霍尔推进器中振荡鞘层对电子与壁面碰撞频率的影响研究

利用二维粒子模拟方法研究振荡鞘层对近壁电导的影响.研究结果表明，当二次电子发射系数大于1时，鞘层处于振荡状态.在振荡鞘层状态下，电子与壁面的碰撞通量沿平行与壁面方向剧烈的周期性振荡，振荡的波长为电子静电波波长量级，电子与壁面的碰撞频率高出经典鞘层状态下电子与壁面碰撞频率1—2个数量级，此时的碰撞频率对通道中电流的贡献不可忽略.振荡鞘层相对与经典鞘层增大了电子与壁面的碰撞频率，但是振荡鞘层的存在，仍然会使一部分慢电子无法穿越鞘层的势垒而打到壁面. 关键词： 霍尔推进器 振荡鞘层 二次电子

The effect of the oscillating sheath on the electron-wall collision frequency in Hall thruster

The effect of oscillating sheath on the near-wall conductivity is studied by using two-dimensional particle-in-cell （PIC） method. The results show that when the secondary electron emission （SEE） coefficient is greater than 1, the sheath is in the state of oscillation, in which the electron-wall collision flux periodically oscillates along the direction parallel to the wall, and the order of oscillating wavelength is the same as that of the electrostatic wavelength. The order of electron-wall collision frequency is 1—2 orders higher than the frequency of the classic shell state, and the contribution of collision frequency to the current in the channel cannot be neglected. Though the oscillating shell increases electron-wall collision frequency compared to classic shell, it prevents electron-wall collision at the same time.