Tuesday, February 1, 2022

Assistant Research Scientist David Hartley has received a $150,000 award from Triad National Security for a project entitled “Using Van Allen Probes and Arase Density and Wave Data to Build a Model of Wave-Particle Interactions for Relativistic Electrons in the Inner Belt.” Triad National Security is part of the Los Alamos National Lab (LANL).

Recent models of relativistic electrons in the terrestrial inner radiation belt predict lifetimes that vary by an order of magnitude due to uncertainties in the cold plasma density and wave properties. The goal of this project is to use state-of-the-art observations of the waves and cold plasma density to build a model that will enable Los Alamos National Laboratory’s DREAM3D radiation belt code to reproduce the observed behavior of relativistic electrons in the inner belt. 

Existing cold plasma density models have been identified as a dominant source of uncertainty and must be improved to explain the behavior of relativistic electrons in the inner belt. The primary cause of this uncertainty is due to the extrapolation of existing density models beyond their regions of validity.  Dr. Hartley has developed a technique for estimating the plasma density from Van Allen Probes EMFISIS observations of an electromagnetic wave mode known as plasmaspheric hiss [Hartley et al., 2018], which is prevalent in the inner radiation belt region.  Plasma densities determined through this method will first be calibrated against data from the Japanese Arase satellite and subsequently used to develop a new plasma density model that specifically targets the inner radiation belt region, thus removing the need to extrapolate existing models.  This new plasma density model will then be incorporated into DREAM3D. 

Hartley, D. P., Kletzing, C. A., De Pascuale, S., Kurth, W. S., and Santolik, O. (2018), Determining plasmaspheric densities from observations of plasmaspheric hiss. Journal of Geophysical Research: Space Physics, 123, 6679– 6691. https://doi.org/10.1029/2018JA025658