부산대학교 도서관

Having the merits of conceptual simplicity, high-output-power capacity, and wide tuning characteristics, the vircator (virtual cathode oscillator) has been investigated as a high-power microwave (HPM) generator. In axial vircator, the power, frequency, and pulsewidth are all sensitive to the cathode shape, and the frequency depends strongly on the anode–cathode gap distance. The efficiency of the vircator is reported to only a few percent. Therefore, we devised the new type cathode to enhance the output power. The new type cathode is adding the ring to the cathode with velvet, so-called cathode-wing. The electron beam is only emitted from cathode with velvet, while a cathode-wing forms the electric fields to prevent the backstream electrons due to virtual cathode from leaking to the diode chamber wall. We investigated the axial vircator with the cathode-wing by the HPM generator “Chundoong” (Max 600 kV, 88 kA, 60 ns). It is found that the cathode-wing contributes to enhancement of the output microwave power efficiency to 7% in comparison with 3% for conventional axial vircator without cathode-wing.