long term behaviour and high miits test in the smc-rmc program · 2019-06-04 · logo area contents...
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Long term behaviour and high MIITs test
in the SMC-RMC program
Hugo Bajas et. al.
H. Bajas 23 May 2019
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Contents
SMC and RMC magnets introduction
Performed tests overview
Magnet performances overview
Thermal cycle effect overview
Powering cycle effect overview
Pre-stress effect overview
High quench integral (MIITs) tests
Conclusions and outlook
2H. Bajas 23 May 2019
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Contents
SMC and RMC magnets introduction
Performed tests overview
Magnet performances overview
Thermal cycle effect overview
Powering cycle effect overview
Pre-stress effect overview
High quench integral tests
Conclusions and outlook
3H. Bajas 23 May 2019
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Based on bladders & keys technology
Aims at :
testing performance of Nb3Sn conductor (PIT, RRP) in
racetrack configuration (block coil)
validating coil manufacturing technologies
electrical insulation (cable, central post, spacers)
impregnation methods, winding procedures
studying pre-stress’ influence on coil’s performances
Φ570 mm
4
Φ540mm
SMC & RMC magnets introduction
SMC
RMC
Racetrack Model Coil (RMC)Short Model Coil (SMC)
H. Bajas 23 May 2019
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Possible tests in 1DP or 2DP configuration
SMC & RMC magnets introduction
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Two double pancake (2DP) configuration:
• SMC #1
• SMC #3a
• SMC #3b
• SMC #4
• SMC #5
• RMC FreSCa2
• RMC QXF
One double pancake (1DP) configuration:
• SMC 11T #1
• SMC 11T #2
• SMC 11T #3
• SMC 11T #4
• SMC 11T #5
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SMC and RMC magnets introduction
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Magnet NameConductor
type
Stotal
(insult. cable)
[mm2]
Meas.
RRR
Bss (4.5 K)
[T]
Bss (1.9 K)
[T]
Iss (4.5 K)
[kA]
Iss (1.9 K)
[kA]
jss (4.5 K)
[A/mm2]
jss (1.9 K)
[A/mm2]
Splice
resistance
(nW)
SMC #3aPIT 288
26.375
12.7 13.4 14.0 15.2 533 579 0.910PIT 288 75
SMC #3bPIT 288
26.375
12.7 13.4 14.3 15.2 545 579 1.500PIT 288 75
SMC #4PIT 192
20.4120
13.3 14.5 11.6 12.8 568 627 0.525PIT 192 130
SMC11T #1 RRP 108/127 24.5 110 13.3 14.7 15.1 16.9 615 689 0.430
SMC11T #2 RRP 108/127 24.5 130 13.0 14.0 14.7 16.0 599 653 0.412
SMC11T #3 RRP 132/169 24.5 124 13.1 14.2 14.8 16.3 603 664 0.385
SMC11T #4 PIT 120 24.5 118 12.8 14.0 14.4 16.0 587 652 0.269
SMC11T #5 PIT 120 24.5 111 12.8 14.0 14.4 16.0 587 652 0.400
RMC_FreSCa2PIT 192
48.9180 15.1 16.8 17.2 19.2 351 392 0.164
RRP 132/169 240 15.5 16.9 17.6 19.4 360 396 0.176
RMC_QXFPIT 192
33.570
14.2 15.7 12.9 14.3 385 427 0.402PIT 192 110
Conductor type, Residual Resistivity Ratio (RRR)
and Short Sample limits (field, current, eng. current density)
H. Bajas 23 May 2019
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Contents
SMC and RMC magnets introduction
Performed tests overview
Magnet performances overview
Thermal cycle effect overview
Powering cycle effect overview
Pre-stress effect overview
High quench integral tests
Conclusions and outlook
7H. Bajas 23 May 2019
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Performed tests overview
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Magnet NameTest
Station
#
cooldowns
#
Quenches
#
Pre-stress
Reached
Ultimate
85% Iss @ 1.9K
Reached
Plateau
@ 4.5 K
Reached
Plateau
@ 1.9 K
Ramp rate
dependence
Temperature
dependence
VI
meas.
AC
loss
meas.
High MIITs
SMC #3a Longue 3 83 2 Y Y Y N N N N 150
SMC #3b Longue 3 19 1 Y ? N N N N N ! (1500 K)
SMC #4 Siegtal 2 60 1 Y Y N N N Y Y 360 K
SMC 11T #1 Longue 4 96 1 Y Y N Y Y Y Y 200 K
SMC 11T #2 Longue 4 129 2 Y Y Y Y N N N 200 K
SMC 11T #3 Siegtal 8 220 4 Y Y Y Y Y N Y 200 K
SMC 11T #4 Siegtal 2 79 2 Y Y Y Y Y Y Y 200 K
SMC 11T #5 Siegtal 2 37 1 Y Y Y Y Y Y Y 400 K
RMC_FreSCa2 Longue 2 (+2) 72 1 Y Y Y Y Y N Y 100 K
RMC_QXF Siegtal 2 70 1 Y Y Y Y Y Y Y 100 K
H. Bajas 23 May 2019
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Contents
SMC and RMC magnets introduction
Performed tests overview
Magnet performances overview
Thermal cycle effect overview
Powering cycle effect overview
Pre-stress effect overview
High quench integral tests
Conclusions and outlook
9H. Bajas 23 May 2019
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RRR measurements comparison
Magnet performances overview
The average RRR for:
PIT conductor: 103±32
RRP conductor: 151±52
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RMC FreSca2
RRP
240
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Splices measurements comparison
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Magnet performances overview
Average resistance:
Rsplice=0.543 ± 0.375 nW
Excellent results!
Rsplice < 1 nW
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Magnet performances overview
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Tested magnets
SMC #3a (SMC #3b)
SMC #4
SMC 11T #1
SMC 11T #2
SMC 11T #3 (SMC 11T #3 shimmed)
SMC 11T #4
SMC 11T #5
RMC FreSCa2
RMC QXF
And training curves
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Magnet performances overview
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One instance (SMC3a) to explain the following analysis?
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92 % 92 %95 %
96 %
81 %
97 %
86 %
95 %
93 %
Main characteristics:
First quench @ 4.2 K
Quench current plateau @ 4.2 K
@ 1.9 K
Training rate
Thermal cycle effect Training memory
Re-training
Performance degradation
Powering cycle effect
Transverse Pre-stress effect 110 MPa 110 MPa 130 MPa
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Magnet performances overview
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Tested magnets and training curves:
SMC #3a (SMC #3b)
SMC #4
SMC 11T #1
SMC 11T #2
SMC 11T #3 (SMC 11T #3 shimmed)
SMC 11T #4
SMC 11T #5
RMC FreSCa2
RMC QXF
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Magnet performances overview
Iq
/Iss (1st quench) measurements comparison
First quench (@ 4.2 K)
occuring at:
Iq
/Iss = 78.7±7.5 %
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Magnet performances overview
Iq/Iss (plateau current) measurements comparison
Average Iq/Iss :
@ 4.2 K
RRP : 98%
PIT : 93%
@ 1.9 K
RRP : 94%
PIT : 95%
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Number of quenches to reach current plateau
Average number of quenches
to reach plateau @ 4.5 K:
N=13 ± 7
Average number of quenches
to reach plateau @ 1.9 K
(after 4.5 K training)
N=9 ± 4
Magnet performances overview
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Training rate @ 4.5 and 1.9 K
Average training rate:
@ 4.5 K
90 ± 43 A/quench
@ 1.9 K
150 ± 59 A/quench
Magnet performances overview
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Ramp rate dependence of the quench current
Magnet performances overview
Core cable
No core
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Contents
SMC and RMC magnets introduction
Performed tests overview
Magnet performances overview
Thermal cycle effect overview
Powering cycle effect overview
Pre-stress effect overview
High quench integral tests
Conclusions and outlook
20H. Bajas 23 May 2019
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Thermal cycle effect overview
Drop of current before/after thermal cycle
Average loss of performance
after thermal cycle:
DIth.cl. =740 A ± 588 A
Permanent degradation ?
Retraining...
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Thermal cycle effect overview
Drop of current before/after re-training
Average degradation after re-training:
@ 4.5 K
DIc/Iss = 2.2 ± 2.2 %
@ 1.9 K
DIc/Iss = 3.6 ± 3.4 %
Some magnets do not degrade
(SMC3#a, SMC11T#3).
Some degrade significantly (> 5%)
(SMC4, SMC11T#5, RMC_FreSCa2).
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Thermal cycle effect overview
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SMC 4 (PIT)
Evidence of degradation only due to
thermal cycle.
-400 A
H. Bajas 23 May 2019
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Contents
SMC and RMC magnets introduction
Performed tests overview
Magnet performances overview
Thermal cycle effect overview
Powering cycle effect overview
Pre-stress effect overview
High quench integral tests
Conclusions and outlook
24H. Bajas 23 May 2019
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Powering cycle effect overview
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Evidence of degradation after a quench at higher Lorentz force
SMC 11T # 5 (PIT)
-1500 A
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Rods’
Ax. Strain vs I2
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Powering cycle effect overview
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SMC 11T # 4 & # 5 (PIT)
Exact same training behavior btw.
both magnets
-1000 A
H. Bajas 23 May 2019
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Powering cycle effect overview
Effect of current plateau on quench current
(RMC QXF, PIT)
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+ 6% increase on quench current
using plateau!
H. Bajas 23 May 2019
or
time
Cu
rre
nt
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Powering cycle effect overview Precursor to quench and training (RMC QXF)
28H. Bajas 23 May 2019
Large gap (gain) of current ≡ Large precursor
Small gap (gain) of current ≡ Small precursor
Plateau current quench ≡ No precursor
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Powering cycle effect overview
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Lorentz forces cycling loading effect (SMC 4)
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Evidence of precursor (voltage spikes) vanishing from ramp to ramp
Less and less activity
at each ramp
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Powering cycle effect overview Lorentz forces cycling loading effect (SMC 4)
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Contents
SMC and RMC magnets introduction
Performed tests overview
Magnet performances overview
Thermal cycle effect overview
Powering cycle effect overview
Pre-stress effect overview
High quench integral tests
Conclusions and outlook
31H. Bajas 23 May 2019
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Pre-stress effect overview
32
Quench current vs. Temperature for different level of pre-stress
SMC 11T # 3 (RRP)
Evidence of permanente degradation
going back to 180 MPa after 200 MPa.
Same degraded performance going back
to 150 MPa from 180 MPa.
Interesting change of slope for T < Tl
Superfluid stabilizing defect
-500 A
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Pre-stress effect overview
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Degradation also observed on the
Iq vs. RR plot.
-1200 A
Quench current vs. Ramp rate for different level of pre-stress
SMC 11T # 3 (RRP)
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Pre-stress effect overview
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Evidence of degradation ~200 A
from 150 to 170 MPa
No test back to 150 MPa...
Again…Change of slope for T < Tl
-200 A
Quench current vs. Temperature for different level of pre-stress
SMC 11T # 4 (PIT)
H. Bajas 23 May 2019
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Contents
SMC and RMC magnets introduction
Performed tests overview
Magnet performances overview
Thermal cycle effect overview
Powering cycle effect overview
Pre-stress effect overview
High quench integral tests
Conclusions and outlook
35H. Bajas 23 May 2019
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High quench integral tests
SMC3b
36
The NbTi cable has fused.
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High quench integral tests
SMC 11T # 1 & #2
37
No degradation after any High Quench
integral tests on SMC11T
Test limited to 220 K due to the small
magnet inductance
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High quench integral tests
SMC 4
38
Using spot heater higher Hot Spot can be reached.
Thot Spot > 300 K No Clear Evidence of permanente degradation (retraining possible)
98%
92%
95%
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High quench integral tests
SMC 11T 5
39
Validation of the Hot Spot Assessment using: Fiber Optic Sensor, Votage taps and Comsol simulation
Thot Spot > 400 K No extra degradation
on top of the existing degradation (70%)
H. Bajas 23 May 2019
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Contents
SMC and RMC magnets introduction
Performed tests overview
Magnet performances overview
Thermal cycle effect overview
Powering cycle effect overview
Pre-stress effect overview
High quench integral tests
Conclusions and outlook
40H. Bajas 23 May 2019
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Conclusions and outlook Excellent splicing techniques (< 1 nW)
RRR: 120 RRP, 110 PIT
A constant in all magnets: First quench @ 80% Iss
Maximum performances
at 4.5 K 98% RRP, 93% PIT
at 1.9 K 94% RRP, 95% PIT
Degradation due to thermal cycle is observed < 4 %
Degradation due to powering cycle is observed < 2 %
Characteristic curves for degradation assessment:
Iq(ramp rate), Iq(Top), , Iq(strsv.)
Importance of the precursors and the current ramp pattern in the training behavior
High quench integral tests performed up to 400 K without clear evidence of degradation
41H. Bajas 23 May 2019
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SMC 11T #2
After cold powering
SMC 11T #2
After impregnation
Thank you for your attention
42H. Bajas 23 May 2019
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Literature and reference
A. Devred et al., 2006, “Overview and status of the Next European Dipole (NED) joint research activity,” Sup. Science Tech., vol. 19.
H. Felice et al., 2007, “Design and test of a subscale dipole magnet for training studies,” IEEE Trans. Applied Superconductivity, vol. 17.
P. Manil et al., 2010, “Magnetic design and code benchmarking of the SMC (Short Model Coil) dipole magnet,” IEEE Trans. Applied Sup., vol. 20.
F. Regis et al., 2010, “Mechanical design of the SMC (Short Model Coil) dipole magnet,” IEEE Trans. Applied Superconductivity, vol. 20.
M. Bajko, et al., 2012, “The Short Model Coil (SMC) Dipole: An R&D program towards Nb3Sn accelerator magnets,” IEEE Trans. Appl. Supercond., vol. 22
C. Kokkinos et al., 2012, “The SMC (Short Model Coil) Nb3Sn program: FE analysis with 3D modeling,” IEEE Trans. Appl. Supercond., vol. 22.
E. Fornassiere et. al., 2013, “Status of the Activities on the Nb3Sn Dipole SMC and of the Design of the RMC”, IEEE Trans. Appl. Sup., vol. 28.
A. Chiuchiolo et. al., 2014, “Fiber Bragg Grating Cryosensors for Superconducting Accelerator Magnets”, IEEE Photonics Journal, Vol .6.
S. Izquierdo Bermudez, H. Bajas, L. Bottura, 2015, “Quench modeling in high-field Nb3Sn accelerator magnets,” Phys. Procedia, vol 67.
J.C. Perez et al., 2015, “Performance of the Short Model Coils Wound With the CERN 11-T Nb3Sn Conductor”, IEEE Trans. Appl. Sup., vol. 25.
Bajas H et al., 2015, “Quench Analysis of High-Current-Density Nb3Sn Conductors in Racetrack Coil Configuration”, IEEE Trans. Appl. Sup., vol. 25.
A. Chiuchiolo et. al., 2016, “ Advances in Fiber Optic Sensors Technology Development for Temperature and Strain Measurements in Superconducting
Magnets and Devices” , IEEE Trans. Appl. Sup., vol. 26.
J.C. Perez et. al., 2016, “16 T Nb3Sn Racetrack Model Coil Test Result”, IEEE Trans. Appl. Sup., vol. 26.
S. I. Bermudez, L. Bottura, H. Bajas, G. Willering, 2018, “Analytical method for the prediction of quench initiation and development in accelerator
magnets”, Cryogenics, vol. 95
Bajas H et al., 2018, “Advanced Nb3Sn Conductors Tested in Racetrack Coil Configuration for the 11T Dipole Project”, IEEE Trans. Appl. Sup., vol. 28.
43H. Bajas 23 May 2019
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Training memory
SMC3a
44
92 % 92 % 95 %
96 %
81 %
97 %
86 %
95 %
93 %
H. Bajas 23 May 2019
110 MPa 110 MPa 130 MPa
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Training memory
SMC3b
45
130 MPa
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Training memory
SMC 11T 1
46
78%
94%
99%
94%92%
130 MPa
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Training memory
SMC 11T 2
47
97%
76%
89%
94% 90%
81%81%
92% 91%
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Training memory
SMC 11T 3
48
150 MPa
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Training memory
SMC 11T 3
49
150 MPa 180 MPa 200 MPa 180 MPa 150 MPa
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Training memory
SMC 11T 4
50
150 MPa 170 MPa
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Training memory
SMC 11T 5
51
150 MPa 150 MPa
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Training memory
SMC 4
52
150 MPa
85%
94%
96%
93%
97%
90%
96%
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RMC FreSCa2
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97%
95%
95%
95%
90%90%
89%
120 MPa
94%
Training memory
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Training memory
RMC QXF
54
120 MPa
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Quench velocity
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