A. VerweijR. Flora28 Feb 2008
What quenches did we observe? What quenches did we observe?
What can we expect?What can we expect?
Arjan Verweij & Robert Flora Arjan Verweij & Robert Flora
on behalf of the MPP, and with the input of many otherson behalf of the MPP, and with the input of many others
A. VerweijR. Flora28 Feb 2008 QuenchQuench
Quench: Transition from the superconducting to the normal state
(resulting in a detectable resistive voltage, exceeding the
threshold voltage and discrimination time).
Quench classification:
Heater induced/provoked quench
Natural (training) quench
Secondary quench (due to temperature increase, ramp rate,
etc)
(Beam induced quench)
Circuits with active QPS: we can distinguish converter trip from
natural quench and we have some possibilities for quench
localisation
For circuits that are protected through the power converter (60-
120 A) we are almost blind.
A. VerweijR. Flora28 Feb 2008
Circuit Nominal current
# circuits # circuits tested towards nominal
# natural quenches
I_q_1/
I_nom
RB 12 kA 1 1 * 3 82%
RQD / RQF 12 kA 2 2 * 1 91%
IPQ (Q4-Q10) 3610-5390 A 13 13 3 90%
IPD (D2-D4) 4400-5520 A 3 3 1 82%
600 A correctors 550 A 46 13 10 63%
undulator 450 A 1 1 3 86%
80-120 A 72 A-100 A 35 12 maybe ?
60 A 55 A 94 92 maybe ?
Natural quenches in 4-5Natural quenches in 4-5
*: nominal not reached
A. VerweijR. Flora28 Feb 2008
7000
8000
9000
10000
11000
12000
13000
0 20 40 60 80 100 120 140
Magnet number
Cu
rren
t [A
]
4.14
4.73
5.32
5.91
6.50
7.09
7.68
En
erg
y [T
eV]
SM-18: 1st training quenchSM-18: maximum currentQuenches sector 4-5SM-18: 2nd training quench
1 2
3
SM-18: 175 quenches to reach 12 kA in all 154 dipoles
RB circuit: correlation with SM-18RB circuit: correlation with SM-18
A. VerweijR. Flora28 Feb 2008
9000
9500
10000
10500
11000
11500
12000
12500
13000
0 5 10 15 20 25 30 35 40 45
Magnet number
Cu
rren
t [A
]
SM-18, 1st training quench
SM-18, 2nd training quench
Maximum current SM-18
Quench sector 4-5
SM-18: 39 quenches to reach 12 kA in all 45 quads
RQD/RQF circuits: correlation with SM-18RQD/RQF circuits: correlation with SM-18
A. VerweijR. Flora28 Feb 2008 IPD’s: correlation with training before IPD’s: correlation with training before
installationinstallation
0
1000
2000
3000
4000
5000
6000
7000
Cu
rren
t [A
]
sector 45: Nominal without quench
sector 45: Quench
Training before tunnel installation
D2L5 D4R4D3R4
A. VerweijR. Flora28 Feb 2008 IPQ’s at 4.5 K: correlation with training IPQ’s at 4.5 K: correlation with training
before installationbefore installation
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
Cu
rren
t [A
]
sector 45: Nominal without quench
sector 45: Quench
Training before tunnel installation
Q4L5 Q6R4Q5R4Q6L5Q5L5
A. VerweijR. Flora28 Feb 2008 IPQ’s at 1.9 K: correlation with training IPQ’s at 1.9 K: correlation with training
before installationbefore installation
0
1000
2000
3000
4000
5000
6000
7000
Cu
rren
t [A
]
sector 45: Nominal without quench
sector 45: Quench
Training before tunnel installation
Q7R4 Q10L5Q7L5Q10R4Q8R4 Q9R4 Q8L5 Q9L5
noquench
Training at 4.5 K
A. VerweijR. Flora28 Feb 2008
Circuits up to 5 TeV 6 TeV 7 TeV
RB 0 ~2 ? (tens)
RQD / RQF 0 ~0 ? (ten(s))
IPQ and IPD 0 ~1 ~4
How many quenches can we expect for How many quenches can we expect for future sectors?future sectors?
Circuits Number of quenches for reaching nominal current
600 A correctors ~35
undulator ~3
80-120 A a few
60 A a few
Numbers are given per sector for all circuits together
This is a rough estimate based on limited experience of sector 4-5 only
A. VerweijR. Flora28 Feb 2008 RB provoked quench @ 9500 ARB provoked quench @ 9500 A
Cryogenic recovery time: see talk Serge ClaudetCryogenic recovery time: see talk Serge Claudet
LBALA.17R4: 0 s, 9500 A
LBBLA.17R4: 0.2 s, 9481 A
LBBLC.17R4: 33.1 s, 6862 A
LBALB.16R4: 155.0 s, 1886 A
A. VerweijR. Flora28 Feb 2008 RB natural quench 1 (9789 A)RB natural quench 1 (9789 A)
LBALA.27L5: 0 s, 9789 A
LBBLA.27L5: 62.4 s, 5220 A
LBALB.27L5: 63.1 s, 5181 A
A. VerweijR. Flora28 Feb 2008 RB natural quench 2 (9859 A)RB natural quench 2 (9859 A)
LBALA.22R4: 0 s, 9859 A
LBBLC.21R4: 126.8 s, 2645 A 381.7 s, 188 A
LBBLA.22R4: 49.7 s, 6013 A
LBALB.22R4: 92.6 s, 3829 A
A. VerweijR. Flora28 Feb 2008 RB natural quench 3 (10274 A)RB natural quench 3 (10274 A)
LBBLA.27R4: 0 s, 10274 A
LBBLC.27R4: 123.5 s, 2844 A 355.7 s, 238 A
LBALA.27R4: 46.6 s, 6464 ALBALB.26R4: 109.1 s, 3330 A
LBBLA.26R4: 167.4 s, 1748 A
A. VerweijR. Flora28 Feb 2008 ConclusionConclusion
Experience during HWC of sector 4-5
We experienced about 20 natural quenches, of which 8 in high current circuits
(with quench heaters). This made it possible to make a rough estimate on the
expected number of quenches during HWC of the other sectors.
For all quenches, the detection and resulting actions (heater firing, energy
extraction, PC shut-down) worked perfectly.
‘De-training’ (w.r.t 1st training quench after magnet reception) has been
observed for 5 quenches (2xMB, 1xMQ, D3, Q5L5), and is somewhat worrying.
Quench behaviour with several circuits powered in parallel has not been
tested.
A first estimate on the expected number of quenches during HWC of the other
sectors is made for several energy levels.
A. VerweijR. Flora28 Feb 2008 ConclusionConclusion
Quench propagation in the RB circuit
MB-to-MB quench propagation time seems to be typically 30-60 s, meaning that
adjacent dipoles will quench at already strongly reduced current (note that 100
s).
2 cases have been observed where the MB-MB propagation time was less than
1 s. The reason for this is under investigation.
2 cases have been observed of MB re-quenching (at low current, after
recovering). For both cases, QPS, heater firing and PM-files generation worked
fine.
Quench propagation from one cryogenic cell to another has not been observed.
The maximum energy dissipated at cold for a quench event has been about 12
MJ, which is about 1% of the total energy in the RB circuit at nominal (1.1 GJ).
Higher quench currents and faster propagation will increase the energy.
