Optimized performance of a powerful hollow-cathode rf oscillator

We have studied the power, efficiency, and frequency ranges achievable for a hollow-cathode based rf oscillator. We have found that the rf component of the discharge current can be much larger (up to ∼4.5 times) than its dc component. In the achievable frequency range of 15–120 MHz, this very simple cold cathode device produces up to 40 kW of rf power with efficiency of up to 25%. The internal resistance of this device always remained within a convenient range of 20–40 Ω. The rf pulse duration could be prolonged up to tens of μs. The physical processes governing the oscillator parameters are discussed.