DIVIMP modeling of tungsten impurity transport in ITER

Abstract

This paper presents a modeling study of the W erosion and plasma accumulation in ITER for different levels of first wall W coverage and plasma configurations using the Monte Carlo impurity transport code DIVIMP. Based on the ion fluxes from the background plasma solutions from B2/EIRENE the W erosion is calculated by taking into account both D and impurity ions (C, Ar and He). Based on these W erosion fluxes the W plasma concentrations are calculated. The calculations are performed for standard steady state divertor plasma geometry and for limiter geometry mimicking the ITER ramp up. The calculations show that in steady state divertor operation the W erosion and plasma concentrations are low even when the W first wall coverage is increased to a full W ITER. In limiter geometry due to the high electron temperatures close to the W limiter, strong W erosion is observed even for pure D plasmas. When seeded impurities are taken into account, intolerable W plasma concentrations of several percent are observed in the limiter plasma configuration.