A low-magnetic field high-efficiency high-power microwave source with novel diode structure

The design of compact, lightweight devices has become an important development direction of high-power microwave source devices, with the reduction of the external magnetic field being the leading innovation. By analyzing the transmission equation of the intense relativistic electron beam (IREB), it can be known that magnetic field strength in the diode region has great influence on the transmission quality of the IREB. In this paper, a new structure that introduces a soft magnetic material as the cathode base is proposed. Considering that soft magnetic materials have the capability to concentrate and enhance the magnetic field, the proposed structure leverages this merit to improve the magnetic field strength in the diode area under certain low external magnetic field conditions. Thus, the proposed structure is capable of effectively improving the emission and transmission quality of the IREB without any increase of the external guiding magnetic field. As for the device design, the new structure was introduced into a previously proposed C-band transit time oscillator, and the particle-in-cell simulation was carried out. The results showed that high power microwaves with a power of 2.7 GW are generated with a corresponding frequency of 40% when the electron beam voltage is 550 kV, the beam current is 12 kA, and the guiding magnetic field is 0.3 T.