Study of plasma edge conditions for a commercial tokamak reactor

Particle and energy fluxes to the first wall and pumped limiter of a commercial-size tokamak power reactor have been studied with a one-dimensional, time-dependent plasma transport code. The plasma is operated in an enhanced radiation mode, with iodine as the high-Z impurity, whereby the transport power to the limiter is held to about half of the alpha-heating power. Recycling of neutral hydrogen and helium is followed in detail. The ion flux to the limiter and the neutral flux to the first wall are found to depend on the removal efficiency of the limiter/vacuum system. These fluxes also depend strongly on whether gas puffing or pellet injection is used for fueling