Efficacy of Passive-Limiter Pumping of Neutral Particles

Abstract

Experiments have been performed to measure the neutral pressure buildup behind the limiter as a function of plasma density and gas species. The results indicate that a passive mechanical limiter effectively removes from the vacuum vessel up to 20% of the atoms injected during a discharge. The feasibility of mechanical limiters removing the fusion-reaction helium ash, thus negating a major need for magnetic divertors, is discussed.