Specific features of the excitation spectrum of helium II in a plasma initiated by an electron beam

The emission of a low-pressure helium plasma (P≤2 Torr) initiated by a monochromatic electron beam is investigated. It is found that an increase in the current leads to a drastic increase in the rate of charge exchange of doubly charged helium ions. The assumption is made that inelastic collisions of He⁺⁺ ions with metastable helium atoms provide the main channel of charge exchange of these ions due to the reaction He⁺⁺+Hem→ He⁺*+He ₀ ⁺ .