Combined repetitive pellet injection and lower hybrid current drive experiments in TORE SUPRA

In order to control the plasma density during long shots (>10-20s), attemps to combine repetitive pellet fuelling and lower hybrid current drive have been carried out in Tore Supra. As expected form previous studies, the penetration of pellets injected during LH pulses is small and corresponds to a poor fuelling efficiency. Nevertheless, a partial recovery of the penetration depth is obtained by switching off the LH power just before each injection, which yields a significant increase of the fuelling efficiency. This difference in the pellet penetrations is interpreted in the frame of an ablation model taking into account the heating in volume of the pellet by the fast electron tail