Pellet injection into ohmically and additionally electron cyclotron resonance heated tokamak plasmas

Frozen H2 and D2 pellets injection into the electron cyclotron resonance heated plasmas of the Fontenay-aux-Roses tokamak are studied. Pellet injection with and without ECR heating are considered. In the first case, pellets penetration into the plasma is deeper than the neutral gas model predictions. In the second case, the position of the ECR layer had practically no influence on the penetration depth (reduced to a few centimeters). Only two-third of the pellet mass was found as ionized matter in the plasma, compared to the ohmic case. On the photographs the ablation clouds showed no particular structure when ECR heating was applied. Also the Hβ intensity was generally free of modulation. The enhanced ablation during ECRH can be simulated by a Parks and Turnbull formula. Perpendicular electron temperature of the hot electrons heated by the EC waves is by orders of magnitude larger than its parallel temperature. The resulting electron density profiles calculated by using the 1-D transport code MAKOKOT are in agreement with experiments, when suitable values of the anomalous radial convection velocity are chosen