Low-energy 3He and 4He ions in interplanetary space during quiet periods of the 23rd solar cycle

Abstract

Data from the ULEIS instrument aboard the ACE spacecraft are used to study the energy spectra of 3He and 4He ions produced during periods of the quiet Sun in the 23rd solar cycle in the energy range ∼0.08–2 MeV/nucleon. Differences in the spectra and 3He/4He relative abundances for three groups of quiet periods dominated by different sources of ions are demonstrated: weak impulsive solar flares, particles of the solar corona, and solar wind particles accelerated to energies of several MeV/nucleon.