Temporary topological trapping and escape of charged particles in a flux tube as a cause of delay in time asymptotic transport

Abstract

The scenario of temporary trapping of magnetic field lines and their subsequent suppressed diffusive escape from topological magnetic structures embedded in turbulence has been offered as a way to understand the persistence of "dropouts", or sharp gradients in observed heliospheric energetic particle intensities. Here a set of numerical experiments is carried out to show the basic physics of this process: charged test particles can be temporarily trapped in flux tubes and then escape due to random turbulent perturbations in the magnetic field. The overall effect is a delay in the onset of time-asymptotic transport. We thus confirm that previous arguments based on field line transport are also applicable to test particle transport. Copyright 2007 by the American Geophysical Union.