High power microwave generation by a coaxial vircator

A coaxial-type virtual cathode oscillator (vircator) was tested in the Pulsed Power Laboratory at Texas Tech University with electron beam parameters of 500 kV, 40 kA, and 30 ns. The major goal of this experiment was to understand the characteristics of the coaxial vircator and the effect of the feedback field on the microwave efficiency. The experimental results have given the output microwave power of ∼ 400 MW, the microwave energy efficiency of ∼ 2 %, the microwave frequency of ∼ 2 GHz, and the microwave mode of TE ₁₁ in circular waveguide. By enhancing the field intensity around the vircator using a microwave reflector, the microwave output power was increased to ∼ 900 MW giving microwave energy efficiency of ∼ 5.5 %. This efficiency is calculated as peak microwave power divided by peak beam power, which does not occur at the same time. The instantaneous efficiency, using the beam power at the time of the peak microwave power is 20%.