A laboratory study of water ice erosion by low-energy ions

TL;DR

This study experimentally measures water ice erosion by low-energy ions at 10 K, confirming theoretical models and estimating erosion rates on outer Solar system objects due to solar wind sputtering.

Contribution

It provides the first laboratory data on sputtering yields of water ice by singly and doubly charged ions at low temperatures, aligning with theoretical predictions.

Findings

Sputtering yields match theoretical models.

No significant difference between singly and doubly charged ions.

Formation of 13CO and 13CO2 during irradiation.

Abstract

Water ice covers the surface of various objects in the outer Solar system. Within the heliopause, surface ice is constantly bombarded and sputtered by energetic particles from the solar wind and magnetospheres. We report a laboratory investigation of the sputtering yield of water ice when irradiated at 10 K by 4 keV singly (13C+, N+, O+, Ar+) and doubly charged ions (13C2+, N2+, O2+). The experimental values for the sputtering yields are in good agreement with the prediction of a theoretical model. There is no significant difference in the yield for singly and doubly charged ions. Using these yields, we estimate the rate of water ice erosion in the outer Solar system objects due to solar wind sputtering. Temperature-programmed desorption of the ice after irradiation with 13C+ and 13C2+ demonstrated the formation of 13CO and 13CO2, with 13CO being the dominant formed species.