title: Operational Characteristics of a 14-W 140-GHz Gyrotron for Dynamic Nuclear Polarization.
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.
authors: Student Member, IEEE, The Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA 02139 USA (e-mail: cjoye@mit.edu ).
authors: Colin D
authors: CD
authors: Joye
authors: Robert G
authors: RG
authors: Griffin
authors: Melissa K
authors: MK
authors: Hornstein
authors: Kan-Nian
authors: KN
authors: Hu
authors: Kenneth E
authors: KE
authors: Kreischer
authors: Melanie
authors: M
authors: Rosay
authors: Michael A
authors: MA
authors: Shapiro
authors: Jagadishwar R
authors: JR
authors: Sirigiri
authors: Richard J
authors: RJ
authors: Temkin
authors: Paul P
authors: PP
authors: Woskov