George Crabtree Ulrich Welp Karen Kihlstrom Alexei Koshelev Andreas Glatz Ivan Sadovskyy WaiKwong Kwok Argonne National Laboratory University of Illinois at Chicago ID: 830110
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Slide1
Critical Current
by Design
George Crabtree, Ulrich
Welp, Karen Kihlstrom, Alexei Koshelev, Andreas Glatz, Ivan Sadovskyy, Wai-Kwong KwokArgonne National LaboratoryUniversity of Illinois at ChicagoNorthern Illinois University
Outline
Superconducting Culture
Materials and Applications
Critical Current < 20% Theoretical
Time Dependent
Ginzburg
-Landau
Critical Current by Design
Slide2Further Reading
PHYSICAL REVIEW APPLIED 5, 014011 (2016)Simulation of the Vortex Dynamics in a Real Pinning Landscape of YBa2Cu3O7−δ Coated ConductorsI. A. Sadovskyy,
A. E. Koshelev
, A. Glatz, V.
Ortalan, M.W. Rupich, and M. Leroux
Slide3Origins in 1911
The Discovery of Superconductivity
Dirk van Delft and Peter Kes,
Physics Today 63(8), 38 (2010)
http://ptonline.aip.org/dbt/dbt.jsp?KEY=PHTOAD&Volume=63&Issue=9&usertype=indiv
Hg
Slide42003
Abrikosov Ginzburg Leggett
1913
1987
1972
Bardeen Cooper Schreiffer
Onnes
Giaver Josephson
1973
Müller Bednorz
Five Nobel Prizes
Discovery
Micrsoscopic
Theory
Superconducting Tunneling
High Temperature Superconductivity 35K - 200K
Vortex Matter
H
Circulating superconducting electrons
Normal core
Increasing Temperature
Increasing Disorder
Liquid
Glass
Lattice
Helium-3
Slide5I
H
I
moving vortices
R
>
0
pinned vortices
R
=
0
pinning defects:
nanodots
, disorder,
2
nd
phases, dislocations
intergrowths
. . .
How Do Superconductors Carry Current Without Resistance?
v
v
v
v
v
V.
Braccini
et al.,
Supercond
. Sci.
Technol
24
, 035001 (2011)
Simple pinning landscape
Large and small point defects
Complex pinning landscape
Points, lines, planes, second phases
Faraday’s Law
E
~
ev
x B
Lorentz force
F
L
~
I x H
Slide66
Typical operational parameters in various superconductor applicationsV. Selvamanickam, HTS4Fusion Workshop, May 26-27, 2011, Karlsruhe, Germany
What Kind of Superconducting Applications?
Slide77
What Kind of Superconducting Wires are Available?Irrad. crystalCoated cond.Films/BZOITER type
W. K. Kwok et al (2016)
NbTi 1960s
Nb3Sn1970sBaFe2(AsP)22010s
BaFe
2
As
2
:Co
2010s
(
BaK
)Fe
2
As
2
2010s
High Temperature Superconductors
Slide8How Good are Superconducting Wires?
The best superconducting wires achieve < 20% of the theoretical critical currentCost is the greatest barrier to widespread deploymentDoubling critical current halves the costPlenty of room for improvementAfter 60 years of vortices, why haven’t we solved this problem?
Conventional
Gearbox
5
MW
~
410 tons
Conventional
Gearless
6
MW
~
500 tons
HTS Gearless
8
MW
~ 480 tons
Transmission and Distribution
Cables
Offshore Wind Turbines
High Field Superconducting Magnets
Slide9The Challenge: Complex Collective Interactions in Vortex Arrays
Long range vortex repulsionLong range attraction to pinning defectsElastic vortex bendingThermal fluctuationsVortex cutting and reconnectionInteraction with currentT and H dependence of above
v
v
v
v
v
One vortex
t
reatable
Two vortices
t
reatable
Many vortices and pin sites
c
hallenging
v
v
v
v
v
Many vortices, pin sites, transport current and dynamics
p
ractically impossible
I
Conventional treatment
Simulate each vortex line and its interactions with each pin site
Long range repulsion and collective response requires thousands of vortices
Reminiscent of H atom
vs
solid and liquid collections of atoms
Slide10Time Dependent Ginzburg
-Landau Simulations Vortex repulsion, vortex-pin interactions, vortex elasticity,vortex cutting and reconnection, T,H dependence included automatically
e
> 0
Phenomenological, not mechanistic
Describes all superconductors in terms of
c
oherence length
ξ
and penetration depth
λ
Continuum theory, solve on a grid
S
olve for a single order parameter
ψ
whose zeros define the vortex positions
Static version enormously useful, dynamic version just coming into its own
Static
Ginzburg
-Landau: 1950
Time dependent GL:
Schmid
1966
I.
Sadovskyy
et al., J. Comput. Phys. 294, 639 (2015)
Albert SchmidPin sites: core pinning
Slide11v
v
v
v
v
Many vortices, pin sites, transport current and dynamics
TDGL Allows Treating Dynamics of Large Vortex Arrays
Vortex interactions included automatically
Multiple kinds of pinning defects: points, lines, planes, inclusions
“Mixed pinning landscape”
Spans
• macroscopic behavior such as current and resistivity
•
nanoscopic
behavior such as individual vortex
Requires large computational resources
Highly parallelized, highly efficient, graphical processing units (GPUs)
~ 1995 - 2012
Early treatment of tens-hundreds of vortices
Limited by computational resources
Illustrative rather than definitive
2012 - present
Large scale treatment of thousands of vortices
Adequate computational resources
Nanoscopic
origins of macroscopic behavior
Slide12TDGL: Single Vortex
Depinning from a Single Large Spherical Pin SiteVortex bends significantly as it moves to the edge of the sphereHighly symmetric configuration at all timesLong range attraction to pin site from disruption of vortex circulating supercurrentsTDGL allows mapping contributions to pinning energy: condensation energy in core, elastic bending, disruption of circulating supercurrents as function of time
Time
Slide13Mixed Pinning Landscapes: Non-additive Pinning
Dense columnar defects formed by BaZrO3 nanorods along c-axis during synthesisSevamanackam et al Supercond Sci Tech 28, 104003 (2015)Angular dependence of critical current due to columnar defects along c-axis (0°)Angle (°)
BaZrO
3
nanorods
0°
Add columnar defects at 45° by irradiation with 1.4
GeV
Pb
ions
Add 1.4
GeV
Pb
ions
Angle (°)
BaZrO
3
nanorods
(0°)
+
Columnar defects (45°)
Non-additive pinning: peak due to
nanorods
at 0° disappears in presence of columnar defects at 45°
TDGL reproduces non-additive pinning and shows why it occurs:
Vortices slide from one
nanorod
to the next along columnar defects.
Macroscopic behavior and its underlying
nanoscopic
origin
Sadovskyy
et al,
Adv
Mater 28, 4593 (2016)
Slide14Simulating Complex Vortex and Pin Site Arrays
3D tomographic mapping of 71 nearly spherical nanoparticles ranging from 12.2 -100 nm diameter in (YDy)BaCuOOrtalan et a,l Physica C 469, 2052 (2009)TDGL simulation of same 71 nanopartcles in nearly same volumeSadovskyy et al, Phys Rev Applied 5, 014011 (2016)
B/H
c2
ExperimentSimulation
Sadovskyy
et al
Phys
Rev Applied 5, 014011 (2016)
Slide15The Opportunity
Large scale complex 3D vortex-pin site simulations have arrived Vortex repulsion, pin site attraction, elastic flexibility, thermal fluctuations, cutting and reconnecting, interaction with current, H and T dependence includedTDGL is a “vortex genome” Bridges nano to macro Pining landscapes critical currents, magnitude and anisotropy Forward design of pinning landscapes for targeted critical currentsAsk fundamental questions Why is practical critical current limited to 20% of the theoretical limit?
What makes pin site - pin site interactions destructive or constructive? What guiding principles control collective vortex behavior?
The Era of Critical Current by Design is Upon Us
Slide16Supplemental Slides
Slide17An Abundance of Superconductors
Burning QuestionsMechanismAttractive Interaction among electronsConventional:Electron-phononBCS Nobel 1972High Tc’s:Magnetic?Another Nobel waiting?Critical current Jc
How high can it be?How to increase it?
Applications
Slide18Breakthrough: Doubling the Critical Current of Commercial Superconductors
Ag-cap (
1 µm)
Superconducting YBCO (
1-2 µm)Commercial HTS wire
M.
Leroux
et al.,
Appl
. Phys. Lett.
107
, 192601 (2015
)
US patent application #14/215,947
3.5 MeV O
1 second
pristine
YBCO layer
Buffer layer
Substrate
Silver
Copper
irradiated
Highly optimized for ~ 20 years
Simple irradiation has large effect (!)
Significant gains in critical
current are
possible
Irradiation with
3.5 MeV Oxygen for 1 Second