Comparison of impurity generation and penetration models with spectroscopy for the Tore Supra ergodic divertor
Three-dimensional (3-D) simulations of impurity dynamics in the vicinity of a Tore Supra ergodic divertor neutralizer are presented and compared with spectroscopic observations for a medium density pulse in the high recycling regime. The numerical tool used for the description of impurity generation and transport is a version of the Monte Carlo code BBQ, while the geometry of the magnetic field lines are calculated by the use of the MASTOC code. Substantial quantitative consistency is found between the experimental data and our simulations based on recent impurity generation and propagation models. For the given plasma conditions, physical spluttering induced by impact from deuterium ions is found to be the dominant mechanism leading to the carbon contamination of the edge plasma. Chemical spluttering releases a comparable number of carbon impurities from the surface interacting with the plasma but those particles are rapidly re-deposited or pumped away. We find the role of friction of the impurities with the background plasma to be of crucial importance for the determination of the impurity distribution close to the neutralizer. We further find that a flow reversal of the background plasma takes place at the leading edge of the neutralizer with a flow velocity of a few percent of the ion sound speed in the region that is just clear of the edge.
Bibliographic Reference: Report: EUR-CEA-FC-1699 EN (2000) 12 pp.
Availability: Available from Association-Euratom, Saint-Paul-Lez-Durance (FR)
Record Number: 200012745 / Last updated on: 2000-09-08
Original language: en
Available languages: en