HTS R&D at North Carolina State UniversityEuroCard 2 Videoconference

Justin Schwartz, Frank Hunte, Xiaotao Liu, Wan Kan Chan, Amir Kajbafvala, Quang Le, Golsa Naderi, Makita

Phillips, Melanie Turenne, Liyang Ye, Yun Zhang

July 26, 2011

Overview of Research Activities

• Bi2212 processing (XL, GN, YZ)– SMP & Sawtooth processing (w/Supercon)– Fiber-optic heat treatment monitoring (w/Muons Inc.)

• Quench Experimentation (FH, LY, MT)– Bi2212 (VHFSMC) & MgB2 (w/GE)– Fiber-optic quench detection (w/Muons Inc.)

• Quench Modeling (WKC, QL, MP)– Experimentally validated YBCO micro & coil models– Peridynamic modeling of Bi2212 failure

• Ancillary Materials (XL, AK)– High strength Ag-Al sheaths for Bi2212 (w/Supercon)– Thermally conducting electrical insulators for improved quench

protection (w/nGimat)

High field quenching of Bi2212 coils

• “Understanding the quench process in RW2212 conductors and test coils so as to provide reliable protection strategies for large magnets”

• Does high magnetic field make quench propagation faster and thus quench detection easier?– What dominates, reduced Tc or reduced Ic, (It/Ic=constant)?

• Small size multilayer coils were wind-and-reacted with OST Bi2212 strands, and both 2-D and 3-D quench propagations were studied at 4.2K and up to 20T.

3

More stability, due to lower It

Less stability, due to lower Tcs

• Higher Field Tcs and MQE decrease, reduced stability (though still very stable, MQE over hundreds mJ).

• NZPV decreases with field in lower field range (<5 T). But at higher field (>8 T), the balanced effects of reduced Ic and Tc result in relatively

constant NZPV.

Bi2212 quench results

40 5 10 15 20

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

NZP

V-Y

&Z(

turn

/s)

B(T)

2-D Coil, It/Ic=60%,Y

2-D Coil, It/Ic=80%, Y

3-D Coil, It/Ic=40%, Z

3-D Coil, It/Ic=60%, Y

3-D Coil, It/Ic=40%, Y

3-D Coil, It/Ic=60%, Z

Y: turn-to-turnZ: layer-to-layer

Quench propagation along transverse directions

0 5 10 15 202

3

4

5

6

7

8

9

NZP

V-X

(cm

/s)

B(T)

3-D Coil, It/Ic=40%2-D Coil, It/Ic=80%

3-D Coil, It/Ic=60%

2-D Coil, It/Ic=60%

Quench propagation along longitudinal direction

0 5 10 15 200

1

2

3

4

5

6

MQ

E(J

)

B(T)

2-D Coil, It/Ic=80%

2-D Coil, It/Ic=60%

3-D Coil, It/Ic=60%

3-D Coil, It/Ic=40%MQE

Fiber optic quench detection• Investigation of Rayleigh

backscattering and fiber Bragg gratings for quench detection– Rayleigh offers a fully distributed

sensor w/ impressive spatial resolution– FBGs are quasi-distributed sensors

with a fast sampling rate (>5 kHz)• Addressing limitations of optical

fibers in cryogenic environments– HTS compatible metallic and/or oxide

based coatings– Integration into a magnet system

5

6

• Start with microscopic CC tape models – center piece for coil models and optimization• Focus on coil models – followed by detection and protection simulations• Aided by experiments – model validations and property characterizations• Finish with cluster-enabled, full-scale 3D HTS quench analysis tool

Quench modeling of YBCO

Experimental Validation

Expt: X. Wang et al., J. Applied Physics 20077

05

10152025303540

45

0.3 0.5 0.7 0.9J a/J co

NZPV

(mm/

s)

40 K

50 K

60 K70 K

77 K

Dashed: experimentSolid: modelModel details: W. K. Chan et al., IEEE

Transactions on Applied Superconductivity, 20(6) 2370-2380 (2010) Now being used to engineer conductors for quench behavior (paper under review)

0.0E+00

5.0E-04

1.0E-03

1.5E-03

2.0E-03

2.5E-03

3.0E-03

3.5E-03

4.0E-03

4.5E-03

5.0E-03

5.5E-03

0.85 1.85 2.85 3.85 4.85 5.85 6.85 7.85 8.85 9.85 10.85

Volat

age (

V)

time (s)

Volta

ge

(V)

Model Experiment

8

Embed conductor model into a hybrid 3D coil model (experimentally validated)

HTS needs a new insulation!• Chemical issues for Bi2212• Fill factor issues for both Bi2212 and YBCO• NCSU & nGimat jointly developing a thin oxide coating (doped TiO2)

that is thermally conducting and electrically insulating

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Coating on Bi2212 after heat treatment

1.0 1.5 2.00.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.10

Y(V

)

time(s)

V_Y4 V_Y3 V_Y2 V_Y1

New oxide

1.0 1.5 2.00.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.10

Y(V

)

time(s)

V_Y4 V_Y3 V_Y2 V_Y1

kapton

Recent & forthcoming publications

• H. Song, K. Gagnon, and J. Schwartz, “Quench behavior of conduction-cooled YBa 2Cu3O7−δ coated-conductor pancake coils stabilized with brass and copper,” Superconductor Science & Technology 23 065021 (10pp) (2010)

• A.L. Mbaruku, Q.V. Le, H. Song and J. Schwartz, “Weibull analysis of the electro-mechanical properties of AgMg sheathed Bi 2Sr2CaCu2O8+x round wires and YBa2Cu3O7-x coated conductors,” Superconductor Science and Technology 23 115014 (2010)

• W.K. Chan, P.J. Masson, C. Luongo and J. Schwartz, “Three-dimensional micrometer-scale modeling of quenching in high aspect ratio YBa 2Cu3O7-

d coated conductor tapes. Part I: Model development and validation,” IEEE Transactions on Applied Superconductivity 20(6) 2370-2380 (2010)• X. Wang, U.P. Trociewitz and J. Schwartz, “Critical current degradation of short YBa 2Cu3O7-s coated conductor due to an unprotected quench,”

Superconductor Science & Technology 24 035006 (2011)• D. Arbelaez, S.O. Prestemon, D.R. Dietderich, A. Godeke, L. Ye, F. Hunte and J. Schwartz, “Numerical investigation of the quench behavior of

Bi2Sr2CaCu2Ox wire,” IEEE Transactions on Applied Superconductivity 21(3) 2787-2790 (2011)• W. T. Nachtrab, X.T. Liu, T. Wong and J. Schwartz, “Effect of solidification conditions on partial melt processed Bi 2Sr2CaCu2Ox/Ag/AgX round wire,”

IEEE Transactions on Applied Superconductivity 21(3) 2795-2799 (2011) X.T. Liu, Q.V. Le and J. Schwartz, “Factors that influence current transport in multifilamentary, split-melt processed Bi2Sr2CaCu2Ox round wires,” Journal of Materials Research (submitted)

• W.K. Chan and J. Schwartz, “Three-dimensional micrometer-scale modeling of quenching in high aspect ratio YBa 2Cu3O7-d coated conductor tapes. Part II: Influence of geometrical and material properties and implications for conductor engineering and magnet design,” IEEE Transactions on Applied Superconductivity (submitted) A. Kajbfvala, W.T. Nachtrab, T. Wong and J. Schwartz, “Electromechanical behavior of Bi 2Sr2CaCu2O8+X

multifilamentary round wire with a high strength Ag/Al2O3 alloy sheath,” IEEE Transactions on Applied Superconductivity (to be submitted)• H. Song, F.L. Hunte and J. Schwartz, “Forensic analysis of degradation in quenched YBa 2Cu3O7-d coated conductor,” Advanced Materials (to be

submitted)• X.F. Gou and J. Schwartz, “Fractal analysis of the rough surfaces of individual filaments extracted from Bi 2Sr2CaCu2Ox/AgMg round wire and their

role in mechanical behavior,” Journal of Applied Physics (to be submitted)• L. Ye, F. Hunte and J. Schwartz, “Quench propagation in Bi2Sr2CaCu2Ox round wires and coils at 4.2 K, high magnetic field,” Superconductor

Science & Technology (to be submitted)• L. Ye, T. Effio, F. Hunte and J. Schwartz, “Quench induced degradation limits in Bi 2Sr2CaCu2Ox round wires and coils at 4.2 K,” Superconductor

Science & Technology (to be submitted)• M. Phillips, P. Masson, W.K. Chan and J. Schwartz, “Influence of turn-to-turn insulation on quench propagation in YBa 2Cu3O7-d-coated conductors,”

IEEE Transactions on Applied Superconductivity (to be submitted)

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