Optimization of ECR-breakdown and plasma discharge formation on T-10 tokamak, using X-mode second harmonic of ECR.

In order to obtain breakdown and suitable plasma parameters for low-voltage OH start-up, high level of EC-power was injected into T-10 tokamak. Input HF-power was varied in the range of 0.15–1.0 MW. Two HF-launcher systems with different output beams allowed to inject EC-waves with maximum power density 0.25 MW/cm 2 and 0.01 MW/cm 2 . Dependence of breakdown time delay on HF-power was obtained. It was shown, that optimal plasma parameters were achieved in presence of plasma equilibrium currents I=3 kA (input HF-power=1.0 MW). Electron temperature T e =100÷150 eV and electron density n e =5·10 12 cm −3 was measured in these discharges. These parameters remained constant during full HF-pulse-length.