Effect of drifts on the high Mach flow associated with the divertor detachment

Abstract Effects of drifts have been studied on high Mach flows near the X -point associated with the divertor plasma detachment. Numerical calculations using a 2D edge plasma simulation code (the B2.5-EIRENE code) have been made for the JT-60U W-shaped divertor geometry. In this article, we mainly focus our attention to the effect of E × B drift. The cases with and without E × B drift in the partial detached state are compared. Due to the strong decrease of electron temperature near the separatrix and the resultant radial electric field, poloidal E × B drift flows are observed in the simulation. But the radial profiles of basic plasma parameters are not so much affected. In addition, simple model has been applied to discuss the numerical results. Although the drifts possibly act as a parallel momentum source/sink, the effect on the parallel flows is shown to be relatively small.