Investigation of the behaviour of injected sodium atoms, plasma ions and intrinsic impurities in the scrape-off layer of MT-1

Abstract

Sodium atoms are injected into MT-1 plasmas by a laser blow-off technique. The edge plasma density is measured by observing the time decay of the resonance line emitted by the sodium atoms at different spatial points. Transport of the injected and intrinsic impurities is investigated using deposition probes. The results of the investigation show a slight toroidal asymmetry of the fluxes and similar exponential decay length for fluxes of each kind of particle. The transport processes for the intrinsic and nonintrinsic impurities seem to be similar to that for the plasma ions. The measured density distribution of the edge plasma can be fairly well described by a parabolic function of the plasma radius and agrees with results from microwave interferometer measurements close to the limiter radius.