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tokens: of the cavity λ H decreased due to subtraction of solar wind He + ions from ∼19.5 to ∼15.5 au, whereas the average ionization factor β H,E decreased from 7.6 × 10 −6 to 3.9 × 10 −6 s −1 . These values are still well above the expected range of 3–6 au for λ H and (0.5–1) × 10 −6 s −1 for β H,E . Therefore, the presence of solar wind He + ions in SWAP observations does not fully explain this discrepancy, but it is an important factor that influences the fitted spectra of H + PUIs. Moreover, a reasonable agreement may not be possible using the Vasyliunas Siscoe ( 1976 ) model, which is only a simple approximation and does not account for most of the transport processes. More advanced models (see, e.g., Zank et al. 2018 ) can give results consistent with the observations for more realistic parameters. 6. Summary Helium, the second most abundant species in the solar wind, is emitted from the solar corona almost entirely in the form of double ionized alpha particles. Due to charge exchange with ISN atoms, some of the He 2+ ions acquire electrons and form a new population of singly charged solar wind He + ions. Charge exchange with ISN hydrogen is the dominant source of this population. The rate of this reaction significantly increases over the range of the solar wind speeds. As a result, the ratio of solar wind He + ions to solar wind He 2+ can exceed 10% at the termination shock for regions of fast solar wind ≥600 km s −1 , such as at high heliolatitudes around solar minimum (McComas et al. 2000 ). Therefore, solar wind He+ ions are an important component of the plasma and, as such, should be included in analyses of the processing of the solar wind and acceleration processes at the termination shock. In this study, we show that this contribution is visible in some part of the SWAP observations as a “bump” just below the cutoff energy of H + PUIs. This paper is a first report on the observation of this population in the outer heliosphere. Earlier reports on solar wind He + ions are very sparse (Tucker Gould 1966 ; Kozlovsky 1968 ; Feldman et al. 1974 ; Gloeckler Geiss 1998 ). We select observations with a local maximum just below the H + PUI cutoff energy. About ∼3/5 of them are related to significant changes in the solar wind speed up to 10 days before the date of the observation. Consequently, the observed spectrum was likely modified due to this change. In the remaining ∼2/5 cases, the solar wind speed remains stable throughout 10 days, and for most of them, we find significant improvements in the goodness of the fit for H + PUIs when solar wind He + ions are adequately accounted for. In only one observation is the improvement not statistically significant. We point out that the observations of solar wind He + ions are more likely to be visible during times of faster solar wind, with lower temperatures and high relative abundances of solar wind alpha particles. We notice that in some observations also, other heavy ions such as oxygen and carbon