Calculated particle inventories in the TFTR moveable limiter and first wall

A model for the time evolution of the particle inventories within the device components of TFTR has been developed using the DIFFUSE code to calculate the one-dimensional diffusion and trapping of particles in the wall and limiters, coupled with the DEGAS neutral transport code which computes the charge-exchange fluxes onto these components. This combined model will be useful in determining the concentrations of isotopes in the device components, overall pumping by the wall and limiter during discharges, degassing rates between discharges, and the rate of isotope exchange in the machine. Example results for a 1.4-MA, 80-cm, ohmically heated discharge shaped by the TFTR moveable limiter are given. One preliminary finding was that the hydrogen inventory in the wall was comparable to that in the limiter. A bound on the diffusivity of hydrogen in graphite was also suggested by these calculations. Pumping of this discharge by the Zr/Al getter system was also simulated, and was found to be negligible