Plasma sheet access to the inner magnetosphere during bursty bulk flows

Energetic particles in the plasma sheet and near-Earth magnetotail can be transported sunward by large-scale magnetospheric convective processes, allowing some populations to be trapped inside the 'Alfven Layer' on close drift paths in the inner magnetosphere. These newly-trapped particles may contribute directly to the seed populations that are subsequently heated to ring current and radiation belt energies, and may also provide a source of free energy for the generation of electromagnetic waves that affect the dynamic variations of the outer radiation belts. In this work, we examine the access of plasma sheet particles to the inner magnetosphere using a combination of global MHD/test particle simulations and observations from geosynchronous, THEMIS, and the Van Allen probes. We focus in particular on transient events associated with substorm activity and bursty bulk flows, and contrast particle access to geosynchronous orbit during these events with that observed during steady driving of the magnetosphere.