STATIC MAGNETIC-FIELD MODELS CONSISTENT WITH NEARLY ISOTROPIC PLASMA PRESSURE

Academic Article

Abstract

  • Using the empirical magnetospheric magnetic field models of Tsyganenko and Usmanov (TU), we have determined the self-consistent plasma pressure gradients and anisotropies along the midnight meridian in the near-Earth magnetosphere. By “inverting” the magnetic field, we determine what distributions of an anisotropic plasma, confined within the specified magnetic field configuration, are consistent with the magnetohydrostatic equilibrium condition, J × B = ∇ · P. The TU model, parameterized for different levels of geomagnetic activity by the Kp index, provided the magnetic field values from which J × B was numerically evaluated. A best fit solution was found that minimized the average difference between J × B and ∇ · P along an entire flux tube. Unlike previous semi-empirical models, the TU models contain magnetic stresses that can be balanced by a nearly isotropic plasma pressure with a reasonable radial gradient at the equator.
  • Authors

  • Spence, Harlan
  • KIVELSON, MG
  • WALKER, RJ
  • Status

    Publication Date

  • August 1987
  • Published In

    Digital Object Identifier (doi)

    Start Page

  • 872
  • End Page

  • 875
  • Volume

  • 14
  • Issue

  • 8