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Title: Feasible voltage-tap based quench detection in a Ag/Bi-2212 coil enabled by fast 3D normal zone propagation

Abstract

For this study, small insert solenoids have been built using a commercial Ag/Bi-2212 multifilamentary round wire, insulated with a new thin TiO 2– polymer coating insulation (thickness in ~20 μm versus ~100 μm for a commonly used mullite braided sleeve insulation), and characterized in background magnetic field up to 14 T at 4.2 K to explore the high-field performance and quench detection of Bi-2212 magnets. The coil has no visible leakage and no electrical shorts after reaction, and it carries 280 A/mm -2 in a background field 14 T and generates an additional 1.7 T. A notable result is that, despite normal zones propagate slowly along the conductor, the hot spot temperature upon detection increases only from 40 K to 60 K when the resistive quench detection voltage threshold increases from 0.1 V to 1 V for all operating current density investigated, showing that quench detection using voltage taps is feasible for this coil. This is in a strong contrast to a coil we previously built to the same specifications but from wires insulated with the mullite braided sleeve insulation, for which the hot spot temperature upon detection increases from ~80 K to ~140 K while increasing from the detectionmore » voltage threshold from 0.1 V to 1 V, and thus for which quench detection using voltage taps presents significant risks, consistent with the common belief that the effectiveness of quench detection using voltage taps for superconducting magnets built using high temperature superconductors is seriously compromised by their slow normal zone propagation. This striking difference is ascribed to the fast transverse quench propagation enabled by thin insulation and improved thermal coupling between conductor turns. Finally, this work demonstrates that quench detection for high-temperature superconducting magnets highly depends on the design and construction of the coils such as insulation materials used and this dependence should be factored into the overall magnet design.« less

Authors:
 [1];  [2];  [2]
  1. Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  2. Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
OSTI Identifier:
1256710
Alternate Identifier(s):
OSTI ID: 1259978
Report Number(s):
FERMILAB-PUB-16-221-TD
Journal ID: ISSN 0953-2048; 1468548; TRN: US1601748
Grant/Contract Number:
AC02-07CH11359; AC02-05CH11231; Early Career Award
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Superconductor Science and Technology
Additional Journal Information:
Journal Volume: 29; Journal Issue: 8; Journal ID: ISSN 0953-2048
Publisher:
IOP Publishing
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 36 MATERIALS SCIENCE

Citation Formats

Shen, Tengming, Ye, Liyang, and Li, Pei. Feasible voltage-tap based quench detection in a Ag/Bi-2212 coil enabled by fast 3D normal zone propagation. United States: N. p., 2016. Web. doi:10.1088/0953-2048/29/8/08LT01.
Shen, Tengming, Ye, Liyang, & Li, Pei. Feasible voltage-tap based quench detection in a Ag/Bi-2212 coil enabled by fast 3D normal zone propagation. United States. doi:10.1088/0953-2048/29/8/08LT01.
Shen, Tengming, Ye, Liyang, and Li, Pei. Fri . "Feasible voltage-tap based quench detection in a Ag/Bi-2212 coil enabled by fast 3D normal zone propagation". United States. doi:10.1088/0953-2048/29/8/08LT01. https://www.osti.gov/servlets/purl/1256710.
@article{osti_1256710,
title = {Feasible voltage-tap based quench detection in a Ag/Bi-2212 coil enabled by fast 3D normal zone propagation},
author = {Shen, Tengming and Ye, Liyang and Li, Pei},
abstractNote = {For this study, small insert solenoids have been built using a commercial Ag/Bi-2212 multifilamentary round wire, insulated with a new thin TiO2– polymer coating insulation (thickness in ~20 μm versus ~100 μm for a commonly used mullite braided sleeve insulation), and characterized in background magnetic field up to 14 T at 4.2 K to explore the high-field performance and quench detection of Bi-2212 magnets. The coil has no visible leakage and no electrical shorts after reaction, and it carries 280 A/mm-2 in a background field 14 T and generates an additional 1.7 T. A notable result is that, despite normal zones propagate slowly along the conductor, the hot spot temperature upon detection increases only from 40 K to 60 K when the resistive quench detection voltage threshold increases from 0.1 V to 1 V for all operating current density investigated, showing that quench detection using voltage taps is feasible for this coil. This is in a strong contrast to a coil we previously built to the same specifications but from wires insulated with the mullite braided sleeve insulation, for which the hot spot temperature upon detection increases from ~80 K to ~140 K while increasing from the detection voltage threshold from 0.1 V to 1 V, and thus for which quench detection using voltage taps presents significant risks, consistent with the common belief that the effectiveness of quench detection using voltage taps for superconducting magnets built using high temperature superconductors is seriously compromised by their slow normal zone propagation. This striking difference is ascribed to the fast transverse quench propagation enabled by thin insulation and improved thermal coupling between conductor turns. Finally, this work demonstrates that quench detection for high-temperature superconducting magnets highly depends on the design and construction of the coils such as insulation materials used and this dependence should be factored into the overall magnet design.},
doi = {10.1088/0953-2048/29/8/08LT01},
journal = {Superconductor Science and Technology},
number = 8,
volume = 29,
place = {United States},
year = {Fri Jul 01 00:00:00 EDT 2016},
month = {Fri Jul 01 00:00:00 EDT 2016}
}

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  • The authors measured operating temperature dependence of normal zone propagation velocity in longitudinal direction and thermal property with regard to Ag sheathed Bi-2223 superconducting single core and multifilamentary tapes. Each experiment, with the test sample cooled by a cryocooler, covers the operating temperature range 10--40K and It/Ic range 0.4--0.9 (where It is the transport current and Ic is the critical current in each operating temperature, Top). And, they also carried out numerical analysis by a three-dimensional finite element method in order to make clear the mechanism of normal zone propagation in high-temperature superconducting (HTS) conductors.
  • This paper describes a study of pinning forces in Ag/Bi-based wires and small coils. The goal of this analysis is to characterize and to compare the main pinning mechanisms in wires (short samples) and prototype practical devices, e.g., coils (long samples). The effects of thermal activation were found to hinder the straightforward determination of the pinning parameters from the critical current data. However, we succeeded in extracting these parameters from the irreversibility line. The scaling law for the pinning force employing the irreversibility field in virtue of the scale for magnetic fields was derived theoretically. The best fit to themore » experimentally determined pinning forces gave the flux-creep model corresponding to the power-law current{emdash}voltage dependence {ital J}{proportional_to}{ital E}{sup {ital n}}. {copyright} {ital 1996 The American Physical Society.}« less
  • The performance of Bi-2212 monofilament tape, produced by the powder-in-tube technique and a decomposition - recovery melt process, was significantly improved by employing an optimum dual atmosphere heat treatment. The atmosphere consists of nitrogen and oxygen applied alternatively at various stages during the process and results in oxygen vacancies within the well aligned crystallites. The investigation was carried out on short (50mm) samples, having a cross-section area of the ceramic core in the range 2x 10{sup 4} {mu}m{sup 2} - 5x10{sup 4} {mu}m{sup 2}. An increase in the transport critical current I{sub c} of up to 11A at 77K andmore » up to 68A at 4.2K in zero field (1{mu}V/cm electric field criterion) has been achieved, yielding a current caring capacity J{sub c} in the range (2-4)x 10{sup 4} A/cm{sup 2} at 77K and (1-3)x 10{sup 5}A/cm{sup 2} at 4.2K. The pinning energy is weaker than in the Bi-2223 tapes, but almost identical to the Bi-2212 epitaxial films. This, combined with a {open_quotes}one deformation - one heat treatment ({approximately}30 h){close_quotes} procedure, makes 2212 a strong competitor for low temperature wire applications.« less