Comparison of DIVIMP and EDGE2D-EIRENE tungsten transport predictions in JET edge plasmas

Abstract

• Monte Carlo DIVIMP and multi-fluid EDGE2D-EIRENE treatment of tungsten were compared. • Tungsten density predictions by DIVIMP and EDGE2D-EIRENE agree within a factor of 2. • DIVIMP predicts consistently 50% more tungsten than EDGE2D-EIRENE in attached plasmas. • The discrepancy is due to the bundling of tungsten charge states to 6 fluid species. • Using 22 tungsten species yields accurate tungsten charge but causes numerical errors. The average tungsten concentrations in the pedestal region (c W ) predicted by the Monte Carlo code DIVIMP and the coupled multi-fluid plasma/kinetic neutral code EDGE2D-EIRENE are found to agree within a factor of 2 for a range of JET-ILW L-mode and H-mode plasma conditions. Under attached divertor conditions with c W exceeding 10 −6 , the c W predicted by DIVIMP is consistently ~ 50% higher than by EDGE2D-EIRENE. In colder plasma scenarios with c W < 10 - 6 , stochastic variations exceed the systematic disagreement between the two codes. The average tungsten charge predicted by EDGE2D-EIRENE in the upstream scrape-off layer is lower by 40–50% due to the bundling of the 74 tungsten ion charge states into 6 fluid species, which explains the reduced tungsten accumulation in the main plasma compared to the DIVIMP predictions.