Title :
Conditioning and protection circuitry for external modulation of a preprogrammed gyrotron cathode voltage command waveform
Author :
Ponce, Dan ; Perron, J.R. ; Legg, R.A.
Author_Institution :
Gen. Atomics, USA
Abstract :
The modulating voltages applied to the DIII-D gyrotrons are controlled by reference signals which are synthesized by arbitrary waveform generators. These generators allow ECH operators to pre-program reference waveforms consisting of ramps, flat tops, and various modulation shapes. This capability is independent of the DIII-D central timing and waveform facilities, which provides the ECH operators operational flexibility. The waveform generators include an amplitude modulation input, providing a means to control the pre-programmed waveform externally. This input is being used to allow the DIII-D plasma control system (PCS) to control gyrotron power in response to selected feedback signals. As the PCS control signal could potentially modulate the gyrotrons beyond operational limits or otherwise in a manner leading to recalcitrant rf generation, the control signal is conditioned so that its effect upon the ECH pre-programmed reference waveform is limited by conditions set by the ECH operators. The design of the circuitry which restricts the range over which the PCS control signal may modulate the reference waveform will be discussed. Test and DIII-D experimental results demonstrating the utility and effectiveness of gyrotron power modulated by the PCS will be presented.
Keywords :
Tokamak devices; amplitude modulation; cathodes; gyrotrons; physical instrumentation control; plasma toroidal confinement; waveform generators; DIII-D central timing; DIII-D experimental results; DIII-D gyrotrons; DIII-D plasma control system; ECH operators; PCS control signal; amplitude modulation input; arbitrary waveform generators; control gyrotron power; external modulation; feedback signals; flat tops; modulating voltages; preprogrammed gyrotron cathode voltage command waveform; protection circuitry; ramps; recalcitrant rf generation; reference signals; various modulation shapes; waveform facilities; Cathodes; Circuit synthesis; Control systems; Gyrotrons; Personal communication networks; Protection; RF signals; Signal generators; Signal synthesis; Voltage control;
Conference_Titel :
Fusion Engineering, 2003. 20th IEEE/NPSS Symposium on
Print_ISBN :
0-7803-7908-X
DOI :
10.1109/FUSION.2003.1426702