考虑到束-波相互作用的速调管离子噪声二维模拟

采用粒子模拟的方法并考虑电子束与电磁波的相互作用，首次直接得到了速调管输出信号的离子噪声图像，阐述了束电子、二次电子、离子、电磁场之间的相互作用的动力学过程. 指出离子噪声所表现出来的相位波动是由电子束速度的波动引起的，电子束速度的变化来源于管内离子数量的变化，离子的数量的变化又与电子束状态变化相互影响，这是离子噪声产生的根本原因. 二次电子对离子噪声产生过程的影响甚微，但是其行为却反映了离子噪声的形成机理. 离子噪声引发的输出信号幅度波动取决于电子束速度和半径的改变，与离子行为密切相关. 关键词： 离子噪声 速调管 粒子模拟 电子束

Analysis of ion noise with beam-wave interaction in klystron by two dimensional particle simulation method

Ion noise in output signal of klystrons was obtained by particle-in-cell method. The interactions between beam electron, ion, secondary electron and electromagnetic field are illustrated. The mechanism of ion noise is analyzed. It shows that phase fluctuation in output signal is caused by the change of the beam current DC velocity which is affected by the change of the amount of ions. The ion interacts with beam electron and has no equilibration state. The amount of secondary electrons is small and it has little effect on ion noise, but its behaviors reflect the process of ion noise. The amplitude fluctuation of output signal is caused by the change of beam velocity and beam radius. It is also affected by the ion behaviors.