The development of initial substorm expansive phase disturbance due to generation of localized electric fields in the region of maximum upward field-aligned current

Abstract

The analysis of the plasma sheet plasma stability for the small scale electrostatic disturbances in the simple approximation of one fluid magnetohydrodynamics show that the region of upward field-aligned current near midnight where fast radial plasma flow take place can become unstable to localized electrostatic disturbances during the growth phase of substorms. Such instability can explain the onset of substorm deep in the magnetosphere near the Earth's border of the tail current sheet.