| Publications [#60215] of Peter K. Haff
Papers Published
- Haff, P.K. and Watson, C.C., The erosion of planetary and satellite atmospheres by energetic atomic particles,
J. Geophys. Res. (USA), vol. 84 no. B14
(1979),
pp. 8436 - 42, Pasadena, TX, USA
(last updated on 2007/04/10)
Abstract: Analytic expressions are presented which may be used to compute the sputter-erosion yield from any unimolecular gravitationally bound gas by any atomic charged particle of energy. A calculation of solar wind proton and alpha particle induced erosion of the CO2 atmosphere of Mars predicts molecular sputtering yields Sp≈0.029 and Sα≈0.21. These numbers are comparable to the results of earlier Monte Carlo simulations. An expression for the emission yield of energetic molecular fragments produced in primary knock-on events is also given in closed form. Such fragment emission is of secondary importance for mass loss compared to the molecular yield itself. Erosion by radiation belt protons of a hypothetical thin O2 atmosphere associated with the Jovian satellite. Ganymede is considered. Molecular sputtering yields for proton energies at 1 keV and 1 MeV are 0.115 and 6.4×10-4, respectively. The yield at the lower energy can have significant effects on atmospheric equilibrium should keV proton fluxes equal or exceed about 108 cm-2 s-1
Keywords: Jupiter;Mars;planetary atmospheres;planetary satellites;solar wind;
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