CW results of a 460 GHz second harmonic gyrotron oscillator - for sensitivity enhanced NMR

We report microsecond pulse and CW results of a gyrotron operating near 460 GHz and 230 GHz at the second electron cyclotron harmonic and fundamental, respectively. Peak power levels of up to 70 W at the fundamental and 3 W at the second harmonic have been obtained in operation at up to 13 kV and 150 mA. The gyrotron has been operated continuously to achieve 3 W CW at the second harmonic. The gyrotron was also demonstrated as a wideband continuous frequency tunable oscillator by magnetically exciting fundamental higher order longitudinal modes. The gyrotron oscillator can be used for dynamic nuclear polarization (DNP) studies in conjunction with a 700 MHz (/sup 1/H), 16.5 T nuclear magnetic resonance (NMR) spectrometer.