Parametric Resonance in the Drift Motion of an Ionic Bubble in near critical Ar Gas

Abstract

The drift mobility of the negative oxygen ion in dense Argon gas near the liquid-vapor critical point has been measured as a function of the density. Near the critical temperature the zero-field density-normalized ion mobility shows a deep minimum at a density smaller than the critical one. This phenomenon was previously intepreted as the result of the formation of a correlated cluster of Argon atoms around the ion because of the strong electrostriction exerted by the ion on the highly polarizable and compressible gas. We now suggest that a possible alternative explanation is related to the onset of a parametric resonance of a bubble surrounding the ion. At resonance a large amount of energy is dissipated by sound waves in addition to viscous dissipation processes, resulting in the large mobility drop observed.