MBHSP109 Test results 11T technical meeting – 30-01-2019 EDMS number: Gerard Willering Marta Bajko, Vincent Desbiolles, Michał Duda, Jerome Feuvrier, Franco Mangiarotti, Daniel Turi, Marcus Wallin Thanks to Jerome Fleiter, Bernardo Bordini, Susana Izquierdo, Lucio Fiscarelli and all involved in the production and preparation of the magnet and discussions about test results 11T technical meeting – 30-01-2019 EDMS number:

Contents Model history Training V-I curves Coil limits Conclusions

Overview on short model magnets tested Collared coil Coil Conductor cu/sc Coil R at 300 K RRR Heater Type Glass heater-coil mΩ 293K/4K mm SP101 CC101 106 RRP 108/127 1.22 423 66 Glued 0.00 107 426 97 0.10 SP102 CC102 108 RRP 132/169 407 185 SP103 CC103 109 1.27 400 131 111 401 124 DP101 SP104 CC104 112 403 125 0.08 (E-glass) 113 115 SP105 CC105 114 RRP 150/169 0.98 432 Impregnated 0.97 436 110 DP102 CC104b CC105b SP106 CC106 116 449 103* 117 450 100* SP107 CC107 120 1.19 413 190* 121 SP109 CC109 119 411 123 409 * 296K/20K Thanks to Susana for the table compilation “Final” heater lay-out Final conductor RED: numbers bellow specifications More details on: https://espace.cern.ch/HiLumi/WP11/Shared%20Documents/tested_magnet_parameters.xlsx?Web=1

Training per collared coil SP107 and SP109 are “fast” training coils single aperture magnets. Ultimate current reached after 10 and 15 quenches Detraining quenches did not occur below nominal current for SP107 and SP109 SP106 was trained at 4.5 K and trained rather slow.

Training SP109 119 123 1 2 3 4 5 6 In some quenches precursors were observed 0 quenches needed after thermal cycle to reach nominal current : good memory 4 quenches needed after thermal cycle to go from 12.4 to 12.85 kA. Quench 21 to 27 are all coil limit quenches, see later slides

Training Memory The memory of all 11T magnets tested so far was good to excellent, even in cases where the collared coils were re-yoked or re-collared. This is an important value for machine operation. SP109 memory will be tested next week.

Comparison SP107 and SP109 120 121 119 123 SP107 SP109 4 6 7 8 5 9 10 After 5 quenches comparable quench level for the 4 coils Coil 119 takes a bit longer to finish training 120 121 Goal for SP107 and SP109 was to show reproducibility of coil production. SP109 119 123

Training per coil Very low first quench current in coil 119 (SP109), but reaching nominal current after 3 quenches All coils of SP107 and SP109 are training fast

Quench location Pole turn takes less than 10 % of training quenches. Earlier coils 107 and coil 113 had an important number of poleturn quenches, very likely linked to the layer jump issue in those coils. Quenches starting in block 6 are normally rare, but not for coil 119. Quench type SP107 Coil 120 Coil 121 SP109 Coil 119 Coil 123 Midplane IL 2 Poleturn IL 1 Block 1 Block 2 Block 3 4 Block 4 Block 5 Block 6 Total 8 6 10 5 4 6 3 Observation: Almost no pole turn quenches in SP107 and SP109 2 5 1

Example of quench data precursor E= 𝑉𝐼𝑑𝑡 Quenching voltage segment Data signatures as used to analyse each quench Damped oscillation in quench antenna

Quench location (longitudinal) 4 6 7 9 1 2 8 5 10 3 SP106 Only first 10 quenches shown for SP106 1 2 3 4 5 6 7 8 9 10 ??4,5,6,7 11 12 13 14 Including block 6 quenches SP106 SP107 SP109 SP107 121 120 SP109 Block 6 quenches seem longitudinally localized (not very precisely) 119 123 SP109 Quenches in the head mainly on the connection side SP109

Summary of endurance and cycling tests MBH magnets Most strained magnet is SP106 (which reached the highest current and field of all magnets) SP104 SP105 DP102 SP106 SP107 5.5 m proto SP109 # QH firings 150 A (at 1.9 K + 4.5 K) At I > 10 kA At I < 10 kA 42 15 ~50 ~5 ~26 ~10 ~110 ~30 ~ 20 ~ 10 ~4 ~71 ~22 ~67 # QH firings 200 A (at 1.9 K) - 1 (coil 119) 5 (coil 119) # current cycles > 10 kA ~48 ~64 ~84 ~170 44 4 132 # cool downs 1 3 2 # quenches at 1.9 K ~35 ~15 ~60 18 ~ 26 17 # quenches at 4.5 K ~7 ~40 ~ 2 2 QH circuits of coil 119 have seen 6 discharges at 200 A > 2000 current cycles (2 min / cycle) > 200 QH firings (20 min / discharge) Requests: > Thermal cycle (1.5 week / TC) Breakdown in SP109 QH to coil: At 130 K: Between 1 and 1.28 kV At 230 K: at 1.01 to 1.04 kV Impossible to say if this breakdown occurred in the magnet, or in the insert. No degradation observed following this breakdown. QH to coil HV test voltage on insert or on test bench, with tests passed SP104 SP105 DP102 SP106 SP107 5.5 m proto SP109 300 K, Air, before powering 1 kV 2.6 kV He gas, before powering - 1.9 K or 4.5 K He before powering 3.3 kV 1.9 K or 4.5 K, He, after powering He gas after powering 1 kV (130 K) 0.9 kV (230 K) 300 K, Air, after powering 600 V 2019-01-11 - Review 11T QH - Cold powering tests and insulation tests in SM18

Magnet Qualification Following our qualification standards, the magnet passes all test performed so far: Ultimate current is reached in both cooldowns The magnet does not suffer from detraining quenches below nominal current level Good memory: no retraining up to nominal current Stable operation for > 1 hour at flattop at ultimate current. HV test cannot be done at > 1 kV in the test station, but good up to that level, even in He gas Splices are OK The next slides are going beyond normal qualifications, looking at magnet limits and margins Very detailed investigations are done to understand the magnet better, including midplane critical current reduction.

Coil limit Focus on the mid plane quenches

V-I measurements – Cooldown 1 V-I curves measured for 1.4 m long straight midplane segments. Consistency between 1.9 and 4.5 K data. In opposing segments in coil 123 and coil 119 a transition was measured. In SP106 the measurement was done, but no voltage rise found up to 13.4 kA 119 123 V-I measurements not done in SP107 (lack of time) Transitions on midplanes shown in coils 109, 112, 114, 115, 119 and 123.

119 123 Quench signature of one of the mid plane limiting quenches 860 V/s 640 V/s 115 V/s 119 123 The 2 midplane turns, quickly followed by multiturns. The slope of the multiturns suggest that in the multiturns 5 to 8 turns are quenching. It means that about 15 turns have a rather high MIIts and hotspot temperature, which could increase the local stress during training since a large portion is warm. Very clear quench propagation signal in QA: Longitudinal center of the coil

Ramp rate studies Comparison SP107 and SP109. SP107 not ramped to limit at 1.9 K Small reduction CD 1 to CD 2 of 0.7 % (90 A) SP109 limited at 12.95 kA, or 90 % of Iss SP107 extrapolation suggests a coil limit at 13.5 kA at 1.9 K (94 % of Iss)

Magnet limits SP106 reached the highest current level, but also had the highest short sample limit. SP102, SP103, SP107, SP109 reached target (ultimate current), but were not trained further. SP104, SP105 and DP102 had clear limit in the midplane Midplane limit 1.9 K consistent with midplane limit at 4.5 K

V-I measurements CD 1 and CD 2 compared Voltage as measured in cooldown 1 and 2 119 C123-I2-I3 Midplane segment 123 Reduction: ~ 250 A 2 % on loadline, 6 % in Ic at fixed B) Degradation in V-I curve Stable voltage at 12.85 kA plateau for 1 hour. Note: At 4.5 K the results are consistent with 1.9 K V-I measurement repeated 3 times more following 3 quenches in the midplane: Very consistent results and no degradation from the midplane quenches

V-I measurements CD 1 and CD 2 compared Voltage as measured in cooldown 1 and 2 119 C119-II-I1 Midplane segment 123 Reduction: ~ 350 A 2.5 % in I/Iq 8 % in Ic (at fixed B) Degradation in V-I curve Stable voltage at 12.85 kA plateau for 1 hour. Note: Iss following V-I curve is reduced by 2 to 2.5 % Iq at 4.5 K is reduced much less (0.7 %) Iq is a local quench start location, V-I is measured over 1.4 meter V-I measurement repeated 3 times more following 3 quenches in the midplane: Very consistent results and no degradation from the midplane quenches

Irreversible or reversible - Studies in MSC-SCD Reversible reduction of critical current Irreversible reduction of critical current https://edms.cern.ch/ui/file/1782503/1/ArticleEucas2017HPFresca_JE_Duvauchelle_1782503.pdf Critical Current Measurements under Transverse Pressure of a Nb3Sn Rutherford Cable based on 1 mm RRP wires J-E Duvauchelle, B. Bordini, J. Fleiter and A. Ballarino High n-value No strong reduction of n-value while critical current reduces significantly Strong change in n-value following degradation Question to be answered: Is low n-value in the magnet always a signature of irreversible degradation, or do other effects play a role

Reminder prototype Raw data measured of a full coil (56 turns per voltage segment) Some impact of inductive components. 3 good coils used as reference, allowing coil D2U (aperture 2, upper coil) to be analysed Very low n-value (<5) Very low critical current

Conclusions on midplane investigations SP109: Conductor limit in midplane defines maximum quench current at 12.9 kA SP109: Degradation of V-I curve in both midplane segments of about 2 to 2.5 % (6 to 8 % in Ic with fixed B) SP107: V-I was never measured (no time), but Iq/Iss was higher SP109: Quench current at 4.5 K only slightly changed from CD 1 to CD2 (<0.7 %) Magnet still qualifies for all requirements, but investigation needed.