W波段回旋行波管绝对不稳定性的分析

Absolute instability in gyro-traveling-wave tube

绝对不稳定性是制约回旋行波管性能的主要因素之一。通过回旋行波管色散方程,详细分析了W波段基波回旋行波管绝对不稳定性的形成和特征,提出了采用多段损耗波导来抑制绝对不稳定性的方法。分析表明,绝对不稳定性的起振存在一定阈值,起振电流对电子注参数和电路参数极其敏感,确定起振电流是稳定器件工作的前提条件。通过PIC模拟,给出了采用无损耗波导结构,且工作电流为25 A和10 A条件下的放大器频谱图和功率图,结果表明绝对不稳定性的出现与否主要由工作电流是否超过起振的阈值电流决定,损耗波导是抑制绝对不稳定性的有效手段。

Absolute instability is a major physics limitation in the realization of the ultimate capability of gyro-traveling-wave tube. The physical interpretations ,character and suppressing methods of absolute instability were analyzed and verified by a Wband TE01 experiment. A threshold current which brings about the transition to absolute instability was investigated. PIC results show that the occurrence of absolute instability is determined by the operating current. The interaction circuit with distributed loss is proved effective for stabilizing amplification by increasing the threshold current.