Critical current density of superconductors as a function of strain in high magnetic fields

✍ Scribed by H.A Hamid; D.P Hampshire

• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 324 KB
• Volume: 38
• Category: Article
• ISSN: 0011-2275
• DOI: 10.1016/s0011-2275(98)00083-6

✦ Synopsis

A probe has been designed and built to measure the critical current density (J C ) of short superconducting wires and tapes as a function of strain (⑀) in small bore high field magnets. The probe can measure currents of up to 100 Amps and strains of ± 1.0% on both low and high temperature superconductors. Measurements can be made in our 40 mm bore 17 T high magnetic field system in pumped cryogens. Strain is measured using commercial strain gauges pasted directly onto the samples. A Agsheathed Bi 2 Sr 2 Ca 2 Cu 3 O X tape has been measured at 4.2 K in magnetic fields up to 12 T. J C is hysteretic in high magnetic fields and is weakly dependent on magnetic field and tensile strain up to ෂ 0.29%. Beyond ෂ 0.29% strain, the filaments break and J C drops precipitously. Results are also presented for the effect of tensile and compressive strain for a 0.37 mm diameter Nb 3 Sn wire at 4.2 K and 2.9 K from 10 T up to 14 T. The data confirm that a simple scaling law that includes the upper critical field (B C2 (T,⑀)) and the reduced field (B/B C2 (T,⑀)) alone cannot accurately describe the field, temperature and strain dependence of J C .