Terrestrial foreshock Langmuir waves: STEREO observations, theoretical modeling, and quasi-linear simulations (original) (raw)

Abstract

Langmuir waves in the terrestrial electron foreshock are investigated using observations from the STEREO spacecraft, theoretical modeling, and quasi-linear simulations. Emphases are placed on spatial variations of Langmuir field strength with distance between the spacecraft and the tangent point and on the effects of ambient density fluctuations on these variations. The STEREO mission provides new observations of foreshock Langmuir waves at distances more than twice as far from Earth as previously observed. Based on established geometric properties of the foreshock region, two methods are developed for separating Langmuir waves of foreshock origin from those of solar and/or heliospheric origins. The observed maximum foreshock Langmuir field strength falls with distance via a power law with an exponent À1.01 ± 0.12. The theory and simulations predict field strengths and power law spatial variations in field strengths that are consistent with the observations when scattering of Langmuir waves by density fluctuations is included. The power law exponents predicted by both theory and simulations fall within the uncertainty of the observations for the typical solar wind conditions observed but differ by a factor of %1.5 from simulations that assume density homogeneity. This indicates that density fluctuations play an important role in the beam-Langmuir wave dynamics in the foreshock.

Loading...

Loading Preview

Sorry, preview is currently unavailable. You can download the paper by clicking the button above.

References (61)

  1. Anderson, K. A. (1981), Measurements of the bow shock particles far upstream from the Earth, J. Geophys. Res., 86, 4445.
  2. Anderson, K. A., R. P. Lin, F. Martel, C. S. Lin, G. K. Parks, and H. Re `me (1979), Thin sheets of energetic electrons upstream from the Earth's bow shock, Geophys. Res. Lett., 6, 401.
  3. Bale, S. D., D. Burgess, P. J. Kellogg, K. Goetz, and S. J. Monson (1997), On the amplitude of intense Langmuir waves in the terrestrial electron foreshock, J. Geophys. Res., 102, 11,281.
  4. Bale, S. D., et al. (2008), The electric antennas for the STEREO/WAVES Experiment, Space Sci. Rev., 136, 529.
  5. Benz, A. O. (1993), Plasma Astrophysics, Kluwer Acad., Dordrecht, Netherlands.
  6. Bougeret, J.-L., et al. (1995), Waves: The radio and plasma wave investiga- tion on the WIND spacecraft, Space Sci. Rev., 71, 231.
  7. Bougeret, J.-L., et al. (2008), S/WAVES: The radio and plasma wave investigation on the STEREO mission, Space Sci. Rev., 136, 487.
  8. Cairns, I. H. (1987a), The electron distribution function upstream from the Earth's bow shock, J. Geophys. Res., 92, 2315.
  9. Cairns, I. H. (1987b), A theory for the Langmuir waves in the electron foreshock, J. Geophys. Res., 92, 2329.
  10. Cairns, I. H. (2000), Role of collective effects in dominance of scattering off thermal ions over Langmuir wave decay: Analysis, simulations, and space applications, Phys. Plasmas, 7, 4901.
  11. Cairns, I. H., and J. G. Lyon (1995), MHD simulations of Earth's bow shock at low Mach numbers: Standoff distances, J. Geophys. Res., 100, 17,173.
  12. Cairns, I. H., and P. A. Robinson (1997), First test of stochastic growth theory for Langmuir waves in Earth's foreshock, Geophys. Res. Lett., 24, 369.
  13. Cairns, I. H., and P. A. Robinson (1999), Strong evidence for stochastic growth of Langmuir-like waves in Earth's foreshock, Phys. Rev. Lett., 82, 3066.
  14. Cairns, I. H., P. A. Robinson, R. R. Anderson, and R. J. Strangeway (1997), Foreshock Langmuir waves for unusually constant solar wind conditions: Data and implications for foreshock structure, J. Geophys. Res., 102, 24,249.
  15. Celnikier, L. M., C. C. Harvey, R. Jegou, M. Kemp, and P. Moricet (1983), A determination of the electron density fluctuation spectrum in the solar wind, using the ISEE propagation experiment, Astron. Astrophys., 126, 293. Ergun, R. E., et al. (2008), Eigenmode structure in solar-wind Langmuir waves, Phys. Rev. Lett., 101, 051101, doi:10.1103/PhysRevLett.101.051101.
  16. Filbert, P. C., and P. J. Kellogg (1979), Electrostatic noise at the plasma frequency beyond the Earth's bow shock, J. Geophys. Res., 84, 1369.
  17. Fitzenreiter, R. J., J. D. Scudder, and A. J. Klimas (1990), Three dimen- sional analytical model for the spatial variation of the foreshock electron distribution: Systematics and comparisons with ISEE observations, J. Geophys. Res., 95, 4155.
  18. Fitzenreiter, R. J., A. F. Vio `as, A. J. Klimas, R. P. Lepping, M. L. Kaiser, and T. G. Onsager (1996), Wind observations of the electron foreshock, Geophys. Res. Lett., 23, 1235.
  19. Genkin, L. G., and L. M. Erukhimov (1990), Interplanetary plasma irregu- larities and ion acoustic turbulence, Phys. Rep., 186, 97.
  20. Gosling, J. T. (1998), The solar wind, in The Encyclopedia of the Solar System, edited by P. Weissman, L.-A. McFadden, and T. Johnson, p. 95, Academic, San Diego, Calif.
  21. Greenstadt, E. W. (1976), Phenomenology of the Earth's bow shock system: A summary description of experimental results, in Magnetospheric Particles and Fields, edited by B. M. McCormac, p. 13, D. Reidel, Norwell, Mass.
  22. Greenstadt, E. W., G. K. Crawford, R. J. Strangeway, S. L. Moses, and F. V. Coroniti (1995), Spatial distribution of electron plasma oscillations in the Earth's foreshock at ISEE-3, J. Geophys. Res., 100, 19,933.
  23. Grognard, R. J. M. (1985), Propagation of electron streams, in Solar Radio- physics, edited by D. J. McLean and N. R. Labrum, p. 253, Cambridge Univ. Press, Cambridge, U. K.
  24. Kaiser, M. L., T. A. Kucera, J. M. Davila, O. C. St. Cyr, M. Guhathakurta, and E. Christian (2008), The STEREO mission: An introduction, Space Sci. Rev., 136, 5.
  25. Kasaba, Y., H. Matsumoto, Y. Omura, R. R. Anderson, T. Mukai, Y. Saito, T. Yamamoto, and S. Kokubun (2000), Statistical studies of plasma waves and backstreaming electrons in the terrestrial electron foreshock observed by Geotail, J. Geophys. Res., 105, 79.
  26. Kellogg, P. J. (2003), Langmuir waves associated with collisionless shocks: A review, Planet. Space Sci., 51, 681.
  27. Krasnoselskikh, V. V., V. V. Lobzin, K. Musatenko, Soucek, J. S. Pickett, and I. H. Cairns (2007), Beam-plasma interaction in randomly inhomo- geneous plasmas and statistical properties of small-amplitude Langmuir waves in the solar wind and electron foreshock, J. Geophys. Res., 112, A10109, doi:10.1029/2006JA012212.
  28. Kuncic, Z., and I. H. Cairns (2005), Planetary foreshock radio emissions, J. Geophys. Res., 110, A07107, doi:10.1029/2004JA010953.
  29. Kuncic, Z., I. H. Cairns, S. Knock, and P. A. Robinson (2002a), A quanti- tative theory for terrestrial foreshock radio emissions, Geophys. Res. Lett., 29(8), 1161, doi:10.1029/2001GL014524.
  30. Kuncic, Z., I. H. Cairns, and S. Knock (2002b), Analytic model for the electrostatic potential jump across collisionless shocks, with application to Earth's bow shock, J. Geophys. Res., 107(A8), 1218, doi:10.1029/ 2001JA000250.
  31. Kuncic, Z., I. H. Cairns, and S. A. Knock (2004), A quantitative model for terrestrial foreshock radio emissions: 1. Predicted properties, J. Geophys. Res., 109, A02108, doi:10.1029/2003JA010125.
  32. Li, B., P. A. Robinson, and I. H. Cairns (2002), Multiple electron beam propagation and Langmuir wave generation in plasmas, Phys. Plasmas, 9, 2976.
  33. Li, B., A. J. Willes, P. A. Robinson, and I. H. Cairns (2003), Dynamics of beam driven Langmuir and ion-acoustic waves including electrostatic decay, Phys. Plasmas, 10, 2748.
  34. Li, B., A. J. Willes, P. A. Robinson, and I. H. Cairns (2005), Second harmonic electromagnetic emission via beam-driven Langmuir waves, Phys. Plasmas, 12, 012103, doi:10.1063/1.1812274.
  35. Li, B., P. A. Robinson, and I. H. Cairns (2006a), Numerical simulations of type-III solar radio bursts, Phys. Rev. Lett., 96, 145005, doi:10.1103/ PhysRevLett.96.145005.
  36. Li, B., P. A. Robinson, and I. H. Cairns (2006b), Quasilinear calculation of Langmuir wave generation and beam propagation in the presence of density fluctuations, Phys. Plasmas, 13, 082305, doi:10.1063/1.2218331.
  37. Li, B., I. H. Cairns, and P. A. Robinson (2008a), Simulations of coronal type III solar radio bursts: 1. Simulation model, J. Geophys. Res., 113, A06104, doi:10.1029/2007JA012957.
  38. Li, B., I. H. Cairns, and P. A. Robinson (2008b), Simulations of coronal type III solar radio bursts: 2. Dynamic spectrum for typical parameters, J. Geophys. Res., 113, A06105, doi:10.1029/2007JA012958.
  39. Lin, R. P., D. W. Potter, D. A. Gurnett, and F. L. Scarf (1981), Energetic electrons and plasma waves associated with a solar type III radio burst, Astrophys. J., 251, 364.
  40. Lin, R. P., W. K. Levedahl, W. Lotko, D. A. Gurnett, and F. L. Scarf (1986), Evidence for nonlinear wave-wave interactions in solar type III radio bursts, Astrophys. J., 308, 954.
  41. Lin, R. P., D. W. Curtis, D. E. Larson, J. G. Luhmann, S. E. McBride, M. R. Maier, T. Moreau, C. S. Tindall, P. Turin, and L. Wang (2008), The STEREO IMPACT Suprathermal Electron (STE) instrument, Space Sci. Rev., 136, 241.
  42. Maksimovic, M., V. Pierrard, and P. Riley (1997), Ulysses electron distri- butions fitted with Kappa functions, Geophys. Res. Lett., 24, 1151.
  43. Melrose, D. B., G. A. Dulk, and I. H. Cairns (1986), Clumpy Langmuir waves in type III solar radio bursts, Astron. Astrophys., 163, 229.
  44. Mitchell, J. J., I. H. Cairns, and P. A. Robinson (2003), New constraints and energy conversion efficiencies for plasma emission, Phys. Plasmas, 10, 3315. Muschietti, L., M. V. Goldman, and D. Newman (1985), Quenching of the beam-plasma instability by large-scale density fluctuations in 3 dimensions, Sol. Phys., 96, 181.
  45. Newbury, J. A., C. T. Russell, J. L. Phillips, and S. P. Gary (1998), Electron temperature in the ambient solar wind: Typical properties and a lower bound at 1 AU, J. Geophys. Res., 103, 9553.
  46. Nishikawa, K., and D. D. Ryutov (1976), Relaxation of relativistic electron beam in a plasma with random density inhomogeneities, J. Phys. Soc. Jpn., 41, 1757.
  47. Pulupa, M. P., S. D. Bale, R. P. Lin, D. E. Larson, K. Goetz, M. L. Kaiser, M. Maksimovic, and R. Ergun (2007), STEREO observations of electron beams and Langmuir waves in the terrestrial electron foreshock, Eos Trans. AGU, 88(52), Fall Meet. Suppl., Abstract SH33A-1095.
  48. Robinson, P. A. (1992), Clumpy Langmuir waves in type III radio sources, Solar Phys., 139, 147.
  49. Robinson, P. A. (1995), Stochastic wave growth, Phys. Plasmas, 2, 1466.
  50. Robinson, P. A., and A. O. Benz (2000), Bidirectional type III solar radio bursts, Sol. Phys., 194, 345.
  51. Robinson, P. A., I. H. Cairns, and D. A. Gurnett (1993a), Clumpy Langmuir waves in type III radio sources: Comparison of stochastic-growth theory with observations, Astrophys. J., 407, 790.
  52. Robinson, P. A., A. J. Willes, and I. H. Cairns (1993b), Dynamics of Langmuir and ion-sound waves in type III solar radio sources, Astrophys. J., 408, 720.
  53. Scarf, F. L., R. W. Fredricks, L. A. Frank, and M. Neugebauer (1971), Nonthermal electrons and high-frequency waves in the upstream solar wind: 1. Observations, J. Geophys. Res., 76, 5162.
  54. Sigsbee, K., C. A. Kletzing, D. A. Gurnett, J. S. Pickett, A. Balogh, and E. Lucek (2004), The dependence of Langmuir wave amplitudes on position in Earth's foreshock, Geophys. Res. Lett., 31, L07805, doi:10.1029/2004GL019413.
  55. Strangeway, R. J., and G. K. Crawford (1995), Comparison of upstream phenomena at Venus and Earth, Adv. Space Res., 16, 125.
  56. Treumann, R. A., and W. Baumjohann (1997), Advanced Space Plasma Physics, Imp. College Press, London.
  57. Wu, C. S. (1984), A fast Fermi process: Energetic electrons accelerated by a nearly perpendicular bow shock, J. Geophys. Res., 89, 8857.
  58. Yuan, X., I. H. Cairns, and P. A. Robinson (2008), Numerical simulation of electron distributions upstream and downstream of high Mach number quasi-perpendicular collisionless shocks, J. Geophys. Res., 113, A08109, doi:10.1029/2008JA013268.
  59. Zimbardo, G., and P. Veltri (1996), Spreading and intermittent structure of the upstream boundary of planetary magnetic foreshocks, Geophys. Res. Lett., 23, 793.
  60. ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ À I. H. Cairns, Z. Kuncic, B. Li, and P. A. Robinson, School of Physics, University of Sydney, Sydney, NSW 2006, Australia. (cairns@physics. usyd.edu.au; z.kuncic@physics.usyd.edu.au; boli@physics.usyd.edu.au; robinson@physics.usyd.edu.au)
  61. R. E. Ergun and D. M. Malaspina, Laboratory for Atmospheric and Space Physics, University of Colorado at Boulder, 1234 Innovation Dr., Boulder, CO 80303, USA. (ree@lasp.colorado.edu; david.malaspina@colorado.edu)