Both cold-dense and hot-tenuous plasmas are observed in the near-Earth tail of the magnetosphere. A cold-dense plasma sheet (CDPS) is known to form during intervals of northward interplanetary magnetic field (IMF), and to be of solar wind origin primarily. The hot-tenuous plasma sheet is generally observed for non-northward IMF conditions and can often contain a large contribution from heavier ions (O+ primarily). Both types of populations are a source for the ring current during magnetically active times. Recent observations have also shown the transport of dense plasma from the dawn side of the plasma sheet boundary layer (PSBL) but the properties of this plasma and the potential influence it might have on the formation of the ring current has not been investigated in any detail.
This project addresses the topic of plasma sheet properties and transport toward the inner magnetosphere and ring current region of the plasma sheet and PSBL particles in order to assess in a systematic fashion the role of plasma sheet density, temperature and local time asymmetries on the strength of magnetic storms. It aims to answer the following scientific questions: (a) How and where does the plasma sheet and boundary layer plasma enter the inner magnetosphere/ring current region? (b) What are the effects of plasma sheet properties (density, temperature, and local time asymmetries) on proton ring current strength and peak location? The research project will address these questions through a combination of data from key magnetospheric and solar wind science missions (Cluster, Los Alamos geosynchronous instruments, ACE) and simulation results using a kinetic model of the ring current. The research will also contribute to an educational goal. An undergraduate student research program is operated at Los Alamos and it is expected that one or more students will become involved in this project.
