Production of high-flux mixed ion beam for study of plasma material interaction

A steady-state and high-flux ion beam irradiation test device (HiFIT) equipped with an ECR ion source and spherical electrodes was developed. Hydrogen irradiation fluxes were 3.6×1021 Hm−2 s−1 for an acceleration voltage Vacc of 3 kV and about 4×1020 Hm−2 s−1 for Vacc from 0.15 to 0.5 kV (dominant ion species is H3+). Mixed ion beams with hydrogen and carbon with the carbon concentration from 0.1% to ∼10% were obtained. Carbon impurity concentration was controlled by puffing methane gas or putting graphite plates in the ion source chamber. Carbon impurity concentration was calculated by using measured effective cross-sections (including dissociation and neutralization) of molecular ions in a beam transport chamber. New mixed material effect on blister formation of tungsten bombarded with hydrogen and carbon mixed ion beam was observed. It was found that carbon impurity of less than 1% in hydrogen beams significantly affected blister formation.