Flux pinning in bronze-processed Nb/sub 3/Sn wires
The scaling law derived by Kramer for magnetic flux pinning in high magnetic fields was examined for its applicability to the magnetic field dependence of critical-current densities in the bronze processed monofilamentary Nb/sub 3/Sn wires. From this it was concluded that: (1) its prediction for the form of the dependence of critical current on magnetic field and grain size (/J vector /sub c/ x H vector/ approx. h/sup 1/2/(1-h)/sup 2/(1-a/sub 0/..sqrt..rho)/sup -2/) was found to be very good in most cases including wires with very small Nb/sub 3/Sn grains (approx. 400 A). It was found very useful in comparison of J/sub c/ for different wires and in extrapolating to obtain H/sub c2/ for these wires. (2) However, it could not account consistently for the anisotropy in critical current of a tape which was measured with H applied perpendicular and parallel to the tape face. (3) The values of kappa/sub 1/ which were determined with the scaling law were too small by a factor of 2 to 3, and the trend in the variation with heat-treating time was opposite to that which is reasonably to be expected. That the behavior of kappa/sub 1/ is thus seriously in contradiction with the expected behavior for Nb/sub 3/Sn suggests basic faults in the derivation of the scaling equation for critical currents at high magnetic fields.
- Research Organization:
- Brookhaven National Lab., Upton, NY (USA)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC02-76CH00016
- OSTI ID:
- 5281217
- Report Number(s):
- BNL-27964; CONF-800587-4
- Country of Publication:
- United States
- Language:
- English
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