Energy transfer in O collisions with He isotopes and Helium escape from Mars

Journal Article (Journal Article)

Accurate data on energy-transfer collisions between hot oxygen atoms and the atmospheric helium gas on Mars, are reported. Anisotropic cross sections for elastic collisions of O(3 P) and O(1 D) atoms with helium gas have been calculated quantum mechanically and found to be surprisingly similar. Cross sections, computed for collisions with both helium isotopes, 3 He and 4 He, have been used to construct the kernel of the Boltzmann equation describing the energy relaxation of hot oxygen atoms. Computed rates of energy transfer in O+He collisions have been used to evaluate the flux of He atoms escaping from the Mars atmosphere. Atmospheric layers mostly responsible for production of the He escape flux are identified. Our results demonstrate that strong angular anisotropy of scattering cross sections increases the collisional ejection of light atoms and is critical in the evaluation of He escape from Mars, Venus and Earth. Copyright © 2011 by the American Geophysical Union.

Full Text

Duke Authors

Cited Authors

  • Bovino, S; Zhang, P; Gianturco, FA; Dalgarno, A; Kharchenko, V

Published Date

  • January 1, 2011

Published In

Volume / Issue

  • 38 / 2

International Standard Serial Number (ISSN)

  • 0094-8276

Digital Object Identifier (DOI)

  • 10.1029/2010GL045763

Citation Source

  • Scopus