Efficiency enhancement of high-power microwave generation from a cylindrical virtual cathode oscillator with ring-type reflector

We have investigated an efficiency enhancement of high-power microwave generation from a cylindrical virtual cathode oscillator by adopting a ring-type reflector. This high-power microwave generator is powered by the "Chundoong" intense relativistic electron beam pulser (Max: 600 kV, 88 kA and 60 ns duration). It is noted in this experiment that the maximum power can be obtained at a cylindrical A-K gap distance of 8 mm with a ring-type reflector width of 7 mm. The microwave frequency has been measured to be 4.8 similar to 5.1 GHz by using a combination of coupled line bandpass filters with a bandwidth of I GHz and a dispersive delay line method. In particular, in this experiment, the maximum microwave output power and efficiency with the optimized ring-type reflector could be enhanced up to 426 MW and 7.1%, respectively.