Erosion of ices: Physical and astrophysical discussion

Abstract

We have irradiated thin films of H₂O ice at 77 K with keV ions (H⁺, He⁺, C⁺, Ne⁺). The measurements of the thicknesses of the films have been performed by in situ infrared spectrometry. We have studied the variation of the erosion rates with the current, the mass and the energy of the incident ions. In particular, we have shown that the erosion is not merely a surface process but occurs through the breaking of the molecules constituting the icy matrices all along the path of the incident particles. We have obtained a rate of 0.2 H₂O/incident proton for the erosion rate of a H₂O icy matrix irradiated by a mixture of ions with composition and energy typical of that of the present solar wind.