LAUSR

Plasma current start-up and pre-ionization is an important motivation in Taban tokamak. The plasma current start-up has been successfully achieved using a central solenoid and a pre-ionization system and the experimental conditions have been optimized. Two distinct schemes were used to start-up the plasma current. Hot cathode emitter and electron cyclotron resonance (ECR) was used as the pre-ionization system. ECR pre-ionization circuit of 2.45 GHz magnetron was modified for long duration pulse mode. The transient plasma parameters were measured during discharge as a function of time in different conditions, while a toroidal field of 0.1 T with 4 ms flat-top was being applied. The experimental results showed that the plasma current could be started up by both ECR and hot cathode emitter. In the optimum conditions, a plasma current of 7.5 kA has been achieved with pulse duration of ~ 0.7 ms using the electron cyclotron pre-ionization system. Under such circumstances, the X-ray emission, as well as, the impurity level was minimized.