Deuterium Treatment Effects On Lithium And Tin-Lithium Sputtering In Solid And Liquid Phase

Abstract

The absolute sputtering yields of D⁺, He⁺ and Li⁺ on solid, liquid lithium and liquid tinlithium have been successfully measured and modeled at low energies in the Ion-surface InterAction Experiment (IIAX). IIAX is used in this work to determine the dependence of Li erosion on the use of hydrogen isotopes to treat liquid metal surfaces of both liquid lithium and liquid tin-lithium. Earlier data from IIAX demonstrates that for He⁺ bombardment of solid phase lithium, the physical sputtering yield is reduced by deuterium treatment of the surface. In this work data for D⁺ bombardment of solid phase lithium is presented also shows similar sputtering reductions. In the case of tinlithium both in the solid and liquid phase, deuterium treatment does not affect the absolute sputtering yield of lithium. The secondary sputtered ion fraction of lithium atoms has also been measured in IIAX and the effect of deuterium coverage is discussed. In IIAX, a Colutron ion source is used to create and accelerate He⁺ or D⁺ onto a 100 mm² metal target, with an influx of the order of 10¹⁴ ions/cm²/sec. The metal targets are heated past their melting point to the desired temperature, where the surface oxide layer is plasma cleaned by a hollow cathode source with an influx in the order of 10¹⁷ ions/cm²/sec and immediately irradiated with D⁺ or He⁺ ion beams. The evaporated flux at the desired temperature is measured before and after beam irradiation. Modeling of the absolute sputtering yield is accomplished by VFTRIM3D, a variant of the TRIM-SP code.