间接馈电柱-锥级联爆磁压缩发生器数值模拟

为了研究间接馈电、两级级联柱-锥构型的爆磁压缩发生器的物理特性，发展了描述爆磁压缩物理过程的2维爆轰磁流体力学程序——MFCG（Ⅴ），并用其分析、计算了一系列模型。通过将计算结果与柱-柱构型的结果进行比较，表明了柱-锥构型更有利于功率放大:在同样的输出电流条件下，不仅爆磁压缩的时间缩短，而且输出功率也相应地增加。MFCG（Ⅴ）程序的建立以及相应的数值模拟结果有助于加深对柱-锥构型的爆磁压缩发生器物理过程的认识，并为实验设计提供参考。

Mode analysis of helical wave guide

Considering the factors such as the left or right turning directions of wave,the wave being forward or backward,all the possible modes in helical wave guide are given by using the coupling wave equations of helical wave guide.The relationships among all the possible modes are analyzed according to the characteristics of coupling wave equations and Blagg conditions,the mode coupling characteristics of traveling wave tube and backward wave tube with the helical corrugation are given correspondingly.The corresponding coupling relationships and the rules of mode coupling are obtained. Combined with the dispersion equations of helical wave guide,the effects of the helical corrugation period and corrugation fluctuation degree on mode coupling are discussed that with the period increase of the helical corrugation,the accelerating voltage of electron beam increases,too.If the period of helical corrugation is too small,the linearity of operating mode becomes very poor.The mechanism of suppressing mode competition in gyrotron traveling wave tube amplifier with helical corrugation is illuminated.With bigger corrugation fluctuation degree,the separation between operating mode and non-operating modes is enhanced and it is very useful for suppressing mode competition.