IEC 61788-4:2016 pdf free download.SUPERCONDUCTIVITY – PART 4: RESIDUAL RESISTANCE RATIO MEASUREMENT – RESIDUAL RESISTANCE RATIO OF NB-TI AND NB[3]SN COMPOSITE SUPERCONDUCTORS.
Copper, Cu/Cu-Ni or aluminium is used as matrix material in Nb-Ti and Nb3Sn composite superconductors and works as an electrical shunt when the superconductivity is interrupted. It also contributes to recovery of the superconductivity by conducting heat generated in the superconductor to the surrounding coolant. The cryogenic-temperature resistivity of copper is an important quantity, which influences the stability and AC losses of the superconductor. The residual resistance ratio is defined as a ratio of the resistance of the superconductor at room temperature to that just above the superconducting transition.
This part of IEC 61788 specifies the test method for residual resistance ratio of Nb-Ti and Nb3Sn composite superconductors. The curve method is employed for the measurement of the resistance just above the superconducting transition. Other methods are described in A.3.
This part of IEC 61788 specifies a test method for the determination of the residual resistance ratio (RRR) of Nb-Ti and Nb3Sn composite superconductors with Cu, Cu-Ni, Cu/Cu-Ni and Al matrix. This method is intended for use with superconductor specimens that have a monolithic structure with rectangular or round cross-section, RRR value less than 350, and crosssectional area less than 3 mm2. In the case of Nb3Sn, the specimens have received a reaction heat-treatment.