Maxwellian distribution. The effects of the heating flow on the electron velocity distribution function, the real and imaginary parts of dielectric function, the resonance frequency and damping rate of ions and electrons, are discussed. With a positive electron drift velocity, the filed-aligned currents will be overestimated by the measurement of upshifted plasma line, and with a minus electron drift velocity, the filed-aligned currents will be underestimated. For the case that both upshifted and downshifted plasma lines are measured, the filed-aligned currents will be overestimated.