Moderately relativistic high-harmonic gyrotrons for millimeter/submillimeter wavelength band

A large orbit gyrotron with a 300 keV, 30 A, 20 ns electron beam has provided selective generation with radiation power from 1.5 MW at fundamental (wavelength of 14 mm) to 100 kW at the fifth cyclotron harmonic (wavelength of 4 mm). The next experiment with unique electron beam (250 keV, 18 A, 10 [[micro]seconds], 0.6 mm in diameter) is in progress. Index Terms - Axis-encircling electron beam, cyclotron resonance maser, high-harmonic gyrotron, kicker, large-orbit gyrotron (LOG), mode interaction, relativistic gyrotron.