等离子体微带开关特性

提出一种基于微放电等离子体的微带开关。它是以“时变等离子体”取代微带线射频微机电开关的“金属悬臂”，利用等离子体的导体或介质特性使电磁波沿其表面进行传输或截止，从而实现微带线上电磁波传输的动态控制。等离子体微带开关的基本结构包括用以隔断电磁波的微带间隙和产生片状等离子体的放电装置。放电产生时，电磁波因等离子体导体性通过开关，形成“开”状态；放电停止后，电磁波被微带间隙反射，形成“关”状态。利用CST软件仿真研究了等离子体开关特性，结果表明:这种开关的带宽由等离子体密度决定，隔离度由间隙决定，而工作插损与等离子体密度和电子碰撞频率有关。等离子体位形（宽度、厚度等）对于开关性能也非常重要。

Electromagnetic field algorithms in particle-in-cell simulation

The centered-difference, time-biased and FDTD algorithms in particle-in-cell (PIC) simulation are studied and the stability conditions of these algorithms are given. The high-frequency noise filtering characters of time-biased and high quality algorithms are analysed and their application scopes are discussed. The calculated results of the three algorithms are compared for the computation of a relativistic backward wave oscillator, further verifying their filtering characters.