相对论速调管放大器双间隙输出腔的粒子模拟

Particle simulation of relativistic klystron amplifier double-gap output cavity

用3维PIC程序对S波段强流相对论速调管放大器(RKA)双间隙输出腔内的微波提取情况进行了模拟,给出了产生微波的详细物理图像。模拟结果表明:采用双间隙输出腔能增加束波互作用长度,使提取到的微波功率和效率得到提高。模拟得到了输出微波功率随直流渡越角、随电子束外径与漂移管之间的距离、随基波调制深度以及耦合孔径向间距变化的规律。在电子束压580 kV、束流4 kA、基波调制深度80%、引导磁场1.5 T的条件下,模拟得到周期时间平均功率800 MW,频率约2.85 GHz,周期时间平均效率34.8%的微波。

Using a three-dimension fully electromagnetic particle-in-cell（PIC） code, double-gap output cavity of the S-band Relativistic Klystron Amplifier is simulated numerically. It is found that the microwave extraction power and efficiency is increased by employing the double-gap output cavity to change the distance of beam-microwave interaction. The relations between output power and depth of the modulated current and that between output power and r-distance of coupler hole, as well as the relation between output power and distance that electron beams is close to drifting wall are obtained. Furthermore, the relation between output power and DC transitional angle is presented and it accords with that of the theory. An 800 MW averaged power over the oscillator period is generated by simulation, with ,580 kV electron beam voltage, 4 kA current, 80% depth of the modulated current and 1.5 T leading magnetic field density. The frequency is 2.85 GHz and the efficiency is 34.8%.