fermilab 03 dec 2007muon collider design workshop1 hts r&d for high field magnets michael lamm...

03 Dec 2007Muon Collider Design Workshop 1Fermilab

HTS R&D for High Field Magnets

Michael Lamm

• Introduction

• Examples of Accelerator Magnet R&D with HTS

• High Field Magnet Design

• National Collaboration

With input from several people at the US National Labs


Colliding Ring/IR Magnets ~10 T, wide aperture/open midplane

Wide(?) aperture pulsed( ?) 20 T solenoids

HCC solenoid rings up to 20 T

Very High Field Solenoids

From MCTF End of year report

Interesting Magnets in Muon Colliders

“Low Emmitance” scenario…


Why consider HTS? Thermal Margin..

Superconducting state a function of Jc, Field and Temperature

IR and Collider ring and target magnets require high thermal margin at modest fields

>10 T on conductor calls for Nb3Sn or HTS materials


Magnets with fields on conductor ~>20T call for HTS


HTS Materials Used in Magnets

• Bi 2223 tape– Has been available in long piece lengths from American

Superconductor

– Stainless steel reinforced to improve tensile strength

– Significant Angular dependence to Jc (field)

• Bi 2212 Round wire– Available in long piece length from OST

– No angular dependence

– Better Je than Bi2223

– Can be made into a Rutherford cable

– Wind and react technology….(problems with treatment)


HTS Materials Used in Magnets II

• 2G YBCO Tape– Excellent tensile

strain sensitivity – Significant

improvement in Je over Bi 2223 tape

– Jc has strong angular dependence with external field.

– Used in 26T solenoid insert

– Relatively new…. Still being studied

From Drew Hazelton Presentation at MT 20


HTS Accelerator Magnet R&D in the US

• HEP National Labs study HTS applications in accelerator magnets as part of broader SC magnet R&D Program (Nb3Sn mostly)– BNL– LBNL– Fermilab– Muons Inc has worked with FNAL and BNL several

topics– Also work at LANL studying HTS materials

• Studies at the National High Magnetic Field Lab on high field solenoids have applicability to Muon Colliders


LBNL HTS Program

• Emphasis on Bi-2212 Wind and React Technology

• With SWCC Showa Cable Systems Co. Ltd.• Build HTS subscale racetrack coils from Bi

2212 Rutherford cables. R&D Issues with Bi-2212 W&R

– Reaction cycle (precise temperature control +/- 2 degrees at >800K)

– Insulation to withstand extreme temperatures

– Important new data on Bi “leakage” issues

• Status: 5 coils manufactured, 3 in progress


Observed at NHMFL as well as HTS vendor: problem not well understood


BNL Program

• Design/built/test prototype quadrupole for RIA projects

• Expected very high heat deposition (15 kW)

• Magnets built with Bi2223 tape from American Superconductor, with plans to build YBCO magnets

Racetrack coils during assembly

Completed 12 Coil magnet


BNL Program

• \

Their experience is well suited toward HTS applications in high radiation/energy deposition


New world record for superconducting magnet

26.9 T field,

>200 MPa hoop stress


FNAL Program

• Emphasis on HTS cable/strand analysis• Two Oxford Instrument Teslatron, capable of

testing up to 17 T solenoid field, from 1.9K to 70K

• Cabling machine• Tests performed on Bi 2212 round wire, Bi 2223

tape and YBCO tape• Data used in 50 T solenoid paper studies• Plans in FY08 to wind small solenoids for

Teslatron


E. Barzi, LTSW 2007, Oct. 29-31, 2007, South Lake Tahoe, CA 15

October 30, 2007

HTS and LTS Performance at 4.2 K

0

200

400

600

800

1000

1200

1400

1600

0 5 10 15 20 25 30

Applied Field, T

J E (

4.2

K, B

), A

/mm2 .

1.2 mc 2G SuperPower Parallel1.2 mc 2G SuperPower Perpendicular348 2G AMSC Parallel348 2G AMSC PerpendicularBSCCO-2212 Round Wire (OST)BSCCO-2223 Tape ParallelBSCCO-2223 Tape PerpendicularNb3Sn (High Jc RRP, OST)Nb3SnNbTi


Conductor Testing at Fermilab

B

SAMPLE

I

B c

b a

IB

Probe for Angular Measurements

Courtesy of E. Barzi


Example of Measurements Performed

4.2 K

1

2

3

4

5

6

7

-11.25 0 11.25 22.5 33.75 45 56.25 67.5 78.75 90 101.25

Angle, o

Ic /I

c(7

7K

,0T

)

0T

1T

2T

3T

4T

6T

8T

10T

12T

15T

Bi-2223 BSCCO-2223

0

100

200

300

400

500

600

700

800

0 2 4 6 8 10 12 14 16B, T

Ic, A

33K ┴

22K ┴

14K ┴

4.2K ┴

1.8K ┴

33K //

22K //

14K //

4.2 K //

Studies performed on Bi-2223 and YBCO tape (not shown) show Strong angular dependence

Studies performed over a wide range of angles, temperatures and fields

E. Barzi, SC R&D Lab

Supported by Muons Inc..

Also extensive temperature and field studies on Bi 2212 wire inc. effect of cabling on Jc (not shown)


E. Barzi, LTSW 2007, Oct. 29-31, 2007, South Lake Tahoe, CA

18

B and T Dependence of Anisotropy

1

2

3

4

5

6

7

8

0 3 6 9 12 15B, T

Icnorm

(Bpar)/ Ic

norm

(Bper

p )

T =33 K

T = 22 K

T = 14 K

T = 4.2 K

0

1

2

3

4

5

6

7

0 2 4 6 8 10 12 14 16B, T

Icnorm(B

par)/

Ic n

orm

(Bperp)

T = 33 KT = 22 KT = 14 KT = 4.2 K

Bi-2223

2G 348

PERPcPERPc

PARcPARc

TKIBI

TKIBI

)0,77(/)(

)0,77(/)(

The B dependence has a linear trend, where the slope value increases with T.

No observable T dependence. The ratio saturates at ~7.



19

0

200

400

600

800

1000

1200

1400

0 2 4 6 8 10 12 14 16

B, T

Ic, A

.

33 K ┴

22 K ┴

14 K ┴

4.2 K ┴

33 K //

22 K //

14 K //

4.2 K //

Comparison with Super Power 2G

Ratio saturates, but decreases with temperature

0

1

2

3

4

5

0 2 4 6 8 10 12 14 16B, T

Icn

orm

(Bp

ar)/

Ic n

orm

(Bp

erp)

33 K22 K14 K4.2 K

Ic(77K, 0T)=1061 A



20

Spectrum No. 1 2 3 Element At. % At. % At. % Ag (L) 0 100 0 Bi (M) 14.91 0 3.59 Sr (L) 9.04 0 2.21 Ca (K) 5.53 0 0.78 Cu (L) 11.49 0 5.80 Mg (K) 0 0 29.33 O (K) 59.03 0 58.28 Totals 100.00 100.00 100.00

SEM/EDS Cable Surface Analysis

The surface of all the cables after reaction showed black spots embedded in the silver coating.

Bi-2212?

Bi-2212+MgO?Caused by filament powder leaks

For all the cables, tested at self-fields of 0.1 to 0.3 T, an Ic degradation of about 50% was measured. This was much larger than the reduction found on the extracted strands.


High Field Magnets Under Study

• Helical Solenoid for Helical Cooling Channel– Demonstration Magnet in FY08

• 0.5 M diameter NbTi 6T on conductor

– Channel for Real HCC calls for high field solenoid

• Design Studies for 50 T Solenoids– Paper studies performed by Palmer/Kahn et al. and

Kashikhin/Zlobin et al• Published at Pac07/MT20


3.3kmSuperconducting cable length

20mmCoil section length along Z axis

4.4MJOperating stored energy

10kAOperational current

5.7TNbTi superconductor peak field

0.54T/mLongitudinal field gradient, Bz/z

-3.86TInitial field, Bz

0.07T/m2Quadrupole field gradient, 2B/r/z

-0.88T/mInitial quadrupole field, B/r

-0.17T/mDipole field gradient, B/z

1.25TInitial dipole field, B

0.255mRadius of beam reference orbit

1.6mHelix twist pitch

3.2mHelical Solenoid length

0.5mInner bore diameter

ValueUnitParameter

3.3kmSuperconducting cable length

20mmCoil section length along Z axis

4.4MJOperating stored energy

10kAOperational current

5.7TNbTi superconductor peak field

0.54T/mLongitudinal field gradient, Bz/z

-3.86TInitial field, Bz

0.07T/m2Quadrupole field gradient, 2B/r/z

-0.88T/mInitial quadrupole field, B/r

-0.17T/mDipole field gradient, B/z

1.25TInitial dipole field, B

0.255mRadius of beam reference orbit

1.6mHelix twist pitch

3.2mHelical Solenoid length

0.5mInner bore diameter

ValueUnitParameter

Helical Solenoid

The solenoid consists of a number of ring coils shifted in the transverse plane such that the coil centers follow the helical beam orbit. 1) NbTi 4-coil demo 2) MANX expt. 3) multi stage HCC in Muon accelerator (probably HTS in final stage)

PAC07 MOPAN117

Issues:•Mechanical Support•Required field quality (construction tolerances)•Cryostat•Powering and Quench Protection


High Field Solenoid

• Proposed for end of cooling channel for final emittances

• 30-50 T DC, 30-50 mm aperture, 1 m length

• Goals: Highest practical field, accelerator field quality, low manufacturing cost, low operating costs

• Superconducting for manageable power reqs– Existing very high field magnets are resistive or resistive/SC

hybrids Megawatt Power, one-of-a-kind, expensive to build/operate

– Engineering current density (Je) of HTS materials measured up to 45 T, have a mild dependence on B… however..

– Building this solenoid is beyond present capabilities, although 25-30T HTS solenoids are proposed, 25 T solenoid inserts demonstrated


High Field Solenoid Designs

• Two high field solenoid paper studies related have been performed in the last ~15 months.– Parameters

• Hybrid magnet with NbTi, Nb3Sn and HTS superconductor

• Utilize Bi-2223 tapes (steel reinforced, long lengths and reasonable Jc)

– Extrapolate Je to 45-50T using low field angular dependence

– Bi-2212 field Je vs. Field

• Bi-2212 wire is also possible, YBCO not considered (yet)


Design Study #1

From PAC07 MOPAN118 Kahn/Palmer et al

Inner diameter set by HTS min bend radius

Bi 2223 inner coil, co-wound with SS tape

SS thickness adjusted radial to compensate for hoop stress

45T Bore Field


Design Issues

Demonstrated feasibility of HTS/hybrid approach

Mitigation of hoop stress through SS tapeNeed to intercept axial forcesPlan to study new YBCO conductor

Quench Protection Issues explored:Internal Heaters unlikely to work Need sensitive quench detection circuitry, probably on every layer of coil, with separate extraction circuits for each layer


Fermilab based study

Va. Kashikhin et al…

Consider two cases: Minimum Volume/Minimum Cost

-Several concentric coils independently supported through SS innertube/outersupport structure. SS rings sized for expected forces

-Coil tension/compression limited to 150 MPa

-Requires bonding/no gaps between inner/outer tubes


Minimum Cost

HTS coils

Nb3Sn

NbTi

Note: “Minimum Radius” eliminates NbTi portion.


National Collaboration on HTS Magnet R&D

• There is little or no market for HTS materials relevant for high field scientific applications.

• From discussion with HTS Vendors, sustained support from magnet community is needed to make progress. Need effort comparable to successful Nb3Sn Conductor Program

• Proposal “White Paper” (David Larbalestier, Lance Cooley, Ken Marken and Alvin Tollestrup) to form collaboration among interested National Labs, Universities and HTS vendors to develop program

• Broad Collaboration of NMR, material science and HEP application interested in >23 T at 4 K and >10 T at 20 K


Collaboration Plans

• Ongoing discussions among the National Magnet Labs and University representatives to define collaboration•BNL, FNAL, LANL, LBNL, NHMFL, NIST, TAMU and others…•Identify common ground for conductor needs•Consolidate existing data on conductor tests•Identify facilities and resources•Near term and longer term plans for magnet related conductor development and testing, magnet development

• Proposal for DOE funding has been written


Conclusion

• Several interesting magnet will need to be designed/built at a reasonable cost– Need to start development of magnet list/specification– All reasonable options should be considered

• Active effort on high field magnets in National labs– Plans for a “National HTS Conductor Program”

analogous to the existing Nb3Sn program

• Paper studies show feasibility of HTS for 50T solenoids– Need to consider 2G-YBCO. Need more data on angular

dependence with field and strain/stress characteristics

fermilab 03 dec 2007muon collider design workshop1 hts r&d for high field magnets michael lamm...

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