Peshkov transducers of second sound

Henjes, Katja; Liu, Mario

doi:10.1007/bf00115044

Cited by 4 publications

(1 citation statement)

References 11 publications

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“…In practice, a selective displacement of the superfluid component is achieved in Peshkov transducers. They are made of a standard acoustic transducer side-by-side with a fixed porous membrane-filter which tiny pores are viscous dampers for the normal fluid but are transparent ("superleak s") for the superfluid [Pes48,HL88]. Alternatively,…”

Section: Generation and Detection Of Second Sound Wavesmentioning

confidence: 99%

Second sound resonators and tweezers as vorticity or velocity probes : fabrication, model and method

Woillez¹,

Valentin²,

Roche³

2023

Preprint

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An analytical model of second-sound resonators with open-cavity is presented and validated against simulations and experiments in superfluid helium using a new design of resonators reaching unprecedented resolution. The model accounts for diffraction, geometrical misalignments and flow through the cavity. It is validated against simulations and experiments using cavities of aspect ratio of the order of unity operated up to their 20 th resonance in superfluid helium. An important result is that resonators can be optimized to selectively sense the quantum vortex density carried by the throughflow -as customarily done in the literature-or alternatively to sense the mean velocity of this throughflow. Two velocity probing methods are proposed, one taking advantage of geometrical misalignements between the tweezers plates, and another one by driving the resonator non-linearly, beyond a threshold entailing the self-sustainment of a vortex tangle within the cavity.After reviewing several methods, a new mathematical treatment of the resonant signal is proposed, to properly separate the quantum vorticity from the parasitic signals arising for instance from temperature and pressure drift. This so-called elliptic method consists in a geometrical projection of the resonance in the inverse complex plane. Its strength is illustrated over a broad range of operating conditions.The resonator model and the elliptic method are applied to characterize a new design of second-sound resonator of high resolution thanks to miniaturization and design optimization. When immersed in a superfluid flow, these so-called second-sound tweezers provide time-space resolved information like classical local probes in turbulence, here down to sub-millimeter and sub-millisecond scales. The principle, design and micro-fabrication of second sound tweezers are detailed, as well as their potential for the exploration of quantum turbulence Contents * present affiliation: CEA-Liten, Grenoble

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Section: Generation and Detection Of Second Sound Wavesmentioning

confidence: 99%