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 available data for pellet studies). The measured penetration depths compare well with the predictions of the NGS model. A refined NGPS model is presented, in which the plasma channel radius is computed self-consistently and the heating of the neutral cloud by the 'cold' plasma sheath is taken into account explicitly. When the value of n(e) is sufficiently high, it fits the experimental penetration values well, and the computed matter deposition profile compares well with the measured H(alpha) signal. The same model has been shown to fit the experimental scaling laws deduced from the JET and ASDEX data.