skip to main content

DOE PAGESDOE PAGES

Title: Quench degradation limit of multifilamentary AgBi 2Sr 2CaCu 2O x round wires

Understanding safe operating limits of composite superconducting wires is important for the design of superconducting magnets. Here we report measurements of quench-induced critical current density Jc degradation in commercial Ag/Bi 2Sr 2CaCu 2O x (Bi-2212) round wires using heater-induced quenches at 4.2 K in self magnetic field that reveal a general degradation behavior. J c degradation strongly depends on the local hot spot temperature T max, and is nearly independent of operating current, the temperature gradient along the conductor dT max/dx, and the temperature rising rate dT max/dt. Both J c and n value (where n is an index of the sharpness of the superconductor-to-normal transition) exhibit small but irreversible degradation when T max exceeds 400-450 K, and large degradation occurs when Tmax exceeds 550 K. This behavior was consistently found for a series of Bi-2212 wires with widely variable wire architectures and porosity levels in the Bi-2212 filaments, including a wire processed using a standard partial melt processing and in which Bi-2212 filaments are porous, an overpressure processed wire in which Bi-2212 filaments are nearly porosity-free and that has a J c(4.2 K, self field) exceeding 8000 A/mm 2, and a wire that has nearly no filament to filamentmore » bridges after reaction. Microstructural observations of degraded wires reveal cracks in the Bi-2212 filaments perpendicular to the wire axis, indicating that the quench-induced I c degradation is primarily driven by strain. These results further suggest that the quench degradation temperature limit depends on the strain state of Bi-2212 filaments and this dependence shall be carefully considered when engineering a high-field Bi-2212 magnet.« less
Authors:
 [1] ;  [2] ;  [2] ;  [3]
  1. Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); North Carolina State Univ., Raleigh, NC (United States)
  2. Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
  3. North Carolina State Univ., Raleigh, NC (United States)
Publication Date:
Report Number(s):
FERMILAB-PUB-16-216-TD
Journal ID: ISSN 0953-2048; 1469367
Grant/Contract Number:
AC02-07CH11359
Type:
Accepted Manuscript
Journal Name:
Superconductor Science and Technology
Additional Journal Information:
Journal Volume: 29; Journal Issue: 3; Journal ID: ISSN 0953-2048
Publisher:
IOP Publishing
Research Org:
Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS
OSTI Identifier:
1258288
Alternate Identifier(s):
OSTI ID: 1236650

Ye, Liyang, Li, Pei, Shen, Tengming, and Schwartz, Justin. Quench degradation limit of multifilamentary AgBi2Sr2CaCu2Ox round wires. United States: N. p., Web. doi:10.1088/0953-2048/29/3/035010.
Ye, Liyang, Li, Pei, Shen, Tengming, & Schwartz, Justin. Quench degradation limit of multifilamentary AgBi2Sr2CaCu2Ox round wires. United States. doi:10.1088/0953-2048/29/3/035010.
Ye, Liyang, Li, Pei, Shen, Tengming, and Schwartz, Justin. 2016. "Quench degradation limit of multifilamentary AgBi2Sr2CaCu2Ox round wires". United States. doi:10.1088/0953-2048/29/3/035010. https://www.osti.gov/servlets/purl/1258288.
@article{osti_1258288,
title = {Quench degradation limit of multifilamentary AgBi2Sr2CaCu2Ox round wires},
author = {Ye, Liyang and Li, Pei and Shen, Tengming and Schwartz, Justin},
abstractNote = {Understanding safe operating limits of composite superconducting wires is important for the design of superconducting magnets. Here we report measurements of quench-induced critical current density Jc degradation in commercial Ag/Bi2Sr2CaCu2Ox (Bi-2212) round wires using heater-induced quenches at 4.2 K in self magnetic field that reveal a general degradation behavior. Jc degradation strongly depends on the local hot spot temperature Tmax, and is nearly independent of operating current, the temperature gradient along the conductor dTmax/dx, and the temperature rising rate dTmax/dt. Both Jc and n value (where n is an index of the sharpness of the superconductor-to-normal transition) exhibit small but irreversible degradation when Tmax exceeds 400-450 K, and large degradation occurs when Tmax exceeds 550 K. This behavior was consistently found for a series of Bi-2212 wires with widely variable wire architectures and porosity levels in the Bi-2212 filaments, including a wire processed using a standard partial melt processing and in which Bi-2212 filaments are porous, an overpressure processed wire in which Bi-2212 filaments are nearly porosity-free and that has a Jc(4.2 K, self field) exceeding 8000 A/mm2, and a wire that has nearly no filament to filament bridges after reaction. Microstructural observations of degraded wires reveal cracks in the Bi-2212 filaments perpendicular to the wire axis, indicating that the quench-induced Ic degradation is primarily driven by strain. These results further suggest that the quench degradation temperature limit depends on the strain state of Bi-2212 filaments and this dependence shall be carefully considered when engineering a high-field Bi-2212 magnet.},
doi = {10.1088/0953-2048/29/3/035010},
journal = {Superconductor Science and Technology},
number = 3,
volume = 29,
place = {United States},
year = {2016},
month = {2}
}