Critical Current Measurements on a NbTi Superconducting Wire Standard Reference Material

Goodrich, Loren F.; Vecchia, Dominic F.; Pittman, E S.; Clark, Alan F.

doi:10.1007/978-1-4613-9868-4_105

Cited by 7 publications

(4 citation statements)

References 3 publications

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“…Critical currents were measured at 2, 4, 6 and 8 T on FRP for temperatures from 3.90 K to 4.24 K using electric field criteria from 5 to 20 µV m −1 . The total uncertainty of the reported critical current values at any of the four magnetic fields was no greater than 2.6% [145]. In subsequent series of measurements, the uncertainties for the critical currents (measured at an electric field criteria of 10 µV m −1 ) were found to be 1.71% and 1.97%, and the difference between the interlaboratory averages and certified critical currents were 0.2% and 0.3% for 6 and 8 T respectively [146].…”

Section: Nbtimentioning

confidence: 85%

“…There is only limited variable-strain 𝐽 " data in the literature. It shows that NbTi is reasonably insensitive to strain [145]. This insensitivity means that very accurate measurements will be required to characterise the strain dependence comprehensively, that include proper account of: the relatively small changes in 𝐵 "V that occur for the different criteria used to define 𝐵 "V ; geometrical changes in the sample on applying the strain; and the small anisotropy in 𝐵 "V associated with the drawing of the wire during fabrication.…”

Section: Nbtimentioning

confidence: 99%

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Characterisation of the Transport Critical Current Density for Conductor Applications

Raine¹,

Keys²,

Hampshire³

2022

Handbook of Superconductivity

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Section: Nbtimentioning

confidence: 85%

Section: Nbtimentioning

confidence: 99%

Characterisation of the Transport Critical Current Density for Conductor Applications

Raine¹,

Keys²,

Hampshire³

2022

Handbook of Superconductivity

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“…Fixed temperature J c measurements are routinely completed in a cryogen such as liquid helium (at 4.2 K) and liquid nitrogen (at 77.4 K). Standard techniques used to vary and control the temperature include cryogenic vapour pressure control (i.e., liquid refrigerant pumping), 10,11 use of cryocoolers, [12][13][14] and use of resistance heaters. 1,15,16 We require a variable-temperature system that provides a large temperature range and is simple and robust.…”

Section: Introductionmentioning

confidence: 99%

Probes for investigating the effect of magnetic field, field orientation, temperature and strain on the critical current density of anisotropic high-temperature superconducting tapes in a split-pair 15 T horizontal magnet

Sunwong

Higgins

Hampshire

2014

Review of Scientific Instruments

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(2014) 'Probes for investigating the eect of magnetic eld, eld orientation, temperature and strain on the critical current density of anisotropic high-temperature superconducting tapes in a split-pair 15 T horizontal magnet.', Review of scientic instruments., 85 (6). 065111.Further information on publisher's website: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. We present the designs of probes for making critical current density (J c ) measurements on anisotropic high-temperature superconducting tapes as a function of field, field orientation, temperature and strain in our 40 mm bore, split-pair 15 T horizontal magnet. Emphasis is placed on the design of three components: the vapour-cooled current leads, the variable temperature enclosure, and the springboardshaped bending beam sample holder. The vapour-cooled brass critical-current leads used superconducting tapes and in operation ran hot with a duty cycle (D) of ∼0.2. This work provides formulae for optimising cryogenic consumption and calculating cryogenic boil-off, associated with current leads used to make J c measurements, made by uniformly ramping the current up to a maximum current (I max ) and then reducing the current very quickly to zero. They include consideration of the effects of duty cycle, static helium boil-off from the magnet and Dewar (b ), and the maximum safe temperature for the critical-current leads (T max ). Our optimized critical-current leads have a boil-off that is about 30% less than leads optimized for magnet operation at the same maximum current. Numerical calculations show that the optimum cross-sectional area (A) for each current lead can be parameterized by . A split-current-lead design is employed to minimize the rotation of the probes during the high current measurements in our high-field horizontal magnet. The variable-temperature system is based on the use of an inverted insulating cup that operates above 4.2 K in liquid helium and above 77.4 K in liquid nitrogen, with a stability of ±80 mK to ±150 mK. Uniaxial strains of −1.4% to 1.0% can be applied to the sample, with a total uncertainty of better than ±0.02%, using a modified bending beam apparatus which includes a copper beryllium springboard-shaped sample holder. © 2014 AIP Publishing LLC. [http://dx

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“…There is also a Japanese Industrial Standard (JIS) for I c measurements in LTS. In 1984, a National Bureau of Standards (NBS) Standard Reference Material (SRM-1457) for the measurement of I c [6] was created using a Nb-Ti (LTS) wire. This SRM allows a laboratory to test its I c measurement system; however, the SRM does not test additional sources of variability among other superconducting materials, such as Nb 3 Sn (LTS) and HTS.…”

Section: Introductionmentioning

confidence: 99%

Interlaboratory comparison on high-temperature superconductor critical-current measurements

Wiejaczka¹,

Goodrich²

1997

J. Res. Natl. Inst. Stand. Technol.

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An extensive interlaboratory comparison was conducted on high temperature superconductor (HTS) critical-current measurements. This study was part of an international cooperative effort through the Versailles Project on Advanced Materials and Standards (VAMAS). The study involved six U.S. laboratories that are recognized leaders in the field of HTS. This paper includes the complete results from this comparison of critical-current measurements on Ag-sheathed Bi2Sr2Ca2Cu3O10–x (2223) tapes. The effects of sample characteristics, specimen mounting, measurement technique, and specimen damage were studied. The future development of a standard HTS measurement method is also discussed. Most of the evolution of this emerging technology has occurred in improvement of the performance of the conductors. The successful completion of this interlaboratory comparison is an important milestone in the evolution of HTS technology and marks a level of maturity that the technology has reached.

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Critical Current Measurements on a NbTi Superconducting Wire Standard Reference Material

Cited by 7 publications

References 3 publications

Characterisation of the Transport Critical Current Density for Conductor Applications

Characterisation of the Transport Critical Current Density for Conductor Applications

Probes for investigating the effect of magnetic field, field orientation, temperature and strain on the critical current density of anisotropic high-temperature superconducting tapes in a split-pair 15 T horizontal magnet

Interlaboratory comparison on high-temperature superconductor critical-current measurements

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