Energy Distributions for Desorption of Sodium and Potassium from Ice: The Na/K Ratio at Europa - INSU - Institut national des sciences de l'Univers Access content directly
Journal Articles Icarus Year : 2002

Energy Distributions for Desorption of Sodium and Potassium from Ice: The Na/K Ratio at Europa

Abstract

The sputtering and decomposition of the surface of Europa by fast ions and electrons lead to the production of an atomosphere containing sodium and potassium atoms. Here time-of-flight energy distributions are measured for Na and K sputtered from a vapor-deposited ice by 200-eV electrons. These data are then used in a Monte Carlo simulation for alkalis in Europa's atmosphere. Na/K ratios versus distance from Europa are calculated and compared to the recent observations in the range 6 to 18 Europan radii from the surface. Normalizing to the observations, the Na/K ratio for the loss rates is ∼27 and the ratio for the average surface source rates is ∼20. These ratios are very different from the Na/K ratio at Io and are larger than the Na/K ratio suggested for Europa's putative subsurface ocean, consistent with fractionation on freezing and upwelling of ocean material.

Dates and versions

insu-02151952 , version 1 (10-06-2019)

Identifiers

Cite

R. E. Johnson, François Leblanc, Yakshinskiy B. V., T. E. Madey. Energy Distributions for Desorption of Sodium and Potassium from Ice: The Na/K Ratio at Europa. Icarus, 2002, 156 (1), pp.136-142. ⟨10.1006/icar.2001.6763⟩. ⟨insu-02151952⟩
22 View
0 Download

Altmetric

Share

Gmail Facebook X LinkedIn More