Impurity transport modelling in the scrape off layer of the MAST tokamak using DIVIMP-OSM-EIRENE and carbon injection

Abstract

Non-hydrogenic impurities play a significant role in the performance of magnetically confined fusion devices, causing increased radiation and dilution of the Deuterium-Tritium fuel isotopes. Impurities are generated at the plasma wall interfaces as well as being deliberately introduced into the plasma in order to reduce heat loads to the vessel walls. The quantity of impurities reaching the core plasma is determined by the impurity source and the nature of transport in the plasma core and scrape-off layer. Direct measurements of impurity transport have been made by injecting carbon ions into the MAST tokamak using an electrical discharge between 2 carbon electrodes. The emission of the resultant carbon plumes was measured by 2 cameras operating at 75kHz − 100kHz mounted on the MAST vessel. The resultant transport of the carbon ions parallel to the background magnetic field was then compared against simulation using the DIVIMP-OSM-EIRENE code