Scrape-off profiles and effects of limiter pumping in Tore Supra

Abstract

A one-dimensional plasma scrape-off model was used to simulate Tore Supra discharges which are limited by various combinations of the pumped and inner limiters. Scrape-off profiles of the electron density and temparature, ion temperature, and neutral density are given. For each case, various fractions of the ion flux to the neutralizers were assumed to be pumped. Modifications of the scrape-off profiles caused by pumping are predicted. Pumping efficiencies are calculated including the effects of flux amplification caused by recycling. The pumping efficiency is estimated to be 8? for low-power discharges formed on the outer pumped limiter, 7.5? for intermediate-pot'er discharges formed on the seven-module pumped-limiter system, and 58 for fullpower discharges formed on both the inner limiter and the pumped-limiter system. The maximum particle removal rate is estimated to be 150 Tl/s.