Skip to main content

Advertisement

Electrostatic quasi-monochromatic waves in the downstream region of the Earth’s bow shock based on Geotail observations

Article metrics

  • 187 Accesses

  • 1 Citations

Abstract

Geotail plasma wave observations show the existence of intense electrostatic quasi-monochromatic (EQM) waves in the downstream region of the Earth’s bow shock. They oscillate parallel to the ambient magnetic field and appear at frequencies between the electron plasma and ion plasma frequencies. Although these waves have been believed to be Doppler-shifted ion acoustic waves, the typical plasma parameters observed in the downstream region do not support the generation conditions for ion acoustic waves. In this paper, the existence of cold electron beam-like components accompanying EQM waves is considered based on waveform and statistical analyses. Linear dispersion analyses using realistic plasma parameters revealed that the cold electron beams cause destabilization of electron acoustic waves at frequencies consistent with those of observed EQM waves. The results of observations and linear analyses suggest that EQM waves are generated by the destabilization of the electron acoustic mode.

References

  1. Fairfield, D. H., Average and unusual locations of the earth’s magnetopause and bowshock, J. Geophys. Res., 76, 6700–6716, 1971.

  2. Feldman, W. C., S. J. Bame, S. P. Gary, J. T. Gosling, D. J. McComas, M. F Thomsen, G. Paschmann, N. Sckopke, M. M. Hoppe, and C. T. Russell, Electron heating within the earth’s bow shock, Phys. Rev. Lett., 49, 199, 1982.

  3. Feldman, W. C., R. C. Anderson, S. J. Bame, S. P. Gary, J. T. Gosling, D. J. McComas, M. F Thomsen, G. Paschmann, and M. M. Hoppe, Electron velocity distribution near the earth’s bow shock, J. Geophys. Res., 88, 96, 1983.

  4. Fredricks, S. A., G. M. Crook, C. F. Kennel, I. M. Green, F. L. Scarf, P. J. Coleman, and C. T. Russell, OGO 5 observations of electrostatic turbulence in bow shock magnetic structures, J. Geophys. Res., 75, 3751, 1970.

  5. Gallagher, D. L., Short-wavelength electrostatic waves in the earth’s mag-netosheath, J. Geophys. Res., 90, 1435–1448, 1985.

  6. Gary, S. P and R. L. Tokar, The electron acoustic mode in a two temperature plasma, Phys. Fluids, 28, 2439, 1984.

  7. Leroy, M. M., D. Winske, C. C. Goodrich, C. S. Wu, and K. Papadopoulos, The structure of perpendicular bow shocks, J. Geophys. Res., 87, 5081–5094, 1982.

  8. Matsumoto, H., I. Nagano, R. R. Anderson, H. Kojima, K. Hashimoto, M. Tsutsui, T. Okada, I. Kimura, Y. Omura, and M. Okada, Plasma wave observations with GEOTAIL spacecraft, J. Geomag. Geoelectr., 46, 59–95, 1994.

  9. Montgomery, M. D., J. R. Asbridge, and S. J. Bame, VELA 4 plasma observations near the earth’s bowshock, J. Geophys. Res., 75, 1217, 1970.

  10. Mukai, T., S. Machida, Y. Saito, M. H. T. Terasawa, N. Kaya, T. Obara, and M. E. A. Nishida, The low energy particle (LEP) experimentonboard the GEOTAIL satellite, J. Geomag. Geoelectr., 46, 669–692, 1994.

  11. Omura, Y., H. Kojima, N. Miki, T. Mukai, H. Matsumoto, and R. R. Anderson, Electrostatic solitary waves carried by diffused electron beams observed by the GEOTAIL spacecraft, J. Geophys. Res., 104, 14,627–14,637, 1999.

  12. Rodriguez, P., Magnetosheath electrostatic turbulence, J. Geophys. Res., 84, 917–930, 1979.

  13. Rodriguez, P. and D. A. Gurnett, Electrostatic and electromagnetic turbulence associated with the earth’s bow shock, J. Geophys. Res., 80, 19–31, 1975.

  14. Shin, K., H. Kojima, H. Matsumoto, and T. Mukai, Electrostatic quasi-monochromatic waves downstream of the bow shock: Geotail observations, in Frontiers in Magnetospheric Physics, COSPAR Colloquia Series Vol. 16, edited by M. Hoshino, Y Omura, and L. J. Lanzerotti, p. 293, Elsevier, Kidlington, Oxford, 2005.

  15. Thomsen, M. F., H. C. Barr, S. P. Gary, W. C. Feldman, and T. E. Cole, Stability of electron distribution within the earth’s bow shock, J. Geophys. Res., 88, 3035, 1983.

  16. Tokar, R. L., and S. Gary, Electrostatic hiss and the beam driven electron acoustic instability in the dayside polar cusp, Geophys. Res. Lett., 11, 1180, 1984.

  17. Watanabe, K. and T. Taniuti, Electron acoustic mode in a plasma of two temperature electrons, J. Phys. Soc. Japan, 43, 1819, 1977.

Download references

Author information

Correspondence to Koichi Shin.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Shin, K., Kojima, H., Matsumoto, H. et al. Electrostatic quasi-monochromatic waves in the downstream region of the Earth’s bow shock based on Geotail observations. Earth Planet Sp 59, 107–112 (2007) doi:10.1186/BF03352683

Download citation

Key words

  • Electrostatic plasma wave
  • electron acoustic mode
  • downstream region of the bow shock