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Quench

What quenches did we observe? What can we expect? Arjan Verweij & Robert Flora on behalf of the MPP, and with the input of many others. Quench.

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Quench

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  1. A. Verweij R. Flora 28 Feb 2008 What quenches did we observe? What can we expect?Arjan Verweij & Robert Flora on behalf of the MPP, and with the input of many others

  2. A. Verweij R. Flora 28 Feb 2008 Quench Quench: Transition from the superconducting to the normal state (resulting in a detectable resistive voltage, exceeding the threshold voltage and discrimination time). Circuits with active QPS: we can distinguish converter trip from natural quench and we have some possibilities for quench localisation For circuits that are protected through the power converter (60-120 A) we are almost blind. Quench classification: • Heater induced/provoked quench • Natural (training) quench • Secondary quench (due to temperature increase, ramp rate, etc) • (Beam induced quench)

  3. A. Verweij R. Flora 28 Feb 2008 Natural quenches in 4-5 *: nominal not reached

  4. A. Verweij R. Flora 28 Feb 2008 RB circuit: correlation with SM-18 3 1 2 SM-18: 175 quenches to reach 12 kA in all 154 dipoles

  5. A. Verweij R. Flora 28 Feb 2008 RQD/RQF circuits: correlation with SM-18 SM-18: 39 quenches to reach 12 kA in all 45 quads

  6. A. Verweij R. Flora 28 Feb 2008 IPD’s: correlation with training before installation

  7. A. Verweij R. Flora 28 Feb 2008 IPQ’s at 4.5 K: correlation with training before installation

  8. A. Verweij R. Flora 28 Feb 2008 IPQ’s at 1.9 K: correlation with training before installation

  9. A. Verweij R. Flora 28 Feb 2008 How many quenches can we expect for future sectors? This is a rough estimate based on limited experience of sector 4-5 only Numbers are given per sector for all circuits together

  10. A. Verweij R. Flora 28 Feb 2008 RB provoked quench @ 9500 ACryogenic recovery time: see talk Serge Claudet LBALA.17R4: 0 s, 9500 A LBBLA.17R4: 0.2 s, 9481 A LBBLC.17R4: 33.1 s, 6862 A LBALB.16R4: 155.0 s, 1886 A

  11. A. Verweij R. Flora 28 Feb 2008 RB natural quench 1 (9789 A) LBALA.27L5: 0 s, 9789 A LBBLA.27L5: 62.4 s, 5220 A LBALB.27L5: 63.1 s, 5181 A

  12. A. Verweij R. Flora 28 Feb 2008 RB natural quench 2 (9859 A) LBALA.22R4: 0 s, 9859 A LBBLA.22R4: 49.7 s, 6013 A LBALB.22R4: 92.6 s, 3829 A LBBLC.21R4: 126.8 s, 2645 A 381.7 s, 188 A

  13. A. Verweij R. Flora 28 Feb 2008 RB natural quench 3 (10274 A) LBBLA.27R4: 0 s, 10274 A LBALB.26R4: 109.1 s, 3330 A LBALA.27R4: 46.6 s, 6464 A LBBLA.26R4: 167.4 s, 1748 A LBBLC.27R4: 123.5 s, 2844 A 355.7 s, 238 A

  14. A. Verweij R. Flora 28 Feb 2008 Conclusion Experience during HWC of sector 4-5 • We experienced about 20 natural quenches, of which 8 in high current circuits (with quench heaters). This made it possible to make a rough estimate on the expected number of quenches during HWC of the other sectors. • For all quenches, the detection and resulting actions (heater firing, energy extraction, PC shut-down) worked perfectly. • ‘De-training’ (w.r.t 1st training quench after magnet reception) has been observed for 5 quenches (2xMB, 1xMQ, D3, Q5L5), and is somewhat worrying. • Quench behaviour with several circuits powered in parallel has not been tested. • A first estimate on the expected number of quenches during HWC of the other sectors is made for several energy levels.

  15. A. Verweij R. Flora 28 Feb 2008 Conclusion Quench propagation in the RB circuit • MB-to-MB quench propagation time seems to be typically 30-60 s, meaning that adjacent dipoles will quench at already strongly reduced current (note that t100 s). • 2 cases have been observed where the MB-MB propagation time was less than 1 s. The reason for this is under investigation. • 2 cases have been observed of MB re-quenching (at low current, after recovering). For both cases, QPS, heater firing and PM-files generation worked fine. • Quench propagation from one cryogenic cell to another has not been observed. • The maximum energy dissipated at cold for a quench event has been about 12 MJ, which is about 1% of the total energy in the RB circuit at nominal (1.1 GJ). Higher quench currents and faster propagation will increase the energy.

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