PELLET ABLATION STUDIES ON TORE-SUPRA

The penetration of deuterium pellets into chemically heated TORE SUPRA plasmas has been studied for various plasma conditions (n(e) = 1 X 10 (19)-6 x 10(19) m-3, T(e) = 1-4 keV) and pellet characteristics (N(p) = 2 x 10(20)-1.3 x 10(21) atoms/pellet, V(p) = 0.6-2.4 km/s = i.e. an increase of about 1 km/s from the velocity range covered by the availa ble data for pellet studies). The measured penetration depths compare well with the predictions of the NGS model. A refined NGPS model is pr esented, in which the plasma channel radius is computed self-consisten tly and the heating of the neutral cloud by the 'cold' plasma sheath i s taken into account explicitly. When the value of n(e) is sufficientl y high, it fits the experimental penetration values well, and the comp uted matter deposition profile compares well with the measured H(alpha ) signal. The same model has been shown to fit the experimental scalin g laws deduced from the JET and ASDEX data.