1. LQ Quench Protection – G. Ambrosio 1 LQ DS video Mtg – May. 23, 2007 BNL - FNAL - LBNL - SLAC Long Quadrupole Quench Protection Giorgio Ambrosio LQ DS Video-Meeting May. 23, 2007 OUTLINE: LQ Quench protection Spikes recorded during TQS01c test Comparison with real quench signals Plan

2. LQ Quench Protection – G. Ambrosio 2 LQ DS video Mtg – May. 23, 2007 TQ/LQ conductor parameters ParameterUnitValue N of strands-27 Strand diametermm0.700 Bare widthmm10.050 Bare inner edge thicknessmm1.172 Bare outer edge thicknessmm1.348 Keystoning angledeg.1.000 Radial insulation thicknessmm0.125 Azimuthal insulation thicknessmm0.125 Copper to non-copper ratio-0.89 Copper RRR-100

3. LQ Quench Protection – G. Ambrosio 3 LQ DS video Mtg – May. 23, 2007 Magnet parameters ParameterUnitLQ N of layers-2 N of turns-136 Coil area (Cu + nonCu)cm 2 29.33 Lengthm3.6 J c (12 T, 4.2 K) = 2400 A/mm 2 4.2 K temperature Quench gradientT/m223.49 Quench currentkA13.47 Peak field in the coil at quenchT11.59 Inductance at quenchmH/m4.1 Stored energy at quenchkJ/m372 1.9 K temperature Quench gradientT/m240.57 Quench currentkA14.57 Peak field in the coil at quenchT12.48 Stored energy at quenchkJ/m435

4. LQ Quench Protection – G. Ambrosio 4 LQ DS video Mtg – May. 23, 2007 LQ Quench Protection QuenchPro Input –Magnet parameters: TQC01 x 3.6 m coils Conductor:TQ cable (Jc 2400 A/mm 2 ) Total energy: 1.3 MJ @ 4.4K Code and input validation –Geometry, inductance, mat. prop (QLASA/Opera/ROXIE/TQC01): Done –Effect of changes to quench propagation routine:Very small Comparison with TQs data –TQ tests  set MIITs limit: in progress Quench protection parameters (aggressive) –Detection time: 5 - 10 msbased on TQs –Heater delay time: 10 - 15 msbased on TQs

5. LQ Quench Protection – G. Ambrosio 5 LQ DS video Mtg – May. 23, 2007 TQs Heater Delay & Detection Time Heater delay time: t ~ 10 ms close to quench plateau; t < 15 ms at I = 62% I ssl Detection time: 3 - 11 ms during TQS01c training –Flux jumps up to 600 mV with MJR cable TQC01 TQC01 protection heater studies by using spot heaters to initiate the quench. msec TQS01c

6. LQ Quench Protection – G. Ambrosio 6 LQ DS video Mtg – May. 23, 2007 MIITs Limit During TQC01 test, one QI vs. T measurement I: 5000 A,QI: 9.05 MIITs, Peak Temp: 340 K Impact on quench performance of high-MIITs quenches (TQS01c) + 4% after 8 MIITs - 2.9% after 8.1 MIITs - 7.4% after 8.7 MIITs - 18.4 after 9.5 MIITs Small bumps at 7.5 MIITs

7. LQ Quench Protection – G. Ambrosio 7 LQ DS video Mtg – May. 23, 2007 100% coverage75% coverage50% coverage 4.4 K Hot Spot 7.6 MIITs Heaters 4.6 MIITs 7.9 MIITs 4.9 MIITs 8.3 MIITs 5.3 MIITs Turn-turn 55 V Ground 446 V 65 V459 V84 V536 V 1.9 K 8.4 MIITs 4.9 MIITs 8.7 MIITs 5.2 MIITs 9.2 MIITs 5.7 MIITs 72 V489 V85 V520 V109 V615 V MIITs and Voltage at quench current Dump = 60 m  Detection time = 5 ms Heater delay time = 12 ms High MIITs at 1.9K Voltages OK

8. LQ Quench Protection – G. Ambrosio 8 LQ DS video Mtg – May. 23, 2007 How to get margin for safe LQ test? –100% heater coverage with 4 independent circuits per coil to be ~safe in case of failure (easier heater manufacturing, see LR) –Shorter detection time and/or heater delay time? Heater design, and QP system upgrade –Larger dump resistance? Hard at 1.9K: with 60 mohm we have ~ 1 kV at the leads Possible at 4.5 K: could go up to 75 mohm –Lower RRR in order to have shorter detection time? …risky… –Improve/upgrade VMTF Quench Detection System: Low threshold * small time: in order to avoid trips induced by spikes Capability of changing QDS threshold easily during tests YY?NYYY?NY LQ quench protection with TQ-like coils is challenging but doable at 4.5K

9. LQ Quench Protection – G. Ambrosio 9 LQ DS video Mtg – May. 23, 2007 Needs for LQ QP Four independent circuits for protection heaters Change dump resistance at 1.9K? Design LQ protection heaters Easily changeable detection threshold Develop smart quench detection to avoid spikes with low threshold? –Time –Voltage slope –Spike recognition –Current depending threshold

10. LQ Quench Protection – G. Ambrosio 10 LQ DS video Mtg – May. 23, 2007 Last trip by flux jump Threshold was 600 mV

11. LQ Quench Protection – G. Ambrosio 11 LQ DS video Mtg – May. 23, 2007 Half coil

12. LQ Quench Protection – G. Ambrosio 12 LQ DS video Mtg – May. 23, 2007 4 coils

13. LQ Quench Protection – G. Ambrosio 13 LQ DS video Mtg – May. 23, 2007 Quad 2 = Coil 8 segments

14. LQ Quench Protection – G. Ambrosio 14 LQ DS video Mtg – May. 23, 2007 VSDS Quench NO quench

15. LQ Quench Protection – G. Ambrosio 15 LQ DS video Mtg – May. 23, 2007 Quenches Quench 51 - I = 9600 A, T = 4.5 K, Rate = 20 A/s Time for decision should be less than 2 ms

16. LQ Quench Protection – G. Ambrosio 16 LQ DS video Mtg – May. 23, 2007 New QDS … in progress FPGA-based system: It is firmware running in a PXI board, and it does not depend on an operating system such as VxWorks, Linux, or Windows. Note that you already depend on this approach for VMTF quench detection and protection: in the current VMTF system, the Quench Logic Module (QLM) logic is programmed in firmware, and you depend on this module to perform properly to protect a magnet. This can really simplify the complexity of the system, as we have seen with the Stand 3 example. It can also make it easier to implement the type of adaptive logic we discussed during the meeting. Of course we need to discuss what level of redundancy or analog backups we need for risk mitigation.

17. LQ Quench Protection – G. Ambrosio 17 LQ DS video Mtg – May. 23, 2007 Appendix

18. LQ Quench Protection – G. Ambrosio 18 LQ DS video Mtg – May. 23, 2007 Quench Pro I Analytical code Adiabatic approximation Temperature computed from Quench Integral –Field is constant (average); different values for hot spot and bulk –Epoxy included in QI –Strand non_Cu = 76% Nb 3 Sn, 33% bronze (by Arup) Longitudinal propagation by QP velocity Quench starts under heaters –after detection time + heater delay time Temperature is uniform (given by QI) in normal zone of each cable –Different between Hot-spot and bulk

19. LQ Quench Protection – G. Ambrosio 19 LQ DS video Mtg – May. 23, 2007 Quench Pro II Current decay –Magnet can be switched to a dump resistance (after detection) or leads are short-circuited –Current decay is computed based on the instantaneous time constant (computed from the growing resistance and the inductance) –Inductance is computed based on position of each turn (inductance matrix) Voltages –Computed based on current, resistance, dI/dt, inductance matrix, (at dI/dt max) –Turn to ground –Turn to turn

20. LQ Quench Protection – G. Ambrosio 20 LQ DS video Mtg – May. 23, 2007 Sensitivity to Quench Prop. simulation New quench propagation routine in QuenchPro to better fit LQ magnet features  Very small effect! Temperature vs. MIITs tuned on TQC01 Dump = 60 m  Detection time = 8 ms Heater delay time = 15 ms 100% coverage75% coverage50% coverage 1.9 K 412 K Hot spot 108 K Heaters 449 K121 K504 K143 K 412 K108 K441 K118 K490 K138 K OLD routine NEW routine