Energy dependence of the fraction of protons of ionospheric origin in the ring current

The energy dependence of a fraction of ring current protons of ionospheric origin is calculated using the AMPTE/CCE data for a typical strong magnetic storm (max|D _st | ≈ 120 nT). It is shown that this fraction monotonically decreases from ～ 83 to 25–30% with an increase in proton energy from 5 to 315 keV at L = 6–7 (L is the McIlwain parameter) and is 30–40% at energy 40–50 keV corresponding to the maximum of proton energy density at L = 6–7. It is demonstrated that the core of the ring current (L = 3.7–4.7) was enriched by solar protons with E ≈ 10–200 keV during the active phase of the storm (the maximum effect is reached at E ≈ 20–50 keV).