Geneva, 12/06/ Results of Magnetic Measurements on MQXC 02 L. Fiscarelli on behalf of TE/MSC/MM section

Geneva, 12/06/2014 Overview  Introduction: – Measurement system – Measurement plan  DC characterization – Stair step cycle (load-line)  Dynamic characterization – Ramp-rate study  Simulated machine cycle – Repeatability and Decay / Snapback  Comparison with ROXIE model (data provided by Per Hagen)  Cold-warm correlation  Measurement resolution  Conclusions

Geneva, 12/06/2014 The two setups 5 coils Support tube R=45 mm – Flexible software Framework for Magnetic Measurements (FFMM) – PXI crate – Fast Digital Integrator (FDI) – Motor + encoder + slip-ring units – Large diameter rotating shaft

Geneva, 12/06/2014 Measurement plan  A short magnetic measurement campaign was requested (limited availability of cryogenic test station)  Minimal set of measurement cycles was planned (“standard program”) – Stair-step (“load-line”) – Ramp-rate study (10, 20, 40, 80 A/s) – Simulated machine cycle 3x (plateau of 1000 s at 820 A and then PELP ramp)  Problems with Power Converter (trips on high current plateaus) wasted some time – Simulated machine cycle repeated only 2 times

Geneva, 12/06/2014 Results: stair-step cycle Stair-step cycle to measure the DC transfer function and DC field quality  quench  pre-cycle (ramp-up at 11 A/s up to 12.8 kA, plateau of 300 s, ramp-down at -11 A/s to 100 A)  from 100 A to 12.8 kA and back with a total of 35 steps  plateaus (140 s)  linear ramps (11 A/s)

Geneva, 12/06/2014 Results: stair-step cycle, TF Transfer function  Strong saturation  -180 units on straight section  -160 units on integral

Geneva, 12/06/2014 Results: stair-step cycle, allowed multipoles

Geneva, 12/06/2014 Results: stair-step cycle, not allowed multipoles

Geneva, 12/06/2014 Results: ramp-rate study Ramp-rate study cycle to measure the effect of eddy currents and cable coupling currents  pre-cycle (ramp-up at 11 A/s up to 12.8 kA, plateau of 300 s, ramp-down at -11 A/s to 100 A)  current cycles from 820 A to 12.8 kA and back  different ramp rates (10, 20, 40, 80 A/s)

Geneva, 12/06/2014 Results: ramp-rate study As expected very small effects of ramp-rate on TF and multipoles

Geneva, 12/06/2014 Results: simulated machine cycle Simulated machine cycles to measure multipoles in machine simulated conditions and the contribution of the persistent current decay and snapback  quench  pre-cycle (ramp-up at 11 A/s up to 12.8 kA, plt of 300 s, ramp-down at -11 A/s to 100 A)  plateau at injection current of 1000 s  ramp to the nominal field with slow parabolic start (no exponential)  repeated two times

Geneva, 12/06/2014 Results: simulated machine cycle, repeatability

Geneva, 12/06/2014 Results: simulated machine cycle, decay and snapback

Geneva, 12/06/2014 Comparison with ROXIE model  Transfer Function – -25 units measured on geometric – Exact match for saturation  b 6 – Good agreement  b 10 – Constant offset * data provided by Per Hagen

Geneva, 12/06/2014 Cold-warm correlation of multipoles Multipoles at 1.9 K are smaller than at 300 K  Correlation factor of 0.91  Elastic deformation ???

Geneva, 12/06/2014 Measurement precision High precision measurement results  better than 0.01 units at 40 mm on multipoles  ±5 units on TF

Geneva, 12/06/2014 Conclusions  Complete MM test campaign at cryogenic temperature on MQXC 02  Saturation  Low ramp-rate dependency  Decay and snapback as expected  High precision results both on TF and multipoles  Disagreement model/measurements on TF solved

Geneva, 12/06/2014 Appendix

Geneva, 12/06/2014 Appendix 1: Correction of thermal contraction of shaft at 1.9 K [1] Material Properties: G-10 CR (Fiberglass Epoxy) [1] We range from 300 K to 1.9 K  thermal coefficient is ‘a’ A coil is a 3D object (width, length, radius)  a normal * a warp * a warp → %

Geneva, 12/06/2014 Appendix 2: Parameterization of Transfer Function [2] L. Bottura, Standard Analysis Procedures for Field Quality Measurement of the LHC Magnets - Part II: Transfer Functions and Parameterization