Dynamics of vortices and interfaces in superfluid³He

Abstract

Rapid new developments have occurred in superfluid hydrodynamics since the\ndiscovery of a host of unusual phenomena which arise from the diverse structure\nand dynamics of quantized vortices in 3He superfluids. These have been studied\nin rotating flow with NMR measurements which at best provide an accurate\nmapping of the different types of topological defects in the superfluid order\nparameter field. Four observations are reviewed here: (1) the interplay of\ndifferent vortex structures at the first order interface between the two major\nsuperfluid 3He phases, 3He-A and 3He-B; (2) the shear flow instability of this\nphase boundary, which is now known as the superfluid Kelvin-Helmholtz\ninstability; (3) the hydrodynamic transition from turbulent to regular vortex\ndynamics as a function of increasing dissipation in vortex motion; and (4) the\npeculiar propagation of vortex lines in a long rotating column which even in\nthe turbulent regime occurs in the form of a helically twisted vortex state\nbehind a well-developed vortex front. The consequences and implications of\nthese observations are discussed, as inferred from measurements, numerical\ncalculations, and analytical work.\n