High power microwave generation from the axially-extracted virtual cathode oscillator

Summary form only given. It has been reported that the virtual cathode is formed when the electron beam current in the drift region exceeds the space charge limiting current. In this experiment, we have fabricated the axially-extracted virtual cathode oscillator (Vircator), which is the new conceptual device and the ultra-high power microwave generator. This Vircator experiment has been conducted by Chungdoong intense relativistic electron beam pulser (Max. 600 kV, 70 kA, 60 ns). The maximum power of extracted microwave has been measured to be 200 MW at the frequency range of 7.25 GHz (/spl Delta/f=0.25 GHz). The power conversion efficiency was calculated to be 3.3% with the diode voltage of 300 kV and the A-K gap of 5 mm. The microwave propagating mode was found to be TM01 from the gas discharge experiment. Formation of the virtual cathode has been simulated with 2-dimensional PIC code "MAGIC", from which the dominant frequency and the extracted power have been evaluated and these simulation results are in good agreement of the experimental data.