Enhanced Transport During Pellet Injection in the Rijnhuizen-Tokamak-Rtp

The evolution of the radial profiles of electron temperature and density in a tokamak plasma during ablation of an injected hydrogen pellet is studied by Thomson scattering with a resolution of 1% of the mirror plasma radius. The energy content is hardly affected until the pellet reaches the sawtooth inversion radius when strongly enhanced transport sets in throughout the plasma. Asymmetric profiles are observed. Peaks of high density are formed, one of which often develops into a density ''snake.''