Evidence for Convective Inward Particle Transport in a Stellarator

Abstract

Radially peaked density profiles were observed in the stellarator W7-AS in discharges with small central particle sources. Particle balance analyses and density modulation experiments revealed the existence of a convective inward particle flux. The peaked density profiles appear only in discharges with flat central electron temperature profiles. In discharges with peaked temperature profiles the convective inward flux is canceled by outward directed thermodiffusion.