Investigation on impurity transport using LBO technique

摘要

Impurity transport has been investigated on the HL-IM tokamak under the conditions of the ohmically heated discharge (OHD) and the lower hybrid current drive (LHCD). A small quantity of metallic impurity Al were injected into the plasma using the laser blow-off (LBO) technique. The ionized metallic impurity lines were measured using a vacuum ultra-violet (VUV) spectrometry. Al impurity transports in the plasma under the conditions of the OHD and LHCD were analyzed. The diffusion coefficient (D(r)) and inward convection velocity (V(r)) were oh tamed using numerical simulation with the impurity transport code (ITC). The simulation results showed that the transport coefficient during the LHCD decreased by fifty per cent compared with that during the OHD. Therefore the impurity-confined characteristics of the LHCD plasma was obviously improved.