LONGITUDINAL PERMITTIVITY OF MAGNETOSPHERIC PLASMAS WITH DIPOLE AND CIRCULAR MAGNETIC-FIELD LINES

Longitudinal permittivity elements of an axisymmetric magnetosphere ar e derived by solving the drift-kinetic equation for the trapped partic les, in a two-dimensional plasma model with dipole and circular magnet ic field lines. The drift-kinetic equation is solved for waves in the frequency range much larger than the drift frequencies. It is shown th at the collisionless dissipation of such waves by the bounce-resonant interaction with the trapped particles differs substantially from one in a straight magnetic field. The estimations of the electron Landau d amping for kinetic Alfven waves in magnetospheric plasmas are presente d. Imaginary part of the longitudinal permittivity is analyzed numeric ally in the wide range of wave frequencies and plasma parameters. (C) 1998 American Institute of Physics. [S1070-664X(98)03612-X].