相对论返波管中击穿现象粒子模拟

随着相对论返波管(RBWO)输出功率的提高，RBWO内部击穿问题日益突出。击穿过程中产生的等离子体，会降低输出功率并导致脉冲缩短，大大限制了RBWO的输出单脉冲能量。采用3维粒子模拟，在反射器、慢波结构、提取腔局部区域产生等离子体，建立了RBWO单点击穿及多点击穿模型，获得了等离子体产生的区域和密度对微波输出性能的影响规律。模拟结果表明，输出微波功率随等离子体密度增加而迅速降低，多点击穿相对于单点击穿情况更容易引起输出微波脉冲提前终止，且发射器击穿产生的等离子体效应更为明显。

Particle-in-cell simulation of field breakdown in a relativistic backward wave oscillator

With the increase of output microwave power, the internal field breakdown in a relativistic backward-wave oscillator (RBWO) gets gradually severe. The plasma generated by the field breakdown would lower the attainable output power and pulse width, which greatly limits the single pulse energy. Using a 3-dimensional particle-in-cell (PIC) simulation, the models involving single or several spot breakdown in the reflector, extractor and slow wave structure are built. The plasma effects existing in different locations or having different density are recognized. As demonstrated in the simulation, the output microwave power decreases rapidly as the plasma density increases, breakdown simultaneously occurring at several locations would result in pulse shortening more intensely in contrast to a single spot breakdown, and the easiest plasma effect exists in the breakdown of the reflector.