GEM: The Sources and Pathways of Ions in the Warm Plasma Cloak

The radiation belts surrounding the Earth consist of different populations of particles. The warm plasma cloak is an ion population that plays a critical role in wave-particle interactions impacting magnetospheric dynamics. This work studies this population. The project is led by a mid-career scientist who is returning to the space physics research field from the technology sector, addressing a goal of the Division of Atmospheric and Geospace Sciences to support mid-career scientists. The research group supported by this award includes several scientists and a graduate student. The main goal of this project is to: Identify the sources of the warm plasma cloak and the pathways and processes that lead to their characteristic distributions. To achieve the goal, the work will answer the following questions: (1) What are the circulation pathways of the warm plasma that bring it to the dayside magnetosphere? What are the characteristic distributions along their path? (2) Is the source of the warm plasma cloak plasma the direct outflow of ionospheric ions or the inward convection of the plasma sheet population? Is there heating observed during the transport? (3) What is the impact of depolarization in the warm plasma cloak formation? To understand the source and transport path of the warm plasma cloak population, the team will perform a statistical study of the field aligned low energy H+ and O+ throughout the inner magnetosphere, using data from NASA’s Magnetospheric Multiscale Mission and Van Allen Probes, combined with Fast Auroral SnapshoT Explorer observations of the outflows at lower altitude and Cluster for cross-calibration. This allows characterization of the origin of the warm plasma cloak ions, their transport pathways and possible heating mechanism, as well as the controlling factors (e.g. dipolarization). A database of observed field-aligned warm H+ and O+ population will be established to address the three science questions listed above. This work will extend our understanding of warm plasma populations within the inner magnetosphere and provide important characteristic properties of the warm plasma cloak population for global simulation and machine learning studies. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.