The moon and the planets

, Volume 24, Issue 2, pp 157–173

Negative ions in comets

  • A. Wekhof


The primary negative ion sources in comets are shown to be: for the inner coma—both polar photodissociation of HCN, electron attachment of OH and collisions with alkalis; in the vicinity of the nucleus—plasma, excavated during interplanetary dust impacts on the nucleus; for both the contaminated solar wind region and sporadic discharges in the non-homogeneous inner coma plasma—dissociative electron attachment and charge inversion during keV positive ion scattering by cometary dust are also significant sources. Negative ion abundance for Halley's Comet has been estimated to be from 10−6 to 10−10 of electron densities. However, this ratio may be more due to the formation of clusters A(H2O)n. Some possible cometary plasma effects, caused by negative ions, have also been discussed.


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  1. Allen, C. W.: 1973;Astrophysical Quantities, 3rd ed., Univ of London, The Athlone Press.Google Scholar
  2. Axford, W. I.: 1979,Cometary Missions, pp. 1–12, Bamberg, West Germany.Google Scholar
  3. Benninghoven, A.: 1973,Appl. Physics,5, 3–16, Springer-Verlag, Berlin.Google Scholar
  4. Behrishch, R., Eckstein, W., Meischner, P., Scherzer, B. M. U., and Verbeek, H.: 1975, in S. Datz (ed.),Atomic Collisions in Solids, pp. 318–330.Google Scholar
  5. Berkowitz, J., Chupka, W. A., and Walter, T. A.: 1969,J. Chem. Phys. 50, 4, 1497–1500.Google Scholar
  6. Chernjak, Yu. and Wekhof, A.: 1979,J. Appl. Phys.-D,12, 539–554, Great Britain.Google Scholar
  7. Coradini, M. and Wekhof, A.: 1980,The Moon and the Planets 22, 178–184.Google Scholar
  8. Dalmann, B. K., Grün, E., Kissel, J., and Dietzel, H.: 1977,Planetary Space Sci. 25, 135–147.Google Scholar
  9. Dietzel, H., Eichhorn, G., Fechtig, H., Grün, E., Hoffman, H. J., and Kissel, J., 1973,J. Phys.-E, Sci. Instrum. 6, 209.Google Scholar
  10. Eichhorn, G.: 1978,Planetary Space Sci. 26, 469–471.Google Scholar
  11. Fechtig, H., Grün, E., and Morfill, G.: 1979,Planetary Space Sci. 27, 511–531.Google Scholar
  12. Formizano, V.: 1979, inCometary Missions, pp. 47–62. Bamberg, West Germany.Google Scholar
  13. Fürstenau, H., Hillenkamp, F., and Nietsche, R., 1979,Int. J. Mass Spectrometry and Ion Physics 31, 85–91.Google Scholar
  14. Heroux, L. and Hinteregger, H. E.: 1978,J. Geophys. Res. 83, A11, 5305–5308.Google Scholar
  15. Hiskes, J. R.: 1979,J. de Physique,40, N7, C7–179 to 192.Google Scholar
  16. Hoffman, M.-J., Fechtig, H., Grün, E., and Kissel, J.: 1975,Planetary Space Sci. 23, 985–991.Google Scholar
  17. Houpis, H., and Mendis, D. A.: January 1980, Report to AAS Meeting, San Francisco.Google Scholar
  18. Ip, W.-H.: 1979,Planetary Space Sci. 27, 121–125.Google Scholar
  19. Ip, W.-H., and Mendis, D. A.: 1976,Icarus 28, 389–400.Google Scholar
  20. Lacmann, K. and Herschbach, D. R.: 1970,Chem. Phys. Lett. 6, 106.Google Scholar
  21. Levy, E. H. and Jokipi, J. R.: 1977,Nature 264, 423–424.Google Scholar
  22. Massey, H.: 1976,Negative Ions, Cambridge Univ. Press, Great Britain.Google Scholar
  23. McDaniel, E. W.: 1964,Collision Phenomena in Ionized Gases, London.Google Scholar
  24. McDonnell, I. A. M., Berg, O. E., and Richardson, F. F.: 1975,Planetary Space Sci. 23, 205–214.Google Scholar
  25. Mendis, D. A.: 1977, Unpublished letter.Google Scholar
  26. Mendis, D. A. and Ip, W.-H.: 1977,Space Sci. Rev. 20, 145–190.Google Scholar
  27. Mendis, D. A., Holtzer, T. E., and Axford, W. I.: 1972,Astrophys. Space Sci. 15, 313–325.Google Scholar
  28. Mosely, J. M., Olson, R. E., and Peterson, R.: 1975,Case Studies in Atomic Physics 5, N.1, 1–45.Google Scholar
  29. Nagy, A., Neugebauer, M., Delsemme, A., Keller, V., Mauersberger, K., Niemann, H., Wetherill, G., and Huntress, W.: 1979,International Comet Mission: Halley and Temple-2, Baseline,3, pp. 2.7–2.24, NASA and ESA Edition, Pasadena, U.S.A.Google Scholar
  30. Newburn, Ray L., Jr.: 1979,Comet Halley Micrometeorite Hazard Workshop, Proc., pp. 35–51, Noordwijk, The Netherlands, ESA SP-153, Paris, France.Google Scholar
  31. Newburn, Ray L., Jr.: 1979,International Comet Mission: Halley and Temple-2, Baseline, 6—Environmental Description, pp. B1-B40, NASA and ESA Edition, Pasadena, U.S.A.Google Scholar
  32. Newburn, Ray L., Jr., and Yeomans, D. K.: 1977,A First Comet Mission, NASA Rep. TM 78420, U.S.A.Google Scholar
  33. Nigham, W. K.: 1977,Phys. Rev 15A, 1701–1720.Google Scholar
  34. Reid, G. C.: 1970,J. Geophys. Res. 75, 2551.Google Scholar
  35. Schlachter, A. S., Stalder, K. R., and Stearns, J. W.: 1980,Phys. Rev. A.,22, N6, 2494–2509.Google Scholar
  36. Shields, H. and Smith, A. L. S.: 1978,Appl. Phys., Springer Verlag,16, 111–118.Google Scholar
  37. Smirnov, V. M.: 1977,Sov. Phys. Uspekhy 20, 119–133.Google Scholar
  38. Verbeek, H., Eckstein, W., and Datz, S.: 1976,J. Appl. Phys., U.S.A.,47, No. 5, 1785–1789.Google Scholar
  39. Wekhof, A.: 1980,The Moon and Planets 22, 185–189.Google Scholar
  40. Zel'dovich, Ya. B. and Raizer, Yu. P.: 1966–67,Physics of Shock Waves and High Temperature Hydrodynamic Phenomena, Pergamon Press, New York.Google Scholar

Copyright information

© D. Reidel Publishing Co 1981

Authors and Affiliations

  • A. Wekhof
    • 1
  1. 1.Space Sciences LaboratoryUniversity of CaliforniaBerkeleyUSA

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