Experimental research based on a C-band compact transit-time oscillator with a novel diode loading an embedded soft magnetic material and shielding structure

Abstract

In order to reduce the external magnetic field and improve the conversion efficiency of high-power microwave generation devices with low external magnetic field, a novel diode with embedded soft magnetic and shielding structure is proposed. The soft magnetic material is designed to enhance the local magnetic field in the diode region. Besides, the diode applies a shielding structure which can reduce the radial electric field. From simulation research, it is found that the emission and transmission quality of the electron beam with low magnetic field is greatly improved when loading this diode. Through simulation research, it is verified that the diode can increase the conversion efficiency of the TTO from 30% to 36.7%. In our experimental study, under the conditions of a diode voltage of 540kV and a current of 10.5kA, the output microwave power is 1.51GW when loading the novel diode and the microwave frequency is 4.27GHz when an external guiding magnetic field of 0.3T is applied. The corresponding conversion efficiency is improved from 20.0% to 26.6%, which is 6.6% higher than the device loaded with a conventional diode. Our experiments have verified that this novel diode can effectively improve the conversion efficiency of high-power microwave sources operating with low magnetic field, and contribute to the miniaturization and compactness of high-power microwaves.