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 cross-sectional area less than 3 mm2. In the case of Nb3Sn, the specimens have received a reaction heat-treatment.<\/p>\n
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| 6<\/td>\n | English CONTENTS <\/td>\n<\/tr>\n | ||||||
| 8<\/td>\n | FOREWORD <\/td>\n<\/tr>\n | ||||||
| 10<\/td>\n | INTRODUCTION <\/td>\n<\/tr>\n | ||||||
| 11<\/td>\n | 1 Scope 2 Normative references 3 Terms and definitions <\/td>\n<\/tr>\n | ||||||
| 12<\/td>\n | 4 Principle 5 Apparatus 5.1 Material of measurement mandrel or of measurement base plate 5.2 Diameter of the measurement mandrel and length of the measurement base plate Figures Figure 1 \u2013 Relationship between temperature and resistance <\/td>\n<\/tr>\n | ||||||
| 13<\/td>\n | 5.3 Cryostat for the resistance (R2) measurement 6 Specimen preparation 7 Data acquisition and analysis 7.1 Resistance (R1) at room temperature 7.2 Resistance (R2 or ) just above the superconducting transition 7.2.1 Correction of strain effect <\/td>\n<\/tr>\n | ||||||
| 14<\/td>\n | 7.2.2 Data acquisition of cryogenic resistance Figure 2 \u2013 Voltage versus temperature curvesand definitions of each voltage <\/td>\n<\/tr>\n | ||||||
| 16<\/td>\n | 7.2.3 Optional acquisition methods 7.3 Correction on measured of Nb-Ti composite superconductor for bending strain 7.4 Residual resistance ratio (RRR) 8 Uncertainty and stability of the test method 8.1 Temperature 8.2 Voltage measurement <\/td>\n<\/tr>\n | ||||||
| 17<\/td>\n | 8.3 Current 8.4 Dimension 9 Test report 9.1 RRR value 9.2 Specimen <\/td>\n<\/tr>\n | ||||||
| 18<\/td>\n | 9.3 Test conditions 9.3.1 Measurements of R1 and R2 9.3.2 Measurement of R1 9.3.3 Measurement of R2 <\/td>\n<\/tr>\n | ||||||
| 19<\/td>\n | Annex A (informative) Additional information relating to the measurement of RRR A.1 Recommendation on specimen mounting orientation A.2 Alternative methods for increasing temperature of specimen above superconducting transition temperature A.3 Alternative measurement methods of R2 or <\/td>\n<\/tr>\n | ||||||
| 21<\/td>\n | Figure A.1 \u2013 Definition of voltages <\/td>\n<\/tr>\n | ||||||
| 22<\/td>\n | A.4 Bending strain dependency of RRR for Nb-Ti composite superconductor <\/td>\n<\/tr>\n | ||||||
| 23<\/td>\n | Figure A.2 \u2013 Bending strain dependency of RRR value forpure Cu matrix of Nb-Ti composite superconductors (comparison between measured values and calculated values) Figure A.3 \u2013 Bending strain dependency of RRR value for round Cu wires <\/td>\n<\/tr>\n | ||||||
| 24<\/td>\n | Figure A.4 \u2013 Bending strain dependency of normalized RRR value for round Cu wires Figure A.5 \u2013 Bending strain dependency of RRR value for rectangular Cu wires <\/td>\n<\/tr>\n | ||||||
| 25<\/td>\n | A.5 Procedure of correction of bending strain effect Figure A.6 \u2013 Bending strain dependency of normalized RRR value forrectangular Cu wires Tables Table A.1 \u2013 Minimum diameter of the measurement mandrel for round wires Table A.2 \u2013 Minimum diameter of the measurement mandrel for rectangular wires <\/td>\n<\/tr>\n | ||||||
| 27<\/td>\n | Annex B (informative) Uncertainty considerations B.1 Overview B.2 Definitions B.3 Consideration of the uncertainty concept <\/td>\n<\/tr>\n | ||||||
| 28<\/td>\n | Table B.1 \u2013 Output signals from two nominally identical extensometers Table B.2 \u2013 Mean values of two output signals Table B.3 \u2013 Experimental standard deviations of two output signals <\/td>\n<\/tr>\n | ||||||
| 29<\/td>\n | B.4 Uncertainty evaluation example for TC 90 standards Table B.4 \u2013 Standard uncertainties of two output signals Table B.5 \u2013 COV values of two output signals <\/td>\n<\/tr>\n | ||||||
| 31<\/td>\n | Annex C (informative) Uncertainty evaluation in test method of RRR for Nb-Ti and Nb3Sn composite superconductors C.1 Evaluation of uncertainty <\/td>\n<\/tr>\n | ||||||
| 34<\/td>\n | C.2 Summary of round robin test of RRR of a Nb-Ti composite superconductor Table C.1 \u2013 Uncertainty of each measurement <\/td>\n<\/tr>\n | ||||||
| 35<\/td>\n | C.3 Reason for large COV value in the intercomparison test on Nb3Sn composite superconductor Figure C.1 \u2013 Distribution of observed rRRR of Cu\/Nb-Ti composite superconductor Table C.2 \u2013 Obtained values of R1, R2 and rRRR for three Nb3Sn samples <\/td>\n<\/tr>\n | ||||||
| 36<\/td>\n | Bibliography <\/td>\n<\/tr>\n<\/table>\n","protected":false},"excerpt":{"rendered":" Superconductivity – Residual resistance ratio measurement. Residual resistance ratio of Nb-Ti and Nb3Sn composite superconductors<\/b><\/p>\n |