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Publications [#281187] of Peter K. Haff

Papers Published

  1. Haff, PK; Watson, CC, The erosion of planetary and satellite atmospheres by energetic atomic particles, Journal of Geophysical Research, vol. 84 no. B14 (1979), pp. 8436-8436, American Geophysical Union (AGU), Pasadena, TX, USA, ISSN 0148-0227 [Gateway.cgi], [doi]
    (last updated on 2023/06/01)

    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;