设计了一个X波段相对论返波管,通过对器件结构的特殊设计,提高了器件的Q值,同时增大了电子束与慢波结构之间的耦合阻抗,从而实现器件的低磁场运行以便对其进行永磁包装; 当引导磁场强度0.46 T、电子束束压750 kV、束流约5.5 kA时,得到频率9.1 GHz、功率1.24 GW的微波输出。根据模拟结果设计加工了一个磁场强度为0.46 T的小型化永磁磁体,该磁体长48 cm,最大外半径15 cm,总重量约116 kg。开展了永磁包装返波管的实验研究,得到以20 Hz的频率运行1 s时功率900 MW、单次运行时功率940 MW的X波段微波输出。

Firstly, an X-band backward-wave oscillator(BWO) with a low guiding magnetic field is designed, whose output microwave power of 1.24 GW at frequency of 9.1 GHz is achieved under the condition of 750 kV voltage and 5.5 kA current when the strength of the guiding magnetic field is 0.46 T. In order to lower the strength of the guiding magnetic field so as to actualize the permanent-magnet-packaging of the relativistic BWO (RBWO), special slow wave structure is designed to increase the quality factor Q of the device, simultaneously increase the coupling impedance between the electron beam and the slow wave structure. Then a 0.46 T permanent magnet is developed, which is 48 cm long and 116 kg in weight. At last, experiment is carried out to investigate the RBWO with the permanent magnet, a 900 MW output power at 9.08 GHz frequency is obtained when the device is operating in 20 Hz repetitive rate for 1 s, while a 940 MW output power is obtained in single pulse condition.