Investigation .on impurity transport using LBO technique

摘要

Impurity transport has been investigated on the HL-1M tokamak under the conrnditions of the ohmically heated discharge (OHD) and the lower hybrid current drive (LHCD). A rnsmall quantity of metallic impurity A1 were injected into the plasma using the laser blow-off (LBO)rntechnique. The ionized metallic impurity lines were measured using a vacuum ultra-violet (VUV)rnspectrometry. Al impurity transports in the plasma under the conditions of the OHD and LHCDrnwere analyzed. The diffusion coefficient (D(r)) and inward convection velocity (V(r)) were obrntained using numerical simulation with the impurity transport code (ITC). The simulation results rnshowed that the transport coefficient during the LHCD decreased by fifty per cent compared with rnthat during the OHD. Therefore the impurity-confined characteristics of the LHCD plasma was rnobviously improved.