Edge plasma modeling of limiter surfaces in a tokamak divertor configuration

Abstract

We describe a 2-D model for edge plasmas with localized limiter surfaces penetrating the scrape-off layer. The model is used to simulate an idealized ITER startup configuration with variations in the limiter penetration depth and surface shape. The results show that the distribution of the total heat load between divertor plates and outer midplane limiter surfaces can be controlled by the penetration depth of the limiter. The limiter surface can be shaped to reduce the peak heat flux without significantly changing the total heat loads. The tentative conclusion is that ITER startup on an outer midplane limiter is reasonable because the total and peak heat loads can be controlled by the limiter positioning and shape.