EFFECTS OF LITHIUM-IMPLANTATION ON THE HYDROGEN RETENTION IN BOTH A-C-H AND A-SIC-H MATERIALS SUBMITTED TO DEUTERIUM BOMBARDMENT

The hydrogen release in plasma facing materials is a challenging probl em for the hydrogen recycling, The hydrogen desorption from the a-C:H and a-SiC:H materials induced by deuterium bombardment has been invest igated. Prior to the deuterium bombardment, both materials were implan ted with different fluences of lithium ions. Before and after each irr adiation, depth profiles of H, Li and deuterium were determined by nuc lear microanalysis. After; deuterium bombardment, it is shown that the retention of the initial hydrogen in both materials was enhanced by i ncreasing the total dose of the implanted Li. For the a-C:H samples, t he hydrogen desorption under deuterium bombardment was strongly reduce d by lithium implantation. This effect was also evidenced in a-SiC:H s amples, even though it is less spectacular than in a-C:H, Also, nuclea r analyses showed that the retained dose of deuterium decreases when t he lithium concentration increases. This could be a result of the form ation of Li-H bonds which occurs to the detriment of deuterium retenti on in both a-C:H and a-SiC:H materials. Preliminary results of both ma terials exposed to TdeV tokamak discharges confirms the role of Li in hydrogen retention, already ol;served in deuterium bombardment exposur e.