A simple kinetic theory calculation of terrestrial atomic hydrogen escape fluxes induced by charge exchange collisions

Shizgal, Bernie D.; Lindenfeld, Michael J.

doi:10.1029/ja087ia02p00853

Cited by 18 publications

(23 citation statements)

References 19 publications

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“…As Tu+ increases, more collisions result in neutral hydrogen with escape velocity. This intuitive conclusion has been substantiated by an analytic expression for the escape flux, which was developed by Shizgal and Lindenfeld [ 1982].…”

Section: H+ +O--h +O + (5)mentioning

confidence: 97%

See 1 more Smart Citation

Simultaneous H_α line profile and radar measurements at Arecibo

Kerr¹,

Atreya²,

Meriwether³

et al. 1986

J. Geophys. Res.

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High resolution measurements of the geocoronal Balmer alpha (Hα) emission were made with a Fabry‐Perot interferometer at Arecibo, Puerto Rico, in six observing campaigns between March 1980 and November 1984. Four of these included simultaneous radar measurements of the topside F region. The nighttime variation of the zenith Hα intensity is highly symmetric about solar midnight. However, effective hydrogen temperatures near the morning exobase are generally hotter than near the evening exobase, implying a depletion of exobase hydrogen density in the early morning hours. The exospheric temperature is derived from the Doppler line profiles and is compared to the topside F region O+ temperature. The cooling of H relative to O+ due to the escape of hot, energetic H is not obvious in our data, and it appears that a downward flux of hot protons often causes heating of the bound neutral H population by charge exchange during low to moderate solar activity conditions. This downward flux is usually strongest between 0200 and 0600 LT, and occurs throughout the night in the late fall and early winter. We have detected a deficiency of inbound high‐energy hydrogen relative to the high‐energy outbound population in radial velocity Hα profiles. We have also detected large distortions of the Hα profile wings during low to moderate solar activity periods and during periods of large downward ion speeds. We attribute these wing distortions to efficient charge exchange of H with H+. A narrowing of zenith profile widths near midnight demonstrates the gravitational cooling of H due to the inverse relationship between geocentric distance and the kinetic energy required for escape. We have also searched for evidence that satellite hydrogen populations with small orbital eccentricities may be contributing to narrow line widths.

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Section: H+ +O--h +O + (5)mentioning

confidence: 97%

“…These symmetric profiles provide good estimates of the critical level temperature Tc [Atreya, 1973;Atreya et al, 1975;Kerr et al, 1984]. T½is used in the parameterization of the thermal escape flux Fj, and the charge exchange escape flux FcE [Shizgal and Lindenfeld, 1982].…”

Section: Exospheric Temperaturementioning

confidence: 99%

Simultaneous H_α line profile and radar measurements at Arecibo

Kerr¹,

Atreya²,

Meriwether³

et al. 1986

J. Geophys. Res.

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“…Charge exchange has been studied as a principal source of non-thermal escape of H atoms at the Earth (Shizgal and Arkos 1996), Venus (Hodges 1993) and Mars (Nagy et al 1990) leading to the high D/H ratio measured in Venus' atmosphere (Donahue et al 1982). Charge exchange production of ENAs is usually considered as a nearly resonant collision, equivalent to the exchange of an electron without significant momentum transfer (Shizgal and Lindenfeld 1982;Shizgal and Arkos 1996). Kallio et al (1997) showed that at Mars the region where ENAs are formed by charge exchange between solar wind H + and exospheric O occurs on the dayside in a thin layer whose size depends on solar activity.…”

Section: Plasma-induced Escapementioning

confidence: 99%

“…Solutions have been developed for a linearized Boltzmann equation in order to describe gas flow in the transition region (Shizgal and Lindenfeld 1982;Shizgal and Blackmore 1986;Shizgal and Arkos 1996;Shizgal 1999). This approximation is used to describe the flow of hot or minor species through the background atmosphere assuming their effect is negligible .…”

Section: Boltzmann Transportmentioning

confidence: 99%

Exospheres and Atmospheric Escape

et al. 2008

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“…These nonthermal escape mechanisms play an important role in the evolution of the atmospheres of these planets [ Shizgal and Arkos , 1996]. The charge exchange process of energetic H + or D + in collision with neutral H can produce a significant population of H and D atoms with energies well above thermal [ Chamberlain , 1977; Shizgal and Lindenfeld , 1982; Hodges and Breig , 1993; Hartle et al , 1996]. The dissociative recombination of O 2 + can produce energetic oxygen atoms on all three terrestrial planets and substantial coronae of hot oxygen exist on Earth, Mars and Venus [ Nagy and Cravens , 1988; Ip , 1988].…”

Section: Introductionmentioning

confidence: 99%

Velocity distributions of energetic atoms in planetary exospheres from dissociative recombination

Кабин

Shizgal

2002

J. Geophys. Res.

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[1] A kinetic theory description of translational energetic atoms in the upper planetary atmosphere is presented. A new analytical result for the velocity distribution of the products of reactive collisions is described. Our calculation takes into account different temperatures of the reactants and arbitrary dependence of the cross section on the relative velocity of the colliding particles. The final result is applied to the production of hot oxygen and carbon by dissociative recombination of O 2 + and CO + , respectively. The nascent distribution of hot atoms generated in this way is compared with the earlier Monte Carlo calculations. We use the Boltzmann equation to study the thermalization of the hot oxygen via collisions with the thermal oxygen population. The results of this calculation demonstrate quasi-steady state velocity distribution of high-energy oxygen atoms near the exobase of Venus for daytime conditions.

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A simple kinetic theory calculation of terrestrial atomic hydrogen escape fluxes induced by charge exchange collisions

Cited by 18 publications

References 19 publications

Simultaneous H_α line profile and radar measurements at Arecibo

Simultaneous H_α line profile and radar measurements at Arecibo

Exospheres and Atmospheric Escape

Velocity distributions of energetic atoms in planetary exospheres from dissociative recombination

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A simple kinetic theory calculation of terrestrial atomic hydrogen escape fluxes induced by charge exchange collisions

Cited by 18 publications

References 19 publications

Simultaneous Hα line profile and radar measurements at Arecibo

Simultaneous Hα line profile and radar measurements at Arecibo

Exospheres and Atmospheric Escape

Velocity distributions of energetic atoms in planetary exospheres from dissociative recombination

Contact Info

Product

Resources

About

Simultaneous H_α line profile and radar measurements at Arecibo

Simultaneous H_α line profile and radar measurements at Arecibo