Experimental Verification of Stability Characteristics for Thermal Acoustic Oscillations in a Liquid Helium System

Gu, Youfan; Timmerhaus, K.D.

doi:10.1007/978-1-4615-2522-6_212

Cited by 9 publications

(3 citation statements)

References 4 publications

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“…Measurements published in [3] indicate that the temperature profile between the warm and cold section can be described by a s-shape function with a rather steep sloop. Since the distances between the installed temperature sensors are rather large the slope of the temperature profile has to be approximated.…”

Section: Temperature Profilementioning

confidence: 98%

“…Besides the general requirements of a half-open tube and a large temperature ratio, the onset of a thermoacoustic oscillation is influenced by the transfer line geometry and the ratio between the warm and the cold length of the tube ξ = l h /l c , too. Existing publications consider the onset of thermoacoustic oscillations theoretically [1] and experimentally [2], [3] in straight, mostly uninsulated pipes. Since the geometry of a transfer line, e.g.…”

Section: Introductionmentioning

confidence: 99%

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Onset of Thermoacoustic Oscillations in Flexible Transfer Lines for Liquid Helium

et al. 2015

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Thermoacoustic oscillations in flexible transfer lines result in an increased evaporation rate of stored cryogen. This kind of oscillation is barely regarded since it only occurs in idle state, i.e. no liquid helium is transferred and a considerable part of the transfer line is close to ambient temperature. The examination of prototype transfer lines with built-in sensors has resulted in a unique knowledge of the oscillation characteristics. As a consequence thermoacoustic oscillations are considered as a common phenomenon in idle flexible transfer lines. The presented paper discusses the conditions for the establishment and a strategy for mitigating thermoacoustic oscillations.

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Section: Temperature Profilementioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Onset of Thermoacoustic Oscillations in Flexible Transfer Lines for Liquid Helium

et al. 2015

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“…While this approach is being widely accepted as a standard method to measure helium level, a simple alternative to this technique is to use a thin capillary tube inserted inside the Dewar to sense thermoacoustic oscillations of LHe. These vibration signals are popularly known as Taconis oscillations [4][5][6] and are inherent to closed LHe containers wherein a gradation of temperature causes helium vapors to move back and forth at the inner walls of the Dewar. These oscillations could be sensed at the warm end of the capillary tube when terminated with a rubber membrane.…”

Section: Introductionmentioning

confidence: 99%

Arduino-Based Novel Hardware Design for Liquid Helium Level Measurement

et al. 2018

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Liquid helium (LHe) is used as a cryogen in a variety of applications involving superconductivity and is routinely monitored for conducting low-temperature experiments. Thermoacoustic oscillations, which are inevitably present inside closed LHe containers, are utilized for level detection by sensing the vibrations at the warm end of a thin capillary tube inserted into the Dewar. The position of the capillary tube at which a sudden change occurs in these oscillations is manually sensed to identify the liquid level. The present work proposes a novel hardware design to identify the thermoacoustic oscillations in a reliable way using an accelerometer driven by an Arduino microcontroller. Further, an automated approach has been devised to quantify the rate of change of these helium oscillations to measure the LHe level. The proposed method has been tested during several trials on a 120 L and 100 L capacity Dewar using the proposed hardware, and the mean error in measuring the LHe level was calculated to be less than 1 cm in comparison with the gold standard niobium-titanium level sensor. The results encourage the use of the proposed method to evolve as a cost-effective alternative to the widely used superconducting level sensors in measuring LHe level.

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Cryogenic Engineering

Weisend

2015

Mechanical Engineers' Handbook

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Cryogenic engineering involves the technology required to both produce and maintain extremely low temperatures. It takes into account the unique properties of fluids and materials at cryogenic temperatures as well as the specific techniques required to operate safely and efficiently at these temperatures. Cryogenic engineering is broad based, using aspects of mechanical, electrical, chemical, and other engineering disciplines. Cryogenic fluids, or cryogens, may be defined as those whose boiling temperature at 1 bar (normal boiling point) is less than 120 K. Good cryogenic engineering practice includes never using materials at cryogenic temperatures unless their behavior at those temperatures is well understood and never extrapolating room temperature properties down to cryogenic temperatures. Cryogenic engineering at sub‐Kelvin temperatures poses a number of challenges. In particular, the heat capacities and available cooling at these temperatures is so small that even microwatt‐scale heat leaks can result in unacceptable temperature rises.

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Experimental Verification of Stability Characteristics for Thermal Acoustic Oscillations in a Liquid Helium System

Cited by 9 publications

References 4 publications

Onset of Thermoacoustic Oscillations in Flexible Transfer Lines for Liquid Helium

Onset of Thermoacoustic Oscillations in Flexible Transfer Lines for Liquid Helium

Arduino-Based Novel Hardware Design for Liquid Helium Level Measurement

Cryogenic Engineering

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