Negative and positive ions in liquid helium

Structure and properties of positive and negative ions in liquid ⁴He are analyzed. The possibility of clusters or bubbles formation around impurity ions of both signs is discussed. It is demonstrated that in superfluid helium around negative alkaline-earth metal ions bubbles are formed and around halogen ions clusters are formed. The nature of “fast” and “exotic” negative ions is also discussed. It is assumed that the “fast” ions are negative ions of helium excimer molecules localized inside bubbles. The “exotic” ions are stable negative impurity ions, which are always present in small amounts in gas discharge plasma. Around such ions bubbles or clusters are created with radius smaller the radius of electron bubbles.