1. 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 –
EDMS number:

2. Contents
Model history
Training
V-I curves
Coil limits
Conclusions

3. 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:

4. 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.

5. 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 kA.
Quench 21 to 27 are all coil limit quenches, see later slides

6. 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.

7. Comparison SP107 and SP109 120 121 119 123 SP107 SP1094 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

8. 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

9. 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

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

11. 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

12. 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 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
Review 11T QH - Cold powering tests and insulation tests in SM18

13. 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.

14. Coil limit
Focus on the mid plane quenches

15. 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.

16. 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

17. 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 kA, or 90 % of Iss
SP107 extrapolation suggests a coil limit at 13.5 kA at 1.9 K (94 % of Iss)

18. 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

19. 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 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

20. 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 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

21. Irreversible or reversible - Studies in MSC-SCD
Reversible reduction of critical current
Irreversible reduction of critical current
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

22. 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

23. 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.