The penetration of deuterium pellets into ohmically heated TORE SUPRA plasmas has been studied for various plasma conditions (ne = 1 × 1019-6 × 1019 m3, Te = 1-4 keV) and pellet characteristics (Np = 2 × 1020-1.3 × 1021 atoms/pellet, Vp = 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 ne is sufficiently high, it fits the experimental penetration values well, and the computed matter deposition profile compares well with the measured Hα signal. The same model has been shown to fit the experimental scaling laws deduced from the JET and ASDEX data

Q S T IOperation of the Phase III outboard pump limiter (OPL) in Tore Supra in 1994 was terminated prematurely when runaway electrons generated during the current decay following a disruption pierced leading edge tube on the electron side and caused a water leak. The location, about 20 mm outside the last closed flux surface during normal operation, and the infrared (IR) images of the limiter indicate that the runaways moved in large outward steps, Le., tens of millimeters, in one toroidal revolution. For plasma (runaway) currents in the range of 150 to 250 kA, the drift orbits open to the outside.Basic trajectory computations suggest that such motion is possible under the conditions present for this experiment. Activation measurements made on sections of the tube to indicate the area of local damage are presented here. An understanding of this event may provide important guidance regarding potential damage from runaways in future tokamaks.

TORE SUPRA is a large superconducting tokamak designed for sustaining long inductive pulses (t -30 s ) . In particular, all the first wall components have been designed for steady-state heat and particle exhaust , particle injection,and additional heating. In addition to these technological assets, a strict control of the plasma-wall interactions is required. This has been done at low power : experiments with ohmic heating have been mainly devoted to the pump limiter, ergodic divertor and pellet injection experiments. Some specific problems arising in large tokamaks are encountered ; the pump limiter and the ergodic divertor yield the expected effects on the plasma edge. The effects on the bulk are discussed.

The relaxation of the ion distribution function was measured for a plasma (n ≃ 1012 cm−3, Ēi = 200 eV) confined in a circularized, stabilized magnetic mirror well. The results were compared with the predictions of a Fokker-Planck computer code. The evolution of an initially skewed angular distribution function appeared to be in good accord with the theoretical model. However, the final anisotropy of the plasma was greater than the calculated one.