TORE SUPRA HIGH SPEED PELLET INJECTOR

This paper reports on the TORE SUPRA high velocity pellet injector which was built in Grenoble and after qualification test installed on TORE SUPRA Tokamak where it is used for plasma and ablation studies. By using a two stage gas gun (TSG), unsupported pellets made directly in the gun barrel by “in situ” condensation have been accelerated to about 2500 ms −1 . So far 3.2 mm diameter pellets (˜ 10 21 atoms) have been launched into Tore Supra plasma at speeds between 1200 ms −1 and 2400 ms −1 . The highest velocities allow a central penetration leading to a strong peaking (n e (0) / e > ˜ 3.5) of the density profile, for central electron temperature higher than 2 keV, with no suprathermal electron population. Experimental pellets penetration is in good agreement with NGS ablation model prediction.