Title :
Active heater control and regulation for the Varian VGT-80 11 gyrotron
Author_Institution :
General Atomics, San Diego, CA, USA
fDate :
30 Sep-3 Oct 1991
Abstract :
On past DIII-D experiments involving the use of Varian VA-8060 gyrotrons for ECH (electron cyclotron heating) power, significant gyrotron heater-emission depletion was experienced for pulse widths >300 ms. This decline in heater-emission directly results in gyrotron-cathode current droop. Since RF power from gyrotrons decreases as cathode current decreases, it is necessary to maintain a constant cathode current level during gyrotron pulses for efficient gyrotron operation. Therefore, it was determined that a filament-heater control system should be developed for the Varian VGT-8011 gyrotron which will include cathode-current feedback. The author discusses the mechanisms used to regulate gyrotron filament-heater voltage by using cathode-current feedback. A 110 GHz ECH system has been completed and is operational using the active filament-heater control and regulation network that has been developed
Keywords :
Tokamak devices; electric current control; feedback; fusion reactor theory and design; gyrotrons; plasma radiofrequency heating; voltage control; DIII-D experiments; ECH; Varian VA-8060 gyrotrons; electron cyclotron heating; filament-heater control system; gyrotron heater-emission depletion; gyrotron-cathode current droop; Cathodes; Control systems; Cyclotrons; Electrons; Feedback; Gyrotrons; Heating; Radio frequency; Space vector pulse width modulation; Temperature control;
Conference_Titel :
Fusion Engineering, 1991. Proceedings., 14th IEEE/NPSS Symposium on
Conference_Location :
San Diego, CA
Print_ISBN :
0-7803-0132-3
DOI :
10.1109/FUSION.1991.218934
