Two-Wave Ka-Band Nanosecond Relativistic Cherenkov Oscillator

This paper presents the results of numerical and experimental study of a Ka-band relativistic Cherenkov oscillator with average diameter of the slow-wave structure ${D} \approx \text {2.6}\lambda $ . ( $\lambda $ is a wavelength). The combined mode selection including the diffraction loss in the electron diode was applied. The high-current accelerator SINUS-200 provided the thin-walled annular electron beam in the range of voltages 350–420 kV and currents of 2.9–3.8 kA at pulsewidth of 10 ns. The generation of 2.5–3-ns pulses at the central frequency 36.4–36.8-GHz and 400–600-MW output microwave peak power was realized. The corresponding efficiency of 42% ± 5% in power conversion has been obtained.