Design and experiment of X-band long-pulse high power microwave source

The difficulties in producing long pulse high-power microwave (HPM) with relativistic backward wave oscillators (RBWOs) are analyzed theoretically. The field distributions of a single-mode slow-wave structure (SWS) and an overmoded SWS with the overmode ration of about 3 are calculated and compared, which indicates that the latter can effectively reduce the RF-field on SWS surface under the same energy storage, but the reduction is not as notable as the increase of the overmode ration due to the change of field distribution. An X-band long pulse HPM source using an SWS with the overmode ration of 3 is designed and investigated experimentally. The devices generates 2 GW microwave power with pulse duration of 80 ns at single shot mode, and 1.2 GW microwave power with pulse duration of 100 ns