Differential and total cross sections for electron-impact ionization of atomic oxygen

Burnett, T.; Rountree, S.P.

doi:10.1103/physreva.20.1468

Cited by 25 publications

(4 citation statements)

References 24 publications

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“…We use a comprehensive database of cross sections for electron‐neutral collisions from Itikawa [] and the compilation of Sung and Fox []. Differential cross sections for secondary electron emission were obtained from Burnett and Rountree [], Opal et al . [], Shyn [], and Shyn and Sharp [].…”

Section: Methodsmentioning

confidence: 99%

“…We use a comprehensive database of cross sections for electron-neutral collisions from Itikawa [2002] and the compilation of Sung and Fox [2000]. Differential cross sections for secondary electron emission were obtained from Burnett and Rountree [1979], Opal et al [1971], Shyn [1983], and Shyn and Sharp [1979]. Angledependent relative scattering cross sections were obtained from Porter and Jump [1978] and Porter et al [1987].…”

Section: Scattering Cross Sectionsmentioning

confidence: 99%

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Electron impact ionization in the Martian atmosphere: Interplay between scattering and crustal magnetic field effects

Lillis

Fang

2015

J. Geophys. Res. Planets

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Precipitating electrons are typically the dominant source of energy input into Mars' nighttime upper atmosphere, with consequences for atmospheric and ionospheric structure, composition, chemistry, and electrodynamics. Mars' spatially heterogeneous crustal magnetic fields affect the fluxes of precipitating electrons, via both the magnetic mirror force and Gauss' law of conservation of magnetic flux. We use a kinetic electron transport model to examine ionization rate profiles that result from the combination of these magnetic effects and elastic and inelastic scattering by atmospheric neutrals. Specifically, we calculate ionization rates as a function of altitude, crustal magnetic field strength, and the initial energy and pitch angle of the precipitating electrons, covering the relevant ranges of these parameters. Several complex behaviors are exhibited, including bifurcating ionization peaks with distinct characteristics and energy-dependent and crustal field strength-dependent increases in ionization with decreasing pitch angle. Elucidating such behavior is important for understanding the effect of Mars' unique crustal fields on the Mars upper atmosphere and ionosphere, both to predict the consequences of measured electron precipitation and to enable, for the first time, downward coupling of global plasma models with thermosphere-ionosphere models.

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Section: Methodsmentioning

confidence: 99%

Section: Scattering Cross Sectionsmentioning

confidence: 99%

Electron impact ionization in the Martian atmosphere: Interplay between scattering and crustal magnetic field effects

Lillis

Fang

2015

J. Geophys. Res. Planets

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“…We developed a comprehensive database of cross sections for O, O 2 , N 2 , CO 2 , CO and Ar from Ajello et al [1990], Cvejanovic and Crowe [1997], Chilton and Lin [1999], Itikawa [2002] and the compilation of Sung and Fox [2000]. Differential cross sections for secondary electron emission were obtained from Shyn and Sharp [1979], Burnett and Rountree [1979] and Opal et al [1971]. Angle‐dependent relative scattering cross sections were obtained from Porter and Jump [1978] and Porter et al [1987].…”

Section: Methodsmentioning

confidence: 99%

Nightside ionosphere of Mars: Modeling the effects of crustal magnetic fields and electron pitch angle distributions on electron impact ionization

et al. 2009

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[1] The night side ionosphere of Mars is known to be highly variable: essentially nonexistent in certain geographic locations, while occasionally nearly as strong as the photoionization-produced dayside ionosphere in others. The factors controlling its structure include thermospheric densities, temperatures and winds, day-night plasma transport, plasma temperatures, current systems, solar particle events, crustal magnetic fields, and electron precipitation, none of which are adequately understood at present. Using a kinetic Monte Carlo approach called Mars Monte Carlo Electron Transport (MarMCET), we model the dynamics of precipitating solar wind electrons on the nightside ionosphere of Mars to study the effects of these last two factors on ionospheric density and structure. We calculate ionization rate profiles and, using simple assumptions concerning atmospheric chemistry, also calculate electron density profiles, total electron content, and equivalent ionosphere slab thickness. We present the first model investigation of the coupled effects of crustal magnetic field gradients and precipitating electron pitch angle distributions (PADs). Including such effects, particularly in cases of nonisotropic PADs, is found to be essential in accurately predicting ionization rate and electron density profiles: peak ionization rates can vary by a factor of 20 or more when these effects are included.

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“…For each of 40 initial pitch angles, 1000 particles with a typical energy distribution from 80 eV to 20 keV [ Mitchell et al , 2001] are sent down a magnetic field line into an MTGCM atmosphere [ Bougher et al , 1999, 2000]. Over 500 types of elastic and inelastic collisions with CO 2 , O, CO, O 2 , and N 2 are included, using cross sections compiled by Sung and Fox [2000], Shyn and Sharp [1979] and Burnett and Rountree [1979]. For each electron, the probabilities for all of these collisions are calculated as a function of distance along the electron's spiral path, and random numbers are used to determine a) where (if at all) a collision occurs, b) if a collision occurs, the amount of energy lost by the electron and c) the scattering angle according to phase functions derived from theory and laboratory experiments [ Porter and Jump , 1978; Porter et al , 1987].…”

Section: Electron Reflectometrymentioning

confidence: 99%

Mapping crustal magnetic fields at Mars using electron reflectometry

Lillis

Mitchell

Lin

et al. 2004

Geophysical Research Letters

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[1] We present a kinetic model for the interaction of electrons precipitating along magnetic field lines into Mars' atmosphere and develop a technique for detecting crustal magnetic fields, which act as magnetic mirrors, reflecting some of the incident electrons back to spacecraft altitudes. We present an initial map covering 20% of the planet, which shows the topology of magnetic sources along the dichotomy boundary and reveals new magnetic sources in the northern lowlands, implying the existence of preserved Noachian crust beneath at least some regions of the apparently young plains.

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Differential and total cross sections for electron-impact ionization of atomic oxygen

Cited by 25 publications

References 24 publications

Electron impact ionization in the Martian atmosphere: Interplay between scattering and crustal magnetic field effects

Electron impact ionization in the Martian atmosphere: Interplay between scattering and crustal magnetic field effects

Nightside ionosphere of Mars: Modeling the effects of crustal magnetic fields and electron pitch angle distributions on electron impact ionization

Mapping crustal magnetic fields at Mars using electron reflectometry

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