Thermally assisted escape of ions from vortices in He II

The theory of ion escape from vortices in helium is re-examined with the introduction of non-Markoffian features of the ion-vortex interaction. After several physically motivated approximations the present theory takes the form of earlier theories except that the hydrodynamic potential is replaced by an effective potential depending on the ion mobility. A conflict with experiment is thereby resolved, and one can proceed to use escape data to investigate the vortex core structure.