Title :
Operational characteristics of a 14-W 140-GHz gyrotron for dynamic nuclear polarization
Author :
Joye, Colin D. ; Griffin, Robert G. ; Hornstein, Melissa K. ; Hu, Kan-Nian ; Kreischer, Kenneth E. ; Rosay, Melanie ; Shapiro, Michael A. ; Sirigiri, Jagadishwar R. ; Temkin, Richard J. ; Woskov, Paul P.
Author_Institution :
Plasma Fusion Center, MIT, Cambridge, MA
fDate :
6/1/2006 12:00:00 AM
Abstract :
The operating characteristics of a 140-GHz 14-W long pulse gyrotron are presented. The device is being used in dynamic nuclear polarization enhanced nuclear magnetic resonance (DNP/NMR) spectroscopy experiments. The gyrotron yields 14 W peak power at 139.65 GHz from the TE(0,3) operating mode using a 12.3-kV 25-mA electron beam. Additionally, up to 12 W peak has been observed in the TE(2,3) mode at 136.90 GHz. A series of mode converters transform the TE(0,3) operating mode to the TE(1,1) mode. Experimental results are compared with nonlinear simulations and show reasonable agreement. The millimeter-wave output beam was imaged in a single shot using a pyroelectric camera. The mode patterns matched reasonably well to theory for both the TE(0,1) mode and the TE(1,1) mode. Repeatable mode patterns were obtained at intervals ranging from 0.8 s apart to 11 min apart at the output of the final mode converter
Keywords :
electron beams; gyrotrons; millimetre wave generation; mode matching; 12 W; 12.3 kV; 136.90 GHz; 139.65 GHz; 14 W; 140 GHz; 25 mA; dynamic nuclear polarization; electron beam; gyrotron; millimeter-wave output beam; mode converters; mode patterns; nonlinear simulations; nuclear magnetic resonance spectroscopy; pyroelectric camera; Anodes; Chemical technology; Electron beams; Frequency; Gyrotrons; Laboratories; Magnetic fields; Millimeter wave technology; Nuclear magnetic resonance; Polarization; Dynamic nuclear polarization; gyrotron; millimeter wave;
Journal_Title :
Plasma Science, IEEE Transactions on
DOI :
10.1109/TPS.2006.875776
