CHAPTER 10: CRITICAL-CURRENT DATA ANALYSIS
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FIG. 10.1
Methods for determining the critical current from a set of V–I curves obtained at different magnetic fields: (a) electric-field criterion, (b) resistivity criterion, and (c) offset criterion
FIG. 10.2
Illustration of the critical current of a superconductor as a function of magnetic field that results from using different criteria
FIG. 10.3
Illustration of V–I curves affected by current-transfer voltage at low current levels
FIG. 10.4
Log–log plot of electric-field vs. current (E–I) for a short Nb3Sn sample
FIG. 10.5
Critical-current density as a function of magnetic field for a number of high-current-density superconductors at liquid-helium temperature
FIG. 10.6
Critical-current density as a function of magnetic field for high-Tc superconductors at liquid-nitrogen temperature
FIG. 10.7
Representation of a vortex lattice in a Type II superconductor
FIG. 10.8
Critical Lorentz-force density FL of several high-field superconductors fitted by using the general pinning-force parameters
FIG. 10.9
Example showing a three-parameter fit of the general pinning-force function
FIG. 10.10
Deviation of the high-field flux-pinning curve from the Kramer-model expression in a high-quality (high-n) Nb3Sn sample with tantalum additions
FIG. 10.11
Kramer plot of a low-n Nb3Sn sample with hydrogen additions, showing a depressed value of the effective depinning field Bc2 due to material inhomogeneities
FIG. 10.12
The first measurement of the transport critical current as a function of magnetic field in granular YBCO, demonstrating extreme weak-link behavior
FIG. 10.13
Transport critical-current density vs. applied field, showing that the Josephson weak-link theory fits the data well without adjustable parameters
FIG. 10.14
Critical-current density versus magnetic field at 77 K of an early YBCO bulk sample, a high-quality Bi-2223 tape, and a YBCO coated conductor
FIG. 10.15
Upper critical field vs. temperature for several low-Tc superconductors
FIG. 10.16
Irreversibility field vs. temperature for several high-Tc superconductor films and round-wire data for high-pressure sintered polycrystalline MgB2
FIG. 10.17
Temperature dependence of the critical-current density of a Nb-Ti/Cu multifilamentary wire at different magnetic fields
FIG. 10.18
Temperature dependence of the critical current of Nb3Sn multifilamentary wire at different magnetic fields
FIG. 10.19
Temperature dependence of the critical current of V3Ga at different magnetic fields
FIG. 10.20
Temperature dependence of the critical current of several high-Tc superconducting thin films at zero magnetic field
FIG. 10.21
Temperature dependence of the critical current of a YBCO coated conductor at different magnetic fields
FIG. 10.22
Temperature dependence of the critical current of a Bi-2212 multifilamentary tape at different magnetic fields
FIG. 10.23
Temperature dependence of the critical current of a Bi-2223 multifilamentary tape at different magnetic fields
FIG. 10.24
Illustration of bending strain and pretensioning axial stress incurred during magnet winding
FIG. 10.25
Representation of a current-carrying loop showing the current density J, the magnetic field B, and the hoop stress σhoop generated by the Lorentz force FL
FIG. 10.26
Critical current Ic of a Nb3Sn conductor as a function of axial strain for different magnetic fields
FIG. 10.27
Effect of strain on the critical current of a Bi-2223 superconductor, illustrating the field-independent irreversible strain limit εirr for permanent damage
FIG. 10.28
Illustration of strain distribution introduced into a conductor from bending
FIG. 10.29
Dependence of critical current on bending strain for Nb3Sn superconductors measured at 8 T
FIG. 10.30
Correlation of data for binary multifilamentary Nb3Sn wires showing the nearly universal effect of axial strain on (a) the effective upper critical field Bc2*(ε0) at 4.2 K and (b) the strain-scaling prefactor g(ε0)
FIG. 10.31
Data correlations showing the nearly universal effect of axial strain on the effective upper critical field Bc2*(ε0) of different types of bronze-process A-15 multifilamentary superconductors at 4.2 K
FIG. 10.32
Fundamental basis of the power law at moderate intrinsic strains (–0.5 % < ε0 < ε0irr): Strain dependence of the critical temperature of binary Nb3Sn calculated by introducing phonon anharmonicity into the McMillan/Kresin equation
FIG. 10.33
Critical temperature of binary Nb3Sn calculated over an extended strain range from a three-dimensional deviatoric strain model by Markiewicz
FIG. 10.34
Power-law fits to the effective upper critical field scaling law prefactor for binary Nb3Sn
FIG. 10.35
Illustration of transformation method for scaling Jc(B) curves to different strains
FIG. 10.36
Data correlation showing the scaling parameter w has the constant value 3 for many different types of Nb3Sn conductors
FIG. 10.37
Data correlation showing the temperature scaling parameter v has the constant value 1.5 indepent of compositional phase and measurement method
FIG. 10.38
Data correlation showing the temperature scaling parameter v has the constant value 1.5 indepent of strain
References
Listing of all References for Chapter 10 Figures
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