Deuterium plasma interactions with liquid gallium

Abstract

Liquid metals such as gallium, tin and lithium are potential plasma-facing materials that may be used to withstand the high heat and particle fluxes in a fusion plasma environment. The interaction of plasma with liquid gallium surfaces has been examined experimentally because of the liquid's wide temperature range (303-2478 K) and relatively low chemical reactivity. The deuterium retention in liquid gallium samples following plasma exposure in the PISCES experimental plasma device is measured using thermal desorption spectroscopy and is found to be independent of exposure temperature. The retention level saturates at a value of roughly 3 × 10 23 D m −3 (or about 5 ppm) for sample exposure temperatures ranging from 333 to 800 K and incident ion fluences up to 1.5 × 10 26 D m −2 . Results from the analyses of the surface after plasma exposure using Auger electron spectroscopy is reported. Micropitting is observed in scanning electron microscope pictures taken after plasma exposure and after resolidification of the gallium surface. Calculations based on the observed retained concentration of deuterium in gallium show that the pumping capabilities of a flowing gallium surface will be small. In addition, measurements of the erosion yield of deuterium-bombarded gallium are presented and compare favourably with results from sputtering yield calculations.

Molecular dynamics modeling of deuterium in liquid lithium surfaces

“…Higher surface temperature increases the stimulated-evaporation low-energy peak. This has also been seen experimentally [2][3][4][5].…”

“…Compared with solid surfaces, the structural and thermodynamic properties of liquid Li surfaces are different, which leads to significant effects on the erosion and reflection. Recent experiments, IIAX at UIUC [2] and PICSES at UCSD [3][4][5], show enhanced erosion with increasing surface temperature. Codes based on the binary collision approximation (BCA) (e.g.…”

Incident-mass dependence of temperature-enhanced ion-induced sputtering in liquid metals

“…Also important is an understanding of any changes in these responses due to elevated surface temperatures as such a divertor will be operated at high temperatures, particularly on a transient basis. Similar to that of other liquid metal PFC candidates [2][3][4][5], tinÕs sputtering yield due to low-energy, light ion bombardment exhibits clear temperature dependence [6,7].…”

Model development and analysis of temperature-dependent lithium sputtering and sputtered Li+ transport for tokamak plasma-facing applications

“…Experiments have measured lithium sputtering to remain under self-sputtering runaway levels for temperatures under $673 K [6,8,9]. Lithium sputtering increases non-linearly with temperature for bombardment with D, He or Li ions between 543-673 K. Several models have attempted to explain this phenomenon [10,11].…”