[Zurück]

P. Szabo, H. Biber, N. Jäggi, M. Brenner, D. Weichselbaum, A. Niggas, R. Stadlmayr, D. Primetzhofer, A. Nenning, A. Mutzke, M. Sauer, J. Fleig, A. Foelske-Schmitz, K. Mezger, H. Lammer, A. Galli, P. Wurz, F. Aumayr:
"Dynamic potential sputtering of lunar analog material by solar wind ions";
Astrophysical Journal, 891 (2020), S. 10001 - 10012.

Pyroxenes ((Ca, Mg, Fe, Mn)2Si2O6) belong to the most abundant rock forming minerals that make up the surface
of rocky planets and moons. Therefore, sputtering of pyroxenes by solar wind ions has to be considered as a very
important process for modifying the surface of planetary bodies. This is increased due to potential sputtering by
multiply charged ions; to quantify this effect, sputtering of wollastonite (CaSiO3) by He2+ ions was investigated.
Thin films of CaSiO3 deposited on a quartz crystal microbalance were irradiated, allowing precise, in situ, real time
sputtering yield measurements. Experimental results were compared with SDTrimSP simulations, which were
improved by adapting the used input parameters. On freshly prepared surfaces, He2+ ions show a significant
increase in sputtering, as compared to equally fast He+ ions. However, the yield decreases exponentially with
fluence, reaching a lower steady state after sputtering of the first few monolayers. Experiments using Ar8+ ions
show a similar behavior, which is qualitatively explained by a preferential depletion of surface oxygen due to
potential sputtering. A corresponding quantitative model is applied, and the observed potential sputtering behaviors
of both He and Ar are reproduced very well. The results of these calculations support the assumption that mainly O
atoms are affected by potential sputtering. Based on our findings, we discuss the importance of potential sputtering
for the solar wind eroding the lunar surface. Estimated concentration changes and sputtering yields are both in line
with previous modeling for other materials, allowing a consistent perspective on the effects of solar wind potential
sputtering.

http://dx.doi.org/10.3847/1538-4357/ab7008