75 GHz Relativistic Surface-Wave Oscillator of Planar Geometry

We present the results of simulations and experimental studies of a W-band surface-wave oscillator powered by a ribbon high-current relativistic electron beam produced by SINUKI accelerator (IAP RAS, Nizhny Novgorod, 1 kA / 650 keV / 17 ns). Planar geometry of the interaction space facilitates efficient mode selection over wide transverse coordinate by using open waveguide at fairly large oversize factor (the width of the waveguide is ~8 wavelengths). Stable oscillation regime is obtained at frequency of 75 GHz with a pulse duration of about 5 ns. The output power measured by the calorimetric method reaches 25 MW.