MQXF coil cross-section status

Paolo Ferracin

HiLumi WP3 Video-meeting28 August, 2012

Outline

• Update of MQXF coil cross-section with cable growth during reaction (from v2 to v3)

• Length of coil ends

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From HQ to MQXF: magnetic design concept(presented on July 26)

• Aperture: from 120 mm to 150 mm • Cable width: from 15 mm to 18 mm wide cable• 2 layers with similar angles and 4 blocks• All harmonics below 1 unit at 2/3 of Rin and 80% of Iss

• Similar iron geometry, but with OD from 520 mm to 558 mm

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HQ MQXF_v2

Cable and coil parameters(presented on July 26)

• From HQ to MQXF– Wider cable– Increased insulation– 43% more conductor

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Units HQ MQXF_v2

Strand # 35 40

Width mm 15.150 18.273

Thickness in/out mm 1.338/1.536 1.396/1.604

Keystone angle 0.75 0.65

Insulation thickness mm 0.100 0.150

Mid-plane insulation mm 0.150 0.250

Interlayer insulation mm 0.250 0.500

Turns per oct. 20 + 26 = 46 23 + 28 = 51

Area supercond. per oct. mm2 380 544

HQ MQXF_v2

New cable dimensions

• Cable growth during reaction (unconfined heat treatment ) taken into account– 2.0% in width– 4.5% in mid-thickness

• Same keystone angle• Similar inner layer• Outer layer wedge slightly higher• One turn less in outer layer– Do we still want it?– Or FRESCA2-type of layer jump?

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HQ

MQXF_v3

Cable and coil parameters

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Units HQ MQXF_v2 MQXF_v3

Strand # 35 40 40

Width mm 15.150 18.273 18.638

Thickness in/out mm 1.338/1.536 1.396/1.604 1.462/1.673

Keystone angle 0.75 0.65 0.65

Insulation thickness mm 0.100 0.150 0.150

Mid-plane insulation mm 0.150 0.250 0.250

Interlayer insulation mm 0.250 0.500 0.500

Turns per oct. 20 + 26 = 46 23 + 28 = 51 22 + 28 = 50

Area supercond. per oct. mm2 380 544 533

HQ MQXF_v2 MQXF_v3

Conductor properties• From 0.80 to 0.85 mm strand• Cu/Sc ratio: 1.13 (53% Cu)

• Assumption on Jc– 2500 A/mm2 at 12 T– 1400 A/mm2 at 15 T

• Resulting Jc for computations with self field correction– 2650 A/mm2 at 12 T– 1450 A/mm2 at 15 T

• Values consistent with D. Dietderich and H. Felice presentation and with FRESCA2 PIT strand data

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Magnet parameters at 1.9 K

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Units HQ MQXF_v2 MQXF_v3

Temperature K 1.9 1.9 1.9

Gradient T/m 170 140 140

Iss % % 81 80 80

Current kA 14.9 16.8 17.3

Peak field T 11.8 12.2 12.2

Stored energy MJ/m 0.86 1.41 1.44

Stored energy / A ins_cable J/cm3 93 104 102

Jo A/mm2 593 503 490

Differential inductance mH/m 7.10 8.68 8.27

HQ MQXF_v2 MQXF_v3

Stress analysis

• Lorentz stress on mid-plane – IL: -101 MPa– OL: -121 MPa

• Bladder press. / interf.– 17 MPa / 0.160 mm

• Max shell stress: 150 MPa

• Lorentz stress on mid-plane – IL: -110 MPa– OL: -126 MPa

• Bladder press. / interf.– 27 MPa / 0.410 mm

• Max shell stress: 229 MPa

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HQ MQXF_v3

Stress analysisCoil peak stress

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HQ @ Gnom

-119 MPa

MQXF_v3 @ 1.9 K-149 MPa

MQXF_v3 @ Gnom

-128 MPa

HQ @ 1.9 K-137 MPa

Outline

• Update of MQXF coil cross-section with cable growth during reaction (from v2 to v3)

• Length of coil ends

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Estimate of MQXF length of coil ends• The HQ case

– Magnetic half-length• 420 mm

– Coil half-length: • 508 mm

– End length (return end)• 90 mm

• The MQXF– End length (return end)

• 90*(150/120) = 113 mm -> 120 mm– Proposed “lengths of the region which

includes everything between the portion of the magnet exceeding the magnetic length to the portion of the next magnet exceeding the magnetic length (R. De Maria)”, in the non-connection side• 500 mm

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Estimate of MQXF length of coil ends

• The HQ case– End-shoe thickness

• ~40 mm– End-shoe extension for NbTi-Nb3Sn splice

• ~150 mm• MQXF (connection side)– Can we incorporate the end plate in the NbTi-Nb3Sn

splice extension (solution adopted in HD2/HD3)?

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Appendix

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From HQ to MQXFMechanical design concept

• Same support structure concept as HQ• Same shell thickness, but OD from 570 mm to 608 mm • Cooling holes and busbar slots added • 10 mm thick LHe vessel included within 630 mm OD

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HQ MQXF

Fringe field

• At 5 mm from the cryostat, fringe field ranging from 3 mT for HQ to 8 mT for MQXF

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HQ MQXF

Stress analysis

• Lorentz stress on mid-plane – IL: -101 MPa– OL: -121 MPa

• Bladder press. / interf.– 17 MPa / 0.160 mm

• Max shell stress: 150 MPa

• Lorentz stress on mid-plane – IL: -113 MPa– OL: -122 MPa

• Bladder press. / interf.– 27 MPa / 0.430 mm

• Max shell stress: 230 MPa

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HQ MQXF_v2

Stress analysisCoil peak stress

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HQ @ Gnom

-119 MPa

MQXF_v2 @ 1.9 K-150 MPa

MQXF_v2 @ Gnom

-129 MPa

HQ @ 1.9 K-137 MPa

Some additional considerations on MQXF (II)

• Cooling holes– 80 mm diameter

• Could be increased to 90 mm, depending on axial support system

• Busbar– 20 x 50 mm slot

• Axial support– 32 mm axial rods

• Some space for end-plate and pad-bolts

• High stress but probably still fine

– Alternative: end-plate welded to vessel

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Some additional considerations on MQXF (III)

• LHe vessel– 10 mm thick cylinder

• OD: 630 mm

– 1 mm gap between vessel and Al shell (nominal dimension)• About 0.500 mm clearance after pre-

loading, cool-down, and excitation

– Still to be verified the welding procedure

• Other modifications/simplifications– Round collars?– No masters?

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MQXF