Plasma waves in planetary magnetospheres

Abstract

The studies of magnetospheric plasma waves in the 1979–1982 quadrennium have included not only intensive studies of plasma waves in the Earth's magnetosphere but also, for the first time, in situ observations and detailed analyses of plasma waves in the magnetospheres of Jupiter and Saturn. While much of the research has involved the continuing identification and classification of plasma wave phenomena in the magnetospheres, increasingly greater emphasis has been placed on understanding the sources of the plasma waves and the interactions of plasma waves with the particles. Many studies have also shown that plasma wave measurements may be used to discern numerous geophysical boundaries and parameters. At the earth, significant progress in plasma wave research has been made that has increased our understanding of wave‐particle interactions and their effects, throughout the magnetosphere from the auroral ionosphere out to the bow shock and back into the tail. Observations of auroral kilometric radiation both in the source region and far from it have provided much new information about this intense emission. Details of the fine structure of the radiation and its polarization and propagation characteristics along with particle distribution and other plasma wave measurements in the source region have provided valuable inputs to various generation theories. Similar progress has also been made in understanding electron cyclotron harmonic emissions and nonthermal continuum radiation. Detailed characterizations of plasma wave phenomena reported during this quadrennium in the plasmasphere, outer magnetosphere, magnetopause, magnetosheath and tail regions have been important in assessing the impact of the waves on the particle distributions and vise versa.

Relativistic effects on parallel whistler-mode propagation and instability

“…Observations of these waves in the magnetosphere of the Earth and their role in the dynamics of the magnetospheric plasma were discussed by many authors (see, e.g., Sazhin, 1982;Carpenter, 1988;Helliwell, 1988). These waves have also been observed in the magnetospheres of other planets (Anderson, 1983;Scarf et al, 1987).…”

CRRES Plasma Wave Observations during Quiet Times, during Geomagnetic Disturbances, and during Chemical Releases

“…For a review of past plasma wave phenomena observed in the magnetosphere, see Shawhan [1979a;1979b), Anderson [1983;1984), Inan [1987), and Kurth [1991). In order to distinguish electromagnetic waves from electrostatic waves, the instrumentation included a search coil magnetometer in addition to inputs from the two electric field antenna srtems.…”

Plasmas in the Earth's Magnetotail

“…This electrostatic noise is also observed along these field lines to low altitudes over the discrete aurora (Gurnett and Frank, 1977). On the other hand, these plasma waves are relatively absent in the plasma sheet, including the current sheet centered on the neutral sheet (Anderson, 1983). Various mechanisms are proposed to account for the presence of broadband electrostatic noise (Huba et al, 1978;Grabbe and Eastman, 1984), none of which are completely successful.…”