ISOTROPIZED MAGNETIC-MOMENT EQUATION OF STATE FOR THE CENTRAL PLASMA SHEET

The AMPTE/IRM plasma and magnetic field data show that the compression in the central plasma sheet (< 20 RE radial distance) near the equatorial plane is governed by the isotropized magnetic‐moment equation of state, P/(NBZ) = constant, derived from the invariance of the magnetic moment under the assumption of isotropic ion pressure P where N is the number density and Bz is the normal field component in the plasma sheet. The adiabatic equation of state, P/N5/3 = constant, can be expected to govern the compression in the distant plasma sheet (> 20 RE) or the plasma sheet boundary layer where fewer particles are likely to escape from a flux tube through the loss cone to meet the particle conservation requirement of the adiabatic condition. Copyright 1990 by the American Geophysical Union.