Pellet fuelling experiments in the HL-1M tokamak

An eight shot pellet injector is used to fuel the HL-1M tokamak from the low field side. The pellet ablation process is investigated with a CCD camera and an array of H-alpha emission detectors. It is observed that the velocity of the pellet ablation cloud is obviously slowed down after it enters the plasma. The ablation clouds are elongated along the magnetic field direction. By means of multi-exposures with the CCD camera during pellet ablation, the safety factor profile is estimated with the ablation cloud inclination angles with respect to the torus on HL-1M. The pellet penetration depth is analysed with Abel inversion of the H-alpha emissions. The result is compared with the prediction of ablation models. Kuteev's model is more suitable for describing pellet ablation processes in the HL-1M plasma than the neutral gas shielding model.