IEC 61788-3:2000 Superconductivity - Part 3: Critical current measurement; DC critical current of Ag-sheathed Bi-2212 and Bi-2223 oxide superconductors
This part of IEC 61788 covers a test method for the determination of the d.c. critical current of short and straight Ag- or Ag alloy-sheathed Bi-2212 and Bi-2223 oxide superconductors that have a monolithic structure and a shape of round wire or flat or square tape containing mono-or multicores of oxides.
This method is intended for use with superconductors that have critical currents less than 500 A and n-values larger than 5. The test is carried out with and without applying external magnetic fields. In the test of the tape specimen in magnetic fields, the magnetic fields are parallel or perpendicular to the tape surface. The test specimen is immersed either in a liquid helium bath or a liquid nitrogen bath during testing. Deviations from this test method that are allowed for routine tests and other specific restrictions are given in this standard.
Substantial parts of the test method covered in this standard are in common with, or similar to, those for Nb3Sn composite superconductors (IEC 61788-2). Special features newly found for oxide superconductors may be classified into two groups. The first group is specific to oxide composite superconductors, including mechanical fragility originating from the presence of weak links, cryogen gas bubble formation, aging degradation, magnetic flux flow and creep, large anisotropy, hysteresis in critical current with magnetic field sweep, etc. The second group is due to the short length of the specimen used in the standard. A critical current measurement on such a specimen may easily pick up different voltage signals due to thermal electromotive force, inductive voltage, thermal noise, current redistribution, specimen motion relative to the holder, etc. Current transfer voltages may be present due to the short distance from a current contact to a voltage tap. Short specimen length may reduce mechanical tolerance against the Lorentz force, for example, by promoting the formation of cryogen gas bubbles within the composite.
IEC 61788-3:2000 history
2006IEC 61788-3:2006 Superconductivity - Part 3: Critical current measurement - DC critical current of Ag- and/or Ag alloy-sheathed Bi-2212 and Bi-2223 oxide superconductors
2000IEC 61788-3:2000 Superconductivity - Part 3: Critical current measurement; DC critical current of Ag-sheathed Bi-2212 and Bi-2223 oxide superconductors