LASER LEVITATION OF SUPERFLUID-HELIUM

We describe experiments on the laser levitation of superfluid helium. Liquid drops of 10-20 mum diameter are produced by a submerged piezoel ectric transducer and suspended in vapor at 2K for up to 3 minutes. Th e optical trap is formed by two counter-propagating, horizontal, focus ed laser beams. Calculations show that Brillouin and Raman scattering of the laser light in the liquid helium produces a negligible rate of evaporation of the drop. Evaporation caused by the enhanced vapor pres sure of the curved drop surfaces appears to be a significant effect li miting the drop lifetimes. We calculate the characteristics of the opt ical trap and the deformation of the liquid drops by the light forces. The observed simultaneous trapping of multiple drops is also discusse d.