Abstract
The ejection of atoms and molecules from an atmosphere due to the energy deposited by plasma bombardment has been shown to play a role in the loss of species from certain planetary and satellite atmospheres. This ejection, often referred to as sputtering, can be produced by the bombarding plasma [Watson et al., 1980; McGrath and Johnson, 1987] and by locally generated [e.g., Kozyra et al., 1982; Ishimoto et al., 1986; Luhmann and Kozyra, 1991]. Although the direct solar wind sputtering of Venus and Mars [Watson et al., 1980] was shown not to be significant compared to other loss processes [Hunten et al., 1989], Luhmann and Kozyra [1991] (LK) recently showed that the sputtering produced by pickup ions is not negligible. They used a particle transport code to calculate the ejected particle flux. However, in earlier work [Watson et al., 1980; Sieveka and Johnson, 1984; McGrath and Johnson, 1987], expressions developed for the sputtering of and ion penetration into condensed materials were used to describe sputtering from planetary atmospheres [e.g. Johnson, 1990]. Here the results of Luhmann and Kozyra [1991] are tested against these analytic expressions after a brief review.
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