1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationSuperconductivityPart 17: Electric characteristic measurements Local critical current density and its distribution in large-area superconducting filmsBS EN 61788-17:2013National
2、forewordThis British Standard is the UK implementation of EN 61788-17:2013. It is identical to IEC 61788-17:2013.The UK participation in its preparation was entrusted to Technical Committee L/-/90, Super Conductivity.A list of organizations represented on this committee can be obtained on request to
3、 its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2013.Published by BSI Standards Limited 2013.ISBN 978 0 580 69204 8 ICS 17.220.20; 29.050 Compliance with a Bri
4、tish Standard cannot confer immunity from legal obligations.This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 April 2013.Amendments issued since publicationDate Text affectedBRITISH STANDARDBS EN 61788-17:2013EUROPEAN STANDARD EN 61788-17 NO
5、RME EUROPENNE EUROPISCHE NORM April 2013 CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Management Centre: Avenue Marnix 17, B - 1000 Brussels 2013 CENELEC - All rights of exploitation i
6、n any form and by any means reserved worldwide for CENELEC members. Ref. No. EN 61788-17:2013 E ICS 17.220.20; 29.050 English version Superconductivity - Part 17: Electronic characteristic measurements - Local critical current density and its distribution in large-area superconducting films (IEC 617
7、88-17:2013) Supraconductivit - Partie 17: Mesures de caractristiques lectroniques - Densit de courant critique local et sa distribution dans les films supraconducteurs de grande surface (CEI 61788-17:2013) Supraleitfhigkeit - Teil 17: Messungen der elektronischen Charakteristik - Lokale kritische St
8、romdichte und deren Verteilung in groflchigen supraleitenden Schichten (IEC 61788-17:2013) This European Standard was approved by CENELEC on 2013-02-20. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the
9、status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CENELEC member. This European Standard exists in three official versions (English, Fr
10、ench, German). A version in any other language made by translation under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions. CENELEC members are the national electrotechnical committees of Austri
11、a, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
12、 Sweden, Switzerland, Turkey and the United Kingdom. BS EN 61788-17:2013EN 61788-17:2013 Foreword The text of document 90/310/FDIS, future edition 1 of IEC 61788-17, prepared by IEC TC 90,“Superconductivity“ was submitted to the IEC-CENELEC parallel vote and approved by CENELEC asEN 61788-17:2013. T
13、he following dates are fixed: latest date by which the document has to be implemented at national level bypublication of an identical national standard or by endorsement (dop) 2013-11-20 latest date by which the national standards conflicting with thedocument have to be withdrawn (dow) 2016-02-20 At
14、tention is drawn to the possibility that some of the elements of this document may be the subject ofpatent rights. CENELEC and/or CEN shall not be held responsible for identifying any or all such patentrights. Endorsement notice The text of the International Standard IEC 61788-17:2013 was approved b
15、y CENELEC as a EuropeanStandard without any modification. BS EN 61788-17:2013EN 61788-17:2013 Annex ZA (normative) Normative references to international publications with their corresponding European publications The following documents, in whole or in part, are normatively referenced in this docume
16、nt and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. NOTE When an international publication has been modified by common modifications, indicated by
17、 (mod), the relevant EN/HDapplies. Publication Year Title EN/HD Year IEC 60050 Series International electrotechnical vocabulary - - BS EN 61788-17:201361788-17 IEC:2013 CONTENTS INTRODUCTION . 6 1 Scope . . 8 2 Normative reference . 8 3 Terms and definitions . 8 4 Requirements . 9 5 Apparatus . 9 5.
18、1 Measurement equipment . 9 5.2 Components for inductive measurements . 10 5.2.1 Coils . 10 5.2.2 Spacer film . 11 5.2.3 Mechanism for the set-up of the coil . 11 5.2.4 Calibration wafer . 11 6 Measurement procedure . 12 6.1 General . . 12 6.2 Determination of the experimental coil coefficient 12 6.
19、2.1 Calculation of the theoretical coil coefficient k 12 6.2.2 Transport measurements of bridges in the calibration wafer 13 6.2.3 U3measurements of the calibration wafer . . 13 6.2.4 Calculation of the E-J characteristics from frequency-dependent Ithdata 13 6.2.5 Determination of the k from Jctand
20、Jc0values for an appropriate E . . 14 6.3 Measurement of Jcin sample films . . 15 6.4 Measurement of Jcwith only one frequency 15 6.5 Examples of the theoretical and experimental coil coefficients . . 16 7 Uncertainty in the test method . . 17 7.1 Major sources of systematic effects that affect the
21、U3measurement . 17 7.2 Effect of deviation from the prescribed value in the coil-to-film distance . 18 7.3 Uncertainty of the experimental coil coefficient and the obtained Jc. 18 7.4 Effects of the film edge . 19 7.5 Specimen protection . 19 8 Test report 19 8.1 Identification of test specimen . .
22、19 8.2 Report of Jcvalues . 19 8.3 Report of test conditions . . 19 Annex A (informative) Additional information relating to Clauses 1 to 8 . 20 Annex B (informative) Optional measurement systems . 26 Annex C (informative) Uncertainty considerations . 32 Annex D (informative) Evaluation of the uncer
23、tainty 37 Bibliography . 43 Figure 1 Diagram for an electric circuit used for inductive Jcmeasurement 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 BS EN 6178
24、8-17:201361788-17 IEC:2013 Figure 4 Illustration for the sample coil and the magnetic field during measurement 13 Figure 5 E-J characteristics measured by a transport method and the U3inductive method . 14 Figure 6 Example of the normalized third-harmonic voltages (U3/fI0) measured with various freq
25、uencies . . 15 Figure 7 Illustration for coils 1 and 3 in Table 1 16 Figure 8 The coil-factor function F(r) = 2H0/I0calculated for the three coils . . 17 Figure 9 The coil-to-film distance Z1dependence of the theoretical coil coefficient k . . 18 Figure A.1 Illustration for the sample coil and the m
26、agnetic field during measurement . 22 Figure A.2 (a) U3and (b) U3/I0plotted against I0in a YBCO thin film measured in applied DC magnetic fields, and the scaling observed when normalized by Ith (insets) . . 23 Figure B.1 Schematic diagram for the variable-RL-cancel circuit . . 27 Figure B.2 Diagram
27、for an electrical circuit used for the 2-coil method . . 27 Figure B.3 Harmonic noises arising from the power source . 28 Figure B.4 Noise reduction using a cancel coil with a superconducting film . . 28 Figure B.5 Normalized harmonic noises (U3/fI0) arising from the power source . . 29 Figure B.6 N
28、ormalized noise voltages after the reduction using a cancel coil with a superconducting film 29 Figure B.7 Normalized noise voltages after the reduction using a cancel coil without a superconducting film . 30 Figure B.8 Normalized noise voltages with the 2-coil system shown in Figure B.2 30 Figure D
29、.1 Effect of the coil position against a superconducting thin film on the measured Jcvalues . 41 Table 1 Specifications and coil coefficients of typical sample coils . 16 Table C.1 Output signals from two nominally identical extensometers . 33 Table C.2 Mean values of two output signals . 33 Table C
30、.3 Experimental standard deviations of two output signals . 33 Table C.4 Standard uncertainties of two output signals 34 Table C.5 Coefficient of variations of two output signals 34 Table D.1 Uncertainty budget table for the experimental coil coefficient k . 37 Table D.2 Examples of repeated measure
31、ments of Jcand n-values . 40 BS EN 61788-17:2013 6 61788-17 IEC:2013 INTRODUCTION Over twenty years after their discovery in 1986, high-temperature superconductors are now finding their way into products and technologies that will revolutionize information transmission, transportation, and energy. A
32、mong them, high-temperature superconducting (HTS) microwave filters, which exploit the extremely low surface resistance of superconductors, have already been commercialized. They have two major advantages over conventional non-superconducting filters, namely: low insertion loss (low noise characteri
33、stics) and high frequency selectivity (sharp cut) 11. These advantages enable a reduced number of base stations, improved speech quality, more efficient use of frequency bandwidths, and reduced unnecessary radio wave noise. Large-area superconducting thin films have been developed for use in microwa
34、ve devices 2. They are also used for emerging superconducting power devices, such as, resistive-type superconducting fault-current limiters (SFCLs) 35, superconducting fault detectors used for superconductor-triggered fault current limiters 6, 7 and persistent-current switches used for persistent-cu
35、rrent HTS magnets 8, 9. The critical current density Jcis one of the key parameters that describe the quality of large-area HTS films. Nondestructive, AC inductive methods are widely used to measure Jcand its distribution for large-area HTS films 1013, among which the method utilizing third-harmonic
36、 voltages U3cos(3t+) is the most popular 10, 11, where , t and denote the angular frequency, time, and initial phase, respectively. However, these conventional methods are not accurate because they have not considered the electric-field E criterion of the Jcmeasurement 14, 15 and sometimes use an in
37、appropriate criterion to determine the threshold current Ithfrom which Jcis calculated 16. A conventional method can obtain Jcvalues that differ from the accurate values by 10 % to 20 % 15. It is thus necessary to establish standard test methods to precisely measure the local critical current densit
38、y and its distribution, to which all involved in the HTS filter industry can refer for quality control of the HTS films. Background knowledge on the inductive Jcmeasurements of HTS thin films is summarized in Annex A. In these inductive methods, AC magnetic fields are generated with AC currents I0co
39、st in a small coil mounted just above the film, and Jcis calculated from the threshold coil current Ith, at which full penetration of the magnetic field to the film is achieved 17. For the inductive method using third-harmonic voltages U3, U3is measured as a function of I0, and the Ithis determined
40、as the coil current I0at which U3starts to emerge. The induced electric fields E in the superconducting film at I0= Ith, which are proportional to the frequency f of the AC current, can be estimated by a simple Bean model 14. A standard method has been proposed to precisely measure Jcwith an electri
41、c-field criterion by detecting U3and obtaining the n-value (index of the power-law E-J characteristics) by measuring Ithprecisely at various frequencies 14, 15, 18, 19. This method not only obtains precise Jcvalues, but also facilitates the detection of degraded parts in inhomogeneous specimens, bec
42、ause the decline of n-value is more remarkable than the decrease of Jcin such parts 15. It is noted that this standard method is excellent for assessing homogeneity in large-area HTS films, although the relevant parameter for designing microwave devices is not Jc, but the surface resistance. For app
43、lication of large-area superconducting thin films to SFCLs, knowledge on Jcdistribution is vital, because Jcdistribution significantly affects quench distribution in SFCLs during faults. The International Electrotechnical Commission (IEC) draws attention to the fact that it is claimed that complianc
44、e with this document may involve the use of a patent concerning the determination of the E-J characteristics by inductive Jcmeasurements as a function of frequency, given in the Introduction, Clause 1, Clause 4 and 5.1. IEC takes no position concerning the evidence, validity and scope of this patent
45、 right. The holder of this patent right has assured the IEC that he is willing to negotiate licenses free of charge with applicants throughout the world. In this respect, the statement of the holder of this patent right is registered with the IEC. Information may be obtained from: _ 1Numbers in squa
46、re brackets refer to the Bibliography. BS EN 61788-17:201361788-17 IEC:2013 7 Name of holder of patent right: National Institute of Advanced Industrial Science and Technology Address: Intellectual Property Planning Office, Intellectual Property Department 1-1-1, Umezono, Tsukuba, Ibaraki Prefecture,
47、 Japan Attention is drawn to the possibility that some of the elements of this document may be subject to patent rights other than those identified above. IEC shall not be held responsible for identifying any or all such patent rights. ISO (www.iso.org/patents) and IEC (http:/patents.iec.ch) maintai
48、n on-line data bases of patents relevant to their standards. Users are encouraged to consult the data bases for the most up to date information concerning patents. BS EN 61788-17:2013 8 61788-17 IEC:2013 SUPERCONDUCTIVITY Part 17: Electronic characteristic measurements Local critical current density
49、 and its distribution in large-area superconducting films 1 Scope This part of IEC 61788 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 an
