Characteristics of pellet injected discharges in TEXTOR

Pellets injected into the TEXTOR tokamak lead to a density profile peaking which is strongest at low plasma current and weakest at high current independent of BT. After the injection two types of density oscillations are excited, the first type follows immediately the injection and the second one is excited with a delay of more than ten milliseconds. The oscillations are also observed in runaway discharges; the synchrotron light from the relativistic electrons drops after the pellet injection and is subsequently modulated due to a trapping of the runaways in magnetic islands. First Faraday measurements have been performed indicating that the distribution of the plasma current is not measurably modified by the pellet. copyright 1995 American Institute of Physics