磁旋返波振盪器在高傳波常數下的線性與非線性行為特性研究

Abstract

起振電流與飽合效率是磁旋返波振盪器的關鍵物理量，分別對應到線性行為與飽合行為，其中電子群聚機制是影響起振電流與飽合效率的關鍵之一。藉由程式數值計算方法模擬電子與電磁波的交互作用，對起振電流與飽合效率做基本的探討，進而模擬出在高傳波常數下，角向群聚被軸向群聚的機制抵消，造成起振電流升高的情況。也模擬出在高傳波常數下，速度分散造成起振電流急遽升高的效應。

Start oscillation current (linear behavior) and efficiency (saturated behavior) are the key points of gyrotron backward-wave oscillators. The electron bunching mechanism plays an important role of start oscillation current and efficiency. By using the numerical method, the interaction of electrons and electromagnetic field are simulated. First, we simulate the basic behavior of start oscillation current and efficiency. Second we increase the parameter of magnetic field, and we find the azimuthal bunching mechanism is cancelled by the axial bunching mechanism. Therefore the start oscillation current increase. We also simulate the start oscillation current at high magnetic field at different velocity spread. We find the start oscillation current increase rapidly at high magnetic field if the velocity spread exists.