Title :
Continuous-wave operation of a 460-GHz second harmonic gyrotron oscillator
Author :
Hornstein, Melissa K. ; Bajaj, Vikram S. ; Griffin, Robert G. ; Temkin, Richard J.
Author_Institution :
Dept. of Electr. Eng. & Comput. Sci., MIT, Cambridge, MA
fDate :
6/1/2006 12:00:00 AM
Abstract :
We report the regulated continuous-wave (CW) operation of a second harmonic gyrotron oscillator at output power levels of over 8 W (12.4 kV and 135 mA beam voltage and current) in the TE0,6,1 mode near 460 GHz. The gyrotron also operates in the second harmonic TE2,6,1 mode at 456 GHz and in the TE2,3,1 fundamental mode at 233 GHz. CW operation was demonstrated for a one-hour period in the TE 0,6,1 mode with better than 1% power stability, where the power was regulated using feedback control. Nonlinear simulations of the gyrotron operation agree with the experimentally measured output power and radio-frequency (RF) efficiency when cavity ohmic losses are included in the analysis. The output radiation pattern was measured using a pyroelectric camera and is highly Gaussian, with an ellipticity of 4%. The 460-GHz gyrotron will serve as a millimeter-wave source for sensitivity-enhanced nuclear magnetic resonance (dynamic nuclear polarization) experiments at a magnetic field of 16.4 T
Keywords :
feedback; gyrotrons; harmonic oscillators (circuits); microwave oscillators; submillimetre wave generation; 12.4 kV; 135 mA; 16.4 T; 233 GHz; 456 GHz; 460 GHz; cavity ohmic losses; continuous-wave operation; dynamic nuclear polarization; ellipticity; feedback control; millimeter-wave source; nonlinear simulations; nuclear magnetic resonance; power stability; pyroelectric camera; radiation pattern; radiofrequency efficiency; second harmonic gyrotron oscillator; Analytical models; Feedback control; Gyrotrons; Magnetic field measurement; Power generation; Power system harmonics; Radio frequency; Stability; Tellurium; Voltage-controlled oscillators; Continuous-wave (CW); dynamic nuclear polarization (DNP); gyrotron oscillator; harmonic; low voltage; nuclear magnetic resonance (NMR); submillimeter; terahertz;
Journal_Title :
Plasma Science, IEEE Transactions on
DOI :
10.1109/TPS.2006.875769
