  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.
