The effect of kinetic-ballooning instability on substorm onset.

Abstract:

Small scale azimuthal structures in optical signatures associated with low frequency Pi 1 & Pi 2 wave activity have been observed around the time of substorm onset. The characteristic frequency and kinetic scale structures have been attributed to the onset of a kinetic ballooning instability, which can occur in high-beta magnetized plasmas in regions where the magnetic curvature and pressure gradient are in the same direction. We describe the pressure profiles and tail stretching parameters that lead to ballooning onset. We also compare onset conditions with observations of the global magnetospheric configuration and satellite observations.