1. Susana Izquierdo Bermudez. With many contributions from Juho Rysti, Gerard Willering and all the people involved in the manufacturing and test of the magnet 25-07-2014

2. Susana Izquierdo Bermudez General magnet parameters 2 Identification: MBSMH101 Coil 101 – Copper coil Coil 105 – OST RRP 108/127, Ta-Doped ODS alloy wedges (Oxide Dispersion Strengthening ) CERN V4 end spacers SLS (Selective Laser Sintering) with springy legs - hinge Metallic saddles and splice blocks External trace, glued on coil OD, carrying V-taps and quench heaters Short sample current limits: 4.3 K: 15.15 kA ± 1 % 1.9 K: 16.69 kA ± 1 % Peak field is at the ends. The short sample limit is about 1.1-1.2kA higher for the straight section. In all the plots linked to quench heater delay, the 2D short sample limit is considered (because the quench heaters are in the straight section) More info… http://indico.cern.ch/event/331147/http://indico.cern.ch/event/331147/

3. Susana Izquierdo Bermudez Overview QH design 3 More details can be found in https://indico.cern.ch/event/311824/https://indico.cern.ch/event/311824/ Main features: Stainless steel 25 µm thick, partially plated with 5 µm thick layer of copper to reduce their overall resistance (design suitable for 5.5 m length) Heating stations are 19 mm wide in the mid-plane (LF) and 24 mm wide in pole area (HF) The distance in between non-plated sections is 90 mm in the LF and 130 mm in the HF where quench propagation is faster in the longitudinal direction. The heaters are embedded in between two layers of polyimide insulation foils. The thickness of the insulation between the heater and the coil is composed of 0.050 mm of polyimide, about 0.025 mm of Epoxy glue plus the additions S2 glass added to the coil outer radius during impregnation. The trace is then glued to the coil and compressed radially during collaring to about 40 MPa. CoverageDistance between stations width 0.2 mm S2 glass 0.025 + mm glue + 0.050 mm kapton QUENCH HEATERS 4x0.5 mm kapton (ground insulation)

4. Susana Izquierdo Bermudez Trace manufacturing and characterization 4 Resistance measurements at RT and 77 K Stainless steel stations: Measured resistance close to expected values 3% difference at RT 8 % difference at 77K Copper regions: Measured resistance higher than expected value 20% difference at RT 25 % difference at 77K High current test No degradation was observed in the bonding Temperature cycling at 77 K No degradation Kapton (50 µm) Glue (<25 µm) Stainless Steel (25 µm) Copper (5 µm) Glue (50 µm) Kapton (25 µm) Trace stack for 11T ρ ss =7.3·10 -7 Ωm, RRR SS =1.34 ρ ss =1.8·10 -8 Ωm, RRR SS =30

5. Susana Izquierdo Bermudez Before trace installation Resistance measurements at RT High voltage test to ground under 20-30 MPa pressure (2kV). After trace installation, every step of the manufacturing process 5 Expected value: R1=R2=1.65 Ω Measured value ≈ 1.7 Ω Resistance QH to ground and QH to coil (1 kV) Discharge test (pulse). Low thermal load to the heaters (under adiabatic conditions and assuming constant material properties, peak current defined to limit the temperature increase to 50 K) (only in the manufacturing steps after collaring) Trace QA

6. Susana Izquierdo Bermudez QH test set up in SM18 6 R LF R HF R add C E + - Circuit 1 Circuit 2 Cu Nb 3 Sn I [A] P LF [W/cm 2 ] P HF [W/cm 2 ] P ave [W/cm 2 ] RC (ms) 8041.325.9 3480 10064.540.4 5264 150145.191.0 11842

7. Susana Izquierdo Bermudez QH test set up in SM18 7 10 kA 6.5 kA 13 kA Quench heater provoked quench performed at different magnet current levels, from 6 kA to 14 kA. We study: QH delay QH efficiency Transversal heat propagation

8. Susana Izquierdo Bermudez Quench Heater Delay 8 2 times to look at: Quench heater onset: start of the quench Quench heater efficient: time where slope of the resistive voltage cross the horizontal axis Gerard Willering What we define as quench heater delay? 28 ms35 ms 18 ms 21ms

9. Susana Izquierdo Bermudez Quench Heater Delay 9 Large difference between “Quench Onset (QO)” and “Quench heater efficient (QE)” at low currents. From now on, if not specified, heater delays plotted correspond to the “Quench Onset” and not “Quench Efficient”

10. Susana Izquierdo Bermudez Comparison to FNAL 11T dipoles 10 MBHSM101 FNAL MBHSM% insulation between heater and coil: 0.125 mm of glass on the outer, impregnated with the coil 0.125 mm of kapton between heater and coil CERN MBHSM101insulation between heater and coil: 0.200-0.250 mm of glass on the outer, impregnated with the coil 0.050 mm of kapton between heater and coil + about 0.025 mm glue FNAL data from https://indico.cern.ch/event/311824/https://indico.cern.ch/event/311824/ Slides from Guram Chlachidze Heater delays are very close to delays measured in FNAL

11. Susana Izquierdo Bermudez Comparison to HQ 11 HQ data data from https://indico.cern.ch/event/311824/https://indico.cern.ch/event/311824/ Slides from Tiina Slami Significant longer delays than in HQ. Main difference: in the case of 11T, heaters are glued on top of the coil after impregnation

12. Susana Izquierdo Bermudez Comparison to modelled delays 12 0.2 mm S2 glass 0.025 + mm glue + 0.050 mm kapton QUENCH HEATERS 4x0.125 mm kapton (ground insulation) Juho Rysti Model by Juho Rysti using the commercial software COMSOL Basis of the model are the same as Tiina’s model (https://indico.cern.ch/event/311824/)https://indico.cern.ch/event/311824/ Quench heater delays modelled for different thickness of S2 glass between coil and heaters. Nominal should be close to 0.3 mm.

13. Susana Izquierdo Bermudez Comparison to modelled delays 13 QO: Quench Onset QE: Quench Efficient Juho Rysti

14. Susana Izquierdo Bermudez Transverse heat propagation 14 4 3 2 1 6 5 Measured propagation consistent with previous FNAL measurements

15. Susana Izquierdo Bermudez Modelling heat propagation within the coil 15 Two principal directions: 1. Longitudinal Length scale is hundreds of m 2. Transverse Length scale is tenths of mm Power exchanged between components in the conductor Joule heating External heat perturbation The conductor is a continuum solved with accurate (high order) and adaptive (front tracking) methods Longitudinal Transverse Power exchange between adjacent conductors 2 nd order thermal network explicitly coupling with the 1D longitudinal model:

16. Susana Izquierdo Bermudez Modelling heat propagation within the coil We are focused on the modelling of the thermal transient process, the hot spot temperature for the same MIITs can be very different depending in the time transient 16 Main simplifications Constant inductance Heat transfer from heater to coil is not included in the model. Quench heaters are modelled as a heat source applied directly on the cable AC loss not included in the model Hot spot temperature for different current decays but with the same QI (13 MIITs)

17. Susana Izquierdo Bermudez Model vs. Experimental 17 Block 5  Block 1 Block 6  Block 2Block 6  Block 3 Nominal inter-layer thickness: 0.5 mm Points at 14 kA not representative because the quench was starting in the layer jump and not under the heaters

18. Susana Izquierdo Bermudez Current decay and resistance growth 8 kA 10 kA 12 kA

19. Susana Izquierdo Bermudez Some comments and remarks 19 Modelled resistance growth gets closer to experimental values when the thickness of the inter layer is set to 0 mm and only the cable insulation is considered. This can be a combination of different effects: AC loss is not considered. Second order thermal network is not “fully catching” the thermal diffusion process in the insulation Uncertanties in the material properties of the insulation The model does not account for heater stations, it assumes that the entire cable length is covered by the heaters. The relative good agreement with the experimental value is an indication that the heater stations are effective.

20. Susana Izquierdo Bermudez Longitudinal propagation and T max 20 Experimental data from Hugo Bajas Not specific studies on hot spot temperature and longitudinal propagation in MBHSM101, but analysis were performed in SMC using 11T cable. More details : https://indico.cern.ch/event/311824/

21. Susana Izquierdo Bermudez Conclusions and final remarks 21 An effort is on going in order to understand the thermodynamic process during quench. Model validation is on going. Thermal conductivity in the insulation plays a key role and a better knowledge of these properties is important. We are using G10 material properties for the insulation. Does anyone have measurements/good reference for actual coils, using the same resin, reaction treatment, ceramic binder … ? Based on the measurements and model, QH delay for the real 11T magnet should be about 20 ms at 80 % of the short sample limit. If we set the MIITs limit to 17 MA 2 s, this is 25 % of our total budget, it is a lot! Shorter delay is expected if the heater is impregnated with the coil. A redundant system with only outer layer heaters seems more than challenging!

23. Susana Izquierdo Bermudez TRAINING 23

24. Susana Izquierdo Bermudez Is the long QH delay at low current a killer? 24 Defining the additional budget as the time we can stay at a certain current to achieve the same MIITs that at 80%Iss one can see that even if the delays are becoming much longer at low current level at lower quench heater current density, the situation is more critical at higher current levels. This is only partially true, because the additional time to detect the quench at lower current level is not included.

25. Susana Izquierdo Bermudez MB vs. 11T ParameterMB11T Magnet MIITs to reach 400 K @ 8T MA 2 s5218 Temperature margin LF48-9 Temperature margin HF3-45-9 Differential Inductance, mH/m6.911.7 Stored energy, kJ/m567897 Quench heater circuit Operational voltage, V Peak Current, A85110-120 Maximum stored energy, kJ2.862.5 - 3.5 Time constant, ms7555-72 Quench Heater Pattern400 mm plated 120 mm un-plated 90-140 mm plated 50 mm un-plated 25

26. Susana Izquierdo Bermudez Cable Parameters 26

27. Susana Izquierdo Bermudez Protection System LHC Magnets 27 The Protection System for the Superconducting Elements of the Large Hadron Collider at CERN K. Dahlerup-Petersen1, R. Denz1, J.L. Gomez-Costa1, D. Hagedorn1, P. Proudlock1, F. Rodriguez-Mateos1, R. Schmidt1 and F. Sonnemann2

28. Susana Izquierdo Bermudez STANDARD LHC HEATER POWER SUPPLIES 28 QUENCH HEATER EXPERIMENTS ON THE LHC MAIN SUPERCONDUCTING MAGNETS F. Rodriguez-Mateos, P. Pugnat,S. Sanfilippo, R. Schmidt, A. Siemko, F. Sonnemann

29. Susana Izquierdo Bermudez 29 Kapton G10 Thermal conductivity Heat capacity https://espace.cern.ch/roxie/Documentation/Materials.pdf Insulation MP

30. Susana Izquierdo Bermudez Insulation MP 30

31. Susana Izquierdo Bermudez Insulation MP 31 Sample nameCompositionHeat treated at 675 C GM12 layers mica/glassno GMG6 layers mica/glass-6 layers glassno GMHT32 layers mica/glassyes CGMG8 cables mica/glass-glassyes CGM8 cables mica/glassyes 12 layers mica/glass NHT 6 layers mica/glass-6 layers glass NHT 32 layers mica/glass HT 8 cables mica/glass-glass HT 8 cables mica/glass HT Thermal Conductivity of Mica/glass Insulation for Impregnated Nb3Sn Windings in Accelerator Magnets * Andries den Ouden and Herman H.J. ten Kate Applied Superconductivity Centre, University of Twente, POB 217, 7500 AE Enschede, The Netherlands

32. Susana Izquierdo Bermudez QH 32