LAUSR

An improved L-band inverted relativistic magnetron powered by a virtual cathode is presented. An extra emitter is introduced at the end of a slow-wave structure to reduce the desired π mode start-oscillation time, which is critical when short radiation pulses are required. Electrons produced by both upstream and downstream emitters are injected into the interacting space simultaneously, and the rapid increase in electron density in this region accelerates the establishment of a virtual cathode. Furthermore, the additional emitter provides more charged particles for beam–wave interaction, so that the amplitude of output power can be improved. The particle-in-cell simulation demonstrates that a power conversion efficiency of 76.5% could be obtained for a diode voltage of 500 kV and guiding magnetic field of 0.165 T. Compared with the same slow-wave structure powered by a single beam, the output microwave power is increased from 1.1 to 3.1 GW and the startup time is shortened from 53 to 29 ns.