MODELING OF THE INTERACTION OF HYDROGEN PLASMA WITH AMORPHOUS-CARBON FILMS REDEPOSITED IN FUSION DEVICES

A model is presented to describe the interaction/retention of hydrogen plasma in redeposited amorphous carbon layers forming in carbon-prote cted tokamaks. The subject is relevant for quantifying the buildup and the possible mobilisation of tritium to be used in the next generatio n of devices. The goal of the model is to predict some of the basic fe atures and properties of amorphous hydrogenated carbon films (e.g., H/ C codeposition rate, bonded versus unbonded hydrogen ratio, thermal st ability and reactivity with air) as a function of some of the key proc ess parameters (e.g., surface temperature, flux, energy, and type of t he particle species incident upon the film surface). The examples pres ented cover: (i) the kinetics of the H/C codeposition process emphasis ing the hydrogen content of the film; (ii) the removal of the film due to energetic ion bombardment; and (iii) the thermal stability of hydr ogen trapped in the codeposited layer in vacuum and in air.