Measurements of plasma convection in the SOL of JET using a Langmuir/Mach probe

Measurements of plasma convection in the SOL (scrape-off layer) have been carried out for JET divertor discharges using a Langmuir/Mach reciprocating probe with sensitive elements facing the divertor (ion drift side for normal BΦ) and the main SOL (electron drift side for normal BΦ). Plasma convection competes with thermal conduction as a mechanism to carry energy to the divertor target and can diminish temperature gradients along the field. Convective flow also provides the basic force that favours the retention of impurities near the target. Hence, it is necessary to assess experimentally its importance in JET divertor discharges and to compare it with results from models for the SOL plasma, which have been validated with experimental measurements. (author) 12 refs., 4 figs