OUTPUT CHARACTERISTICS OF THE AXIALLY EXTRACTED VIRTUAL CATHODE OSCILLATOR WITH A CATHODE-WING

摘要

The vircator (virtual cathode oscillator) has been investigated as a high-power microwave generator. The vircator has the merits of conceptual simplicity, high-output-power capacity, and wide tuning ability. In axial vircator, the power, frequency, and pulse width 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. So, 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. We investigated the axial vircator with the Cathode-wing by the high power microwave generator "Chundoong" (Max 600 kV, 88 kA, 60 ns). It is found that the Cathode-wing contributes to enhancement of the output microwave power.