superconducting magnet program march 17-18, 2003 gian luca sabbi nb 3 sn magnet development at lbnl...

March 17-18, 2003

Gian Luca SabbiSuperconducting Magnet Program

Nb3Sn Magnet Development at LBNL

Advanced Accelerator Magnet WorkshopArchamps, March 17-18, 2003

Gian Luca Sabbi

March 17-18, 2003


Develop and establish the technologies associated with high-field superconducting magnets, in order to provide cost-effective options for the next-generation high energy physics accelerators. Apply our expertise towards the goals of the HEP community.

Materials

Design

Technology

LBNL Program Goals

Prototype Magnets

March 17-18, 2003


Accelerator Magnet Requirements

1) Fundamental requirements:

• Achieve operating field• Meet field quality specs• Safely withstand quench

2) Efficiency/cost issues:

• Operating point near short sample limit• Minimum/no training• Minimize conductor & structural materials• Simple, reliable fabrication procedures

Accelerator QualityMagnets

March 17-18, 2003


Single aperture, shell-type (1992-1997)

Twin aperture, common coil

Single aperture, block-type (1998-2003)

Subscale (common coil)

• D:

• RD:

• HD:

• SM:

LBNL Prototype Series

March 17-18, 2003


LBNL Prototype Highlights

RD3-c - 10 TeslaD20 - 13.5 Tesla RD3-b - 14.7 Tesla

RD2 - 6 TeslaRT1 - 12 Tesla

March 17-18, 2003


Prototype Objectives and Features

Magnet Year Field Type Design Features

D19H 1996 10.2 T Cos Coil Fabrication Process

D20 1997 13.5 T Cos Clear bore 50 mm, body/end optim.

RD2 1998 5.9 T Comm. Coil New “RD” configuration

RT-1 1999 12.2 T Comm. Coil High Field in RD configuration

RD3b 2001 14.7 T Comm. Coil New support structure, high stress

RD3c 2002 10.0 T Comm. Coil Clear bore 35 mm, auxiliary coils

HD-1 2003 (16.2 T) Block New “HD” configuration

RD3d (2004) (11.0 T) Comm. Coil Bore 40 mm, saturation, end field

March 17-18, 2003


Accelerator Quality in Cos Magnets

End saddle for internal bore support and physical aperture at coil ends

Midplane turns formagnetic efficiency

Pole turns for field quality

Wedges for field quality

Keystoned cable, Roman arch for coil self-support

D19 End Spacersfor field quality

Fillers fortransitionsat lead end

Main goal of D19H and D20 was to transfer these features to Nb3Sn technology

March 17-18, 2003


RD Series: Common Coil Layout

Advantages:

• Large end radius (react and wind)• Flat cable• High packing in small aperture • Simpler support structure

Challenge:

Incorporate accelerator quality while maintaining simplicity

A new design paradigm aiming at conductor compatibility and cost reduction

Gupta, PAC 1997

March 17-18, 2003


Bladders & Load Keys

Island/Pole

25 mm Bore Plate

Load Pads

RD3b Common Coil Magnet

RD Series: Support Structure

Pressurized Bladders

RD3b Magnet Assembly and Cooldown

Fx = 12 MN/m @ 14.7 T

March 17-18, 2003


RD Series: Conductor Limits

RT-1, RD3B – No performance degradation up to 14.7 T, 120 MPa

RD3B\Q43.TSV:Ramp History

B(T

), I(K

A))

T(Mins) Q43HISTA.HGL

20 40 60 80 100 0

2

4

6

8

10

12

14

Imag

Bhall

RD3B ramp cycle to quench (#43)

3000

4000

5000

6000

7000

8000

9000

10000

11000

12000

13000

14000

10 11 12 13 14 15 16

B (T)

Cab

le C

urr

ent

(A)

Inner CoilNew Outer CoilOuter Load-LineInner Load-LineBore-fieldRD-3b TrainingHighest CurrentOld Outer Coil

RD3B load lines and conductor limit B [ T ]

March 17-18, 2003


RD Series: Accelerator Quality

Geometric field quality

Bore support, coil deflections

Physical Aperture at coil ends

Magnetic efficiency

High field

Saturation/Magnetization

End optimization

RD3C RD3D RD4 RD5

March 17-18, 2003


RD3c Objectives

Simple coil configuration:

• RD3B Outer Modules• New, RD3B-type inner module

Geometric field quality features:

• Auxiliary (pole) turns• Central spacer

Design field: 10.9 T

1. Demonstrate central geometric harmonics at 10-4 level in a 35 mm bore 2. Perform measurements of other relevant geometric and dynamic effects 3. Compare experimental data with calculated values

For the first time in a common coil dipole:

March 17-18, 2003


RD3c Magnetic Design

Coil geometry Field at the probe

March 17-18, 2003


RD3c Integrated Harmonics

Normal calculated measured

b3 (unit) -5.44 -10.39

b5 (unit) -0.24 -0.02

b7 (unit) 0.58 0.61

b9 (unit) <0.01 <0.01

Skew calculated measured

a2 (unit) -31.2 -15.65

a4 (unit) -1.56 -1.45

a6 (unit) 0.01 -0.20

a8 (unit) <0.01 <0.01

Integral over 43 cm is affected by coil ends, generally lower central harmonics

Normal sextupole: Value: saturation, ends. Discrepancy: coil geometry

Skew quadrupole: Value: saturation, ends. Discrepancy: geometry, saturation

Octupole & higher: Value: small, in agreement with expectations.

Iop=10 kA, Rref=10 mm

March 17-18, 2003


Normal Sextupole MM03-MM04 Cycles

-200

-150

-100

-50

0

50

100

150

0 1 2 3 4 5 6 7 8 9 10 kA

10-4

Un

its

@ 1

0 m

m

MM03MM04, First CycleMM04, Second Cycle

30 A/s10 A/s

RD3c Field Quality Analysis

Z-scan - Normal Sextupole

-15

0

15

30

45

-400 -300 -200 -100 0 100 200 300 mm

10-4

Un

its

@ 1

0 m

m

Calculated

MM03 - Dz

MM04 - DzDz=18 mmOre 130(RD3b outer)

Ore 88-90-103(RD3a outer)

Conductor Magnetization – Eddy Currents Iron Saturation

End FieldNb3Sn Strand Design

March 17-18, 2003


RD Series: Next Steps

RD3D RD4 RD5

• Single layer aux. coils• End optimization• 10-4 geom. harmonics• 11 T, 40 mm clear bore

• Two-layer inner module• Flared ends for aperture • 10-4 geom. harmonics• 13 T, 40 mm clear bore

• Four layers, flared ends• 10-4 geometric, end harm. • Saturation, magnetization • 15 T, 40 mm clear bore

March 17-18, 2003


HD Series

New High Field Dipole Test Configuration

Design Features: • Single bore• Two flat double pancakes• Horizontal configuration• Dipole field 15-18 T

Magnet cross-section Coil cross-section Coil end field

March 17-18, 2003


RD/HD Similarities

Basic features

• Block-coil• Flat cable• Double pancake

Fabrication

• Winding• Reaction • Impregnation

Mechanics

• Force distribution• Bore support

Magnetics

• Field profile• Lorentz stress

Assembly

• Bladders & keys• Support structure

March 17-18, 2003


RD/HD Differences (1)

Parameter RD HD

Number of apertures 2 1

Conductor, energy, forces 2X 1X

Size (longitudinal, transverse) Larger Smaller

R&D prototype:

Parameter RD HD

Arrangement Vertical Horizontal

Force on structure 2X 1X

Conductor, energy, forces Larger Smaller

Size (longitudinal, transverse) Larger Smaller

Two-in-one:

March 17-18, 2003



Parameter RD HD

Grading Coil modules Nested coils

Field/stress enhancement Iron island Iron pole

Symmetry Left-right Up-down

Central field quality Aux. coils Spacers

End peak field Low High

End Efficiency Flared ends End saddle

Magnetics:

March 17-18, 2003


Mechanics and Fabrication:

Parameter RD HD

Minimum winding radius Large Small

React-and-wind Yes No

Load direction on cable Narrow edge Wide face

Load direction on coil High modulus Low modulus

End support Iron Non-magnetic

End compactness Low High

Layer transition Low field High field

Midplane gap No Maybe


March 17-18, 2003


HD1 Dipole

• Flat double-pancakes for simplicity (open midplane, less efficient)

• Magnetic pole for high field/stress (RD3B equivalent)

• Bending radius 10 mm (20 mm horizontal coil aperture)

• Midplane gap (vertical coil aperture): 10 mm

At one time, new coil configuration and new field record: 16+ T

Design Features:

Goal (and challenge):

March 17-18, 2003


HD1 Performance Parameters

SHORT SAMPLE PARAMETERS

Parameter Unit HD1 RD3B B0

(ss) T 16.2 14.6 I(ss) kA 10.5 10.8 Bmax T 15.6 14.8 Jcu

(ss) kA/mm2 1.2-1.4 1.1/1.5

Parameter Unit HD1 RD3B Inner Outer Strand diameter mm 0.8 0.8 0.8 No. strands 36 40 26 Cu/Sc 0.72-0.96 0.9 1.4 Nt

(quad, 1ap) 35+35 50 49+49

CABLE PARAMETERS

Parameter Unit HD1 RD3B Stored Energy MJ/m 0.62 1.2 Inductance MH/m 11 21 Fx (quadrant, 1ap) MN/m 4.1 3.7 Fy (quadrant, 1ap) MN/m -1.3 -2.3 Max. coil stress MPa 150 120

ENERGY and FORCES

14

14.5

15

15.5

16

16.5

10.1 10.3 10.5 10.7 10.9 kA

T

Bpk (body)B0Bpk (end)Bcond

B0(ss)

Iss

March 17-18, 2003


Design features Dipole field (T) Iss (kA) HD1 reference 16.2 10.5 RD3B conductor 15.3 10.0 Nb3Sn graded coil 8 turns 1/2 dens 17.5 14.0 HTS insert 7 turns 0.8 mm 361 A @ 18 T 18.6 13.0

Iron insert

Midplane gap

Coil grading/HTS insert

HD Series: Dipole Field

March 17-18, 2003


Stress Analysis Room temp. 4.3 K Nominal field

Shell stress (MPa) 14 115 120

Coil horiz. stress (MPa) 19 148 0 - 155

Coil vert. stress (MPa) 5 17 5 - 40

Coil max eq. stress (MPa) 20 150 155

Lorentz forces per quadrant:

Fx = 4750 N/mm xcoil = 153 MPa

Fy = 1550 N/mm ycoil = 30 MPa

HD1 Dipole - Design field 16.5 T

Approaching 200 MPa @ 18 T

HD Series: Conductor Limits

March 17-18, 2003


HD Series: Accelerator Quality

1. Saddle ends for efficiency 2. Clear bore size and support3. Spacers & field quality

Design issues (and priority):

Coil Spacer

Saddle end

Bore plate

Dual bore configuration: S-LHC?

March 17-18, 2003


SM Series

• Scaled version of main magnet– Approx. 1/3 scale

• Field range of 9 – 12 Tesla

• Two-layer racetrack coils– 5 kg of material per coil

• Streamlined test facility– Small dewar– Basic instrumentation

Parallel Program for Technology Development

Mini-Me

March 17-18, 2003


SM Magnet Features

compression padSC-01

SC-02

compression pad

yoke

shell

Coil module Two layer coil

Assembled Magnet

March 17-18, 2003


SM Prototypes

• SM-01– Developed the SM concept– Baseline “background” coils– Two preload configurations

– SM-01a• 92 MPa horizontal preload• First quench at 85% short sample

– SM-01b• Reduced preload to 10 MPa• Short sample at 11.9 Tesla

• SM-02– Mixed-strand– Low quench performance

• SM-03– Mixed-strand– Better performance than SM-02

• SM-04– CTD Ceramic Insulation System– Excellent performance

• SM-05– Quench protection limits– Analysis in progress

March 17-18, 2003


DOE Conductor Development Program

Jc vs. TimeNb3Sn

IGC I.T.

OST MJR

UTD1 PITRD3 OST MJR

UTD1PIT

D20 MJRMSUT PIT

D20IGC I.T.

ITERIGC I.T.

D10IGC I.T.

0

500

1000

1500

2000

2500

3000

1980 1985 1990 1995 2000 2005Year

J c(A

/mm

2 ) @ 1

2 T,

4.2

K

Project Management(LBNL)

Conductor Advisory Group

Nat’l LaboratoryGroups

IndustrialCompanies

UniversityGroups

Parameter Unit Goal Progress Jc kA/mm2 > 3.0 2.4-2.6

Deff m < 40 70-100 Lpiece km > 10 1.0-1.5

H.T. time hr < 400 150 Cost $/kA-m

(12 T) < 1.5 6

Started in 2000Phase I : improve performancePhase II : Scale-up, cost issues

March 17-18, 2003


Nb3Sn Critical Current Density

500

1000

1500

2000

2500

3000

9 10 11 12 13 14 15 16 T

A/mm2 HD1 (OST#6555)HD1 (OST#6445)RD3b inner (ORe 125)RD3c inner (ORe 143c)D20 inner (IGC)RD3b outer (ORe 130)

D20(1996)

RD3b/c(2000)

HD1(2002)

no self-fieldcorrection

Nb3Sn wires for High Field Dipoles, 1996-2002

March 17-18, 2003


RD3C Fast Flux Changes MM02 Fast Flux Changes vs. Imag

1

10

100

1000

0 2 4 6 8 10Imag (KA)

# F

M's

MM02-U1MM02-D1

MM02-U2MM02-D2Q25(30A/s)

“Stick-Slip”

“Flux Jump”

RD3C\Q15.LCA:1st Event > 300V/s (Imag = 1KA)

V(m

V)

T(ms) Q15FFC1B.HGL

0 2 4 6 8 10-50

0

50

100

150

200

250D2-1

D1:L4-3

D3:C1-2

D2:L4-3

RD3C\Q15.LC6:Quench Trigger (Imax = 10.9KA)

V(m

V)

T(ms) Q15FF55B.HGL

2.4 2.6 2.8 3.0 3.2 3.4 3.6

0

200

400

600

D2-1

D1:L4-3

D3:C1-2

D2:L4-3

10 ms

D2-1

D2-1

1 ms

Flux jumps:

Can trigger quench detection system Also observed in RT-1, RD3B

• “Slow” (10 ms)• Low current• No training• Repeat at down ramp

• “Fast” (0.1 ms)• High current• Trigger quenches• Some training• Not at down ramp

Flux Jump:

Stick-slip:

Flux Jumps at High Jc , Deff

March 17-18, 2003


LBNL Cable R&D

React-and-Wind

Mixed-strand

Flat, low compaction

Keystoned, w/core

March 17-18, 2003


Three prototype series to pursue the Program Goals:

- RD : From high-field coil testing to accelerator quality magnets – best approach to VLHC

- HD : A path towards the highest fields in full-scale structures – best approach to S-LHC

- SM : Technology development and moderate field magnets in subscale structures

Summary

March 17-18, 2003


Superconducting Magnet Group

Scott Bartlett, Paul Bish, Sharon Buckley, Shlomo Caspi,

Luisa Chiesa, Daniel Dietderich, Paolo Ferracin, Steve Gourlay,

Modeste Goli, Aurelio Hafalia Jr, Charles Hannaford, Hugh Higley,

Alan Lietzke, Nate Liggins, Sara Mattafirri, Al McInturff,

Kelly Molnar, Mark Nyman, GianLuca Sabbi, Ronald Scanlan,

Jim Smithwick, James Swanson, Kathleen Weber

superconducting magnet program march 17-18, 2003 gian luca sabbi nb 3 sn magnet development at lbnl...

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