MBSMH101 11T practise coil Collaboration meeting

1. MBSMH101 11T practise coil Collaboration meeting Gerard Willering TE-MSC-TF 21-07-2014 on behalf of the test team: Jerome Feuvrier, Vincent Desbiolles with thanks for support during test to Susana Izquierdo, Juho Rysti and Philippe Grosclaude with thanks to everyone involved in the design and preparation of the coil that deserve the credits nanos gigantum humeris insidentes

2. Content Magnet parameters Conductor parameters Short circuit and instrumentation Training and quench performance Mechanical measurements Quench heater efficiency

3. Magnet Parameters Identification: MBSMH101 Coil 101 – Copper coil Coil 105 – OST RRP 108/127, Ta-Doped Coil ID: HCMBHSP0003_105 from billets 13925, 13926 Cabled at CERN, cabling run 86A Cable ID: H15OC0127A Overview of the different design of magnet cross-sections This coil has the CERN type Single-aperturs cross-section Lots of info during 11T design review on: http://indico.cern.ch/event/273023/

4. Magnetic Field 13 kA 10 kA In the half-coil dipole configuration the outer blocks and Quench Heaters are in rather low field region. Highest field is in the end turns. 6.5 kA Images by S. Izquierdo

5. Conductor Parameters Cable Caracteristics Wire Caracteristics Similar cable as for SMC_11T coil #1 that had magneto-thermal instabilities SMC_11T #1MBSMH101 48 hrs 210 °C 48 hrs 210 °C 48 hrs 400 °C 48 hrs 400 °C 50 hrs 650 °C 50 hrs 640 °C Keystone Lower T should increase RRR and lower Ic Rectangular Measured RRR of full coil 77 Reference: Internal note to be published, B. Bordini, A. Ballarino, A. Bonasia, L. Oberli, «Cable H15OC0127A for Coil 105 (11 T Magnet Project)»

6. Short sample and load line 2 sets of Vamas witness samples measured. Load lines calculated Resulting short sample current limits: 4.3 K: 15.15 kA ± 1 % 1.9 K: 16.69 kA ± 1 % Variation inbetween 2 samples about 300 A. Uncertainties on loadline Field modulus is used Theoretical position of the coil is used 3D loadline will be re-evaluated Reference: Internal note to be published, B. Bordini, A. Ballarino, A. Bonasia, L. Oberli, «Cable H15OC0127A for Coil 105 (11 T Magnet Project)» Loadlines calculated by S. Izquierdo using Roxy.

7. Cooldown Rather fast cooldown in 45 hours with a ΔT between top and bottom of the yoke of 100 K. Temperature in the coil (calculated from ρ) follows closely the top temperature.

8. Short circuit in the coil? First ramp of the magnet led to trip at 2.5 kA. Suspicion of a short circuit in the coil Conclusion: No short between turns, but shorts through instrumentation. Post mortem investigation started last Friday. Changes in load on Power Converter Jumps in total voltage and inner layer voltage during discharge after the quench Only normal behavior: Time constant and inductance during energy extraction: coil inductance around 3.8 mH. Inductive voltage on coil not equal to resistive voltage in the dump (6 kA, no quench) Only 3.3 mH instead of 3.8 as was calculated! Strong jumps in voltage from 1 to 3 kA

9. Instrumentation – outer layer 12 outer layer voltage taps 2 outer layer heaters

10. Instrumentation – Inner layer 15 inner layer voltage taps Many signals for investigation of events !!

11. Training Quench performance Training at 4.3 K up to 14.3 kA First quench at 9 kA After 5 quenches at “nominal” 11.8 kA After 16 quenches 11 T in the coil ends Most training quenches seem to initiate in the coil ends, but in both inner and outer layer. “Holding quenches”: no quench during 40 minutes at 15 kA at 1.9 K.

12. Comparison SMC 11T_2 SMC 11T_2 and 11T practise coil are made from the same cable. SMC 11T_2 suffered from conductor instabilities at 1.9 K between 14.1 and 16 kA. 11T practise coil seems to have a “smooth training” up to 16 kA.

13. Comparison with MBHSM01 tested at FNAL Single coil versus magnetic mirror CERN coil has a higher I_ss Plots for comparison, but between two coils with different characteristics.

14. Mechanical Measurements Laboratory M.Guinchard/P. Grosclaude Mechanical measurements Pole wedge compression stresses Ramp to 16 kA Strong fluctuations seen from 15 to 16 kA. Needs further explanation Capa Gauge size 120 by 15 mm Many probes did not perform as expected, instrumentation is already revised for the next coil. Good correlation calculations with measurements on traction stress in the shell in the different stages of coil life. Reference: https://edms.cern.ch/file/1352279/1/11T_results.pptx https://edms.cern.ch/file/1387744/1/11T-2_Measurements_on_the_instrumented_collar_packs_report.pdf

15. Quench Heater studies Quench heater response time within calculated range, except at 14 kA Calculations by S. Izquierdo Resistance growth comparison between model and measurements is progressing

16. Quench Heater studies QH delay at 4.3 K is very consistent up to 14 kA. QH delay at 1.9 K is very fast at 13 and 14 kA, faster than at 4.3 K. Confirmed for multiple cases Cannot be explained with “normal” heat transfer from heater to coil. In addition the quench starts in interlayer jump, far from Quench heaters Small benefit in resistance growth, but not an effect to count on for protection.

17. Quench Heater studies Large set of data acquired for model validation and futher QH efficiency studies Example 1 Example 2 Resistive voltage in the coil at 1.9 K following QH discharge Resistive voltage different coil blocks at 12 kA at 1.9 K

18. Preliminary conclusions • Good training performance up to 16 kA, 13 T • Very good memory after thermal cycle • No “Holding quenches” • No degradation during testing • Quench heater delays as expected • QH efficiency studies is work in progress, in the right direction • Gives a good motivation to keep on going….

19. End of presentation