Abstract

Various properties of barium clusters (charged or neutral ones) embedded into liquid helium are dis-cussed. The model in which a separate barium atom does not form a negative ion is proposed. A cluster formed of a large number of barium atoms possess-es this ability. In applications, this property is important to explain the observed details in experiments with laser ablation of barium metal surface in liquid helium. A qualitative difference in the mechanisms of formation of quasi-one-dimensional chains of metal or dielectric dust under its implantation into superfluid helium is noted. For a dispersed metal, a dendritic scenario for breakdown in a parallel plate capacitor, filled with metal dust, with a finite potential difference between planes looks good. In a dielectric problem, one does not manage to use a dendritic mechanism of cluster development. One speaks there of participation in gathering of fine particles of vorticity fields of a superfluid. However, the details of this mechanism do not agree with the existing observations. An alternative to a vortex scenario for formation of long chains with dielectric links is outlined in the present work.

PACS: 71.10.–w Theories and models of many-electron systems;
PACS: 41.75.Cn Negative-ion beams;
PACS: 41.74.Ak Positive-ion beams.

Key words: positive ion, negative ion, abliation, vortex line, liquid helium.

Published online: March 27, 2018