MQXF Design and Conductor Requirements P. Ferracin MQXF Conductor Review November 5-6, 2014 CERN

Outline Overview of MQXF design Baseline strand and insulated cable Coil design and magnetic analysis Magnet parameters Mechanical analysis and quench protection 5/11/2014 Paolo Ferracin2

Overview of MQXF design 5/11/2014 Paolo Ferracin3 Target: 140 T/m in 150 mm coil aperture To be installed in 2023 (LS3) Q1/Q3 (by US LARP collaboration) – 2 magnets with 4.0 m of magnetic length within 1 cold mass Q2 (by CERN) – 1 magnet of 6.8 m within 1 cold mass, including MCBX (1.2 m) Baseline: different lengths, same design – Identical short model magnets SQXF by E. Todesco

From LARP HQ to MQXF Strand, cable and coil The aperture/cable width is approximately maintained – Aperture from 120 mm to 150 mm – Cable from 1.5 to 1.8 mm width – Similar stress with +30% forces Same coil lay-out: 4-blocks, 2-layer with same angle Optimized stress distribution Strand increase from mm to 0.85 mm – Same filament size from 108/127 to 132/169 – Maximum # of strands: 40 Lower J overall from quench protection (from 580 to 480 A/mm 2 ) 5/11/2014 Paolo Ferracin4 HQ MQXF

From LARP HQ to MQXF Magnet design Same structure concept Pre-load capabilities of HQ design qualified and successfully tested Larger OD: from 570 to 630 mm Additional accelerator features Larger pole key for cooling holes Cooling channels Slots for assembly/alignment LHe vessel and welding blocks and slots 5/11/2014 Paolo Ferracin5 HQ MQXF

Overview of MQXF design 5/11/2014 Paolo Ferracin6 OD: 630 m SS shell, 8 mm for LHe containment Al shell, 29 mm thick Iron yoke – Cooling holes (77 mm) – Slots of assembly/alignment Iron Master plates – 58 mm wide bladder Iron pad Al bolted collars – Coil alignment with G10 pole key Ti alloy poles

Overview of MQXF design 5/11/2014 Paolo Ferracin7 OD: 630 m SS shell, 8 mm for LHe containment Al shell, 29 mm thick Iron yoke – Cooling holes (77 mm) – Slots of assembly/alignment Iron Master plates – 58 mm wide bladder Iron pad Al bolted collars – Coil alignment with G10 pole key Ti alloy poles

MQXF magnet design 5/11/2014 Paolo Ferracin8

Outline Overview of MQXF design Baseline strand and insulated cable Coil design and magnetic analysis Magnet parameters Mechanical analysis and quench protection 5/11/2014 Paolo Ferracin9

0.85 mm strand Filament size <50 μm OST 132/169: μm Bruker PIT 192: 42 μm Cu/Sc: 1.2  0.1  55% Cu Critical current at 4.2 K and 15 T – 361 A at 15 T MQXF strand (from CERN technical specification document) 5/11/2014 Paolo Ferracin10 Bruker PIT strand, 192 OST RRP strand, 132/169

MQXF baseline cable and insulation 5/11/2014 Paolo Ferracin11

MQXF baseline cable 40-strand cable Mid – thickness after cabling – / mm – Thin/thick edge: /1.612 mm Width after cabling – / mm Keystone angle – / deg. – Pitch length – 109 mm – SS core 12 mm wide and 25 μm thick Assumed expansion during reaction – 4.5% in thickness: ~70 μm, same keystone angle – 2% in width: ~360 μm Mid – thickness after reaction – mm – Thin/thick edge: 1.505/1.682 mm Width after reaction – mm 5/11/2014 Paolo Ferracin12 PIT cable RRP cable 70 μm 360 μm

Dimensional changes during heat treatment Unconfined cables and strands (RRP) at LBNL – axial contraction: 0.1 to 0.3 % – thickness increase: 1.5 to 4 % – width increase: 1.5 to 2 % Data on PIT strands and cables (FRESCA2) – larger axial contraction, comparable cross-section increase In HQ01, only 1-2% space for expansion left in design – Clear signs of over compressed and degraded coils So in HQ02, reduction of strand diameter (0.8  mm) – Thickness: 4.5%, from 29 μm (HQ01) to 65 μm (HQ02) – Width: 2% – Very good HQ02 quench performance Same assumptions used for MQXF – No signs of over-compression in first coils – Work in progress: Ten stack measurements at CERN and MQXF LARP coil 1 cross- section measurements at LBNL 5/11/2014 Paolo Ferracin13

Cable insulation AGY S2-glass fibers 66 tex with 933 silane sizing 32 (CERN, CGP) or 48 (LARP, NEW) coils (bobbins) Variables: # of yarn per coil and of picks/inch Target:  150 μm per side (145  5 μm) at 5 MPa, average 3 cycles 5/11/2014 Paolo Ferracin14 SampleIns. Cable thickness (mm)Bare cable thick/ (mm)Insulation thick. (mm) 001_ _ _ _ _ _ _ _

Tooling design Cable dimension after reaction and 150 μm thick insulation Coil cured in larger cavity Coil closed in reaction fixture in larger cavity Coil after reaction and during impregnation in nominal cavity Theoretical pressure ~5 MPa 5/11/2014 Paolo Ferracin15

Impact of cable dimensions optimization Up to 20 μm of thickness increase with same keystone angle – Compensated by insulation thickness from 150 to 140 μm  20 μm – “Transparent” modification, no impact on schedule More than 20 μm of thickness increase and/or change of keystone angle – Example: from 0.55 to 0.4 deg., with same mid- thickness Thin edge from to mm  25 μm – Considering 28 turns  700 μm on the outer layer – Change of wedges/pole/end-spacers ~10 months from new cable geometry to beginning of winding 5/11/2014 Paolo Ferracin = 50 turns

Outline Overview of MQXF design Baseline strand and insulated cable Coil design and magnetic analysis Magnet parameters Mechanical analysis and quench protection 5/11/2014 Paolo Ferracin17

Coil design and magnetic analysis Two-layer – four-block design, = 50 turns Criteria for the selection – Maximize gradient and # of turns (protection) – Distribute e.m. forces and minimize stress All harmonics below 1 units at R ref = 50 mm 6 blocks in the ends 1% peak field margin in the end (ss pad) 5/11/2014 Paolo Ferracin18

Persistent currents Estimates using magnetization measurements of actual QXF 169 wires performed at Ohio State University Harmonics are provided for second up-ramp following a pre- cycle corresponding to the one used for strand measurements 5/11/2014 Paolo Ferracin19 Measured magnetization (OSU)Calculated b 6 (after pre-cycle)

Persistent-current effect evaluation Effect of ±20% magnetization on b 6, b 10 included – Nominal b 6 value of -10 units can be adjusted using current reset level during pre-cycle – Dynamic aperture simulations have validated a persistent current b 6 up to 20 units at injection Present value of magnetization average and spread are compatible with field quality requirements For future study: assessment of the variability in wire magnetization and resulting uncertainty and random harmonics 5/11/2014 Paolo Ferracin20 Persistent current harmonics b6b6 b 10 NominalD(+20%M)NominalD(+20%M) 1.0 kA (injection) kA (high field)

Coil design and magnetic analysis Magnet lengths 5/11/2014 Paolo Ferracin21 Magnetic length RT = 1198 mm

Coil design and magnetic analysis Magnet lengths 5/11/2014 Paolo Ferracin22 Short modelQ1/Q3 (half unit)Q2 Magnetic length [mm] at 293 K Magnetic length [mm] at 1.9 K “Good” field quality [m] Coil physical length [mm] at 293 K Iron pad length [mm] at 293 K Yoke length [mm] at 293 K Longitudinal thermal contraction = 3 mm/m (as LHC magnets)

Coil design and magnetic analysis Conductor quantities 5/11/2014 Paolo Ferracin23 Short modelQ1/Q3 (half unit)Q2 Cable length per coil [m] (Roxie) Cable length per coil [m] (with margin) Strand per coil [km] (with margin) Strand per coil [kg] (with margin) Strand length = cable length * 40 * km of 0.85 mm strand: 5 Kg.

Outline Overview of MQXF design Baseline strand and insulated cable Coil design and magnetic analysis Magnet parameters Mechanical analysis and quench protection 5/11/2014 Paolo Ferracin24

Superconductor properties Virgin strand, no self field correction Godeke’s parameterization 5/11/2014 Paolo Ferracin at 12 T 1400 at 15 T 2040 at 15 T 3270 at 12 T 632 at 12 T 361 at 15 T 527 at 15 T 844 at 12 T Ca1*41.24T Ca2* = 1034 x Ca1*42642T eps_0,a0.250% Bc2m*(0)31.50T Tcm*15.34K C*1541TA p0.5 q2 Strain=-0.20%

Magnet parameters Self field corr. (ITER barrel) T/kA 5% cabling degradation Operational grad.: 140 T/m I op : 17.5 kA B peak_op : 12.1 T 80-81% of I ss at 1.9 K G ss : 171 T/m I ss : 21.6 kA B peak_ss : 14.7 T Stored energy: 1.3 MJ/m Inductance: 8.2 mH/m 5/11/2014 Paolo Ferracin26 Impact of higher I max strand – +10% increase in critical current  about +3% in I ss

Magnet parameters Temperature margin (K) Peak field (T) 5/11/2014 Paolo Ferracin27

Outline Overview of MQXF design Baseline strand and insulated cable Coil design and magnetic analysis Magnet parameters Mechanical analysis and quench protection 5/11/2014 Paolo Ferracin28

Mechanical analysis ≥2 MPa of contact pressure at up to 155 T/m (~90% of I ss ) Peak coil stress: -160/-175 MPa Strain effect not included in I ss computation Similar stress as HQ ~20% of margin 5/11/2014 Paolo Ferracin29 Inner layer Outer layer

Quench protection 5/11/2014 Paolo Ferracin30 Protection studied in the case of 2 magnets in series (16 m) protected by one dump resistor (48 mΩ, 800 V maximum voltage) – Voltage threshold: 100 mV – Cu/Non-Cu: 1.2 – Validation time: 10 ms – Protection heaters on the outer and on the inner layer Hot spot T with 1.2 Cu/Non-Cu ratio: ~263 K Negligible effect of ~6-7 K from RRR ( ) and Cu/non-Cu ratio (1.1 to 1.2)

Conclusions Strand critical current of 361 A at 15 T – Corresponding to current density of ~2500 A/mm 2 at 12 T – ~80-81% of I ss Reasonable margin, probably the most critical parameter – 10% of critical strand current  3% of load-line margin Cu/non-Cu of 1.2 – In HQ: Intermediate value between 0.85 (HD) and 1.6 (LHC) – Safe margin for protection Filament size <50 μm – Same filament size as one used in HQ02 successfully tested – Consistent with field quality requirements Cored cable required for reduction of dynamics effects (as in HQ02) Peak stress of ~170 MPa, similar to TQ/HQ series 5/11/2014 Paolo Ferracin31

Appendix 5/11/2014 Paolo Ferracin32

MQXF project schedule 5/11/2014 Paolo Ferracin33 Short model program: 5 CERN-LARP models, – Coil fabrication starts in 02-03/2014 – First magnet test (SQXF1) in 07/2015 (3 LARP coils, 1 CERN coil) Long model program: 2 (CERN) + 3 (LARP) models, – Coil fabrication starts in 2015: 02 (LARP), 10 (CERN) – First magnet test in 08/2016 (LARP) and 07/2017 (CERN) Series production: 10 (CERN) + 10 (LARP) cold masses, – Coil fabrication starts in 01/2018 – First magnet test in 10/2019

Impact of cable dimensions optimization CERN MQXF current schedule 5/11/2014 Paolo Ferracin RRP short model 1 RRP short model 2 PIT short model 1 RRP long model 1 PIT long model 1