Development of new steady-state, low-energy, and high-flux ion beam test device

A new steady-state, low-energy, and high-flux ion beam test device has been developed to study erosion, re-deposition, and hydrogen retention mechanisms of plasma facing materials under high flux conditions. Source plasma was produced by electron cyclotron resonance discharge with 2.45 GHz microwave. Ion extraction was made by spherical multiaperture triode electrodes to obtain high ion flux at the focal point. Ion extraction aperture geometry was designed so that high current density can be obtained in the case of low energy (<500 eV) by applying high deceleration voltage. It was demonstrated that low-energy and high-flux ion beam can be produced by increasing deceleration voltage with the fixed acceleration voltage (beam energy). In the case of hydrogen beam energy of 300 eV, beam power density has rapidly increased with a deceleration voltage over accel–decel ratio 4, and maximum beam flux is ${\text{4.1×10}}^{20}\hspace{0.17em}{\mathrm{H/m}}^2 \mathrm{s}.$ On the other hand, maximum beam flux of ${\text{3.6×10}}^{21}\hspace{0.17em}{\mathrm{H/m}}^2 \mathrm{s}$ was obtained for 3 keV hydrogen beam. These fluxes are much higher than that of conventional mass analyzed ion beam ${\text{(<1.0×10}}^{20}\hspace{0.17em}{\mathrm{H/m}}^2 \mathrm{s}\mathrm{).}$