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Cross-section of the 150 mm aperture case
Paolo Ferracin HiLumi WP3 Video-meeting 26 July, 2012
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Outline Design concept Conductor properties Magnet parameters
Stress analysis Some additional considerations Paolo Ferracin 26/07/2012
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From HQ to MQXF Magnetic 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 HQ MQXF Paolo Ferracin 26/07/2012
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From HQ to MQXF Mechanical 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 HQ MQXF Paolo Ferracin 26/07/2012
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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 Paolo Ferracin 26/07/2012
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Cable and coil parameters
From HQ to MQXF Wider cable Increased insulation 43% more conductor HQ MQXF Units HQ MQXF Strand # 35 40 Width mm 15.150 18.273 Thickness in/out 1.338/1.536 1.396/1.604 Keystone angle 0.75 0.65 Insulation thickness 0.100 0.150 Mid-plane insulation 0.250 Interlayer insulation 0.500 Turns per oct. = 46 = 51 Area supercond. per oct. mm2 380 544 Paolo Ferracin 26/07/2012
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Stored energy / A ins_cable Differential inductance
Magnet parameters at 1.9 K HQ MQXF Units HQ MQXF Temperature K 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 1802 1575 JCu 1598 1397 Differential inductance mH/m 7.10 8.68 Paolo Ferracin 26/07/2012
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Magnet parameters at 1.9 K Comparison with expectations
see “Proposal for aperture”, E. Todesco, 02/07/2012 MQXF expect. 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) Paolo Ferracin 26/07/2012
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Fringe field At 5 mm from the cryostat, fringe field ranging from 3 mT for HQ to 8 mT for MQXF HQ MQXF Paolo Ferracin 26/07/2012
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Stress analysis Lorentz stress on mid-plane Bladder press. / interf.
HQ MQXF Lorentz stress on mid-plane IL: -101 MPa OL: -121 MPa Bladder press. / interf. 17 MPa / mm Max shell stress: 150 MPa Lorentz stress on mid-plane IL: -113 MPa OL: -122 MPa Bladder press. / interf. 27 MPa / mm Max shell stress: 230 MPa Paolo Ferracin 26/07/2012
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Stress analysis Coil peak stress
1.9 K -137 MPa 1.9 K -150 MPa Gnom -119 MPa Gnom -129 MPa Paolo Ferracin 26/07/2012
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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) 51 turns 53 turns Paolo Ferracin 26/07/2012
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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 Paolo Ferracin 26/07/2012
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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 mm clearance after pre-loading, cool-down, and excitation Still to be verified the welding procedure Other modifications/simplifications Round collars? No masters? MQXF Paolo Ferracin 26/07/2012
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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 Paolo Ferracin 26/07/2012
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Appendix Paolo Ferracin 26/07/2012
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Stress analysis Comparison 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 Units HQ MQXF_15 mm MQXF_17 mm IL OL Lorentz stress MPa -100 -120 -113 -128 -108 Paolo Ferracin 26/07/2012
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