针对过模返波振荡器中泄漏微波在二极管区谐振,造成微波脉冲缩短的现象,设计了内置吸波材料的阳极结构来抑制这种泄漏微波对器件输出的影响。利用粒子模拟软件对不同阳极结构下过模返波管微波输出特性进行模拟研究,模拟结果表明,带吸波材料的阳极结构可以减小泄漏微波对微波输出功率、器件工作模式及脉冲宽度的影响。在长脉冲过模返波振荡器实验中,电子束参数为(800 kV,7 kA)时,器件输出微波频率为8.58 GHz,效率为30%。通过模拟计算和实验验证,这种带吸波材料的阳极结构有效降低了泄漏微波对过模返波管微波输出的影响,将器件输出微波脉冲宽度从70 ns提高到110 ns。

In order to overcome the pulse shortening problem caused by the microwave leakage inside the device, the anode of the oversized backward wave oscillator was specially designed. In the PIC simulation, oversized backward wave oscillators with different anode structure were studied under the beam voltage of 800 kV and the current of 7 kA. By adding the microwave absorbing materials in the anode, the influence of the leaked microwave on the microwave output could be significantly reduced, and the pulse duration increased. The experimental result shows that the pulse duration at the frequency of 8.58 GHz increased obviously from 70 ns to 110 ns when the efficiency was 30%.