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Large‐scale transport of plasma in the Earth's plasma sheet: comparative analysis for adiabatic and non‐adiabatic cases
Author(s) -
Zakharov V. E.,
Meister C.V.
Publication year - 1997
Publication title -
astronomische nachrichten
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.394
H-Index - 63
eISSN - 1521-3994
pISSN - 0004-6337
DOI - 10.1002/asna.2113180108
Subject(s) - physics , adiabatic process , magnetosphere , plasma , pitch angle , plasma sheet , scattering , magnetohydrodynamics , computational physics , classical mechanics , atomic physics , geophysics , quantum mechanics
A system of multi‐fluid MHD‐equations is used to compare adiabatic and non‐adiabatic transport of the energetic particles in the magnetospheric plasma sheet. A “slow‐flow” approximation is considered to study large‐scale transport of the anisotropic plasma consisting of energetic electrons and protons. Non‐adiabatic transport of the energetic plasma is caused by scattering of the particles in the presence of both wave turbulence and arbitrary time‐varying electric fields penetrating from the solar wind into the magnetosphere. The plasma components are devided into particle populations defined by their given initial effective values of the magnetic moment per particle. The spatial scales are also given to estimate the non‐uniformity of the geomagnetic field along the chosen mean path of a particle. The latters are used to integrate approximately the system of MHD‐equations along each of these paths. The behaviour of the magnetic moment mentioned above and of the parameter which characterizes the pitch‐angle distribution of the particles are studied self‐consistently in dependence on the intensity of non‐adiabatic scattering of the particles. It is shown that, in the inner magnetosphere, this scattering influences the particles in the same manner as pitch‐angle diffusion does. It reduces the pitch‐angle anisotropy in the plasa. The state of the plasma may be unstable in the current sheet of the magnetotail. If the initial state of the plasma does not correspond to the equilibrium one, then, in this case, scattering influences the particles so as to remove the plasma further from the equilibrium state. The coefficient of the particle diffusion across the geomagnetic field lines is evaluated. This is done by employing the Langevin approach to take the stochastic electric forces acting on the energetic particles in the turbulent plasma into account. The behaviour of the energy density of electrostatic fluctuations in the magnetosphere is estimated.