ECRH SYSTEMS ON TOKAMAKS SST-1 AND ADITYA

The 82.6 GHz/200 kW and 42 GHz/500 kW electron cyclotron resonance heating (ECRH) systems will be used in Tokamak SST-1 to carry out preionization and start-up experiments at 3.0- and 1.5-T operation. The 82.6-GHz gyrotron system has been tested for continuous waves (1000-s duration) using a conventional high-voltage power supply and for pulsed operation (200 kW for 1 s) using a regulated high-voltage power supply. The 42-GHz ECRH system is a pulsed system (500 ms), which will be used to carry out preionization and start-up experiments at 1.5 T (fundamental harmonic) on SST-1 and at 0.75 T (second harmonic) on Tokamak Aditya. The circular corrugated waveguide-based transmission line system contains two wave guide switches: one to test the gyrotron on a dummy load or the tokamak and the second switch to launch the ECRH power, either in SST-1 or in Aditya. The 42-GHz system has been tested on a dummy load, and the gyrotron delivers 500-kW power at beam voltage similar to 49 kV and beam current similar to 18 A. The output of the gyrotron is Gaussian (TEM00 mode) with mode purity >99%. The system is commissioned on both tokamaks (SST-1 and Aditya) to launch power in any tokamak.