Pellet injection into ohmically heated and electron cyclotron resonance heated tokamak plasmas
Frozen hydrogen and deuterium pellets were injected into ohmically heated and additionally electron cyclotron resonance (ECR) heated plasmas of the TFR tokamak at Fontenay-aux-Roses. Without ECRH, 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/Turnbull formula when a slightly stronger electron density dependence is assumed than is predicted by this original model. Pellet injection during ECRH led to increased ablation in the outer plasma region and in the limiter shadow. The position of the ECR layer had practically no influence on the pellet penetration depth, which was reduced to a few centimetres. Only two-thirds of the pellet mass were found as ionised matter in the plasma, compared to the Ohmic case. On photographs the ablation clouds showed no particular structure when ECRH was applied. Also the H(beta) intensity was generally free of modulation. By using the 1-D transport code MAKOKOT it was possible to simulate the electron density evolution when suitable values of the anomalous radial convection velocity were chosen.
Bibliographic Reference: Article: Nuclear Fusion, Vol. 29 (1989), No. 10, pp. 1681-1695
Record Number: 199010084 / Last updated on: 1994-12-01
Original language: en
Available languages: en