EFFECT OF LONGITUDINAL MAGNETIC-FIELD ON MICROWAVE EFFICIENCY OF VIRTUAL CATHODE OSCILLATOR

The effect of a longitudinal magnetic field on the microwave efficienc y of a virtual cathode oscillator is investigated by particle-in-cell simulations, The mechanism of the oscillation associated with microwav e emission is physically understood, It is found that the reflection o f the electron beam back to the diode region is important to the oscil lation, When a longitudinal magnetic field is applied, the residence t ime of the electrons in the potential well is lengthened, resulting in a large energy spread of the electron beam, which reduces the output power of the microwave.