Superconductivity Research Laboratory (SRL) - ISTEC
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
World map of magneto-optical imaging (MOI-map)
ISSP (Russia)
SRL
(Japan)
Superconductivity Research Laboratory (SRL) - ISTEC
MO 効果の種類
Various MO effects
These effects are close to our life....
Faraday effect
Magnetic Kerr effect Cotton-Mouton effect
Magnetic circular dichroism
Magneto-optical recording
Optical fiber networks
High voltage electric power lines
Cotton-Mouton effect
Kerr effect
Faraday effect
€
θ
F= Vl H
Faraday rotation angle for
diamagnetism samples (ex. glass)
V : Verde constant
ℓ : thickness of specimen H : magnetic field
て て
Principle of MOI
Superconductor
Magnetic flux MO indicator film
Brightness is proportional to the magnetic flux density.
External field
Superconductor Flux
Different
polarized 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 of polarized angle
Magnet
θ2θ
(linearly)
two times of θF
(←Faraday effect)
Irreciprocity
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Superconductivity Research Laboratory (SRL) - ISTEC
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 time
even if existence of stabilization Ag layer relatively easily
two 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
[
て て
Classification of HTS studies
Fundamental 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
Levitation
High speed communication
Low heat conduction
Power applications Magnet applications etc....
MOI can contribute to both studies !
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Superconductivity Research Laboratory (SRL) - ISTEC
YBCO(LPE) bicrystals
artificial grain boundary
Machi et al., Advances in Superconductivity Vol.12 (2000).
B z
( x )
= B
f ln
x W
2
− a
2 +
W x
2
− a
2
a x
2
− W
2
( x > a )
B f
= 4
c
d • J
c IG
Brandt et al.
Intragrain J
cIGJ
cIG=1.37 x 10
7[A/cm
2]
0.5 0.4 0.3 0.2 0.1
0.00 20 40 60 80 Temperature (K)
200G 400G 600G 800G
( Conduction via grain )
Intergrain J
cGBて て
2W
B z
plot line
X Y
1000
800
600
400
200
0
1.5 1.0
0.5 0.0
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
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Superconductivity Research Laboratory (SRL) - ISTEC
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 機器応用の ための評価 素線評価 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 substrate
Aligned metals (Ni, Ni-W, etc) Non-aligned metals (Hastelloy)
RABiTS : rolling assisted biaxially textured substrate
Buffer layers
Gd2Zr2O7, MgO, Y2O3, CeO2, etc...
HTS layers
Pulsed laser deposition (PLD) method Metal organic deposition (MOD) method
Molecular chemical vapor deposition (MOCVD) method
Electron 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.
Superconductivity Research Laboratory (SRL) - ISTEC
IBAD/PLD : TFA-MOD :
Hastelloy/IBAD(GZO)/PLD(CeO
2)/PLD(YBCO)
Hastelloy/IBAD(GZO) /PLD(CeO
2)/TFA-MOD(YBCO)
Experimental Sample for MOI
GZO=Gd2Zr2O7, YBCO=YBa2Cu3O7-d
TFA-MOD=metal organic deposition using trifluoroacetates
MOI experiments Short specimens
Ordinary 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 cryocooler Whole view
Macro
microscope Procedure of RTR-MOI
MO
装置 開発
MO装置
開発