36th DPS Meeting, 8-12 November 2004
Session 16 Jovian System
Poster I, Tuesday, November 9, 2004, 4:00-7:00pm, Exhibition Hall 1A

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[16.16] Mechanisms of O2 Sputtering from Water Ice by 100KeV Ar+

B. D. Teolis, R. Vidal, J. Shi, R. A. Baragiola (University of Virginia), Laboratory for Space Research Team

We have conducted laboratory studies of the sputtering of water ice using 100keV Ar+ ions, between 20K and 150K. We have found that the temperature dependence of the total sputtering yield is heavily influenced by the thermal and irradiation history of the ice. The sputtering yield also shows a complex dependence on irradiation fluence, which is correlated to the rate of ejection of O2 molecules from the ice. A diffusion model is proposed to explain the observed behaviors in the O2 emission. It is argued that the diffusing species, produced by the Ar+ below the ice surface, are transported to an open surface, whereupon O2 is ejected via sputtering or thermal desorption. At 130K and above, thermal diffusion is dominant, whereas at 100K and below, radiation enhanced diffusion is most important. The influence of radiation damage, defects and traps on the thermal and radiation enhanced diffusion rates will be discussed, together with the implications of these findings for the Jovian and Saturnian systems.

Work supported by NSF Astronomy and NASA’s Cassini and Planetary Atmospheres Program.

The author(s) of this abstract have provided an email address for comments about the abstract: bdt4z@virginia.edu

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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.