Transcript Felice - HQ protection

HQ
Summary of quench protection studies
2nd Joint HiLumi LHC – LARP Annual Meeting
INFN Frascati – November 14th to 16th 2012
LBNL: Helene Felice – Tiina Salmi – Ray Hafalia – Maxim Martchevsky
FNAL: Guram Chlachidze
CERN: Ezio Todesco – Hugo Bajas
HQ protection heaters
•
•
•
•
PH strip on both layers
2 strips per layer
4 strips per coil
Strip R: ~ 4.5 W at 4.2 K
Layer 2
B02
B01
Layer 1
A02
A01
• Powering scheme
• Typical: 4 circuits
• all B02, all A02, all B01, all A01
• PH hipot failure to coil can lead to replacement by a resistance
• In some cases, enough power supplies to power a few strips individually
• Coverage of about 60 % (including propagation between station)
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MIITs curve and Time margin
30
•
Well-known that material properties play an important role
•
Example of HQ MIITS computation:
MIITs (10^6*A^2*s)
25
20
NIST+cryocomp /cryocomp /quenchpro
At 2K and 12 T RRR 60 = 20.6 / 21.6 / 19.5
At 2K and 0 T RRR 60 = 25.2/ 26.3 / 23.5
15
10
5
T0 = 2 K
0
0
50
12 T, RRR = 60
12 T, RRR = 100
0 T, RRR = 100
0 T, RRR = 60
100
150
200
Hotspot temperature (K)
250
Average: 2 K, 12 T and RRR 60 = 20.6 +/- 1 MIITs
300
Figure of merit: the time margin (E. Todesco)
(MIITS budget – MIITS decay)/I2 = time to quench
HQ time margin of the order of 27 ms
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HQ
Protection studies overview
• Several tests
• Magnets: HQ01a to e
• Mirror: HQM01 and HQM04
• Protection Heaters (PH) studies
• Heater power
• Margin
• Kapton thickness
• Quench back
• MIITS limits
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Protection Heater (PH)
Delay time versus peak power
HQ01d
80
Tau = 31 ms
Time delay (ms)
70
HQ01d
60
30 % Iss, circ#1 (IL circ)
50
30 % Iss, circ#5 (OL strip)
40
60% Iss, circ#5 (OL strip)
30
20
HQM01
10
100
0
20
40
60
2
Peak power (W/cm )
• Some saturation of the delay at high peak power
• Tau => total energy impacts the delay time
• Strongly at low fraction of Iss
• Marginally at higher fraction of Iss
• Some studies on optimization of energy deposition
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Imag/ Iss
90
80
Delay to quench onset (ms)
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2nd Joint HiLumi LHC - LARP Annual
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tau = 24 ms
tau = 47 ms
29 %
80
70
60
50
29 %
40
30
42 %
42 %
20
10
70 %
0
40
60
80
Peak power (W/cm2)
100
5
Impact of Kapton thickness
on PH delay
Kapton
thickness
Delay to quench onset (ms)
60
50
40
HQM04, 4.6 K
75 mm
HQM01, 4.6 K
50 mm
HQ01e, 4.4 K
25 mm
• Large increase of PH delay
with Kapton thickness
30
20
• From 60 to 150 % from
HQ01e to HQM04
10
0
0
20
60
40
Imag/iss (%)
80
100
HQ01e at CERN: Pw0 = 50 W/cm2, tau 40 ms: Iss = 17.3 kA @ 4.4 K; 19.1 kA @ 1.9 K
HQM04 at FNAL: Pw0 = 45 W/cm2, tau 46 ms: Iss = 16.2 kA @ 4.6 K; 18.2 kA @ 2.2 K
HQM01 at FNAL: Pw0 = 47 W/cm2, tau 46 ms: Iss = 17.0 kA @ 4.6 K
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meeting
H. Bajas et al., “Test Results of the LARP
HQ01 Nb3Sn quadrupole magnet at 1.9 K”,
presented at ASC2012
T. Salmi et al.: “Quench protection
challenges in long Nb3Sn accelerator
magnets”, AIP Conf. Proc. 1434, 656 (2012)
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Il versus OL
HQM04VPH
(75=mm
250 kapton)
V
HQ01e at CERN – coil 9 tested
(25 mm Kapton)
PH delay time (ms)
80
2
OL - 4.4 K 40 -49 W/cm
60
IL - 4.4 K
40
55 W/cm2
20
Delay to quench onset (ms)
60
50
40
30
20
45 W/cm^2 -OL - 4.6 K
0
10
20
40
60
Imag/Iss (%)
80
100
49 W/cm^2 - IL - 4.6 K
0
0.0
20.0
40.0
60.0
Imag/iss (%)
80.0
100.0
• In HQ01e: OL PH delay faster than IL
• In HQM04: IL PH delay faster than OL
• Possible differences between HQ01e and HQM04
=> Cooling of the bore?
=> high compression due to mechanical preload in HQ01e: better thermal contact
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meeting
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Bath Temperature
VPH = 250 V - OL
HQ01e at CERN
60
HQM04: 45 W/cm^2 -4.6 K
OL - 1.9 K
IL - 1.9 K
80
HQM04: 45 W/cm^2 - 2.2 K
OL - 4.4 K
IL - 4.4 K
Delay to quench onset (ms)
PH delay time (ms)
100
60
40
20
50
HQM01: 47 W/cm^2 - 4.6 K
HQ01e: 50 W/cm^2 - 4.4 K
40
HQ01e: 50 W/cm^2 - 1.9 K
30
20
0
20
30
40
50
60
Imag/Iss (%)
70
80
90
10
0
0.0
20.0
40.0
60.0
Imag/iss (%)
80.0
100.0
• From HQ01e and HQM04:
No effect of the bath temperature observed on the PH delay
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meeting
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Next steps on PH studies
• Development of a 2D thermal model (Tiina Salmi, LBNL)
• Simulation of heat transfer from PH to coil for design optimization
• Heater longitudinal layout
• PH to coil insulation layout
• PH powering
• Optimization of energy deposition: Square pulse, Truncated capacitance
discharge
• Minimizing PH Temperature and Voltage
• Comparison with experimental data showing good agreement
HQM04 simulation
Thermal system: half PH period
y, radial
Tbath
PH delay (ms)
q’’’gen (t,T)
Cable Tmax
0
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Tbath
Cov/2
x, mag
Per/2 axial
3rd turn sim. PH cov=3 cm
80
70
60
50
40
30
20
10
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7th turn sim. PH cov=6 cm
HQM04 test
20
40
60
I/Iss (%)
80
100
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HQ01e – Quench-Back
• Magnet seating at a constant current: from 5 to 13 kA
• Discharge in the dump resistor of 40 mW without PH
H. Bajas et al., “Test Results of the LARP
HQ01 Nb3Sn quadrupole magnet at 1.9 K”,
presented at ASC2012
• Does the magnet quench by eddy current generation in the cable (form of quenchback)?
• From the current decay:
𝐼 𝑡 =
𝑅𝑚𝑎𝑔
•
•
•
•
−𝑅 𝑡
𝐼0 𝑒 𝐿
𝑑
𝐼 𝑡
𝑡 = −𝐿 ln
𝑑𝑡
𝐼0
− 𝑅𝑑𝑢𝑚𝑝
At 5 and 10 kA: no sign of quench
A 13 kA: signs of quench
At 15 kA: fraction of the magnet is quenching
Last 15 kA test with PH: no clear impact
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meeting
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Estimate of HQ01 resistance during extraction
1) Find energy dissipated in the dump resistor
A36
X
300 ms
Edump= I(t) * Vdump(t) dt = 0.425 MJ
10 ms
2) Find total energy in the magnet:
Magnet inductance is L=7.5 mH; Then, at I = 14819 A, Emag = LI2/2 = 0.823 MJ
3) Find energy dissipated in the cryostat: Ecryo = 0.823-0.425 = 0.398 MJ
300 ms
4) Find magnet resistance:
A = I2(t) dt = 7.13 106 =>
10 ms
=> Rav = Ecryo/A = 0.055 W - average magnet resistance during extraction (10-300 ms)
2012/11/14
2nd Joint HiLumi LHC - LARP Annual
meeting
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HQ01e MIITS limit
H. Bajas et al., “Test Results of the LARP
HQ01 Nb3Sn quadrupole magnet at 1.9 K”,
presented at ASC2012
18.3 Miits
13.2 Miits
16.9 Miits
• Explored high MIITS by removing the dump resistor and inner layer PH
• HQ01e-3 validation quench required to claim no degradation
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meeting
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PH and Trace revision
• Avoid overlapping PH strip with metallic end parts: Rev C
• first implemented in HQ16
• Fit the “LHQ style” extension (Rev D): will be first implemented in HQ20
HQ02:
- coil 15 OL: rev B
- coil 17 OL: rev C
- coil 16 OL: rev C
- coil 20 OL: rev D
HQ02 coils will have 75 microns between PH strips and coil
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2nd Joint HiLumi LHC - LARP Annual
meeting
-IL unchanged
13
Summary
• Protection heaters:
• A wide mapping of the delay has been made with the HQ01 series and the mirrors
• Good start to benchmark models
• From HQ01e: OL PH seem more efficient than IL PH
• PH efficiency seems independent from temperature
• HQ01e test at CERN explored High MIITs regime
• The dump resistor as well as the IL PH were removed
• HQ01e test at CERN exposed quench-back in the cable for current above 13 kA
• HQ01e coils do not have a core
• Need to reproduce these tests with HQ02
• core cable
• 75 microns Kapton between coil and PH strip
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