The diagnostics of high-power microwave from virtual cathode oscillator with the coupled line band pass filter

The research of high-power microwave generation has been studied a lot by several methods. virtual cathode oscillator (vircator) can be one of the most promising high-power microwave sources due to its conceptual simplicity and high-output power capability. It is also noted that the frequency bandwidth of vircator is known to be wide. In this experiment, a high-power microwave generator has been obtained from the intense relativistic electron beam pulser, "Chundoong" (Maximum voltage: 600 kV, maximum current 85 kA, and pulse duration of 60 ns). It is of great importance to investigate the measurement of high power microwave frequency, along with the improvement of its output power. For the purpose of accurate measurement of high power microwave frequency, the coupled line band pass filters have been designed and fabricated in this experiment. The frequency spectrum of high power microwave generated from the virtual cathode oscillator based on the "Chundoong" system has been investigated by the coupled line band pass filter. With the use of several coupled line band pass filters swept from 4 to 8 GHz with band resolution of 1 GHz, the microwave frequency and its power have been investigated under A-K gap distance of 4, 6 and 8 mm. It is found that the microwave frequency has been measured to be 5.2 GHz by the dispersive delay line method under the A-K gap distance 6 mm, which is well agreed with that obtained from the coupled line band pass filter.