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IEC 61788-17
Edition 2.0 2021-04
INTERNATIONAL
STANDARD
colour
inside
Superconductivity –
Part 17: Electronic characteristic measurements – Local critical current density
and its distribution in large-area superconducting films
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IEC 61788-17
Edition 2.0 2021-04
INTERNATIONAL
STANDARD
colour
inside
Superconductivity –
Part 17: Electronic characteristic measurements – Local critical current density
and its distribution in large-area superconducting films
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 17.220.20; 29.050 ISBN 978-2-8322-9663-9
– 2 – IEC 61788-17:2021 © IEC 2021
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 8
4 Requirements . 9
5 Apparatus . 10
5.1 Measurement equipment . 10
5.2 Components for inductive measurements . 11
6 Measurement procedure . 12
6.1 General . 12
6.2 Determination of the experimental coil coefficient . 12
6.3 Measurement of J in sample films. 16
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6.4 Measurement of J with only one frequency . 16
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6.5 Examples of the theoretical and experimental coil coefficients . 17
7 Uncertainty in the test method . 18
7.1 Major sources of systematic effects that affect the U measurement . 18
7.2 Effect of deviation from the prescribed value in the coil-to-film distance . 19
7.3 Uncertainty in the experimental coil coefficient and the obtained J . 20
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7.4 Effects of the film edge . 20
7.5 Specimen protection . 20
8 Test report . 21
8.1 Identification of test specimen . 21
8.2 Report of J values . 21
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8.3 Report of test conditions . 21
Annex A (informative) Additional information relating to Clauses 1 to 8 . 22
A.1 Comments on other methods for measuring the local J of large-area HTS
c
films . 22
A.2 Requirements . 22
A.3 Theory of the third-harmonic voltage generation . 23
A.4 Calculation of the induced electric fields . 24
A.5 Theoretical coil coefficient k and experimental coil coefficient k′ . 25
A.6 Scaling of the U –I curves and the constant-inductance criterion to
3 0
determine I . 25
th
A.7 Effects of reversible flux motion . 27
Annex B (informative) Optional measurement systems . 28
B.1 Overview. 28
B.2 Harmonic noises arising from the power source and their reduction . 29
Annex C (informative) Evaluation of the uncertainty . 33
C.1 Evaluation of the uncertainty in the experimental coil coefficient . 33
C.2 Uncertainty in the calculation of induced electric fields. 34
C.3 Experimental results on the effect of the deviation of the coil-to-film distance . 35
C.4 Examples of the Type-A uncertainties of J and n-values, originating from
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the experimental uncertainty in the U measurement . 35
C.5 Evaluation of the uncertainty in the obtained J . 36
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C.6 Experimental results that reveal the effect of the film edge . 37
Bibliography . 39
Figure 1 – Diagram for an electric circuit used for inductive J measurement
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of HTS films . 10
Figure 2 – Illustration showing techniques to press the sample coil to HTS films . 11
Figure 3 – Example of a calibration wafer used to determine the coil coefficient . 12
Figure 4 – Illustration of the sample coil and the magnetic field during measurement . 13
Figure 5 – Illustration of the sample coil and its magnetic field generation . 14
Figure 6 – E-J characteristics measured by a transport method and the U inductive
method . 16
Figure 7 – Illustration of coils 1 and 3 in Table 2 . 17
Figure 8 – The coil-factor function F(r) = 2H /I calculated for the three coils. 18
0 0
Figure 9 – The coil-to-film distance Z dependence of the theoretical coil coefficient k . 19
Figure A.1 – Illustration of the sample coil and the magnetic field during measurement . 24
Figure A.2 – U and U /I plotted against I in a YBCO thin film measured in applied
3 3 0 0
DC magnetic fields, and the scaling observed when normalized by I (insets) . 26
th
Figure A.3 – Example of the normalized third-harmonic voltages (U /fI ) measured
3 0
with various frequencies . 26
Figure B.1 – Schematic diagram for the variable-RL-cancel circuit . 29
Figure B.2 – Diagram for an electrical circuit used for the two-coil method . 29
Figure B.3 – Harmonic noises arising from the power source . 30
Figure B.4 – Noise reduction using a cancel coil with a superconducting film . 30
Figure B.5 – Normalized harmonic noises (U /fI ) arising from the power source . 31
3 0
Figure B.6 – Normalized noise voltages after the reduction using a cancel coil with a
superconducting film . 31
Figure B.7 – Normalized noise voltages after the reduction using a cancel coil without
a superconducting film . 32
Figure B.8 – Normalized noise voltages with the two-coil system shown in Figure B.2 . 32
Figure C.1 – Effect of the coil position against a superconducting thin film on the
measured J values . 38
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Table 1 – Specifications and theoretical coil coefficients k of sample coils . 14
Table 2 – Specifications and coil coefficients of typical sample coils . 17
Table C.1 – Uncertainty budget table for the experimental coil coefficient k′ . 34
Table C.2 – Examples of repeated measurements of J and n-values . 36
c
– 4 – IEC 61788-17:2021 © IEC 2021
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SUPERCONDUCTIVITY –
Part 17: Electronic characteristic measurements –
Local critical current density and its distribution
in large-area superconducting films
FOREWORD
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