Seminar: "Visualizing Quantum Turbulence in Superfluid 3He-B using quasiparticles"

We present studies of quantum turbulence in superfluid 3He-B in zero temperature limit. While the flow of bulk superfluid must be irrotational it can mimic classical turbulence by supporting singly quantised vortices. We use a two-dimensional quasiparticle detector to observe quantum turbulence in superfluid 3He-B at ultra-low temperatures. The detector consists of 25 pixels each containing a miniature quartz tuning fork. The damping on each fork provides a measure of the local quasiparticle flux. The detector is illuminated by a beam of ballistic quasiparticles generated from a near-by black-body radiator. Vortices have a large cross-section for Andreev reflecting ballistic quasiparticles at low temperatures. We generate a tangle of vortices (quantum turbulence) in the path of the beam using a vibrating wire resonator. The vortices cast shadows onto the face of the detector due to the Andreev reflection. This allows us to image the vortex tangle and to investigate the tangle dynamics. Single vortex resolution is attainable. We present some initial measurements and compare with simulations.