Medium and High Field HTS Magnet R&D at BNLSuperconducting Magnet Division LTHFSW13 Ramesh Gupta Medium and High Field HTS Magnet R&D at BNL November 5, 2013 Slide No. 3 Active HTS

Superconducting Magnet Division

Ramesh Gupta Medium and High Field HTS Magnet R&D at BNL November 5, 2013 Slide No. 1 LTHFSW13

Medium and High Field

HTS Magnet R&D at BNL

Ramesh Gupta

BNL



Overview

• Variety of HTS Magnet Programs at BNL

• Focus of this Presentation

– Medium Field HTS Quad for FRIB

• Significant test results

– High Field (>30 T) HTS Solenoid for MAP

• Continuation of PBL/BNL program under MAP funding

• Feedback to Conductor Manufacturer

• Summary



Active HTS Magnet Programs at BNL (1)

• HTS Solenoid for Energy Recovery Linac (ERL)

– To be inducted in a significant R&D facility at BNL shortly

• HTS Magnet for Synchrotron Radiation Source

– To be delivered to an experimental program at BNL shortly

• MgB2 Phase II SBIR (DOE/NP) with HyperTech

– Technology development to upgrade e-lens for RHIC at BNL

(high power required by copper solenoids not available locally)




• HTS Quad for FRIB at MSU (funded by DOE/NP)

– A major HTS program at BNL from last decade

• HTS Dipole Phase II SBIR (DOE/NP) with Muons, Inc.

– Longer length (>2m) radiation tolerant curved dipole for FRIB

• Development of Quench Protection Technology

– Partly supported by BNL internal program development funds

and partly by individual project funds to fulfill their specific

requirements (MAP, FRIB, ARPA-E and SBIR’s)




• High Field (>30 T) Solenoid for MAP

– PBL/BNL solenoid SBIRs (funded by DOE/HEP) created

record fields (~16 T peak insert, ~9 T peak half-midsert). The

goal is to use these existing coils to develop and demonstrate

technology for high field solenoid for MAP

• High Field (~24 T) HTS Solenoid for SMES

– A significant HTS R&D program in recent years. Program is

funded by DOE/ARPA-E (collaborators: ABB, BNL,

SuperPower, UH; BNL/SMD responsible for SMES coil)

Having acquired over 50 km of HTS (4 mm tape equivalent), made hundreds of

HTS coils and tens of HTS magnets, BNL has a unique experience with HTS.



HTS Quad for FRIB

Highlights:

• HTS Magnet built with significant amount

of ReBCO (2G HTS) from two vendors

• No observable degradation during winding,

cool-down or testing

• Large temperature margin - thanks to HTS

• Magnet survived several events (quenches?)

near or above design field

HTS coils in

support structure



Radiation Tolerant HTS Quad for the

Facility for Rare Isotope Beams (FRIB)

Exposure in the first magnet itself:

Head Load : ~10 kW/m, 15 kW

Fluence : 2.5 x1015 n/cm2 per year

Radiation : ~10 MGy/year

Pre-separator quads and dipole

To create intense rare isotopes, 400 kW beam hits the production target.

Several magnets in Fragment separator region (following the target) are

exposed to unprecedented level of radiation and heat loads.

Courtesy: Zeller, MSU

Radiation resistant

Court

esy: A

l Z

elle

r, F

RIB

/MS

U



Second Generation HTS Quad for FRIB (higher gradient and operating temperature)

Eight coils wound

4 coils made with ASC:

~210 m double sided

(420 m HTS per coil)

~2x125 turns

4 coils with SuperPower:

~330 m per coil

~213 turns

Note: This is a 12 mm tape

(3X the standard 4 mm)

First generation quad was made with the 1G HTS (Bi2223)

Higher performance 2nd generation quad is made with 2G HTS

(over 8 km of 4 mm equivalent used)



Completed Second Generation HTS Quad for FRIB

{8 racetrack coils, 4 made with SP tape and four with ASC tape (double)}



Test Results Large Temperature Margin

(+20% in Ic &

+10 K in Tc)

(+15% in Ic &

+20 K in Tc)

Design Current @38 K:

SuperPower 210 A

ASC (double tape) 310 A

(50K,375A)

(60K,240A)

• Magnet with significant amount of HTS performed well

• Unprecedented temperature margin – only possible with HTS

No observable

degradation

during cool-down

or energizing



-100

0

100

200

300

400

500

12:04:19 PM 12:05:02 PM 12:05:46 PM 12:06:29 PM 12:07:12 PM 12:07:55 PM 12:08:38 PM 12:09:22 PM 12:10:05 PM 12:10:48 PM 12:11:31 PM

Cur PS 2

-2

0

2

4

6


-600

-500

-400

-300

-200

-100

0

100


Event (Quench?) while ASC Coils were held at 382 A (design: 310 A)

Cu

rren

t (A

) C

oil

Vo

ltag

es

(m

V)

Zo

om

Slow logger:

One point/sec

Shut-off

Shut-off

Events prior

to Shut-off

Co

il V

olt

ag

es

(m

V)



Snap Shot of the Event in ASC Coils (individual and difference voltages)

-40

-20

0

20

40

60

80

1001 7

13

19

25

31

37

43

49

55

61

67

73

79

85

91

97

Vo

ltag

e (m

V)

Time (msec)

B-C, ACS-4

D-E, ACS-1

ASC1-ASC4

Dif

fere

nc

e V

olt

ag

e

Fast data logger:

One point/msec

Shut-off



-0.8

-0.6

-0.4

-0.2

0

0.2

1 7

13

19

25

31

37

43

49

55

61

67

73

79

85

91

97

Vo

ltag

e (m

V)

Time (msec)

ASC1-ASC4

Snap Shot of the Event (Quench?) that Triggered the Shut-off

-40

-20

0

20

40

60

80

100

1 7

13

19

25

31

37

43

49

55

61

67

73

79

85

91

97

Vo

ltag

e (m

V)

Time (msec)

B-C, ACS-4

D-E, ACS-1

ASC1-ASC4

-20

0

20

40

60

80

100

1 7

13

19

25

31

37

43

49

55

61

67

73

79

85

91

97

Vo

ltag

e (m

V)

Time (msec)

ASC1-ASC4

Difference Voltage

Low threshold (few hundred mV) can be kept

due to the advanced quench detection system

No degradation in performance observed after the event



-10

10

30

50

70

90

4:30 PM 4:31 PM 4:32 PM 4:32 PM 4:33 PM 4:34 PM 4:35 PM

170

175

180

185

190

16:30:43 16:31:26 16:32:10 16:32:53 16:33:36 16:34:19 16:35:02

-600

-500

-400

-300

-200

-100

0

100

16:30:43 16:31:26 16:32:10 16:32:53 16:33:36 16:34:19 16:35:02

Cu

rren

t (A

)

Voltage and

Voltage Difference (mV)

Voltage (mV)

and

Voltage Difference (mV)

Event (Quench?) During the Ramping of the SuperPower Coils

Zo

om

Slow logger:

One point/sec

Vacuum leak made the

temperature increase to

~57 K (design temp ~38 K)



Snap Shot of the Event (Quench?) that Triggered the Shut-off

-200

-100

0

100

200

300

400

5001 7

13

19

25

31

37

43

49

55

61

67

73

79

85

91

97

Vo

ltag

e (m

V)

Time (msec)

P-R, SP#1

S-T, SP#2

SP#1-SP#2

-10

0

10

20

30

40

50

1 7

13

19

25

31

37

43

49

55

61

67

73

79

85

91

97

Vo

ltag

e (m

V)

Time (msec)

P-R, SP#1

S-T, SP#2

SP#1-SP#2

7 per. Mov. Avg. (SP#1-SP#2)

Fast logger: One point/msec

Large inductive voltage in

individual coils (ramp)

Small quench detection

threshold (2 mV) kept during

the ramp by monitoring

difference voltage



Analysis of the Events

• Quench detection system determined the event a

quench as the voltage threshold was exceeded

• Quench protection system extracted the energy

rapidly

• All coils were re-tested a few times after the event

• No degradation in performance was found in coils

made with either SuperPower or ASC conductor

• This shows that the quench protection system can

protect the HTS coils against the events like this



High Field (>30T) Solenoid for MAP

b

a

ca) >12 T HTS solenoid (insert)

b) >10 T HTS (midsert)

c) >10 T LTS (outsert)

Promising demos with a series PBL/BNL SBIR (DOE/HEP)

Work continues under Muon Accelerator Program (MAP)



Initial Test of HTS Insert and Midsert and Preparation for High Field (>22 T) Test

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0 2 4 6 8 10 12 14 16 18 20 22

Vo

ltag

e G

rad

ien

t (m

V/c

m)

Current (Amp)

Test of 100 mm HTS Solenoid (Each curve represents 12 coils)

• HTS Insert (14 pancakes, ran at 16 T peak field)

and Midsert (24 pancakes, 12 ran at 9 T peak)

• Expected on axis field at 4 K: > 22 T (design)

• All worked well during 77 K Pre-test



Test Results of Combined Structure (HTS Insert and HTS Midsert)

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26

Vo

ltag

e (m

V)

Current (A)

coil #1 coil #2

coil #3 coil #4

coil #5 coil #6

coil #7 coil #8

coil #9 coil #10

coil #11 coil #12

coil #13 coil #14

coil #15 coil #16

coil #17 coil #18

coil #19 coil #20

coil #21 coil #22

coil #23 coil #24

#15

#8

#11

#15

#8

#11

#16

Several pancakes got degraded during one @77 K test with LN2

• No further degradation seen after repeated test after this event

• Assumed cause: excessive thermo-mechanical strain during system testing



Repairing the Pancakes

-0.004

0.000

0.004

0.008

0.012

0.016

0.020

0 10 20 30 40

Vo

ltag

e (V

)

Current (A)

Coil 15 before repair

Coil 15 after repair

Became Good

Was Bad

Several (but not all) pancakes have been repaired by removing inner-

most turn and by making a new splice between the two single pancakes



Status and Moving Forward

• Repair as many HTS pancake coils as possible. Then rebuild the

magnet structure with either fewer pancakes (lower field) or with

replacement pancakes, depending on the funding (SuperPower has

kindly offered to contribute some conductor).

• Reduce the thermal strain on HTS coils with improved design (better

cooling with copper disks, etc.) and with slow controlled cooling.

• Retest the magnet to high fields to verify the analysis and the design.

• Future high field solenoid R&D at BNL relies on MAP (with all

SMES coils built and no similar high field program on the radar).

• We want to build upon the positives and lessons learnt and use

the existing coils, hardware and experience to complete the task.

• Modest support may produce significant results (remember: 16 T

HTS insert and 9 T half-midsert have already been tested once).



Feedback to

Conductor Manufacturer



Ic (77K, self field) and (4K, in-field)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

1 2 3 4 5 6 7 8

Ic(8T)/Ic(77K)

Ic(8T)/Ic(77K)

Courtesy: Arup Ghosh

0.0

0.5

1.0

1.5

2.0

2.5

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0

Ic(H

)/Ic

(8T)

H, T

Series1

Series2

Series3

Series4

Series5

Series6

Series7

600700800900

100011001200130014001500

300 325 350 375 400 425 450

I C(8

T, F

ield

Pe

rp)

IC (77K, self field)

A factor of 2

variation in 4K

field perp Ic

Identical dependence of

(4K/77K) scaling as a function

of field (1 at 8T and 2 at 3T)

A large variation

in scaling ratio

• An opportunity to understand and

improve Ic significantly (2X or more)

• No variation in 4K scaling Vs Bperp.

• Means low field measurements are OK.

• Add curves at different temperatures.

• Make Ic Vs. T curves at different fields.

• Cheaper measurements improves stat.

See p

oste

r b

y A

rup

Gh

osh

3T

8T

2

1



More Wish-list on 2G Conductor

• One of the major strength of 2G HTS is its mechanical strength (high

modulus to deal with large Lorentz forces). However, current electro-

plating may be a weal link. Improve on it and add measurements of

various mechanical properties (including peel strength of copper), as

needed.

• Wider and/or multi-tape designs (for example like ASC supplied tape

for FRIB). It reduces inductances (good for quench protection) and

also the impact of weak-spots (a bit more forgiving).

• 2G cables – variety of types may be possible, each with its own

advantage for a given application.



Summary • HTS magnets offer unique solutions. There is no option but to use HTS to

build superconducting magnets operating either at very high fields or at very

high temperatures (cryo-free) or with large energy deposition (as in FRIB).

• We may be near the exciting period of “1968 Summer Study” in LTS

http://www.bnl.gov/magnets/staff/gupta/Summer1968/.

• We have several impressive results to indicate what HTS magnets can offer.

However, significant work remains to take advantage of their full potential.

• Initial test results of FRIB quad show that HTS may be able to handle quench

type events. However, more clear demonstrations are needed.

• Initial results of PBL/BNL high field HTS solenoid have been impressive

(particularly demonstration of 16 T insert and 9 T half midsert HTS solenoids

under the limited budget of SBIR).

• There is a potential to create ~25 T in HTS solenoid with modest funding, by

continuing the above program and coils. This would be a significant

contribution to the field with applications in many areas. With conventional

LTS outsert, we should be able to address a critical technology area for MAP.
http://www.bnl.gov/magnets/staff/gupta/Summer1968/http://www.bnl.gov/magnets/staff/gupta/Summer1968/http://www.bnl.gov/magnets/staff/gupta/Summer1968/http://www.bnl.gov/magnets/staff/gupta/Summer1968/

Documents

Medium and High Field HTS Magnet R&D at BNLSuperconducting Magnet Division LTHFSW13 Ramesh Gupta Medium and High Field HTS Magnet R&D at BNL November 5, 2013 Slide No. 3 Active HTS