Scheme of transitions between charge states of He resulting from the considered binary interaction with heliosheath background ion, electron, and neutral atom populations (cf. text). The heavy arrows denote transitions of greatest importance in most of heliosheath regions, the dashed arrow (crossed over) is the neglected production of low-energy He⁺ ions. Emissivity (source funtion) of He ENA is determined by transitions a + f + g + h + i.