L‐Value and Energy Dependence of 0.1–50 keV O⁺, He⁺, and H⁺ Ions for CME and CIR Storms Over the Entire Van Allen Probes Era

Abstract

The variation of energetic ion composition in the ring current during geomagnetically disturbed intervals has been extensively studied in various aspects since the 1980s. The ring current primarily comprises of ∼1-200 keV ions (mainly O + , He + , and H + ) and electrons in the region of ∼2-7 R E (Daglis et al., 1999;Gonzalez et al., 1994;Hamilton et al., 1988). The energy density of O + ions is usually comparable to the H + ions and sometimes dominates the H + ions during the geomagnetic storms (Daglis et al., 1998;Gloeckler et al., 1985;Hamilton et al., 1988). Earth's plasma sheet is the main region for transporting ions from solar wind and ionospheric origin to the inner magnetosphere, where O + and He + ions increase in comparison with that of H + ions (Nosé et al., 2001).The structure and dynamics of the ring current are determined by these particle populations, which are largely controlled by the time-varying magnetic and electric fields depending on solar wind conditions. Mainly, two types of solar wind drivers are responsible for magnetic storms, that is, Coronal Mass Ejection (CME) and Corotating Interaction Region (CIR) Gonzalez et al., 1999).