IEC 61788-17:2013 describes the measurements of the local critical current density (Jc) and its distribution in large-area high-temperature superconducting (HTS) films by an inductive method using third-harmonic voltages. The most important consideration for precise measurements is to determine Jc at liquid nitrogen temperatures by an electric-field criterion and obtain current-voltage characteristics from its frequency dependence. Although it is possible to measure Jc in applied DC magnetic fields, the scope of this standard is limited to the measurement without DC magnetic fields. This technique intrinsically measures the critical sheet current that is the product of Jc and the film thickness d. The range and measurement resolution for Jcd of HTS films are from 200 A\/m to 32 kA\/m, with a measurement resolution of 100 A\/m.<\/p>\n
| PDF Pages<\/th>\n | PDF Title<\/th>\n<\/tr>\n | ||||||
|---|---|---|---|---|---|---|---|
| 6<\/td>\n | English CONTENTS <\/td>\n<\/tr>\n | ||||||
| 8<\/td>\n | INTRODUCTION <\/td>\n<\/tr>\n | ||||||
| 10<\/td>\n | 1 Scope 2 Normative reference 3 Terms and definitions <\/td>\n<\/tr>\n | ||||||
| 11<\/td>\n | 4 Requirements 5 Apparatus 5.1 Measurement equipment <\/td>\n<\/tr>\n | ||||||
| 12<\/td>\n | 5.2 Components for inductive measurements 5.2.1 Coils Figure\u00a01 \u2013 Diagram for an electric circuit used for inductive Jc measurement of HTS films <\/td>\n<\/tr>\n | ||||||
| 13<\/td>\n | 5.2.2 Spacer film 5.2.3 Mechanism for the set-up of the coil 5.2.4 Calibration wafer Figures Figure\u00a02 \u2013 Illustration showing techniques to press the sample coil to HTS films Tables <\/td>\n<\/tr>\n | ||||||
| 14<\/td>\n | 6 Measurement procedure 6.1 General 6.2 Determination of the experimental coil coefficient 6.2.1 Calculation of the theoretical coil coefficient k Figure\u00a03 \u2013 Example of a calibration wafer used to determine the coil coefficient <\/td>\n<\/tr>\n | ||||||
| 15<\/td>\n | 6.2.2 Transport measurements of bridges in the calibration wafer 6.2.3 U3 measurements of the calibration wafer 6.2.4 Calculation of the E-J characteristics from frequency-dependent Ith data Figure\u00a04 \u2013 Illustration for the sample coil and the magnetic field during measurement <\/td>\n<\/tr>\n | ||||||
| 16<\/td>\n | 6.2.5 Determination of the k\u2019 from Jct and Jc0 values for an appropriate E Figure\u00a05 \u2013 E-J characteristics measured by a transport method and the U3 inductive method <\/td>\n<\/tr>\n | ||||||
| 17<\/td>\n | 6.3 Measurement of Jc in sample films 6.4 Measurement of Jc with only one frequency Figure\u00a06 \u2013Example of the normalized third-harmonic voltages (U3\/fI0) measured with various frequencies <\/td>\n<\/tr>\n | ||||||
| 18<\/td>\n | 6.5 Examples of the theoretical and experimental coil coefficients Figure\u00a07 \u2013 Illustration for coils 1 and 3 in Table\u00a01 Table\u00a01 \u2013 Specifications and coil coefficients of typical sample coils <\/td>\n<\/tr>\n | ||||||
| 19<\/td>\n | 7 Uncertainty in the test method 7.1 Major sources of systematic effects that affect the U3 measurement Figure\u00a08 \u2013 The coil-factor function F(r) = 2H0\/I0 calculated for the three coils <\/td>\n<\/tr>\n | ||||||
| 20<\/td>\n | 7.2 Effect of deviation from the prescribed value in the coil-to-film distance 7.3 Uncertainty of the experimental coil coefficient and the obtained Jc Figure\u00a09 \u2013 The coil-to-film distance Z1 dependence of the theoretical coil coefficient k <\/td>\n<\/tr>\n | ||||||
| 21<\/td>\n | 7.4 Effects of the film edge 7.5 Specimen protection 8 Test report 8.1 Identification of test specimen 8.2 Report of Jc values 8.3 Report of test conditions <\/td>\n<\/tr>\n | ||||||
| 22<\/td>\n | Annex A (informative) Additional information relating to Clauses 1 to 8 <\/td>\n<\/tr>\n | ||||||
| 24<\/td>\n | Figure\u00a0A.1 \u2013 Illustration for the sample coil andthe magnetic field during measurement <\/td>\n<\/tr>\n | ||||||
| 25<\/td>\n | Figure\u00a0A.2 \u2013 (a) U3 and (b) U3\/I0 plotted against I0 in a YBCO thin film measured in applied DC magnetic fields, and the scaling observed when normalized by Ith (insets) <\/td>\n<\/tr>\n | ||||||
| 28<\/td>\n | Annex B (informative) Optional measurement systems <\/td>\n<\/tr>\n | ||||||
| 29<\/td>\n | Figure\u00a0B.1 \u2013 Schematic diagram for the variable-RL-cancel circuit Figure\u00a0B.2 \u2013 Diagram for an electrical circuit used for the 2-coil method <\/td>\n<\/tr>\n | ||||||
| 30<\/td>\n | Figure\u00a0B.3 \u2013 Harmonic noises arising from the power source Figure\u00a0B.4 \u2013 Noise reduction using a cancel coil with a superconducting film <\/td>\n<\/tr>\n | ||||||
| 31<\/td>\n | Figure\u00a0B.5 \u2013 Normalized harmonic noises (U3\/fI0) arising from the power source Figure\u00a0B.6 \u2013 Normalized noise voltages after the reduction using a cancel coil with a superconducting film <\/td>\n<\/tr>\n | ||||||
| 32<\/td>\n | Figure\u00a0B.7 \u2013 Normalized noise voltages after the reduction using a cancel coil without a superconducting film Figure\u00a0B.8 \u2013 Normalized noise voltages with the 2-coil system shown in Figure\u00a0B.2 <\/td>\n<\/tr>\n | ||||||
| 34<\/td>\n | Annex C (informative) Uncertainty considerations <\/td>\n<\/tr>\n | ||||||
| 35<\/td>\n | Table\u00a0C.1 \u2013 Output signals from two nominally identical extensometers Table\u00a0C.2 \u2013 Mean values of two output signals Table\u00a0C.3 \u2013 Experimental standard deviations of two output signals <\/td>\n<\/tr>\n | ||||||
| 36<\/td>\n | Table\u00a0C.4 \u2013 Standard uncertainties of two output signals Table\u00a0C.5 \u2013 Coefficient of variations of two output signals <\/td>\n<\/tr>\n | ||||||
| 39<\/td>\n | Annex D (informative) Evaluation of the uncertainty Table\u00a0D.1 \u2013 Uncertainty budget table for the experimental coil coefficient k\u2019 <\/td>\n<\/tr>\n | ||||||
| 42<\/td>\n | Table\u00a0D.2 \u2013 Examples of repeated measurements of Jc and n-values <\/td>\n<\/tr>\n | ||||||
| 43<\/td>\n | Figure\u00a0D.1 \u2013 Effect of the coil position against a superconductingthin film on the measured Jc values <\/td>\n<\/tr>\n | ||||||
| 45<\/td>\n | Bibliography <\/td>\n<\/tr>\n<\/table>\n","protected":false},"excerpt":{"rendered":" Superconductivity – Electronic characteristic measurements. Local critical current density and its distribution in large-area superconducting films<\/b><\/p>\n |