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O ++ at Mars

O ++ at Mars. Photoionisation (primary production) Electron impact (second production) Production: Losses: recombination and reaction with other species. Modelling dications in the diurnal ionosphere of Venus G. Gronoff et al., A & A, 2007.

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O ++ at Mars

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  1. O++ at Mars • Photoionisation (primary production) • Electron impact (second production) • Production: • Losses: recombination and reaction with other species

  2. Modelling dications in the diurnal ionosphere of VenusG. Gronoff et al., A & A, 2007 • Model: solar 2000 a semi-empirical solar EUV/XUV model • Input: solar flux and neutral atmosphere • Mechanism: Photochemistry and recombination • For species: O++ , CO2++, N2++ • Compute range: 110-400km

  3. Modelling dications in the diurnal ionosphere of VenusG. Gronoff et al., A & A, 2007 The coefficient of recombination of O++ is much smaller and depends on averaged electron-ion temperature N2++ and CO2++ only depend on the electron temperature. This difference becomes negligible for the total densities when considering all the reactions.

  4. Modelling dications in the diurnal ionosphere of VenusG. Gronoff et al., A & A, 2007 Model and Pioneer Venus Orbiter for O++ O++ most abundant at 300km Dashed line without O+ photoionisation typical values is 80 cm-3 different solar condition The average ionosphere height at subsolar is about 333km (L. H. Brace et al., 1980)

  5. Modelling dications in the diurnal ionosphere of VenusG. Gronoff et al., A & A, 2007 • Dominant species:CO2 below 160kmO below 340kmH and He above 340km • Model results:

  6. Modelling dications in the diurnal ionosphere of VenusG. Gronoff et al., A & A, 2007 Conclusion: • The O++ density was computed and successfully compared to PVO measurement • These densities have been calculated by using a kinetic code for the production rates and a simple chemical scheme for the chemical losses • Doubly-charged ions were produced on the dayside through primary photoionisation and secondary electron impact ionisation • Consequently, a molecular dication layer can be created

  7. Prediction of a N2++ layer in the upper atmosphere of TitanJ. Lilensten et al., GRL, 2005 • Model: A similar model of the previous • Mechanism: Photochemistry and recombination • For species: only N2++

  8. Prediction of a N2++ layer in the upper atmosphere of TitanJ. Lilensten et al., GRL, 2005 Primary photo production (dotted line) Secondary electron impact production (dashed line) Total ion production (full line) Different solar condition

  9. Prediction of a N2++ layer in the upper atmosphere of TitanJ. Lilensten et al., GRL, 2005 Conclusion: • N2++ density has been calculated by using a kinetic code for the production rates and a simple chemical scheme for the chemical losses • The chemical reaction rate constants have been measured in recent laboratory experiments • These ions are produced in the dayside through the ionisation of nitrogen • They are essentially lost by dissociative recombination with thermal electrons and by chemical reactions with N2 and CH4 • A layer is created with a peak density of 104m-3 around 1100km

  10. Prediction and modelling of doubly-charged ions in the Earth’s upper atmosphereC. Simon et al., Annales Geophysicae, 2005 • O++ reaches 60 to 100 ions cm-3 at 500 km

  11. Prediction of a CO22+ layer in the atmosphere of MarsO. Witasse et al., GRL, 2002 • Model: A similar model of the previous (earlier model) • Mechanism: Photochemistry and recombination • For species: only CO2++

  12. Prediction of a CO22+ layer in the atmosphere of MarsO. Witasse et al., GRL, 2002 Neutral densities (left) Modeled and measured electron density Neutral and electron temperature (right) CO2++ density modeled Ions density measured Conclusion: CO2++ get a peak of 5 cm-3 at 160km

  13. Prediction of a CO22+ layer in the atmosphere of MarsO. Witasse et al., GRL, 2002 Conclusion: • The chemical coefficient rates have been measured in the laboratory • The ions are produced in the dayside by the ionization of carbon dioxide and are lost by dissociative recombination with thermal electrons and by chemical reactions with CO2 • A layer is created with a density peak of 5 cm-3 at 160 km • This work opens a series of promising studies on double ionization processes in the Mars inosphere

  14. Three-dimensional, multispecies, high spatial resolution MHD studies of the solar wind interaction with MarsY. Ma et al., JGR, 2004

  15. Ionospheric plasma acceleration at Mars: ASPERA-3 resultsR. Lundin et al., Icarus, 2006

  16. Modelling dications in the diurnal ionosphere of Venus(2007) • Prediction of a N2++ layer in the upper atmosphere of Titan(2005) • Prediction and modelling of doubly-charged ions in the Earth’s upper atmosphere(2005) • Prediction of a CO22+ layer in the atmosphere of Mars(2002) • The dynamic behavior of the Venus Ionosphere in Response to Solar wind interaction(1980) • Three-dimensional, multispecies, high spatial resolution MHD studies of the solar wind interaction with Mars(2004) • Ionospheric plasma acceleration at Mars: ASPERA-3 results(2006)

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