The effect of transient density profile shaping on transport in large stellarators and heliotrons

Abstract

\u3cp\u3eTransport studies of pellet fuelling experiments on LHD are reported. Spatio-temporal evolutions after pellet injection into LHD discharges show cases where central density increases on the time scale of particle transport processes. Both the temperature gradient and the density gradient change during the density relaxation, the latter even in sign. The resulting thermodynamic forces influence radial electric fields - both as a driving term but also by, e.g. affecting the E \u3csub\u3er\u3c/sub\u3e dependence of ion transport. Magnetic fluctuations have been found to be induced by pellet injection but die out with the relaxation of the pressure profile.\u3c/p\u3