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Innovation with Integrity

Bruker Energy & Supercon Technologies (BEST) BRUKER HTS

RECENT DEVELOPMENTS OF COATED CONDUCTORS AT BRUKER

U. Betz, K. Schlenga, A. Usoskin, V. Selvamanickam

CCA 2016 Sep 13, Contribution ID: IO-15

This work was supported in part by the EC 7th Program, EUROTAPES project, Grant 280432 and EuCARD-2 project, CERN.

CCA 2016 #IO-15 BHTS All rights reserved PAGE 1


BRUKER HTS OUTLINE

(CUSTOMIZED INSULATION NOT SHOWN HERE)

Cu ENCAPSULATION

Ag CAP LAYER

YBCO LAYER

YSZ BUFFER LAYER

STAINLESS STEEL standard width 4 mm standard thickness 0.1 mm

Ø  Deposition routes implemented

Ø  Dynamic drum vs. reel-to-reel technology : comparison - tape travel speed/throughput - heat losses - reel diameter: physical limit

Ø  High-field tapes: up-scaling of length

Ø  12 mm wide tapes for CERN


Innovation with Integrity 3

BRUKER HTS BHTS at the new site

Ø  Successful relocation of the operation BHTS in Q3 2015

Ø  Since August 2015: BHTS at the new site in the Röntgenstr. 9 in Alzenau

Ø  More than 2000sqm operation area available

Ø  Excellent infrastructure and media supply for vacuum coating fab lines

BRUKER HTS GmbH Industriepark Nord

Röntgenstr. 9 63755 Alzenau

Germany



Manufacturing Chain



BRUKER HTS Buffer layer coating (ABAD)

•  Alternating Ion Beam Assisted Deposition ABAD

•  ABAD vacuum coating equipment designed for long length production of coated conductors

•  Both, drum batch processing and reel-to-reel processing equipment available

•  Coating materials Y2O3, Al2O3, MgO and YSZ



BRUKER HTS YBCO layer coating (PLD)

•  Pulsed Laser Deposition PLD vacuum coating equipment

•  Drum batch processing concept

•  Quasi-Equilibrium heating concept

•  Industrial excimer laser providing stabilized UV power @ 308nm



Multi plume HR-PLD (MB PLD)

•  Efficiency of material transfer is above 70%

•  Pulse energy of 600 mJ is sufficient for 8 beams; thus further increase of throughput is possible



BRUKER HTS BHTS’s core competence

Ø  Manufacturing of coated conductors (HTS 2G) tailored for it’s application in high magnetic fields

Ø  Structural design of the YBCO superconducting thin films on a nano-scale by pulsed laser deposition PLD

EXTRINSIC second phase nano-structures

in the YBCO film

INTRINSIC stoichio-metric deviations in the YBCO film



Deposition route: Introduction of nano-periodic disorder/precipitation during PLD:

Quasi-equilibrium heater 1, 2, 5, 6 with

a substrate tape 3 helically wound on the cylindrical drum 4.

1

2

3

4

5

6

7

8

TABLE I AVERAGE PERIOD BETWEEN MAXIMA OF O2 PRESSURE PULSE

Parameter Model Experiment

thickness period 18.8 nm 14.5 nm

effective repetition rate of laser pulses

230 pulses/s 225 pulses/s

number of deposition pulses 18,800 17,900 time period 82 s 84 s

.

pressure triggered stoichiometry deviations (=“intrinsic” disorder/precipitations)

Tape translation: both a drum and reel-to reel routes are considered



Drum vs. RtR: limiting factors

a) throughput/travel speed of the tape

•  In Reel-to-Reel (RtR) and drum cases: tape should travel with about 1 m/s speed. Slower motion leads to increase of local repetition rate of deposition pulsed which results in Ic deterioration

•  In drum case, this travel is achieved via fast drum rotation

•  In RtR case, the tape is permanently traveling between reels. Pre-heating of tape is needed therefore. Length of tape to be pre-heated is shown in figure for different heating temperatures and single/double side heating.

Length of tape to be pre-heated vs. temperature of IR heater in RtR route Addition heating power is estimated to 1.5 kW




b) drum concept (cont.)

•  In drum case, tape quick travel is achieved via fast drum rotation

•  Drum versus RtR translation:

•  Limiting factor: tape throughput is limited by heat capacity of the drum

•  “Dynamic” drum with reduced heat capacity and advanced mechanical stability is developed and employed in deposition of 600m long tapes.

•  Dynamic drum enables tape throughput of > 60 m/hour

(a) (b)

Kinetics of tape + drum heating (a) and substrate temperature variation during PLD process (b) where drum rotates within a tubular IR heater with deposition window

980 1090 12001050

1055

1060

tim e, m s x 10

subs

trate

tem

pera

ture

, K

Time, s 0 1.1 1.2

1.060

1.050 200 0 100 200 300200

400

600

800

1000

1200

time, s

tem

pera

ture

, K

Ti 1....c ρ t

..ε σo 10 4

1 Th100

4 Ti100

4

dτ Ti

Time, s 0 100 300

1.2

1.0

Sub

stra

te te

mpe

ratu

re, a

.u.

0.8

0.6

0.4

0.2

Sub

stra

te te

mpe

ratu

re, a

.u.

1.055

200




c) reel diameter is limited by cumulative normal pressure coming from tape windings

•  Damage threshold by winding on reel with 300mm core diameter is estimated to 1000 m length

Ft

Fn

(=T)

Tape length, m

Nor

mal

pre

ssur

e, M

Pa

(a)

(b)



Drum vs. RtR: summary

Drum Reel-to-Reel

•  Tape translation drum rotation multiple tape instead of travel needed multiple travel (typically >20 cycles)

•  Tape throughput > 60 m/hour >60 m/hour with “dynamic” drum

•  Tape length > 600 m 1000 m with “dynamic” drum limited by 1000m to be validated cumulative pressure

•  Additional heating power no 50%, additional

impurity source

•  Both concepts undergo further feasibility and applicability analyses



Up-scaling to piece length above 600 m:

223 m and 610 m long tape after deposition of HTS layer



BRUKER HTS

For the standard configuration:

•  L > 500m single piece length •  Ic > 1500A/cm at 4.2K 5T Bllc •  Ic std. dev. of +/-2.5% at 77K •  σc: 650MPA critical tensile stress

•  Long length 2G HTS single wires with high in-field Ic performances at 4.2K

YBCO thin films coating by pulsed laser deposition PLD



Ic per cm-width versus piece length (at 4.2 K,18T, B//c)

•  Highest critical currents correspond to 1250 A/cm-width in 22 m batch. HTS film thickness is always between 1.5 and 1.7 µm in tapes longer than 100m. In 22 m long tape the HTS thickness is ~2 µm.

In 2016, HTS tapes were upgraded to 600m WITHOUT REDUCTION of Ic

2015 2016



Comparison Ic(4K; B) in 4mm tapes : FSU + BHTS updated

B, T

1-905N3 1-905N4

309 A at 31 T



Ic homogeneity: TapeStar

Major recent achievements: the transfer of high Ic in-field performances on long single piece tape lengths

Example

Ø  4 mm wide and 550 m long HTS tape with I @ 4.2 K/5 T well above 700 A measured on samples from both tape ends

Ø  Enhanced Ic uniformity measured with Hall-probe measurements at 77 K (Tapestar)

0 50 100 150 200 250 300 350 400 450 500 550 600 Tape length, m

0

20

40

80

60

Crit

ical

cur

rent

at 7

7K,

A 100



Ic homogeneity: FFT analysis

580 m long tape, interval analyzed: from 175 to 221 m

Expanded low frequency range



12mm wide tapes for EUCARD2 CERN

BHTS manufactured several 12mm wide tapes for EUCARD2, CERN

The high field performance (18T) was confirmed: - minimum Je of 400 A/mm2 @ 4.2K/18T is required for the C12 tapes, - most tapes are far above this spec (in spite of thick substrate tape)

Ic=1086 A/cm-w



Highlight Summary

•  “Dynamic” drum and reel-to-reel concepts are compared and analyzed. Advantages of both systems will be used in further development. Presently PLD machines are based on “dynamic” drum.

•  Based on ABAD and PLD with double disordered HTS layers Bruker confirmed reproducibility of very high critical currents in high field and 4.2 K

•  Technology was scaled up from 200m to 600m tape length with no considerable change of critical current. Accessible range of critical currents: 600-800 A/cm-width at 18 T, Bǁ‖c, 4.2 K.

•  Processing of 12 mm wide tapes with high Ic and Je is in pilot production status. Most number of tapes yields Ic > 900 A/cm-width at 18 T, 4.2 K, Bǁc



www.bruker-HTS.com

Bruker Confidential

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