Critical Current by Design - PowerPoint Presentation

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

Further 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

Origins 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

2003

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

I

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

6

Typical operational parameters in various superconductor applicationsV. Selvamanickam, HTS4Fusion Workshop, May 26-27, 2011, Karlsruhe, Germany

What Kind of Superconducting Applications?

7

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

How 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

The 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

Time 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

v

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

TDGL: 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

Mixed 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)

Simulating 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)

The 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

Supplemental Slides

An 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

Breakthrough: 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