MODELING OF HYDROGEN CONDITIONING, RETENTION AND RELEASE IN TORE-SUPRA

A model based on a local mixing model has been previously developed at JET to explain the recovery of tritium after the first PTE experiment . This model is extended by a OD plasma particle balance model and is applied to data from Tore Supra wall saturation experiments. With only two free parameters, representing the diffusion of hydrogen atoms and the volume recombination process between hydrogen atoms into molecule s, the model can reproduce experimental data. The time evolution of th e after-shot outgassing and the integral amount of particles recovered after the shot (assuming 13 m(2) of interacting surfaces between plas ma and walls) are in good agreement with the experimental observations . The same set of parameters allows the model to simulate after-shot o utgassing of five consecutive discharges. However, the model fails to predict the observed saturation of the walls by the plasma. Results fr om helium glow discharge (HeGD) can only be partially described. Good agreement with the experimental hydrogen release and its time evolutio n during HeGD is observed, but the model fails to describe the stabili ty of a saturated graphite wall.