低磁场过模慢波结构型高功率毫米波发生器的改进  

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

作　　者：朱俊[1] 舒挺[1] 张军[1] 张泽海[1] 樊玉伟[1] 高景明[1] 李国林[1] 周生岳[1] 许流荣[1] 

机构地区：[1]国防科学技术大学光电科学与工程学院,长沙410073

出　　处：《强激光与粒子束》2011年第11期3051-3054,共4页High Power Laser and Particle Beams

基　　金：国家自然科学基金项目(11075211);国家高技术发展计划项目

摘　　要：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33.56GHz、功率约110MW的微波输出,但功率难以进一步提高,脉宽仅为7～8ns,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0.8T导引磁场下,当电压和电流分别为590kV与5.2kA时,实验得到频率33.56GHz、功率320MW的毫米波输出,微波模式为准TM01模,效率约10%,脉宽延长至约13ns,器件内表面无明显击穿痕迹。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 wave with an output power of about 110 MW and pulse duration of 7-8 ns was measured.It was then hard to increase the output power and pulse width,and evidences of RF breakdown were also found at the edges of SWSs.Numerical calculations showed that the frequency of TM01-π mode did not change much when the edges of SWSs were rounded.After the improvements,with guiding magnetic field of 0.8 T,and diode voltage and current of 590 kV and 5.2 kA,respectively,a 33.56 GHz millimeter wave with an output power of 320 MW and efficiency of about 10% was generated,the microwave mode was quasi-TM01 mode,the pulse duration was lengthened to 13 ns,and no obvious evidence of breakdown was observed.

关 键 词：高功率微波 毫米波发生器 过模慢波结构 击穿 

分 类 号：TN125[电子电信—物理电子学]