Influence of sideband oscillations on gyrotron efficiency

Author

Guss, W.C. ; Basten, M.A. ; Kreischer, K.E. ; Temkin, R.J. ; Antonsen, T.M., Jr. ; Cai, S.Y. ; Saraph, G. ; Levush, B.

Author_Institution

Plasma Fusion Center, MIT, Cambridge, MA, USA

Volume

22

Issue

5

fYear

1994

fDate

10/1/1994 12:00:00 AM

Firstpage

871

Lastpage

877

Abstract

We report the observation of sideband mode effects on the efficiency of overmoded gyrotron operation. Two cavities were designed and operated which differed in the presence of sideband modes. In one version of the cavity, parasitic backward waves modes were observed and efficiencies were approximately 22% at 40 A beam current. With the use of a multi-mode self-consistent nonlinear code, a modified design was generated which eliminated the sideband modes. Experiments were conducted with this new cavity which produced efficiencies of approximately 33% at 30 A and 27% at 40 A beam current, but with a slightly higher velocity ratio than seen with the earlier cavity. An additional cavity, also with no sideband modes but with a longer cavity length and therefore higher Q obtained powers up to 1.3 MW with an efficiency of 39% at a 40 A beam current

Keywords

backward wave oscillators; electromagnetic oscillations; gyrotrons; millimetre wave generation; millimetre wave oscillators; 22 percent; 27 percent; 30 A; 33 percent; 39 percent; 40 A; Q; beam current; cavities; gyrotron efficiency; multi-mode self-consistent nonlinear code; overmoded gyrotron operation; parasitic backward waves modes; sideband mode effects; sideband oscillations; Cyclotrons; Educational institutions; Electrons; Frequency; Gyrotrons; Heating; Microwave oscillators; Plasma sources; Power system harmonics; Resonance;

fLanguage

English

Journal_Title

Plasma Science, IEEE Transactions on

Publisher

ieee

ISSN

0093-3813

Type

jour

DOI

10.1109/27.338302

Filename

338302