Self-consistent model of mirror structures

The purpose of this work is to give a self-consistent model of the magnetic mirrors using a perturbative magnetohydrostatic approach. With the help of this model a number of features have been revealed like geometry, stability and behavior for different temperature anisotropies (A = T-perpendicular to/T-parallel to). The basic relations we use in order to derive the model for the mirror structures are the magnetohydrostatic equilibrium condition and an expression for the anisotropy in the case of bi-Maxwellian distribution (Lee et al., J. Geophys. Res. 92 (1987) 2343). Based on these equations, we have found analytical expressions for the magnetic field (deltaB), pressure (deltap) and temperature (deltaT) perturbations. From the investigation of the dependence of the magnetic mirrors on the unperturbed anisotropy (A(0)), we have found the well-known behavior (opposite phase variations of the magnetic field intensity and number density) for A(0) > 1 (Tsurutani et al., Geophys. Res. 87 (1982) 6060). For A(0) < 1, the behavior is different but the mirror structures still exist. However, if the anisotropy is in a range of values depending on the plasma parameter beta(0perpendicular to) = p(0perpendicular to)/(B-0(2)/2mu(0)), the magnetic mirrors can no longer exist. From the comparison between the current density deduced from the Ampere law, necessary to sustain the magnetic mirror, and the gradient-curvature drift current density actually being inside the magnetic mirror, we have been able to determine instability regions in the (A(0), beta(0perpendicular to))-plane. (C) 2002 Elsevier Science Ltd. All rights reserved.