高功率微波作用下介质窗表面电子运动2维仿真

2-D simulation of electron movement on dielectric window surface under high power microwave

建立了真空中高功率微波作用下介质窗表面电子运动2维仿真模型,充分考虑了微波电磁场及介质表面静电场等影响因素。通过对不同电子出射初始角度和微波场参数(电场幅值、频率及电子出射时电场相位)对电子运动状态影响的仿真分析,得到了二次电子倍增过程中电子在复合场下的运动轨迹、电子重新返回介质表面的撞击能量及返回时间等状态参数,获得了电子运动状态参数随电子出射角度和微波场参数的变化规律。研究发现:电子出射角度对其运动状态有显著影响,电子存在运动轨迹最大的某一出射角度,该角度下电子拥有最大的撞击能量;微波电场幅值的增加将使电子撞击能量增加,返回时间减小,微波电场相位的变化使电子的撞击能量和返回时间呈周期振荡,这从本质上解释了电子数量在二次电子倍增过程中以微波频率两倍周期振荡的原因;随着微波频率的增加电子将由简单的类抛物线运动转变为复杂的振荡运动。

A 2-D simulation model of electron movement on the dielectric window surface under HPM in vacuum is established, and the influences of microwave electromagnetic field and dielectric surface electrostatic field are considered. The influences of different emergence angles of electron and microwave electromagnetic parameters are investigated, such as the amplitude and frequency of electric field, and the phase of electric field when electrons are emitted from the surface. Movement trajectories of electrons under complex field and state parameters when electrons return to the dielectric surface are obtained by simulation, such as impact energy and return time. Variation laws of electron movement with emergence angle and microwave electromagnetic parameters are also derived. The emergence angle of electron has significant effect on the movement of electron, and there is an emergence angle in which the electron has the maximum trajectory length and impact energy. Impact energy will increase and return time will reduce as increasing the amplitude of electric field, and both parameter would oscillate with the phase of electric field, which can essentially explain that multipactoring electron number oscillates in twice the frequency with the increase of microwave frequency, electron trajectory will change from parabolic-like movement to complex oscillation.