Analysis on impurity control of scrape-off layers generated by a pump limiter and an ergodic magnetic limiter

The results of theoretical analyses on impurity control effects of a scrape-off layer in a toroidal system are reported, where two types of limiter systems are considered, a pump limiter and an ergodic magnetic limiter. Carbon is assumed as the representative low-Z material. The screening efficiency of a scrape-off layer and the redeposition effect on to the first wall and limiter sides are analysed with a Monte Carlo simulation of the particle behavior in relation to the scrape-off plasma parameters such as density and temperature profiles, and diffusion coefficients. (orig.)