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

Volume

34

Issue

3

fYear

2006

fDate

6/1/2006 12:00:00 AM

Firstpage

524

Lastpage

533

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 TE_0,6,1 mode near 460 GHz. The gyrotron also operates in the second harmonic TE_2,6,1 mode at 456 GHz and in the TE_2,3,1 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;

fLanguage

English

Journal_Title

Plasma Science, IEEE Transactions on

Publisher

ieee

ISSN

0093-3813

Type

jour

DOI

10.1109/TPS.2006.875769

Filename

1643271