NJIT Physics Department Seminar

September 8th, 2014, Monday

Ring Current He-Ions: Two years of observations from NJIT's Radiation Belt Storm Probe Ion Composition Experiment (RBSPICE) on the NASA Van Allan Probes*

Prof. Andy Gerrard

NJIT

(Terrestrial Physics)

Time: 11:45am-12:45pm with 11:30am tea time

Room: ECE 202

Abstract:

The Radiation Belt Storm Probe Ion Composition Experiment (RBSPICE) instrument aboard the Van Allan Probes makes unique measurements of, among other ring current species, He-ions in the ~65-keV to ~520-keV energy range in Earth's inner magnetosphere.  In this talk we report the spatial and temporal variability of such He-ions over the past two years.  Specifically, we show 1) the climatological structure of He-ions, 2) the observations of a unique high-energy/low L-shell band of He-ions that is controlled by ionospheric electric field variability, and 3) variability of the low energy/high L-shell He-ions.  For this last issue, we find that the He-ion phase-space densities (PSDs) at these locations and energies change dramatically from orbit to orbit across similar regions of the magnetosphere, and this variability is often related to simultaneously-observed variability in H-ion PSD (also at high L-shell and low energy).  We show that the hourly modulation of both species is highly correlated to Pc1 and Pc3 wave activity.  Specifically, we conclude that Pc3 frequency bounce-resonant ULF waves are responsible for scattering of He-ions, and thus control the non-storm morphology of ring current He-ions.  All combined, we note that the NJIT RBSPICE instrument is making unique and valuable contributions to our understanding of Earth's inner magnetosphere.

*This work has been done by A. Gerrard, L. Lanzerotti, J. Bortnik, K. Urban, and J. Manweiler.