Superconductivity - Part 9: Measurements for bulk high temperature superconductors - Trapped flux density of large grain oxide superconductors

Specifies a test method for the determination of the trapped field (trapped flux density) of bulk high temperature superconductors. This International Standard is applicable to large grain bulk oxide superconductors that have well defined shapes such as round discs, rectangular, and hexagonal pellets. The trapped flux density can be assessed at temperatures from 4,2 K to 90 K. For the purpose of standardization, the trapped flux density will be reported for liquid nitrogen temperature.

Supraleitfähigkeit - Teil 9: Messungen an massiven Hochtemperatursupraleitern - Eingefrorene magnetische Flussdichte bei grobkörnigen oxidischen Supraleitern

Supraconductivité - Partie 9: Mesures pour supraconducteurs haute température massifs - Densité de flux résiduel des oxydes supraconducteurs à gros grains

Spécifie une méthode d'essai pour la détermination du champ résiduel (densité de flux résiduel) des supraconducteurs haute température massifs. La présente Norme internationale s'applique aux oxydes supraconducteurs à gros grains ayant des formes bien définies telles que les disques et les pastilles rectangulaires et hexagonales. La densité de flux résiduel peut être déterminée pour des températures comprises entre 4,2 K et 90 K. Pour les besoins de la normalisation, la densité de flux résiduel sera consignée pour la température de l'azote liquide.

Superprevodnost - 9. del: Meritve volumskih lastnosti visokotemperaturnih superprevodnikov - Ujet magnetni pretok v oksidnih superprevodnikih z velikimi zrni (IEC 61788-9:2005)

General Information

Status
Published
Publication Date
11-Aug-2005
Technical Committee
Drafting Committee
Parallel Committee
Current Stage
6060 - Document made available
Due Date
12-Aug-2005
Completion Date
12-Aug-2005

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SLOVENSKI SIST EN 61788-9:2005
STANDARD
december 2005
Superprevodnost – 9. del: Meritve volumskih lastnosti visokotemperaturnih
superprevodnikov - Ujet magnetni pretok v oksidnih superprevodnikih z
velikimi zrni (IEC 61788-9:2005)
Superconductivity – Part 9: Measurements for bulk high temperature
superconductors – Trapped flux density of large grain oxide superconductors (IEC
61788-9:2005)
ICS 17.220.20; 29.050 Referenčna številka
SIST EN 61788-9:2005(en)

© Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljeno

---------------------- Page: 1 ----------------------
EUROPEAN STANDARD EN 61788-9
NORME EUROPÉENNE
EUROPÄISCHE NORM August 2005
ICS 17.220; 29.050
English version
Superconductivity
Part 9: Measurements for bulk high temperature superconductors -
Trapped flux density of large grain oxide superconductors
(IEC 61788-9:2005)
Supraconductivité Supraleitfähigkeit
Partie 9: Mesures pour supraconducteurs Teil 9: Messungen an massiven
haute température massifs – Hochtemperatursupraleitern -
Densité de flux résiduel des oxydes Eingefrorene magnetische Flussdichte
supraconducteurs à gros grains bei grobkörnigen oxidischen Supraleitern
(CEI 61788-9:2005) (IEC 61788-9:2005)

This European Standard was approved by CENELEC on 2005-06-01. CENELEC members are bound to

comply with the CEN/CENELEC Internal Regulations which stipulate 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 Standard 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 national electrotechnical committees of Austria, Belgium, Cyprus, Czech

Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,

Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden,

Switzerland and United Kingdom.
CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
Central Secretariat: rue de Stassart 35, B - 1050 Brussels

© 2005 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.

Ref. No. EN 61788-9:2005 E
---------------------- Page: 2 ----------------------
EN 61788-9:2005 - 2 -
Foreword

The text of document 90/167/FDIS, future edition 1 of IEC 61788-9, prepared by IEC TC 90,

Superconductivity, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC

as EN 61788-9 on 2005-06-01.
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) 2006-03-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2008-06-01
Annex ZA has been added by CENELEC.
__________
Endorsement notice

The text of the International Standard IEC 61788-9:2005 was approved by CENELEC as a European

Standard without any modification.
__________
---------------------- Page: 3 ----------------------
- 3 - EN 61788-9:2005
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

The following referenced documents are indispensable for the application of this document. For dated

references, only the edition cited applies. For undated references, the latest edition of the referenced

document (including any amendments) applies.

NOTE Where an international publication has been modified by common modifications, indicated by (mod), the relevant

EN/HD applies.
Publication Year Title EN/HD Year
IEC 60050-815 2000 International Electrotechnical Vocabulary - -
(IEV)
Chapter 815: Superconductivity
---------------------- Page: 4 ----------------------
NORME CEI
INTERNATIONALE IEC
61788-9
INTERNATIONAL
Première édition
STANDARD
First edition
2005-04
Supraconductivité –
Partie 9:
Mesures pour supraconducteurs
haute température massifs –
Densité de flux résiduel des oxydes
supraconducteurs à gros grains
Superconductivity –
Part 9:
Measurements for bulk high temperature
superconductors –
Trapped flux density of large grain
oxide superconductors
© IEC 2005 Droits de reproduction réservés ⎯ Copyright - all rights reserved

Aucune partie de cette publication ne peut être reproduite ni No part of this publication may be reproduced or utilized in any

utilisée sous quelque forme que ce soit et par aucun procédé, form or by any means, electronic or mechanical, including

électronique ou mécanique, y compris la photocopie et les photocopying and microfilm, without permission in writing from

microfilms, sans l'accord écrit de l'éditeur. the publisher.

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Pour prix, voir catalogue en vigueur
For price, see current catalogue
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61788-9 ¤ IEC:2005 – 3 –
CONTENTS

FOREWORD...........................................................................................................................5

INTRODUCTION.....................................................................................................................9

1 Scope.............................................................................................................................11

2 Normative references .....................................................................................................11

3 Terms and definitions .....................................................................................................11

4 Principle .........................................................................................................................11

5 Requirements .................................................................................................................15

6 Apparatus.......................................................................................................................17

7 Measurement procedure.................................................................................................19

8 Precision and accuracy of the test method......................................................................19

9 Test report......................................................................................................................21

Annex A (informative) Additional information related to Clauses 3 to 6.................................23

Annex B (informative) Measurements for levitation force of bulk high temperature

superconductors ...................................................................................................................29

Annex C (informative) Test report (example)........................................................................35

Bibliography..........................................................................................................................39

Figure 1 – Principle of trapped flux density in bulk superconductor .......................................13

Figure 2 – Schematic view of the experimental set-up..........................................................15

Figure A.1 – Thickness dependence of the trapped flux density (B ).....................................23

Figure A.2 – Gap dependence of the field strength ...............................................................27

Figure C.1 – Distribution map of trapped flux density ............................................................37

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61788-9 ¤ IEC:2005 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
__________
SUPERCONDUCTIVITY –
Part 9: Measurements for bulk high temperature superconductors –
Trapped flux density of large grain oxide superconductors
FOREWORD

1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising

all national electrotechnical committees (IEC National Committees). The object of IEC is to promote

international co-operation on all questions concerning standardization in the electrical and electronic fields. To

this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,

Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC

Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested

in the subject dealt with may participate in this preparatory work. International, governmental and non-

governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely

with the International Organization for Standardization (ISO) in accordance with conditions determined by

agreement between the two organizations.

2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international

consensus of opinion on the relevant subjects since each technical committee has representation from all

interested IEC National Committees.

3) IEC Publications have the form of recommendations for international use and are accepted by IEC National

Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC

Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any

misinterpretation by any end user.

4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications

transparently to the maximum extent possible in their national and regional publications. Any divergence

between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in

the latter.

5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any

equipment declared to be in conformity with an IEC Publication.

6) All users should ensure that they have the latest edition of this publication.

7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and

members of its technical committees and IEC National Committees for any personal injury, property damage or

other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and

expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC

Publications.

8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is

indispensable for the correct application of this publication.

9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of

patent rights. IEC shall not be held responsible for identifying any or all such patent rights.

International Standard IEC 61788-9 has been prepared by IEC technical committee 90:

Superconductivity.
The text of this standard is based on the following documents:
FDIS Report on voting
90/167/FDIS 90/175/RVD

Full information on the voting for the approval of this standard can be found in the report on

voting indicated in the above table.

This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

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61788-9 ¤ IEC:2005 – 7 –

IEC 61788 consists of the following parts, under the general title Superconductivity:

Part 1: Critical current measurement – DC critical current of Cu/Nb-Ti composite super-

conductors

Part 2: Critical current measurement – DC critical current of Nb Sn composite super-

conductors

Part 3: Critical current measurement – DC critical current of Ag-sheathed Bi-2212 and

Bi-2223 oxide superconductors

Part 4: Residual resistance ratio measurement – Residual resistance ratio of Nb-Ti

composite superconductors

Part 5: Matrix to superconductor volume ratio measurement – Copper to superconductor

volume ratio of Cu/Nb-Ti composite superconductors

Part 6: Mechanical properties measurement – Room temperature tensile test of Cu/Nb-Ti

composite superconductors

Part 7: Electronic characteristic measurements – Surface resistance of superconductors at

microwave frequencies
Part 8: AC loss measurements – Total AC loss measurement of Cu/Nb-Ti composite
superconducting wires exposed to a transverse alternating magnetic field by a
pickup coil method

Part 9: Measurements for bulk high temperature superconductors – Trapped flux density of

large grain oxide superconductors

Part 10: Critical temperature measurement – Critical temperature of Nb-Ti, Nb Sn, and

Bi-system oxide composite superconductors by a resistance method

Part 11: Residual resistance ratio measurement – Residual resistance ratio of Nb Sn

composite superconductors

Part 12: Matrix to superconductor volume ratio measurement – Copper to non-copper

volume ratio of Nb Sn composite superconducting wires

Part 13: AC loss measurements – Magnetometer methods for hysteresis loss in Cu/Nb-Ti

multifilamentary composites

The committee has decided that the contents of this publication will remain unchanged until

the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in

the data related to the specific publication. At this date, the publication will be

• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
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61788-9 ¤ IEC:2005 – 9 –
INTRODUCTION

Large grain bulk high temperature superconductors (BHTSC) have significant potential for a

variety of engineering applications, such as magnetic bearings, flywheel energy storage

systems, load transports, levitation, and trapped flux density magnets. Large grain

superconductors have already been brought to market worldwide.

For industrial applications of bulk superconductors, there are two important material

properties. One is the magnetic levitation force, which determines the tolerable weight

supported by a bulk superconductor. The other is the trapped flux density, which determines

the maximum field that a bulk superconductor can generate. The users of bulk

superconductors must know these values for the design of their devices. However, these

values are strongly dependent on the testing method, and therefore it is critically important to

set up an international standard for the determination of these values both for manufacturers

and industrial users.

The test method covered in this standard is based on the VAMAS (Versailles Project on

Advanced Materials and Standards) pre-standardization work on the properties of bulk high

temperature superconductors.
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61788-9 ¤ IEC:2005 – 11 –
SUPERCONDUCTIVITY –
Part 9: Measurements for bulk high temperature superconductors –
Trapped flux density of large grain oxide superconductors
1 Scope

This part of IEC 61788 specifies a test method for the determination of the trapped field

(trapped flux density) of bulk high temperature superconductors.

This International Standard is applicable to large grain bulk oxide superconductors that have

well defined shapes such as round discs, rectangular, and hexagonal pellets. The trapped flux

density can be assessed at temperatures from 4,2 K to 90 K. For the purpose of

standardization, the trapped flux density will be reported for liquid nitrogen temperature.

2 Normative references

The following referenced documents are indispensable for the application of this document.

For dated references, only the edition cited applies. For undated references, the latest edition

of the referenced document (including any amendments) applies.

IEC 60050(815):2000, International Electrotechnical Vocabulary – Part 815: Superconductivity

3 Terms and definitions

For the purposes of this document, the terms and definitions given in IEC 60050(815) and the

following apply.
3.1
trapped flux density

strength of the magnetic flux density (T) trapped by a bulk high temperature superconductor

(BHTSC) at a defined gap and at a defined temperature
3.2
maximum trapped flux density
peak value of the trapped flux density

NOTE For most measurements, only the z component of the flux density is measured, which is strongly affected

by the sample geometry or the demagnetizing effect (see Clause A.2). Thus the total flux density, which is the

integration of all the field components, may also be regarded as the materials property to stand for the trapped flux

density (see Clause A.1).
4 Principle

Superconductors that exhibit flux pinning are capable of trapping magnetic fields, as shown in

Figure 1. Here the internal magnetic flux density rotation (’uB ) in the BHTSC is proportional

to the critical current density (J ), as expressed by the following equation:
’ uB P J
0 c
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61788-9 ¤ IEC:2005 – 13 –
In one dimension, the equation is reduced to
dB dx = µ J
z 0 c
in rectangular coordinates or to
dB dr = µ J
z 0 c
in cylindrical coordinates.

The maximum value of the trapped flux density in the z component (B , ) in an infinite

z max
cylinder (2 R in diameter) is given by the following equation:
B = µ J R
z,max 0 c

In practical samples, this value is reduced by the demagnetizing effect or the geometrical

effect as follows:
B =D(R /t) µ J R
z,max 0 c
where D(R/t) is a geometrical constant that depends on the shape (the ratio of
radius/thickness) of the BHTSC.
dB /dx = J
z c
IEC 557/05
Figure 1 – Principle of trapped flux density in bulk superconductor
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61788-9 ¤ IEC:2005 – 15 –

Figure 2 shows a schematic diagram of the experimental set-up for trapped flux density

measurements [1] . There are several ways to measure the trapped flux density of BHTSC.

A typical measurement procedure is as follows. Firstly, the field is applied on the

superconductor. Secondly, the sample is fixed on the cold head of a cryostat, which is cooled

to the target temperature by using a cooling device. After reaching the target temperature, the

external field is removed. The distribution of the field trapped by the BHTSC is then measured

by scanning a Hall sensor over the specimen surface at a defined gap. This is the so-called

field-cooled (FC) method of magnetization.
Hall sensor
Superconductor
Cryostat
Superconducting magnet
IEC 558/05
Figure 2 – Schematic view of the experimental set-up
5 Requirements

Upon removal of the external field, the trapped flux density will decay with time from its initial

value. This is due initially to flux flow and later to flux creep (collectively termed flux

relaxation). The initial peak value shall not be used for the design of machines.

The trapped flux density values are those measured after a sufficiently long time has passed

since the appropriate measurement conditions were reached. The trapped flux density values

shall be measured at least 15 min after the external field is removed from the specimen under

test.

The target precision of this method is that the coefficient of variation in any inter-comparison

test shall be 5 % or less for measurements performed within 1 month of each other [2].

It is the responsibility of the user of this standard to consult and establish appropriate safety

and health practices and to determine the applicability of regulatory limitations prior to use.

Specific precautionary statements are given below.
———————
Figures in square brackets refer to the bibliography.
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61788-9 ¤ IEC:2005 – 17 –

Hazards exist in this type of measurement. Very large direct currents with very low voltages

do not necessarily provide a direct personal hazard, but strong magnetic fields trapped by the

BHTSC may cause the problem. It is imperative to shield magnetic fields. Also the energy

stored in the superconducting magnets commonly used for generating the magnetic field can

cause large current and/or voltage pulses, or deposit a large amount of thermal energy in the

cryogenic systems causing rapid boil-off or even explosive conditions. Direct contact of skin

with cold liquid transfer lines, storage dewars or apparatus components can cause immediate

freezing, as can direct contact with a spilled cryogen. It is imperative that safety precautions

for handling cryogenic liquids be observed.
6 Apparatus
6.1 Cryostat
The
...

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