High power microwave generation from a reflex triode virtual cathode oscillator

Experiments were carried out to generate intense relativistic electron beams and High Power Microwaves (HPM) with reflex triode geometry from 1 kJ pulse power system. The typical electron beam parameters were 300 kV, 12 kA, and 300 ns, with a current density of a few hundreds of amperes per square centimeter. We present a power optimization study of the HPM generated from the reflex-triode vircator for various anode-cathode (AK) gaps. A horn antenna setup with diode detector and attenuators was used to measure the microwave power. The HPM frequency was measured with a D-dot probe along with a high band width oscilloscope. It was found that the microwave power and E-field peaks at 15 mm AK Gap and the frequency at this gap is 2.2 GHz. The highest microwave power is emitted when all the power is delivered into a single frequency with minimal mode hopping.