Synchronous mode locking in a closed cavity electron cyclotron maser

It is theoretically demonstrated that mode locked operation can be achieved in a closed cavity electron cyclotron maser (gyrotron). This work is unique in two respects. First, the cavity provides a highly dispersive guiding structure for the electromagnetic wave, hence, the mode frequency spacing varies by an amount comparable to the average spacing between modes. The dispersive properties of the electron beam are used to compensate that of the cavity to allow eight longitudinal TE11n modes to lock together. Second, the locking is obtained by rf modulation of the axial velocity of the electron beam. A numerical example shows that subnanosecond radiation pulses can be generated at 16 GHz with an order of magnitude increase in power level over the free-running maser.