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HQ test at CERN: overview and protection studies

HQ test at CERN: overview and protection studies

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HQ test at CERN: overview and protection studies

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  1. HQ test at CERN: overview and protection studies H. Bajas H. BAJAS | Hi-Lumi special session on HQ test results

  2. OUTLINE • Training curve at 4.2 K and 1.9 K • Ramp rate study • Final test main results

  3. OUTLINE • Training curve at 4.2 K and 1.9 K • Ramp rate study • Final test main results

  4. Training curve at 4.2 K and 1.9 K 16,216 kA 184 T/m 14,681 kA Nominal current 14900 A

  5. Training curve at 4.2 K and 1.9 K Normalisation to short sample limit HQ01e performance: 85 % Iss 1st & 2ndcooldown 3rd cooldown H. BAJAS | Hi-Lumi special session on HQ test results

  6. Training curve at 4.2 K and 1.9 K Importance of the way one goes to quench current: need plateau. 1st & 2ndcooldown 3rd cooldown H. BAJAS | Hi-Lumi special session on HQ test results

  7. Training curve at 4.2 K and 1.9 K H. BAJAS | Hi-Lumi special session on HQ test results

  8. Quench initiating in the 4 coils. Coil 7 and 8 are basically limiting. Training curve at 4.2 K and 1.9 K 8 ? 9 7 5 8 8 8 8 7 9 9 8 5 7 8 9 8 7 8 8 9 7 7 9 9 ? 7 9 7 7 7 8 5 7 7 8 7 7 7 7 7 5 7 7 7 7 7 7 8 7 7 7 7 8 H. BAJAS | Hi-Lumi special session on HQ test results

  9. OUTLINE • Training curve at 4.2 K and 1.9 K • Ramp rate study • Final test main results

  10. Ramp rate study H. BAJAS | Hi-Lumi special session on HQ test results

  11. OUTLINE • Training curve at 4.2 K and 1.9 K • Ramp rate study • Final test main results

  12. Final test main results • Fast current discharge in the dump resistor for various currents : • @ 5 kA • @ 10 kA • @ 13 kA • @ 15 kA • @ 15 kA (with PHs firing) (without firing the PHs) Goal: does the discharge cause quench back? H. BAJAS | Hi-Lumi special session on HQ test results

  13. Final test main results • Comparison of the magnet total resistance Computation based on the instantaneous time constant of the exponential current decay: exp (-) • Magnet resistance increase during fast ramp down ≡ quench At 5 kA and 10 kA, magnetdoes not quench At13 kA, magnetpartiallyquenches At 15 kA, strongevidencethat a relevant fraction of the magnetisquenched H. BAJAS | Hi-Lumi special session on HQ test results

  14. Final test main results • Comparison of the current discharge @ 15 kA Negligible difference of the current decay when the PHs are used or not. H. BAJAS | Hi-Lumi special session on HQ test results

  15. Final test main results • High Miits quenches without dump resistor: Goal: can the HQ survive with all energy deposited in the helium bath? • Iq = 15,448 A with PHs firing • Iq = 15,917 A without inner layer PHs Goal: What is the final temperature of the magnet for high Miits? H. BAJAS | Hi-Lumi special session on HQ test results

  16. Final test main results • Comparison of the current decay with and without dump 18.3 Miits 16.9 Miits 13.2 Miits Strong increase of the Miits when no dump is used, a lot of He loss. H. BAJAS | Hi-Lumi special session on HQ test results

  17. Final test main results • Magnet resistance increase H. BAJAS | Hi-Lumi special session on HQ test results

  18. Final test main results • Attempt to compute magnet resistance from adiabatic model. H. BAJAS | Hi-Lumi special session on HQ test results

  19. conclusion • The HQ01e has undergone 3 warm-up/cool-down, and more than 70 quenches during 8 weeks of test. • Maximum magnet current: 14,681 A @ 4.2K & 16,216 A (184 T/m)@ 1.9K i.e. 85% of the short sample limitand greater than nominal current 14.9 kA • Regular training quenches can be obtained with pauses during the ramp and decrease of the ramp rate.Using the same ramp rate all the way has proved to limit the performance due to early quench in COIL 7. Coil 7 and 8 are statistically the limiting coils. • The final test tends to show that when one has a fast dump on the resistor at 15 kA, the magnet quenches: • PHs have no significant impact when a dump resistor is used • Without dump resistor current discharge is in agreement with a 20 ms delay of heaters • 16.6 MITTS at 16 kA, so hot spot below 300 K. 02/09/2012 H. BAJAS | Hi-Lumi special session on HQ test results 19