两种外磁场形式对介质面次级电子倍增的抑制

利用自编1D3V PIC程序，数值研究了不同外加磁场方式对次级电子倍增抑制的物理过程，给出了次级电子数目、平均能量、密度、运动轨迹、渡越时间、介质表面静电场及沉积功率等物理量时空分布关系。模拟结果表明:不同方向外加磁场抑制次级电子倍增的机理有所不同。轴向外加磁场利用电子回旋运动干扰微波电场对电子加速过程，使其碰壁能量降低以达到抑制二次电子倍增的效果；横向外加磁场利用电子回旋漂移过程中，电子半个周期被推离介质表面（不发生次级电子倍增），半个周期被推回介质表面（降低电子碰撞能量）的作用机理，达到抑制二次电子倍增的效果。讨论了横向磁场在回旋共振下，电子回旋同步加速导致回旋半径增大，电子能量持续增加的特殊过程。两种外加磁场方式都可以通过增加磁场达到进一步抑制次级电子倍增的目的。轴向外加磁场加载容易，但对磁场要求较高；横向外加磁场需要磁场较低，但加载较为困难。

Multipactor discharge suppressing on dielectric surface by two patterns of external magnetic fields

Using a 1D3V PIC code programmed by authors, the physical course of multipactor discharge suppressing on dielectric surface with different external magnetic field patterns is studied numerically. The secondary electron number, average electron energy, electron density, electron trajectories, transition time, static electric field and deposited power on dielectric surface are given in simulations. The numerical results could be concluded as follows: The mechanism of different external magnetic field loading patterns is not the same. For the normal direction external magnetic field loading, the rotation caused by external magnetic field disturbs microwave electric field accelerating electron course in order to decrease the impact energy which could suppress the multipactor discharge. For the parallel direction external magnetic field loading, the electrons are pushed out of dielectric surface in half microwave period which could not induce multipactor discharge, and the electrons are pushed in dielectric surface in the other half microwave period which could decrease the impact energy for suppressing the multipactor discharge. The resonant magnetic field condition is also discussed which could cause electron rotation radius and energy increasing continuously. The multipactor discharge suppressing effect could be improved by increasing the value of magnetic field for every external magnetic field loading pattern. It is easy to achieve loading but with higher value of magnetic field for normal direction external magnetic field. On the contrary, it is hard to achieve loading but with lower value of magnetic field for parallel direction external magnetic field.