ybco 次世代超電導線材の mo 磁束観察法による特性評価

Superconductivity Research Laboratory (SRL) - ISTEC

低温工学協会　九州・西日本支部研究会 2006 July 20-22 YBCO線材のMO法による評価

YBCO次世代超電導線材のMO磁束観察法による特性評価

町　敬人超電導工学研究所

本研究は，超電導応用基盤技術研究体の研究として，新エネルギー産業技術総合開発機構の委託により実施したものである。

Outline

MO（磁気光学）磁束観察の原理と特徴

reel to reel MOI (RTR-MOI)装置の開発

機器応用のための YBCO線材の評価

YBCO線材の素線評価

MOI : magneto-optical imaging


YBCO線材のMO法による評価低温工学協会　九州・西日本支部研究会 2006 July 20-22

World map of magneto-optical imaging (MOI-map)

ISSP (Russia)

SRL(Japan)



MO効果の種類Various MO effects

These effects are close to our life....

Faraday effectMagnetic Kerr effectCotton-Mouton effectMagnetic circular dichroism

Magneto-optical recordingOptical fiber networksHigh voltage electric power lines

Cotton-Mouton effect

Kerr effect

Faraday effect

€

θF = Vl H

Faraday rotation angle for diamagnetism samples (ex. glass)

V : Verde constantℓ : thickness of specimenH : magnetic field

MOについて



Principle of MOI

Superconductor

Magnetic fluxMO indicator film

Brightness is proportional to the magnetic flux density.

External field

SuperconductorFlux

Differentpolarized angle

Mirror

MO film

magnetization

Detecting the canted component of the in-plane magnetization

Faraday effect is used for magneto-optical imaging.

Faraday angle

Polarized light Rotation ofpolarized angle

Magnet θ2θ

(linearly)

two times of θF

(←Faraday effect)

Irreciprocity

MOについて



MOI can visualize the distribution of magnetic flux !

Real time mapping of weak region (=defects)（ J = rot H）Distribution of current density

a wide area at a timeeven if existence of stabilization Ag layerrelatively easilytwo dimensional image

Real-time

Non-destructive

General properties of MO imaging (using MO films with in-plane anisotropy)

Response time 〜 psec Spatial resolution 〜 0.5µm Flux sensitivity 〜 0.2 Gauss (Bi-YIG film)

MO観察の長所

[

MOについて



Classification of HTS studiesFundamental study Application study

Origin of HTS

Symmetry of Cooper pair

Co-existence of AF fluctuation

Vortex physics

Devices applications

Bulk applications

Tape and wire applications

Searching for new materials

High speed response

Pinning properties

LevitationHigh speed communication

Low heat conductionPower applications

Magnet applicationsetc....

MOI can contribute to both studies !

MOについて



YBCO(LPE) bicrystals

artificial grain boundary

Machi et al., Advances in Superconductivity Vol.12 (2000).

Bz

( x )

=

Bf

ln

x W

2

−

a

2

+

W x

2

−

a

2

a x

2

−

W

2

( x > a )

Bf

=

4

c

d • Jc

IG

Brandt et al.

Intragrain JcIG

JcIG=1.37 x 107 [A/cm2]

0.5

0.4

0.3

0.2

0.1

0.0 806040200Temperature (K)

200G 400G 600G 800G

( Conduction via grain )Intergrain Jc

GB

MOについて

2W

B

z

plot line

X Y

1000

800

600

400

200

0

1.51.00.50.0

Distance [mm]

550G

500G

450G

400G

350G

300G

250G

200G

150G

100G

50G

30G

Intra-grain

7K

H // c

X Y

fitting line

2a



MOI study in SRL

Single crystals Thin films

Wires and tapes

Bulk materials Devices

Various targets of MOI

Coated conductors

MOについて



線材作製技術

超電導ケーブル

機器要素技術

超電導変圧器

超電導モーター

超電導限流器

機器共通基盤要素技術

線材評価応力印加前後のMO観察

フィードバック

過電流印加前後のMO観察

スクライビングの評価→耐過電流要素技術

→導体化要素技術

→低交流損失化要素技術接続試料の評価→接続要素技術

機器応用のための評価

素線評価

MO評価が次世代線材研究に果たす役割



What is the coated conductors ?

Metallic substrate

Stabillizing layer (Ag)

Structure of coated conductors

Buffer layers

HTS(123) layer Metallic substrateAligned metals (Ni, Ni-W, etc)Non-aligned metals (Hastelloy)

RABiTS : rolling assisted biaxially textured substrate

Buffer layersGd2Zr2O7, MgO, Y2O3, CeO2, etc...

HTS layersPulsed laser deposition (PLD) methodMetal organic deposition (MOD) methodMolecular chemical vapor deposition (MOCVD) methodElectron beam (EB) deposition method

There are many choise to obtain the coated conductors.

The property is not same within each coated conductors.

The shape of coated conductors is suitable to observe MO images.



IBAD/PLD : TFA-MOD :

Hastelloy/IBAD(GZO)/PLD(CeO2)/PLD(YBCO)

Hastelloy/IBAD(GZO) /PLD(CeO2)/TFA-MOD(YBCO)

ExperimentalSample for MOI

GZO=Gd2Zr2O7, YBCO=YBa2Cu3O7-d TFA-MOD=metal organic deposition using trifluoroacetates

MOI experiments

Short specimensOrdinary flow type MOI equipment

Long tape samples (> 5cm)Reel to reel MOI equipment

MO indicator film

~ 50 mm

SRL fabricates two types of coated conductors



長尺MOI装置の開発 RTR(reel to reel)-MOI for long tapes

(1) MO film removes from tape(2) Displacement of tape(3) Contacting MO film(4) Wait a stable of temperature(5) Applying field(6) MO Observation(7) Repeat to (1)

Controller

Reel and cryocoolerWhole view

Macro microscope

Procedure of RTR-MOI

MO装置開発

ybco 次世代超電導線材の mo 磁束観察法による特性評価

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