Cross-section of the 150 mm aperture case

Paolo Ferracin

HiLumi WP3 Video-meeting26 July, 2012

Outline

• Design concept

• Conductor properties

• Magnet parameters

• Stress analysis

• Some additional considerations26/07/2012Paolo Ferracin 2

From HQ to MQXFMagnetic design concept

• 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

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

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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Cable and coil parameters

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

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Units HQ MQXF

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

Magnet parameters at 1.9 K

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Units HQ MQXF

Temperature K 1.9 1.9

Gradient T/m 170 140

Iss % % 81 80

Current kA 14.9 16.8

Peak field T 11.8 12.2

Stored energy MJ/m 0.86 1.41

Stored energy / A ins_cable J/cm3 93 104

Jo A/mm2 593 503

JSc A/mm2 1802 1575

JCu A/mm2 1598 1397

Differential inductance mH/m 7.10 8.68

HQ MQXF

Magnet parameters at 1.9 K

• Comparison with expectations – see “Proposal for aperture”, E. Todesco, 02/07/2012

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MQXF expect. MQXF MQXF-HQ

expect. MQXF-HQ

Units

Current kA 16.3 16.8 +12% +13%

Stored energy MJ/m 1.34 1.41 +56% +64%

JSc A/mm2 1485 1575 -18% -6%

Stress MPa 136* 150/129** +6% +10/+8%

* Analytical peak stress on mid-plane** FEM peak stress (1.9 K / Gnom)

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

Stress analysisCoil peak stress

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HQ @ Gnom

-119 MPa

MQXF @ 1.9 K-150 MPa

MQXF @ Gnom

-129 MPa

HQ @ 1.9 K-137 MPa

Some additional considerations on MQXF (I)

• Coil optimization– Alternative solution with 53 turns

• +2 in outer layer

– Sharp wedge and 1 unit of b14

– But….• 1% of additional margin wrt. Iss

• 2% reduction of JO

– Reduction of few (4-5) MPa of Lorentz stress on mid-plane (IL)

• But smaller effect coil peak stress during operation (work in progress)

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51 turns

53 turns

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

Conclusions• Preliminary analysis of MQXF design based on HQ-concept

– 150 mm aperture, wider cable, OD 630 mm

• MQXF can generate a gradient of 140 T/m with 20% margin at 1.9 K

• 65% higher stored energy than HQ, but similar stored energy density and lower J0

• About 10 MPa higher coil peak stress (from 140 to 150 MPa)– Support structure within stress limits

• Further optimization of coil and structure in progress

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Appendix

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Stress analysisComparison at 80% of Iss

• From HQ to MQXF_15mm– IL Lorentz stress: +13%– Peak stress: +15 MPa

• From MQXF_15mm to 17mm– Reduction of 10 MPa in peak

stress

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Units HQ MQXF_15 mm MQXF_17 mm

IL OL IL OL IL OL

Lorentz stress MPa -100 -120 -113 -128 -108 -128