A diffraction radiation oscillator operating on the second spatial harmonic

Performance data on a 4-mm wavelength diffraction radiation oscillator (DRO) designed to operate on the second spatial harmonic of a diffraction grating are presented. (Earlier DROs and orotrons have operated on the first harmonic.) Dimensions (external, grating groove spacing and depth, mirror positioning, waveguide section), applied accelerating voltage, mean operating frequency (75 GHz), starting currents, output power, phase velocity of the harmonic, and electronic retuning slope are cited. The resonator cavity is open-ended. This DRO does not operate in a BWO mode. The DRO shows some promise as a highly stable oscillator.