Turbulent loss of ring current protons

TLDR

Ring current protons below 50 keV, unaffected by ion cyclotron waves outside the plasmapause, experience strong turbulent diffusion just inside the plasmapause. During the main phase of a geomagnetic storm the protons rapidly diffuse across the plasmapause (probably at the Bohm rate) and are lost before reaching the noon meridian, giving rise to the asymmetric part of the ring current; during recovery the ring current decays on a timescale of a day or less as the turbulent region moves outward with the plasmapause expansion, with further decay on a charge‑exchange timescale. Lifetimes from ion cyclotron turbulence are predicted to be of the order of one hour, as observed by Frank for L between 3 and 5.

Abstract

Ring current protons (<50 kev), which are unaffected by ion cyclotron waves outside the plasmapause, undergo strong turbulent diffusion just inside the plasmapause. Lifetimes from ion cyclotron turbulence are predicted to be of the order of 1 hour, as observed by Frank for 3≤L≤5. During the main phase of a geomagnetic storm, the protons rapidly diffuse across the plasmapause (probably at the Bohm rate) and are lost before reaching the noon meridian, thus giving rise to the asymmetric part of the ring current. During recovery phase the ring current decays on a time scale of a day or less, as the turbulent region moves outward with the expansion of the plasmapause. Further decay takes place on a charge exchange time scale.