Title :
Anomalous switching phenomenon in critical-current measurements when using conductive mandrels
Author :
Goodrich, L.F. ; Wiejaczka, J.A. ; Srivastava, A.N.
Author_Institution :
Nat. Inst. of Stand. & Technol., Boulder, CO, USA
Abstract :
NIST and other laboratories have observed an anomalous switching phenomenon that can occur in critical-current measurements of coiled Nb-Ti and Nb/sub 3/Sn superconductors when mounted on an electrically-conductive measurement mandrel. During acquisition of the voltage-current (V-I) characteristic, large voltage discontinuities are observed, This switching phenomenon results in a multivalued V-I curve, and apparently multiple "critical current" values, An explanation of this phenomenon, some necessary conditions for the switching to occur, as well as methods of detecting the phenomenon are given.<>
Keywords :
critical currents; electric current measurement; multifilamentary superconductors; niobium alloys; switching; tin alloys; titanium alloys; type II superconductors; NIST; Nb-Ti; Nb/sub 3/Sn; anomalous switching phenomenon; coiled Nb-Ti superconductor; coiled Nb/sub 3/Sn superconductor; conductive mandrels; critical-current measurements; multiple critical current values; multivalued V-I curve; voltage discontinuities; voltage-current characteristic; Conductivity measurement; Contact resistance; Current measurement; Electric variables measurement; Electrical resistance measurement; Laboratories; Magnetic field measurement; Niobium-tin; Superconductivity; Voltage;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
