The dependence on ion energy and temperature of helium trapping in nickel

The reduction of helium concentration in the core of the plasma is a major issue to control the fusion reaction. Nickel has been proposed to be used in the vicinity of the divertor as a helium selective pumping material. In this study, the amount of trapped helium in nickel after helium plasma irradiation was measured by thermal desorption spectroscopy (TDS). The incident energy of helium ion was adjusted by the negative bias voltage. The dependence of the trapped amount of helium on the helium incident energies was studied using different irradiation temperature. Besides a peak at low temperature, desorption peaks of helium appeared in the high temperature region when the energy of the helium ion is relatively high. For irradiation temperatures below 400°C, the amount of trapped helium increased linearly with the energy of the helium ion. For irradiation temperatures higher than 500°C, the trapping of helium needed of relatively high incident ion energies. The dependence of the amount of trapped helium on the irradiation fluence was also investigated.