Abstract
Fluxes of geomagnetically trapped energetic helium ions in the immediate vicinity of the geomagnetic equator have been unambiguously identified and measured with Explorer 45. The observations presented span the L shell range 2.25 ≲ L ≲ 5 and extend the observational coverage of radiation belt helium ions. During geomagnetically quiescent conditions these fluxes are found to peak sharply near L = 3.25 with equatorially mirroring intensities of 80 and 34 ions/cm² s sr keV in the 1.16–1.74 Mev and 1.74–3.15 Mev per particle passbands, respectively. The helium ion fluxes are observed to exhibit a significant B/B0 dependence and indicate that the ion flux pitch angle distribution j(α) is very anisotropic. If j(α) ≃ j⊥ sinm α, then m values of 8 and 10 correspond to the responses of the two passbands within the B/B0 range of 1.0–1.4 observed. When the B/B0 dependence is removed, the fluxes exhibit no detectable decay over a 2‐week period covered by the study.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call