Design and cold test of a rectangular cavity beam position monitor

The CBPM is a kind of monitor which is used for the measurement of beam transverse position. It is becoming increasingly popular due to its high potential in resolution performance. In theory, the resolution can reach about 1 nanometer. In this paper, a rectangular CBPM is designed for it has better X-Y isolation than a cylindrical one. It has been simulated and measured, and the results agree with each other very well. The procedures and results for the simulation and the cold test will be shown later and it will be proved that this is a reliable method for the CBPM design.     

磁控管的电荷分布

回顾了几种磁控管理论模型,对这些理论模型中得到的电荷分布进行了分析。利用计算机对X波段磁控管进行PIC模拟,监视粒子相空间分布,并与理论结果进行对比,证明布里渊理论能部分解释轮轭层的高度及其内部的电荷密度分布,但模拟结果中电子在相空间存在一定的分布,而布里渊理论采用的是单粒子运动理论,因此无法解释模拟结果中轮轭边界下降沿特性。模拟得到的轮辐内电荷分布与各种理论均有较大差异,分析发现,不同的轮轭边界下降沿特性是造成差异的主要原因。讨论了利用导向中心流体理论得到更准确的轮辐内电荷分布的可能方法。     

衰减瓷对同轴磁控管起振过程的影响

通过建立X波段同轴磁控管模型,对起振过程进行PIC模拟,结果表明:当衰减瓷损耗角正切大于0.010时,起振过程中可能受干扰模影响,但均能正常工作;当选用损耗角正切为0.001或不具有衰减性能的材料时,磁控管可能无法正常工作。因此同轴磁控管中需要选用损耗角正切大于0.010的电介质材料。进一步对该磁控管进行冷态微波特性模拟研究,重点分析了磁控管主模、N/2-1干扰模在不同参数衰减瓷下的品质因数,模拟结果表明衰减瓷位置合理,当损耗角正切大于0.010时,对N/2-1模的吸收效果明显改善,验证了PIC模拟的结论。