He²⁺ in field‐aligned beams: ISEE results

He 2+ concentrations are determined for 14 field‐aligned proton beam events observed in the ion foreshock region upstream from the Earth's bow shock by the ISEE spacecraft. For all 14 events, most under normal solar wind conditions, the He 2+ concentrations were a factor of 10 or more below the H + concentrations in the field‐aligned beams when normalized by the solar wind He 2+ to H + density ratio. These results indicate that field‐aligned beams do not provide the principal He 2+ seed population for ion acceleration in the ion foreshock region.