低磁场过模慢波结构型高功率毫米波发生器的改进

利用粒子模拟的方法设计了一个高功率毫米波发生器，并对其进行了实验研究及改进。采用过模慢波结构以增大束波作用空间，从而提高功率容量；为实现过模慢波器件的单模、单频工作，选择TM01模的π模作为工作模式。采用过模慢波结构，结合合理的器件结构设计，可降低器件工作所需的导引磁场。实验在TORCH-01加速器平台进行，产生的微波频率由色散线法测量，其功率由远场积分法得到。最初的器件采用矩形波纹慢波结构，得到频率为33.56 GHz、功率约110 MW的微波输出，但功率难以进一步提高，脉宽仅为7~8 ns，且在慢波结构边沿发现击穿痕迹。对矩形慢波结构进行倒圆角处理后，借助数值模拟，发现其TM01模的π模频率变化不大。改进后的器件在0.8 T导引磁场下，当电压和电流分别为590 kV与5.2 kA时，实验得到频率33.56 GHz、功率320 MW的毫米波输出，微波模式为准TM01模，效率约10%，脉宽延长至约13 ns，器件内表面无明显击穿痕迹。

Improvement of high power overmoded millimeter-wave generator operating at low magnetic field

A high power millimeter wave generator has been investigated and improved by particle in cell(PIC) simulations and experiments. Overmoded slow wave structures(SWSs) were adopted to increase power capacity. In order to realize single mode and single frequency operation, one useful method for mode selection was used, i.e. to shift the operating point close to π mode of TM01 wave. Due to the adoption of overmoded SWSs and proper design of the device, the guiding magnetic field could be reduced. The experiments were carried out at the TORCH-01 accelerator. The produced microwave frequency was measured by dispersive line method, and the power was estimated by integrating over the radiation pattern in far field. Rectangular-shaped SWSs were used in primary design, and a 33.56 GHz millimeter wav