Pellet injection into ohmically and additionally electron cyclotron resonance heated tokamak plasmas
Frozen H(2) and D(2) pellets were injected into ohmically and additionally electron cyclotron resonance heated (ECRH) plasmas of the tokamak TRF. Without ECR heating, the pellets penetrated deeply into the plasma and the ablation clouds were striated. The neutral gas shielding model predicts deeper penetration than was observed. The radial ablation profiles can be simulated by the Parks and Turnbull formula when a stronger electron density dependance is assumed than predicted by theory. Pellet injection during ECR heating led to enhanced ablation in the outer plasma region and in the limiter shadow. Enhanced ablation during ECRH can be simulated by an expression of the form given by Parks and Turnbull assuming two groups of electrons, the one representing the electrons of the bulk plasma, the other one being a "hot" group of low density heated by the EC waves. There are strong indications that the "perpendicular" temperature of this group is orders of magnitude larger than its "parallel" temperature. Using the calculated radial ablation profiles as initial profiles in the 1-D transport code MAKOKOT permits calculation of the electron density profiles after pellet injection. Resulting electron density profiles are in broad agreement with the experiments.
Bibliographic Reference: Report: EUR-CEA-FC 1340 EN (1988)
Availability: Available from CEA, Département de Recherches sur la Fusion Contrôlée, Saint-Paul-lez-Durance (FR)
Record Number: 198910440 / Last updated on: 1994-12-01
Original language: en
Available languages: en