Electron impact excitation of atomic oxygen: Revised cross sections

Zipf, E. C.; Erdman, P. W.

doi:10.1029/ja090ia11p11087

Cited by 100 publications

(79 citation statements)

References 45 publications

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“…The recommendation of Laher and Gilmore (1990) for process (a), deduced from calculations, is in qualitative agreement with the laboratory measurements reported by Stone and Zipf (1974), later corrected by Zipf and Erdman (1985) and Doering and Gulcicek (1989); the uncertainty reaches 50 %. At 70 eV energy, process (b) is around 50 times less efficient than process (a).…”

Section: Ionospheric Response: Modelling the Optical Emissionssupporting

confidence: 74%

Polar cap arcs from the magnetosphere to the ionosphere: kinetic modelling and observations by Cluster and TIMED

et al. 2012

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Abstract. On 1 April 2004 the GUVI imager onboard the TIMED spacecraft spots an isolated and elongated polar cap arc. About 20 min later, the Cluster satellites detect an isolated upflowing ion beam above the polar cap. Cluster observations show that the ions are accelerated upward by a quasistationary electric field. The field-aligned potential drop is estimated to about 700 V and the upflowing ions are accompanied by a tenuous population of isotropic protons with a temperature of about 500 eV.The magnetic footpoints of the ion outflows observed by Cluster are situated in the prolongation of the polar cap arc observed by TIMED GUVI. The upflowing ion beam and the polar cap arc may be different signatures of the same phenomenon, as suggested by a recent statistical study of polar cap ion beams using Cluster data.We use Cluster observations at high altitude as input to a quasi-stationary magnetosphere-ionosphere (MI) coupling model. Using a Knight-type current-voltage relationship and the current continuity at the topside ionosphere, the model computes the energy spectrum of precipitating electrons at the top of the ionosphere corresponding to the generator electric field observed by Cluster. The MI coupling model provides a field-aligned potential drop in agreement with Cluster observations of upflowing ions and a spatial scale of the polar cap arc consistent with the optical observations by TIMED. The computed energy spectrum of the precipitating electrons is used as input to the Trans4 ionospheric transport code. This 1-D model, based on Boltzmann's kinetic formalism, takes into account ionospheric processes such as photoionization and electron/proton precipitation, and computes the optical and UV emissions due to precipitating electrons. The emission rates provided by the Trans4 code are compared to the optical observations by TIMED. They are similar in size and intensity. Data and modelling results are consistent with the scenario of quasi-static acceleration of electrons that generate a polar cap arc as they precipitate in the ionosphere. The detailed observations of the acceleration region by Cluster and the large scale image of the polar cap arc provided by TIMED are two different features of the same phenomenon. Combined together, they bring new light on the configuration of the high-latitude magnetosphere during prolonged periods of Northward IMF. Possible implications of the modelling results for optical observations of polar cap arcs are also discussed.

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Section: Ionospheric Response: Modelling the Optical Emissionssupporting

confidence: 74%

Polar cap arcs from the magnetosphere to the ionosphere: kinetic modelling and observations by Cluster and TIMED

et al. 2012

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“…They found that the incorporation of partial frequency redistribution also enhanced the predicted limb brightening. Their model calculations reproduced the measurements if the O densities from the BNMS model were reduced by about 40~o, but their analysis was based on cross sections for electron impact production of emission at 1304 and 1356 ~_ reported by Stone and Zipf (1974) that were later reduced by a factor of 2.8 (Zipf and Erdman, 1985;Zipf, 1986). A model of the terrestrial dayglow oxygen emissions (Meier et al, 1985) suggested that the Stone and Zipf cross sections should be scaled down by 40~o.…”

Section: Species Sourcementioning

confidence: 75%

“…The analysis of Rottman and Moos was based on the Venus model of Strickland (1973), except for the cross sections for electron impact excitation of O, which were adopted from Zipf and Stone (1971). These cross sections have recently been shown to be too large, by a factor of about 7 for the 1304 A emission and a factor of 2 for the 1356 A emission (Stone and Zipf, 1974;Zipf and Erdman, 1985;Zipf, 1986). Rottman and Moos found electron impact excitation to be the major source of both of the emissions.…”

Section: The Sources Of Dayglow Emission Features Include Photoionizamentioning

confidence: 99%

“…Calculations based on the O 1356 A emission cross sections of Stone and Zipf (1974) indicated that the 1354 A intensity would contribute little to the observed 1356 ]~ signal. Revised calculations, using the renormalized 1356 A electron impact emission cross sections of Zipf and Erdman (1985) give a lower integrated intensity for the 1356 2t emission of about 150 R at low solar activity (see Table II). Hence, the (3, 0) Lyman-Birge-Hopfield band may contribute about 15~o of the observed intensity.…”

Section: N 2 and Nf Emissionsmentioning

confidence: 99%

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Structure, luminosity, and dynamics of the Venus thermosphere

Fox

Bougher

1991

Space Sci Rev

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We review here observations and models related to the chemical and thermal structures, airglow and auroral emissions and dynamics of the Venus thermosphere, and compare empirical models of the neutral densities based in large part on in situ measurements obtained by the Pioneer Venus spacecraft.Observations of the intensities of emissions are important as a diagnostic tool for understanding the chemical and physical processes taking place in the Venus thermosphere. Measurements, ground-based and from rockets, satellites, and spacecraft, and model predictions of atomic, molecular and ionic emissions, are presented and the most important sources are elucidated. Coronas of hot hydrogen and hot oxygen have been observed to surround the terrestrial planets. We discuss the observations of and production mechanisms for the extended exospheres and models for the escape of lighter species from the atmosphere. Over the last decade and a half, models have attempted to explain the unexpectedly cold temperatures in the Venus thermosphere; recently considerable progress has been made, although some controversies remain. We review the history of these models and discuss the heating and cooling mechanisms that are presently considered to be the most important in determining the thermal structure. Finally, we discuss major aspects of the circulation and dynamics of the thermosphere: the sub-solar to anti-solar circulation, superrotation, and turbulent processes.

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“…The absolute excitation cross sections for the resonance lines at 1304, 1027, 989, and 878 Å are also reported by Kanik et al (2001) at 30, 50, and 100 eV using the electron-energy-loss method with uncertainties similar to the recent measurements of the Doering & Yang (2001). Emission cross sections for the 1304 Å line are measured by Noren et al (2001), while the measured emission cross sections for the lines at 1304, 1027, 989, and 878 Å are presented by Wang & McKonckey (1992), Zipf & Erdman (1985), and Zipf & Kao (1986).…”

Section: Introductionmentioning

confidence: 99%

Electron Collisional Excitation Rates for O i Using the B ‐Spline R ‐Matrix Approach

Zatsarinny

Tayal

2003

ASTROPHYS J SUPPL S

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The B-spline R-matrix approach has been used to calculate electron collisional excitation strengths and rates for transitions between the 3 P, 1 D, and 1 S states of ground configuration and from these states to the states of the excited 2s 2 2p 3 ns (n ¼ 3 5), 2s 2 2p 3 np (n ¼ 3 4), 2s 2 2p 3 nd (n ¼ 3 4), 2s 2 2p 3 4f , and 2s2p 5 configurations. The nonorthogonal orbitals are used for an accurate description of both the target wave functions and the R-matrix basis functions. The thermally averaged collision strengths are obtained from the collision strengths by integrating over a Maxwellian velocity distribution of electron energies, and these are tabulated over a temperature range from 1000 to 60,000 K. The parametric functions of scaled energy have also been obtained to represent collision strengths over a wide energy range or thermally averaged collision strengths at any desired temperature.

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Electron impact excitation of atomic oxygen: Revised cross sections

Cited by 100 publications

References 45 publications

Polar cap arcs from the magnetosphere to the ionosphere: kinetic modelling and observations by Cluster and TIMED

Polar cap arcs from the magnetosphere to the ionosphere: kinetic modelling and observations by Cluster and TIMED

Structure, luminosity, and dynamics of the Venus thermosphere

Electron Collisional Excitation Rates for O i Using the B ‐Spline R ‐Matrix Approach

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