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Bibliographic Details
Main Authors: Dunca, Tomáš, Novotný, Filip, Talíř, Marek, Szalai, Balázs, Ustinov, Nikita, Skrbek, Ladislav, Varga, Emil
Format: Preprint
Published: 2025
Subjects:
Online Access:https://arxiv.org/abs/2509.14103
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Table of Contents:
  • We report preliminary results on spherical thermal counterflow generated by a small central heater in an open geometry, an open bath of superfluid He~II, as closed-cell experiments could have introduced artifacts such as overheating and boundary-induced flows. In order to eliminate them, we measure second sound attenuation in a plane-parallel resonator. Our results are at variance with the previous experiments in closed spherical cavity that showed plateau in the steady-state vortex line density and its inverse time decay, neither of which is observed presently. We find that in open geometry the vortex line density $L$ increases steadily with counterflow velocity $v_\mathrm{ns}$, displaying a crossover between $L \propto v_\mathrm{ns}^2$ typical for counterflow and $L \propto v_\mathrm{ns}^{3/2}$, characteristic for the quasi-classical scaling.