QFS 2016 Book of Abstracts

Abstracts

P3.34 Effects of a magnetic field on vortex states in superfluid 3 He-B Kenichi Kasamatsu(1), Ryota Mizuno(2), Utkan G¨ung¨ord¨u(3), Tetsuo Ohmi(1), and Mikio Nakahara(1) 1) Department of Physics, Kindai University, Higashi-Osaka, 577-8502, Japan 2) Department of Physics, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka, 560-0043, Japan 3) Department of Physics and Astronomy and Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588, USA Superfluid 3 He-B possesses three locally stable vortex structures known as a normal-core vortex (o-vortex), an A-phase-core vortex (v-vortex), and a double-core vortex (d-vortex). In this work, we study the effects of a magnetic field on these vortex structures by solving the two-dimensional Ginzburg-Landau equation. We find that the energetic stability of the v-vortex and d-vortex states exhibits nontrivial dependance on the magnitude of the magnetic field as well as its direction, while the o-vortex has the highest free energy among three vortices for any situations we analyzed. P3.35 Dramatic effect of superfluidity on the collapse of He4 vapor bubbles Qu An, Trimeche Azer, Jacquier Philippe, Grucker Jules Laboratoire Kastler Brossel, ENS-PSL Research University, CNRS, UPMC-Sorbonne-Universit´es, Coll´ege de France, 24 rue Lhomond, 75005 Paris, France The lifetime of cavitation bubbles produced by an acoustic wave focused in liquid helium-4 is investigated. This lifetime is found to be different by orders of magnitude depending on whether the liquid is superfluid or not. We show that if the liquid is in the superfluid state, the bubble lifetime is well explained by a purely mechanical model, corresponding to the so-called Rayleigh regime. In the normal state, the Rayleigh-Plesset regime applies, in which heat diffusion plays a crucial role and dramatically increases the bubble lifetime.

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