Magnetic measurements on MBHSP104 Lucio Fiscarelli Second debriefing meeting on the cold tests of the 11T dipole model MBHSP104 6 July 2016 CERN

Conclusions Outline Measurement list Measurement systems Provisional results Central TF b3 (persistent currents) Multipoles Effect of magnetic shims Comparison with other models Conclusions

Measurement list Ambient temperature, central and integral field at ±20 A After collaring (CC) After shell welding (CM) Cryogenic temperature, central and integral field up to nominal* At 1.9 K Machine simulation cycle (quench at the end of ramp-up 11.75 kA) Stair-step cycle (quench at the end of ramp-up 11.49 kA) At 4.3 K Machine simulation cycle (ok)

Measurement system at ambient temp. Motor + encoder + slip-ring unit (MRU) Fast Digital Integrator (FDI) FuG low voltage power supply (40 V, 20 A) DCCT Hitec MACC-plus Search coil shafts Number of turns (-) 256 Inner width (mm) 13.41 Inner length 1195.60 Groove thickness 1.40 Magnetic surface (m2) 3.37 Radius 21.33 A measurement is an average over 1.2 m Measurements in 3 positions: Shaft centered -> central field Two adjacent positions -> integral field

Measurement system at cryogenic temp. Fast Digital Integrators (FDI) Motor + encoder + slip-ring unit (MRU) Vertical shaft rotating in liquid He Segment 7 7 segments: 5 short in the middle + 2 longer on the ends Number of turns - 36 Inner width mm 10.3 Inner length 431.5 246.5 Groove thickness 0.57 Magnetic surface m2 0.17 0.10 Radius 21.5 A measurement is an average over 250 mm (432 mm) The shaft cannot be translated along the magnet after installation Segment 1

Measured transfer function Ambient temperature Measured transfer function SP101 SP102 SP103 SP104 Central T/kA 0.9874 0.9926 0.9917 0.9891 Integral Tm/kA 1.6725 1.6833 1.6756 1.6722

Inverse analysis We do expect that SP104 is similar to SP103 and SP102 We can compute the differences and reconstruct their distribution in the x-y plane This points to a localized source of field distortion: shim made of magnetic material n Δ bn Δ an 2 9.71 -25.00 3 -13.63 -9.09 4 -5.47 3.84 5 1.97 4.16 6 2.45 -1.44 7 -0.06 -1.19 8 -1.24 -0.16 9 0.01 0.42 10 0.00 11 0.02 -0.11 12 13 -0.04 14 15

Inverse analysis We can compute with ROXIE the effect of the magnetic shim at low excitation current But we need to know the permeability curve 301LN MH curve found in literature Materials Research, Vol. 10, No. 4, 359-366, 2007 Emelie Kristina Nilsson Susana Izquierdo Bermudez

Inverse analysis Then we can compute with ROXIE the effect of the magnetic shim at high field Emelie Kristina Nilsson Susana Izquierdo Bermudez

Inverse analysis Then we can compute with ROXIE the effect of the magnetic shim at high field 11850 A n bn an ROXIE 5% degrad. ROXIE 26% degrad. ROXIE no magnetic shim 2 0.1 0.3 0.0 -0.1 3 6.0 5.9 6.1 -0.2 4 5 0.4 6 7 8 9 0.9 10 11 0.5 12 13 14 15 Emelie Kristina Nilsson Susana Izquierdo Bermudez

Cryogenic temperature Comparison MBHSP104 and MBHSP103 Agreement on TF (to be confirmed) Some data are noisy Larger spread on b3 loops at low field on MBHSP104 SC cables or shims?

Cryogenic temperature Other multipoles at high field (11.85 kA) We assume a negligible effect of magnetic shims at high field (ROXIE calculations) Field quality of MBHSP104 is similar to previous models “Good” magnet to magnet reproducibility for geometric multipoles

Decay and snapback Δb3 = b3 - b3(tstart inj plateau) “decay/snapback” effect is visible on MBHSP104 as well Dependence on longitudinal position as on previous models Slightly larger amplitude on MBHSP104 Different behavior at 4.3 K

Current redistribution at high field Change of b3 and a3 on a plateau at high field At 12.00 kA before a quench (holding current test) for MBHSP104 At 11.85 kA (mm pre-cycle) for MBHSP103

Conclusions MBHSP104 Magnetic measurement results at ambient temperature are affected by the presence of magnetic shims Calculations with ROXIE show small effect of shims at high field Measured field quality at high field is comparable with previous models Larger spread on b3 at low field (SC cables or shims?) “decay/snapback” effects are visible with slightly larger amplitude Larger current redistribution effects at high field