Tunable vircators with e-beam premodulation

The paper describes theoretical, numerical, and experimental studies of a decimeter wavelength vircator with electron beam premodulation. Possible mechanisms for the excitation of electromagnetic oscillations in virtual cathode systems are analyzed. In experiments employing the SINUS-7 high-current repetitively-pulsed electron accelerator, single-mode microwave generation in the S-band was obtained with /spl sim/1 GW peak power and /spl sim/25 ns pulse width at about 5% efficiency. Frequency tuning and repetitive batch operation were demonstrated.