LQ Mechanical Behavior Overview and Next Steps

1. LQ Mechanical Behavior Overviewand Next Steps 2nd Joint HiLumi LHC – LARP Annual Meeting INFN Frascati – November 14th to 16th 2012 Helene Felice Paolo Ferracin Work supported by the U. S. Department of Energy, under Contract No. DE-AC02-05CH11231

2. Overview • Magnet Overview • Mechanical analysis and SG data comparison • Next steps 2nd Joint HiLumi LHC - LARP Annual Meeting - H. Felice

3. LQ Design overview • 90 mm aperture coils with Ti poles • Iron pads, masters, yokes, Al shell • Pre-load with bladders and keys • LQS01-2 Short-sample limits (4.5 K – 1.9 K) • Gss: 240 T/m – 267 T/m • Iss: 13.8 kA – 15.4 kA • Peak field: 12.3 T - 13.6 T • LQS03 Short sample limit • -Gss: 227 T/m – 250 T/m • Iss: 12.9 kA – 14.4 kA • Peak field: 11.5 T - 12.8 T • End support: plate and rods • Magnet/coil length: 3.7/3.4 m 2nd Joint HiLumi LHC - LARP Annual Meeting - H. Felice

4. LQ assembly • Total of 60 gauges mounted (q and z) • 20 on shell, 32 on coil poles, 8 on rods • Four axial locations along coil length 2nd Joint HiLumi LHC - LARP Annual Meeting - H. Felice

5. LQ strain gauges • Shell and coil stations • q and z gauges thermally compensated • 10 shell stations • 4 stations per coil • 2 gauges/rod => 1 signal/rod • Total of 60 gauges Measurements presented here are averages of the various gauges 2nd Joint HiLumi LHC - LARP Annual Meeting - H. Felice

6. Mechanical AnalysisTypical Stress distribution Rod Shell Pole • Preload for 260 T/m • sq and eq at 300 K • target (3D): + 56 MPa • + 750 me • sq and eq at 4.3 K • target (3D): + 183 MPa • +2080 me • sq (MPa) • Preload for 240 T/m: 471 kN • sz and ez at 300 K • target (3D): +88 Mpa (178 kN) • +455 me • sz and ez at 4.3 K • target (3D): + 239 MPa • + 1138 me • Preload for 260 T/m • sq and eq at 300 K • target (3D): -82 MPa • -580 me • sq and eq at 4.3 K • target (3D): -157 MPa • -1031 me • sq (MPa) End Contact pressure (Mpa) NO gap 2nd Joint HiLumi LHC - LARP Annual Meeting - H. Felice

7. LQSD: structure validation (2009) • Loading and cool-down to 77K with instrumented aluminum dummy coils • Validation of the structure behavior 2nd Joint HiLumi LHC - LARP Annual Meeting - H. Felice

8. LQS01a SummaryAzimuthal stress Radial shim thickness LQS01a Gradient preload: 230-240 T/m 30 mils ~ 750 mm LQS01b LQS01a From LQS01a to LQS01b Reduction of the radial shimming from 30 to 15 mils Fuji Test to confirm Some unloading of the pole suggested lack of preload Nominal Oversized 2nd Joint HiLumi LHC - LARP Annual Meeting - H. Felice

9. LQS01b SummaryAzimuthal stress Radial shim thickness LQS01a Gradient preload: 230-240 T/m LQS01b Gradient preload: 260-270T/m 15 mils ~ 375 mm 30 mils ~ 750 mm LQS01b loading required a bladder pressure of 8000 psi = 55 MPa 2nd Joint HiLumi LHC - LARP Annual Meeting - H. Felice

10. LQS02 SummaryAzimuthal stress Radial shim thickness LQS01a Gradient preload: 230-240 T/m LQS01b Gradient preload: 260-270T/m LQS02 Gradient preload: 260-270 T/m 15 mils ~ 375 mm 15 mils ~ 375 mm 30 mils ~ 750 mm 2nd Joint HiLumi LHC - LARP Annual Meeting - H. Felice

11. LQS03 assembly target and motivation • LQS03 assembly target were chosen identical to LQS02 assembly targets • Some uncertainty about the reason behind the lack of performance of LQS02 • Concern about mid-plane block quenches • conservative approach in keeping the same preload • 1-to-1 comparison with LQS02 – only change of conductor • Unloading of the pole can be handled by a “healthy magnet” => TQS03a LQ TQS03 227 T/m 93% Iss 209 T/m 2nd Joint HiLumi LHC - LARP Annual Meeting - H. Felice

12. LQS03 Loading conditions Radial shim thickness LQS01a Gradient preload: 230-240 T/m LQS01b Gradient preload: 260-270T/m LQS02 Gradient preload: 260-270 T/m LQS03 same preload as LQS02 15 mils ~ 375 mm 15 mils ~ 375 mm 30 mils ~ 750 mm 10 mils ~ 250 mm 56 MPa -82 MPa 2nd Joint HiLumi LHC - LARP Annual Meeting - H. Felice

13. Comparison of SG data during assembly

14. SG shell data during assembly LQS01a LQS01b 67 +/- 6 MPa 34 +/- 8 MPa LQS02 LQS03 57 +/- 8 MPa 56 +/- 8 MPa Shell SG behave consistently during assembly 2nd Joint HiLumi LHC - LARP Annual Meeting - H. Felice

15. SG Rod data during assembly LQS01a LQS01b 94 +/- 5 MPa 60 +/- 3 MPa LQS02 LQS03 92 +/- 3 MPa 92 +/- 2 MPa Rod SG behave consistently during assembly 2nd Joint HiLumi LHC - LARP Annual Meeting - H. Felice

16. SG Coil Pole pieces data LQS01b +5 12 MPa LQS01a -107  26 MPa LQS02 -69+/- 27 MPa LQS03 After LQS01a: -SG in compression -Large spread -77 +/- 21 MPa 2nd Joint HiLumi LHC - LARP Annual Meeting - H. Felice

17. SG Comparison during cool-down

18. SG shell data during cool-down LQS01a LQS01b 199+/- 8 MPa 147+/- 6 MPa LQS02 177+/- 9MPa 183+/- 9MPa Shell SG behave consistently during cool-down LQS03 2nd Joint HiLumi LHC - LARP Annual Meeting - H. Felice

19. SG rod data during cool-down LQS01a LQS01b 239+/- 9 MPa 197+/- 11 MPa LQS03 LQS02 LQS03 230+/- 10 MPa Rod SG behave consistently during cool-down 235+/- 10 MPa 2nd Joint HiLumi LHC - LARP Annual Meeting - H. Felice

20. SG Coil Pole pieces strain data during cool-down LQS01a -179+/- 104 me LQS01b LQS03 LQS02 Pole SG remain difficult to trust during cool-down -764+/- 372 me 2nd Joint HiLumi LHC - LARP Annual Meeting - H. Felice

21. LQS03 SG Investigation • No correlation in terms of station location • No correlation in terms of coil • No correlation between T and Z • Amplitude of SG signals is inconsistent with magnet performance • Impact on the magnet performance are unclear: • No signs of mechanical motion recorded during training • No clear precursor to quench • Temperature compensator might be in cause • SG de-bonding? • Might require a visual inspection 2nd Joint HiLumi LHC - LARP Annual Meeting - H. Felice

22. Excitation LQS01a LQS03 • LQS03 • SG in tension still respond to excitation • Slightly different rate of unloading observed from one coil to the other • 1 station shows sign of unloading LQS01b 2nd Joint HiLumi LHC - LARP Annual Meeting - H. Felice

23. LQS03 Warm upShell and rods SG • Shell remains consistent • Usual relaxation after the first test 716 +/- 101 me 584 +/- 101 me • Rods recover their initial tension 485+/- 15 me 495+/- 15 me 2nd Joint HiLumi LHC - LARP Annual Meeting - H. Felice

24. LQS03 Warm upCoil pole SG • After warm-up, the pole SG do not recover the initial strain and still read some tension 2nd Joint HiLumi LHC - LARP Annual Meeting - H. Felice

25. LQ series: Summary on mechanical performance • Trust in the capability of the structure to provide required preload: • LQSD • Linear unloading of the poles monitored by SG • Shell and rods are behaving according to the FEM • BUT • Absolute value of pole pieces SG cannot be trusted • Challenge resides in the coil size and matching between pads and coil OD • Impact on the magnet performance are unclear: • No signs of mechanical motion recorded during training 2nd Joint HiLumi LHC - LARP Annual Meeting - H. Felice

26. Next steps – LQS03b • Option 1: increase of preload • Some concern: • Risk of damaging the outer layer • Mid-plane quenches in LQS02 • Signs of pole unloading in LQS02 • Limit in bladder pressure • LQS03: 7500 psi (52 Mpa) • Option 2 • A this point: complete disassembly seems to be the way to learn something • 3 to 4 months from magnet at LBL to magnet ready to be shipped to FNAL • After disassembly: coil inspection – 2 possible outcomes: • Signs of damage on the SG => repair => reassembly • No sign of damage of the SG => ? 2nd Joint HiLumi LHC - LARP Annual Meeting - H. Felice