Generation of Magnetic Field Aligned Currents, Parallel Electric Fields, and Inverted-V Structures by Plasma Pressure Inhomogeneities in the Magnetosphere

摘要

Magnetic field aligned currents driven by plasma pressure inhomogeneities (plasma clouds) in the distant magnetosphere are analyzed. A parallel potential drop is found to be established in the upward current region whenever a spatial scale for the pressure gradient in the equatorial magnetosphere is 3goBi/Bo, where go is a hot electron gyroradius in the equatorial magnetic field Bo, and Bi is the magnetic induction in the ionosphere. A theoretical derivation is given for the experimentally observed linear relation T=AEp+To between the characteristic energy T of precipitating magnetospheric electrons and the peak energy Ep in inverted-V electron spectra. Three-dimensional potential structures accelerating electrons earthward are shown to be established beneath model clouds which could correspond to a large scale inverted-V structure and to a thin (1 km) auroral arc.