The Importance of Ion Composition for Radiation Belt Modeling

The banded structure of electromagnetic ion cyclotron (EMIC) wave spectra and their resonant interactions with radiation belt electrons depend on the cold composition. However, there is a great deal uncertainty in composition inner magnetosphere due to difficulties direct flux measurements. Here, we show that hydrogen helium band are most consistent oxygen few percent. Less than 10% intensity high fraction ∼20%. Similarly, only ∼20% an torus Furthermore, find decay ultra-relativistic belts by EMIC waves depends sensitive fraction, strongest agreement Van Allen Probes data found when We suggest more observations would significantly help understand set constraints ultrarelativistic belts.