Decay of grid turbulence in superfluid helium-4: Mesh dependence

Yang, Ji-Woon; Ihas, G. G.

doi:10.1088/1742-6596/969/1/012004

Cited by 4 publications

(1 citation statement)

References 15 publications

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“…The literature being vast, we only list a few thermistor materials and bibliographic entry points. Materials with a negative temperature coefficients 1 include carbon in various forms (aquadag paint, fiber, pencil graphite,..) [HVS01], doped Ge [Sny62], RuOx [YI18], ZrN x /Cernox [YYK97,FS04] and Ge-on-GaAs [MMP + 07]. Transition edge superconductor thermometers are often preferred when large sensitivity or low resistivity is important, for instance Au 2 Bi [Not64], PbSn [CR83,RR01], granular Al [CA68,MSS76] and AuSn [Not64,Lag76,BSS83].…”

Section: Figurementioning

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: Figurementioning

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

Woillez,

Valentin,

Roche

2023

Review of Scientific Instruments

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An analytical model of open-cavity second sound resonators is presented and validated against simulations and experiments in superfluid helium using a new resonator design that achieves unprecedented resolution. The model incorporates diffraction, geometrical misalignments, and flow through the cavity and is validated using cavities operated up to their 20th resonance in superfluid helium. An important finding is that resonators can be optimized to selectively sense either the quantum vortex density carried by the throughflow—as typically done in the literature—or the mean velocity of the throughflow. We propose two velocity probing methods: one that takes advantage of misalignments between the tweezers’ plates and other that drives the resonator non-linearly, beyond a threshold that results in the self-sustainment of a vortex tangle within the cavity. A new mathematical treatment of the resonant signal is proposed to adequately filter out parasitic signals, such as temperature and pressure drift, and accurately separate the quantum vorticity signal. This elliptic method consists in a geometrical projection of the resonance in the inverse complex plane. Its effectiveness is demonstrated over a wide range of operating conditions. The resonator model and elliptic method are being utilized to characterize a new design of resonators with high resolution, thanks to miniaturization and design optimization. These second-sound tweezers are capable of providing time-space resolved information similar to classical local probes in turbulence, down to sub-millimeter and sub-millisecond scales. The principle, design, and microfabrication of second sound tweezers are being presented, along with their potential for exploring quantum turbulence.

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Quantum turbulence in superfluid helium

Ефимов

2021

Phys. Usp.

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Decay of grid turbulence in superfluid helium-4: Mesh dependence

Cited by 4 publications

References 15 publications

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

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

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

Quantum turbulence in superfluid helium

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