Experimental study of virtual cathode oscillator in uniform magnetic field

High-frequency high-power microwave radiations by a virtual cathode oscillator have been obtained. We performed experiments using 350 kV. 7 kA, 30 ns electron beam. A virtual cathode forms when the magnetized relativistic electron beam is injected into circular waveguide. The microwave generation exists in wide range of magnetic field magnitudes (2 kGs-40 kGs). The measured peak microwave power is about 15 MW at frequency region of 11-17 GHz. The radiation frequency has not depend on the magnetic field intensity. A nonsymmetric TM mode is observed. The sources of the microwave emission are both the reflexing electrons and the oscillating virtual cathode.