Venus Ionosphere: Photochemical and Thermal Diffusion Control of Ion Composition

@article{Bauer1979VenusIP,
  title={Venus Ionosphere: Photochemical and Thermal Diffusion Control of Ion Composition},
  author={Siegfried J. Bauer and Thomas M. Donahue and Richard E. Hartle and Harry A. Jr. Taylor},
  journal={Science},
  year={1979},
  volume={205},
  pages={109 - 112}
}
The major photochemical sources and sinks for ten of the ions measured by the ion mass spectrometer on the Pioneer Venus bus and orbiter spacecraft that are consistent with the neutral gas composition measured on the same spacecraft have been identified. The neutral gas temperature (Tn) as a function of solar zenith angle (χ) derived from measured ion distributions in photochemical equilibrium is given by Tn (K) = 323 cos1/5χ. Above 200 kilometers, the altitude behavior of ions is generally… 
Dynamical response of the dayside ionosphere of Venus to the solar wind
Dayside ion composition measurements made by the orbiter ion mass spectrometer and the orbiter electron temperature probe on the Pioneer Venus orbiter are used to infer the dominant processes
Ion temperature anisotropy and heat flow in the Venus lower ionosphere
Motivated by the recent observations of supersonic ion flow in the Venus ionosphere near the terminator, we have studied the extent to which such a flow can induce an ion temperature anisotropy and a
Model calculations of the dayside ionosphere of Venus - Ionic composition
Comprehensive model calculations of the dayside ion density distributions were carried out and compared with results from the Pioneer Venus ion mass spectrometer. The coupled continuity and momentum
Comparison of Calculated and Measured Ion Densities on the Dayside of Venus
TLDR
The distributions of five minor ions are calculated for the chemically controlled region and the agreements are poor, an indication that the present understanding of the Venus minor ion chemistry is still incomplete.
A Two-Dimensional Model of the Ionosphere of Venus
A substantial nightside ionosphere has been observed on Venus during most orbits of the Pioneer Venus Orbiter. However, on some orbits during which the solar wind dynamic pressure was large, the
Transport of ionospheric O+ ions across the Venus terminator and implications
Vector velocities of O+ ions in the Venus ionosphere are reported for the dawn and dusk terminator regions. The velocity vectors are generally directed antisunward and radially inward toward the
Evidence of upward H+ flow in the Venus dayside ionosphere
At Venus H + is expected to be under diffusive equilibrium above about 400 km, but it is difficult to verify this under normal circumstances, because solar wind interaction terminates the subsolar
Thermal diffusion calculations for the ionosphere of Venus
Simplified multicomponent diffusion calculations are made for the ionosphere of Venus. Large differences in temperature between electrons and ions and appreciable temperature gradients that are near
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References

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Thermal plasma quantities measured by, the retarding potential analyzer (RPA) are, together with companion Pioneer Venus measurements, the first in situ measurements of the Venus ionosphere. High
Ionosphere of Venus: First Observations of the Effects of Dynamics on the Dayside Ion Composition
Bennett radio-frequency ion mass spectrometers have returned the first in situ measurements of the Venus dayside ion composition, including evidence of pronounced structural variability resulting
Comparison of Calculated and Measured Ion Densities on the Dayside of Venus
TLDR
The distributions of five minor ions are calculated for the chemically controlled region and the agreements are poor, an indication that the present understanding of the Venus minor ion chemistry is still incomplete.
Ionosphere of Venus: First Observations of the Dayside Ion Composition Near Dawn and Dusk
The first in situ measurements of the composition of the ionosphere of Venus are provided by independent Bennett radio-frequency ion mass spectrometers on the Pioneer Venus bits and orbiter
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Measurements of the composition, temperature, and diurnal variations of the major neutral constituents in the thermosphere of Venus are being made with a quadrupole mass spectrometer on the Pioneer
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TLDR
Measurements in situ of the neutral composition and temperature of the thermosphere of Venus are being made with a quadrupole mass spectrometer on the Pioneer Venus orbiter, with O/CO2 ratios in the upper atmosphere being greater than was commonly expected.
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TLDR
Elevated temperatutres observed at times of low solar wind flux exhibit height profiles that are consistent with a model in which less than 5 percent of the solar wind energy is deposited at the ionopause and is conducted downward through an unmagnetized ionosphere to the region below 200 kilomneters where electron cooling to the neutral atmosphere proceeds rapidly.
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TLDR
The Bennett radio-frequency ion mass spectrometer on the Pioneer Venus orbiter is returning the first direct composition evidence of the processes responsible for the formation and maintenance of the nightside ionosphere, revealing a surprising abundance of O+ from the dayside leading to the formation of O2+ through charge exchange with CO2.
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