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Title: Quench-Spot Detection for Superconducting Accelerator Cavities Via Flow Visualization in Superfluid Helium-4

Abstract

Superconducting radio-frequency (SRF) cavities, cooled by superfluid helium-4 (He II), are key components in modern particle accelerators. Quenches in SRF cavities caused by Joule heating from local surface defects can severely limit the maximum achievable accelerating field. Existing methods for quench-spot detection include temperature mapping and second-sound triangulation. These methods are useful but also have known limitations. Here we describe an alternative method for surface quench-spot detection by visualizing the heat transfer in He II via tracking He2 molecular tracer lines. A proof-of-concept experiment is conducted, in which a miniature heater mounted on a plate is pulsed on to simulate a surface quench spot. A He2 tracer line created nearby the heater deforms due to the counterflow heat transfer in He II. By analyzing the tracer-line deformation, we well reproduce the heater location within a few hundred microns, which clearly demonstrates the feasibility of this alternative technology. Our analysis also reveals that the heat content transported in He II is only a small fraction of the total input heat energy. We show that the remaining energy is essentially consumed in the formation of a cavitation zone near the heater. By estimating the size of this cavitation zone, we discuss howmore » the existence of the cavitation zone may explain a decades-long puzzle observed in many past second-sound triangulation experiments.« less

Authors:
 [1];  [1]
  1. Florida State Univ., Tallahassee, FL (United States). National High Magnetic Field Lab. (MagLab), Mechanical Engineering Dept.
Publication Date:
Research Org.:
Florida State Univ., Tallahassee, FL (United States). National High Magnetic Field Lab. (MagLab)
Sponsoring Org.:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
OSTI Identifier:
1504264
Alternate Identifier(s):
OSTI ID: 1504544
Grant/Contract Number:  
FG02-96ER40952
Resource Type:
Accepted Manuscript
Journal Name:
Physical Review Applied
Additional Journal Information:
Journal Volume: 11; Journal Issue: 4; Journal ID: ISSN 2331-7019
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 47 OTHER INSTRUMENTATION; Superconducting Radio Frequency Cavity; Superfluid helium-4; quench spot; flow visualization; helium excimer molecules; second sound triangulation

Citation Formats

Bao, Shiran, and Guo, Wei. Quench-Spot Detection for Superconducting Accelerator Cavities Via Flow Visualization in Superfluid Helium-4. United States: N. p., 2019. Web. doi:10.1103/PhysRevApplied.11.044003.
Bao, Shiran, & Guo, Wei. Quench-Spot Detection for Superconducting Accelerator Cavities Via Flow Visualization in Superfluid Helium-4. United States. doi:10.1103/PhysRevApplied.11.044003.
Bao, Shiran, and Guo, Wei. Mon . "Quench-Spot Detection for Superconducting Accelerator Cavities Via Flow Visualization in Superfluid Helium-4". United States. doi:10.1103/PhysRevApplied.11.044003.
@article{osti_1504264,
title = {Quench-Spot Detection for Superconducting Accelerator Cavities Via Flow Visualization in Superfluid Helium-4},
author = {Bao, Shiran and Guo, Wei},
abstractNote = {Superconducting radio-frequency (SRF) cavities, cooled by superfluid helium-4 (He II), are key components in modern particle accelerators. Quenches in SRF cavities caused by Joule heating from local surface defects can severely limit the maximum achievable accelerating field. Existing methods for quench-spot detection include temperature mapping and second-sound triangulation. These methods are useful but also have known limitations. Here we describe an alternative method for surface quench-spot detection by visualizing the heat transfer in He II via tracking He2 molecular tracer lines. A proof-of-concept experiment is conducted, in which a miniature heater mounted on a plate is pulsed on to simulate a surface quench spot. A He2 tracer line created nearby the heater deforms due to the counterflow heat transfer in He II. By analyzing the tracer-line deformation, we well reproduce the heater location within a few hundred microns, which clearly demonstrates the feasibility of this alternative technology. Our analysis also reveals that the heat content transported in He II is only a small fraction of the total input heat energy. We show that the remaining energy is essentially consumed in the formation of a cavitation zone near the heater. By estimating the size of this cavitation zone, we discuss how the existence of the cavitation zone may explain a decades-long puzzle observed in many past second-sound triangulation experiments.},
doi = {10.1103/PhysRevApplied.11.044003},
journal = {Physical Review Applied},
number = 4,
volume = 11,
place = {United States},
year = {2019},
month = {4}
}

Journal Article:
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This content will become publicly available on April 1, 2020
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