Ring current ion.

Soto-Chavez, A., Lanzerotti, L., Gerrard, A., Kim, H., Bortnik, J., & Manweiler, J. (2016). RBSPICE measurement of ion loss during the 2015 March storm: Adiabatic response to the geomagnetic field change. Journal Of Geophysical Research: Space Physics. http://doi.org/10.1002/2016JA022512 (Original work published September 2016)