Author :
Kreischer, K.E. ; Grimm, T.L. ; Guss, W.C. ; Temkin, R.J.
Author_Institution :
Plasma Fusion Center, MIT, Cambridge, MA, USA
Abstract :
The operation of a high-power, tunable gyrotron oscillator at wavelengths extending into the submillimeter-wave regime is reported. Using a 14-T Bitter magnet, frequencies from 141 GHz (TE/sub 15,2,1/ mode) up to 328 GHz (TE/sub 27,6,1/ mode) have been measured. As in earlier experiments, it was possible to step tune through a sequence of TE/sub m,p1/ modes over this range. From 198 GHz to 328 GHz, these modes corresponded to p=4, 5, and 6. Even though the cavity is highly overmoded at 328 GHz, output powers remain quite high, with a peak output power of 430 kW at 80 kV and 35 A. This corresponds to an efficiency of 15%. This is the highest power generated by a gyrotron in the submillimeter region. Even better results were obtained in the TE/sub 22,5,1/ mode at 267 GHz. A peak power of 600 kW was produced when operating at 80 kV and 35 A, for an efficiency of 21%. A detailed study of the TE/sub 16,2,1/ mode at 148 GHz has been made, and the beam parallel velocity was measured with a capacitive probe.<>
Keywords :
gyrotrons; 14 T; 14-T Bitter magnet; 141 to 328 GHz; 15 percent; 21 percent; 35 A; 430 to 600 kW; 80 kV; EHF; THF; beam parallel velocity; capacitive probe; efficiency; megawatt gyrotron; operation; overmoded; peak output power; step tune; sub-MM-waves; submillimeter wave region; tunable gyrotron oscillator; Electrons; Frequency measurement; Gyrotrons; Heating; Oscillators; Plasma measurements; Plasma waves; Power generation; Submillimeter wave technology; Toroidal magnetic fields;
