The Aditya tokamak has been upgraded to Aditya-U by changing it’s vacuum vessel from rectangular to circular to accommodate the diverter coil for shaped plasma. The 42 GHz ECRH (Electron Cyclotron Resonance Heating) system has been integrated with the tokamak. The system is capable to deliver 500 kW power for 500 ms duration. The ECRH system with modified layout has been integrated successfully on Aditya-U; the burn pattern close to tokamak port ensures good Gaussian beam. Earlier the Aditya Tokamak used to operate at lower magnetic field (Max. 1.0 T) and the ECRH assisted low-loop voltage (˜6 V) plasma start-up experiments were carried out at second harmonic. Now the upgraded Aditya is operated at higher magnetic field up to 1.5 T. Initial ECRH experiments have been carried out at fundamental harmonic at magnetic field from 1.2 T to 1.35 T. Approximately 150 kW to 250 kW power in fundamental O-mode is launched from low field side. The ECH pulse of ˜40 ms is launched at the flat-top of plasma current. The effect of ECR heating is seen as some increase in soft X-ray signal. In some small plasma shots, the EC power is launched after the shot and EC breakdown effect has been observed.
