Generation of ultrahigh-power electromagnetic-radiation pulses of microsecond duration

Experimental results are presented on a Cerenkov oscillator operating in the multimode regime with microsecond duration of microwave pulses. Measurements of the magnetic-field dependence of peak power and duration were made, and a power of about 200 MW was obtained for a base pulse duration of 0.5-0.6 microsec. The results lead to the conclusion that HF breakdown of the slow-wave structure and nonlinear effects in the interaction of the electron beam with the multimode field play an important role in limiting the duration of microwave pulses.