1、BRITISH STANDARDBS EN 61788-7:2006Superconductivity Part 7: Electronic characteristic measurements Surface resistance of superconductors at microwave frequenciesThe European Standard EN 61788-7:2006 has the status of a British StandardICS 17.220; 29.050g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g
2、56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58BS EN 61788-7:2006This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 January 2007 BSI 200
3、7ISBN 978 0 580 49999 9National forewordThis British Standard was published by BSI. It is the UK implementation of EN 61788-7:2006. It is identical with IEC 61788-7:2006. It supersedes BS EN 61788-7:2002 which is withdrawn. The UK participation in its preparation was entrusted to Technical Committee
4、 L/-/90, Superconductivity.A list of organizations represented on L/-/90 can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application.Compliance with a British Standard cannot co
5、nfer immunity from legal obligations.Amendments issued since publicationAmd. No. Date CommentsEUROPEAN STANDARD EN 61788-7 NORME EUROPENNE EUROPISCHE NORM December 2006 CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee
6、 fr Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B - 1050 Brussels 2006 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members. Ref. No. EN 61788-7:2006 E ICS 17.220; 29.050 Supersedes EN 61788-7:2002English version Superconduct
7、ivity Part 7: Electronic characteristic measurements - Surface resistance of superconductors at microwave frequencies (IEC 61788-7:2006) Supraconductivit Partie 7: Mesures des caractristiques lectroniques - Rsistance de surface des supraconducteurs aux hyperfrquences (CEI 61788-7:2006) Supraleitfhig
8、keit Teil 7: Charakteristische elektronische Messungen - Oberflchenwiderstand von Supraleitern bei Frequenzen im Mikrowellenbereich (IEC 61788-7:2006) This European Standard was approved by CENELEC on 2006-11-01. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which sti
9、pulate the conditions for giving this European Standard the 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 Central Secretariat or to any CENELEC member. This European Stand
10、ard exists in three official versions (English, French, 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 Central Secretariat has the same status as the official versions. CENELEC members are the nation
11、al electrotechnical committees of Austria, Belgium, Cyprus, the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerla
12、nd and the United Kingdom. Foreword The text of document 90/193/FDIS, future edition 2 of IEC 61788-7, prepared by IEC TC 90, Superconductivity, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as EN 61788-7 on 2006-11-01. This European Standard supersedes EN 61788-7:2002.
13、Examples of technical changes made are: closed type resonators are recommended from the viewpoint of the stable measurements; uniaxial-anisotropic characteristics of sapphire rods are taken into consideration for designing the size of the sapphire rods; recommended measurement frequency of 18 GHz an
14、d 22 GHz are added to 12 GHz described in EN 61788-7:2002. The following dates were fixed: latest date by which the EN has to be implemented at national level by publication of an identical national standard or by endorsement (dop) 2007-08-01 latest date by which the national standards conflicting w
15、ith the EN have to be withdrawn (dow) 2009-11-01 Annex ZA has been added by CENELEC. _ Endorsement notice The text of the International Standard IEC 61788-7:2006 was approved by CENELEC as a European Standard without any modification. _ EN 61788-7:2006 2 CONTENTS INTRODUCTION.5 1 Scope.6 2 Normative
16、 references .6 3 Terms and definitions .6 4 Requirements .6 5 Apparatus.7 5.1 Measurement system 7 5.2 Measurement apparatus for Rs8 5.3 Dielectric rods .10 6 Measurement procedure.11 6.1 Specimen preparation .11 6.2 Set-up .11 6.3 Measurement of reference level 11 6.4 Measurement of the frequency r
17、esponse of resonators12 6.5 Determination of surface resistance of the superconductor and and tan of the standard sapphire rods 14 7 Precision and accuracy of the test method15 7.1 Surface resistance 15 7.2 Temperature16 7.3 Specimen and holder support structure .16 7.4 Specimen protection17 8 Test
18、report17 8.1 Identification of test specimen .17 8.2 Report of Rsvalues .17 8.3 Report of test conditions17 Annex A (informative) Additional information relating to Clauses 1 to 818 Bibliography32 Figure 1 Schematic diagram of measurement system for temperature dependence of Rsusing a cryocooler .7
19、Figure 2 Typical measurement apparatus for Rs 9 Figure 3 Insertion attenuation IA, resonant frequency f0and half power bandwidth f, measured at T Kelvin 12 Figure 4 Reflection scattering parameters (S11and S22)14 Figure 5 Term definitions in Table 4.16 Figure A.1 Schematic configuration of several m
20、easurement methods for the surface resistance.19 Figure A.2 Configuration of a cylindrical dielectric rod resonator short-circuited at both ends by two parallel superconductor films deposited on dielectric substrates 21 Figure A.3 Computed results of the u-v and W-v relations for TE01pmode.22 Figure
21、 A.4 Configuration of standard dielectric rods for measurement of Rsand tan .23 EN 61788-7:2006 3 Annex ZA (normative) Normative references to international publications with their with their corresponding European publications 31 Figure A.5 Three types of dielectric resonators 23 Figure A.6 Mode ch
22、art to design TE011resonator short-circuited at both ends by parallel superconductor films 11 .26 Figure A.7 Mode chart to design TE013resonator short-circuited at both ends by parallel superconductor films 11 .27 Figure A.8 Mode chart for TE011closed-type resonator28 Figure A.9 Mode chart for TE013
23、closed-type resonator29 Table 1 Typical dimensions of pairs of standard sapphire rods for 12 GHz, 18 GHz and 22 GHz 10 Table 2 Dimensions of superconductor film for 12 GHz, 18 GHz, and 22 GHz 11 Table 3 Specifications on vector network analyzer .15 Table 4 Specifications on sapphire rods.15 EN 61788
24、-7:2006 4 INTRODUCTION Since the discovery of some Perovskite-type Cu-containing oxides, extensive research and development (R requires no sample preparation; does not damage or change the film; is highly repeatable; has great sensitivity (down to 1/1 000ththe Rsof copper); has great dynamic range (
25、up to the Rsof copper); can reach high internal powers with only modest input powers; and has broad temperature coverage (4,2 K to 150 K). The dielectric resonator method is selected among several methods 5,6,7 to determine the surface resistance at microwave frequencies because it is considered to
26、be the most popular and practical at present. Especially, the sapphire resonator is an excellent tool for measuring the Rsof HTS materials 8,9. The test method given in this standard can be also applied to other superconductor bulk plates including low Tc material. This standard is intended to provi
27、de an appropriate and agreeable technical base for the time being to engineers working in the fields of electronics and superconductivity technology. The test method covered in this standard is based on the VAMAS (Versailles Project on Advanced Materials and Standards) pre-standardization work on th
28、e thin film properties of superconductors. _ 1)Figures in square brackets refer to the Bibliography. EN 61788-7:2006 5 SUPERCONDUCTIVITY Part 7: Electronic characteristic measurements Surface resistance of superconductors at microwave frequencies 1 Scope This part of IEC 61788 describes measurement
29、of the surface resistance of superconductors at microwave frequencies by the standard two-resonator method. The object of measurement is the temperature dependence of Rsat the resonant frequency. The applicable measurement range of surface resistances for this method is as follows: Frequency: 8 GHz
30、35 0,5 18 7,6 25 0,5 22 6,2 20 0,5 In case of using closed type resonators, the dimensions of the superconductor films shall also be designed taking into account the dimension of the copper cylinder between the superconductor films. A design guideline for the dimension of the copper cylinder of the
31、closed type resonator is described in Clause A.6. 6.2 Set-up Set up the measurement equipment as shown in Figure 1. All of the measurement apparatus, standard sapphire rods, and superconductor films shall be kept in a clean and dry state as high humidity may degrade the unloaded Q-value. The specime
32、n and the measurement apparatus shall be fixed in a temperature-controlled cryocooler. The specimen chamber shall be generally evacuated. The temperatures of the superconductor films and standard sapphire rods shall be measured by a diode thermometer, or a thermocouple. The temperatures of the upper
33、 and lower superconductor films, and standard sapphire rods must be kept as close as possible. This can be achieved by covering the measurement apparatus with aluminum foil, or filling the specimen chamber with helium gas. 6.3 Measurement of reference level The level of full transmission power (refe
34、rence level) shall be measured first. Fix the output power of the synthesized sweeper below 10 mW because the measurement accuracy depends on the measuring signal level. Connect the reference line of semi-rigid cable between the input and output connectors. Then, measure the transmission power level
35、 over the entire measurement frequency and temperature range. The reference level can change several decibels when temperature of the apparatus is changed from room temperature to the lowest measurement temperature. Therefore, the temperature dependence of the reference level must be taken into acco
36、unt. EN 61788-7:2006 11 Reference level at T K3,01 dBIAFrequency GHzAttenuation dB0f0fIEC 007/02Figure 3 Insertion attenuation IA, resonant frequency f0and half power bandwidth f, measured at T Kelvin 6.4 Measurement of the frequency response of resonators The temperature dependence of the surface r
37、esistance Rscan be obtained through the measurements of resonant frequency f0and unloaded quality factor Qufor TE011and TE013resonators, which shall be measured as follows. a) Connect the measurement apparatus between the input and output connectors (Figure 1). Insert the standard short sapphire rod
38、 near the centre of the lower superconductor film and fix the distance between the rod and each of the loops of the semi-rigid cables to be equal to each other, so that this transmission-type resonator can be under-coupled equally to both loops. Put down the upper superconductor film gently to touch
39、 the top face of the rod. Be careful not to damage the surface of the superconductor films by excessive pressure. Evacuate and cool down the specimen chamber below the critical temperature. b) Find the TE011mode resonance peak of this resonator at a frequency nearly equal to the designed value of f0
40、. c) Narrow the frequency span on the display so that only the resonance peak of TE011mode can be shown (Figure 3). Confirm that the insertion attenuation IA of this mode is larger than 20 dB from the reference level, which depends strongly on the temperature. d) Measure the temperature dependence o
41、f f0and the half power band width f. The loaded Q, QL, of the TE011resonator is given by ffQ=0L(1) e) The unloaded Q-value, Qu, shall be extracted from the QLby at least one of the two techniques described below. One technique for extracting the unloaded Q-value involves measuring the insertion atte
42、nuation IA. The Quis given by 20/dBttLu10,- 1IAAAQQ= (2) EN 61788-7:2006 12 This technique of using insertion attenuation assumes that the coupling on both sides of the resonator is identical. The coupling loops are difficult to fabricate, the orientation of the loop is difficult to control, and any
43、 movement of the sapphire rod during measurement is not known. These assembly dependent effects are also temperature dependent. This potential asymmetry in coupling can result in large errors in calculating the coupling factor if the coupling is strong (IA 20 dB), asymmetry in the coupling becomes l
44、ess important. Another technique for extracting the unloaded Q-value involves measuring the reflection scattering parameters at the resonant frequency of both sides of the resonator. )1(21Lu += QQ (3) |12211111SSS+= (4) |12211222SSS+= (5) In the above equations, S11and S22are the reflection scatteri
45、ng parameters as shown in Figure 4, and are measured in linear units of power, not relative dB. 1and 2are the coupling coefficients. This technique of using the reflection scattering parameters has two advantages. It does not require the additional step of calibration of the reference level and it g
46、ives a measurement of the coupling values for both sides of the resonator. This also has two disadvantages. It only works for a narrow band resonance (which is fortunately the case) and is limited by the dynamic range of the network analyzer in measuring the reflection coefficients. A combination of
47、 the two techniques is an excellent “double” check and is therefore recommended. f) The f0and Qumeasured for this short rod are denoted as f01and Qu1. By slowly changing the temperature of the cryocooler, the temperature dependence of f01and Qu1shall be measured. g) After the temperature dependence
48、measurement of f01and Qu1is finished, the measurement apparatus shall be heated up to room temperature. h) Then, replace the TE011resonator in the apparatus with the TE013resonator at room temperature, cool down the apparatus to a temperature lower than the critical temperature, and measure the temp
49、erature dependence of f0and Quof its TE013resonance mode, denoted as f03and Qu3, in a similar way as the TE011resonator case. When the length of the sapphire rod of the TE013resonator is precisely three times longer than that of the TE011resonator, the f03of the TE013resonator must coincide with f01of the TE011resonator. If carefully designed, the difference between f01and f03is usually very small (0,25%). We can treat as f0= f01=
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