Transcript Session1Summaryx

What did we learn without beam in 2008 ?
Roberto Saban & Mirko Pojer
Training the dipoles
Superconducting electrical circuits
The Sector 34 Incident
Calorimetric and electrical
measurements and related software
LHC Cryogenics: What did we learn
from cool-down to first beams
What else did we learn?
A.Werveij
K-H.Meß
Ph.Lebrun
N.Catalan
-Lasheras
S.Claudet
M.Pojer
Training the dipoles
in sector 56
13000
12500
12000
7 TeV
Quench current [A]
11500
190
S56
11000
6.5 TeV
S56 in SM-18
10500
6 TeV
10000
S45
9500
5.5 TeV
A.Verweij
9000
S78
8500
R.Saban Feb 24th , 2009
1
10
100
1000
Quench number
LHC Performance Workshop Chamonix - What did we learn without beam in 2008?
2
Training the dipoles
in sector 56
13000
12000
7 TeV
Current [A]
11000
10000
6 TeV
9000
ALS: 1st training quench SM18
ANS: 1st training quench SM18
NOE: 1st training quench SM18
8000
ANS: Quenches sector 56
A.Verweij
NOE: Quenches sector 56
7000
R.Saban Feb 24th , 2009
0
20
40
60
80
100
120
140
Magnet number (ordered by 1st quench in SM18)
LHC Performance Workshop Chamonix - What did we learn without beam in 2008?
3
Training the dipoles
in sector 56
A.Verweij
Number of magnets
Number of quenches to 7 TeV
Sector
ALS
ANS
NOE
@6
TeV
(±2)
@ 6.5
TeV
(±30%)
Est. 1
Est. 2
Est. 3
Est. 4
1-2
49
96
9
0
4
22
41
40
49
2-3
56
60
38
1
8
23
97
92
130
3-4
56
65
33
1
8
21
87
83
116
4-5
46
46
62
2
12
22
145
136
198
5-6
28
42
84
1
15
21
190
178
262
6-7
57
36
61
2
12
20
142
133
194
7-8
54
40
60
2
12
14
140
132
192
8-1
64
24
66
2
13
19
151
142
208
Total
11
84
162
993
936
1349
Est. 1: Based on 115 MB’s that have been submitted to a thermal cycle in SM-18
(2008 before HWC, P. Xydi and A. Siemko)
993 / 8 = 124
124 / 3 = 41
Est. 2: Extrapolation from sector 5-6 data + estimate 1 for ALS & ANS
Est. 3: 2 quenches per NOE magnet + estimate 1 for ALS & ANS
Est. 4: 3 quenches per NOE magnet + estimate 1 for ALS & ANS
R.Saban Feb 24th , 2009
LHC Performance Workshop Chamonix - What did we learn without beam in 2008?
4
Superconducting electrical circuits
Surprises
Harmless
The third current lead shared by two circuits (Kirchoff’s Law)
Short inside the dump resistor on the QF of Sector 45
Short to ground on the dump resistor on the QD of Sector 56
Missing resistor on one of the poles of an undulator which gave a very
exotic transfer function
 Leveling of the DFB to properly wet the superconducting cable




Potential inconvenience to operation
 Distribution of the conductors on cables sharing the same DFB but on
different circuits – symptom: apparent detraining
 The reference magnet puzzle – magnetization cycle
Potentially dangerous
K-H.Meß
 Symmetric quenches
 Transient spike when the dump switch opens due to the difference in
Eddy currents in the two apertures
 Quench back in corrector circuits inducing coupling on other circuits …
up to quenching the main magnets
 Pending: splice and voltage tap non-conformities
Unresolved
R.Saban Feb 24th , 2009
 MCBX and MCBY mystery: unexplainable transfer functions
 The hunch on the MCBYs
 Fast quench propagation observed on only the dipole circuits
LHC Performance Workshop Chamonix - What did we learn without beam in 2008?
5
The Sector 34 Incident
Mandate of the Task Force 70
1.99
Valve opening [%], current [kA], CC flow [g/s]
80
LBALA_24R3_TT821.POSST
LBALA_25R3_TT821.POSST
Cold-mass temperatue [K]
 1.97
Establish the sequence of facts, based on
60
experimental
measurements
before
1.95
50
incident, observations after incident and
1.93
timing
40
 1.91
Analyse and explain the development of
30
events, in relation with design assumptions,
1.89
20
manufacturing & test data
and risk
analyses performed
1.87
10
 Recommend preventive and corrective
1.85
0
actions
for
Sector
3-4
and
others
18:00
19:00
20:00
21:00
22:00
LBALA_26R3_TT821.POSST
LBALA_27R3_TT821.POSST
LBALB_24R3_TT821.POSST
LBALB_26R3_TT821.POSST
Measured versus simulated
incident with 220 n joint
and bad contact with Uprofile and wedge
LBBLA_24R3_TT821.POSST
LBBLA_25R3_TT821.POSST
LBBLA_26R3_TT821.POSST
LBBLA_27R3_TT821.POSST
LBBLD_25R3_TT821.POSST
LBBLD_27R3_TT821.POSST
LQASB_23R3_TT821.POSST
LQOAA_25R3_TT821.POSST
LQOBA_24R3_TT821.POSST
LQOBA_26R3_TT821.POSST
QRLAA_25R3_CV910.POSST
QRLAB_23R3_CV910.POSST
QURCA_4_FT201.POSST
RPTE.UA43.RB.A34:I_MEAS
Ph.Lebrun
Temperature drift during the 7
kA current flat top (15 Sep
2008)
No electrical contact between wedge and Uprofile with the bus on at least one side of the joint
R.Saban Feb 24th , 2009
No bonding at joint with the
U-profile and the wedge
LHC Performance Workshop Chamonix - What did we learn without beam in 2008?
6
The Sector 34 Incident
Ph.Lebrun
The current decay from 8700 A
R.Saban Feb 24th , 2009
Energy
MJ
%
Stored in the magnets
595.0
100
Dissipated in UJ33
71.0
12
Dissipated in UA43
104.8
18
Dissipated in cold mass
144.4
24
Dissipated in electrical arcs
274.8
46
LHC Performance Workshop Chamonix - What did we learn without beam in 2008?
7
The Sector 34 Incident
QV
Q
SV
D
D
D
PT
QV
Q
D
Cold-mass
Vacuum vessel
Line E
Cold support post
Warm Jack
Compensator/Bellows
Vacuum barrier
D
D
SV
D
D
Q
QV
Q
D
D
12000
25
Ins Vac A19R3
Ins Vac A27R3
I DCCT
10000
20
8000
Current (A)
15
6000
10
I dump 3
I dump 4
P CM Q19-21.R3
P CM Q23-25.R3
P CM Q27-29.R3
Vac beam 23R3.R
Vac beam 23R3.B
Vac beam 31R3.R
Vac beam 31R3.B
5
2000
0
0
:4
9
:1
11
:3
9
:1
11
:3
:2
9
:1
11
9
:1
11
:2
:1
9
:1
11
9
:1
11
:1
9
:1
0
5
0
5
0
5
0
5
0
5
0
5
0
5
Time
11
:0
9
:1
11
:0
9
:1
11
:5
:5
8
:1
11
8
:1
11
:4
:4
8
:1
11
8
:1
11
:3
8
:1
11
Ph.Lebrun
Q
Ins Vac A23R3
4000
R.Saban Feb 24th , 2009
QV
D
D
P He vessel (bar), P beam (mbar), P insulation (bar)
QV
LHC Performance Workshop Chamonix - What did we learn without beam in 2008?
8
The Sector 34 Incident
Prevention of initial fault
Recommendations
Mitigation of consequences
•
Calorimetric measurements
•
•
Electrical
measurements
on
«suspect» cells/subsectors powered
at limited current
•
During further power tests, track
temperature
evolution
in
normalized conditions
•
•
•
Ph.Lebrun
•
•
Modify quench detection system
to include interconnects and bus
bar splices
Consider
option
to
measure
currents in 13 kA circuits at both
ends of sector and detect
differentials
Review possible improvement of
mechanical
clamping
of
interconnects
and
gradually
implement whenever possible
R.Saban Feb 24th , 2009
•
•
•
•
•
•
Increase number/size of relief
devices on cryostat vacuum
vessels
Review number, size & position of
pressure relief devices on beam
vacuum system
Review closure logic of beam
vacuum sector valves
Consider possibility of triggered
opening of quench relief valves
below set pressure
Consider general firing of quench
heaters
Reinforce external anchoring at
locations of vacuum barriers
Reexamine personnel underground
access rules
Review location of AUG in tunnel
and protection from blast
Review recorded signals, recording
frequency and time stamping
coherence
among
different
systems
LHC Performance Workshop Chamonix - What did we learn without beam in 2008?
9
Calorimetric and electrical measurements
Relative temp
Sector 12
+40 mK
Sector 23
7 kA
7 kA
Sector 34
Sector 45
7 kA
9.3 kA
-10 mK
+40 mK
Relative temp
Relative temp
N.Catalan-Lasheras
Sector 56
Sector 67
7 kA
7 kA
Sector 78
Sector 81
8.5 kA
7 kA
-10 mK
•
•
1 or 2 hour flat tops
R.Saban Feb 24th , 2009
All the current plateaux were scrutinized for suspect
temperature increase
Unstable conditions and dynamic temperature control
prevent accurate calculations.
LHC Performance Workshop Chamonix - What did we learn without beam in 2008?
10
Calorimetric and electrical measurements
the baseline slope (valve opening
the temperature increase during
powering plateau
the internal energy variation (J/kg)
1.88
Temperature [K]
mismatch)
the deposited energy assuming a
mass of 26 l/m of He
Before heating
With heating
-1.1
78
N.Catalan-Lasheras
M [kg]
1.86
0.6
1.85
0.4
1.84
0.2
1.83
0
1
2
Time [hour]
Dipole (5 sectors)
-0.92
64.2
t [s]
2880
6600
W [W]
-0.3
9.7
10
The new powering procedures will
demand mandatory calorimetric and
electrical tests in ALL sectors at the
beginning of the next LHC powering
campaign
R.Saban Feb 24th , 2009
0.8
823
ΔU [kJ]
ΔW [W]
1
1.87
0
3
4
Quadrupole (4 sectors)
25
NNXN: Confirmed by electrical measurements
20
# of sub-sectors [-]
ΔU [J/kg]
1.2
Temperature
Current
DU(DT
1.89
I / Iplateau [-]
Assessment of
~ 2 W @ 7 kA
15
10
5
31R7
31R1
31R6
15R1
23R3
0
-50 -40 -30 -20 -10 0
10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200
Sub-sector resistance variation w/r to baseline [n]
LHC Performance Workshop Chamonix - What did we learn without beam in 2008?
11
Calorimetric and electrical measurements
Calorimetric measurements spotted a suspect region in Sector 12
0.7mV/7kA=100nOhm
0.7mV*7kA=4.9W
1.40
D1_L-Ua
D2_U-La
Error Bars:±2σ/√n
1.00
Voltage (mV)
N.Catalan-Lasheras
1.20
105 nOhms
0.80
Snapshot on 03.09.08 : 0.85mV*8.4kA=7.1W
0.60
0.40
1.6 nOhms
0.20
0.00
0
2000
-0.20
R.Saban Feb 24th , 2009
4000
6000
Current (A)
8000
10000
12000
14000
an inter-pole splice
resistance of 105
nOhm in magnet
2334 (B16R1)
LHC Performance Workshop Chamonix - What did we learn without beam in 2008?
12
Cryogenics: from cool-down to first beams
“25 days for 20K”
≈15K/d x 13 d
+ 3 days for Filling
+ 2 days for 1.9K
≈8 K/d x 8 d
 30 days
(4 to 5 wks)
S.Claudet
≈12 K/d x 4 d
R.Saban Feb 24th , 2009
LHC Performance Workshop Chamonix - What did we learn without beam in 2008?
13
1.8 K Refrigeration Unit
Warm Compressor
Station
Ex-LEP 4.5 K Refrigerator
Warm Compressor
Station
New 4.5 K refrigerator
1.8 K Refrigeration Unit
Warm Compressor
Station
Warm Compressor
Station
Upper Cold Box
Surface
Cryogenics: from cool-down to first beams
Cold Box
Shaft
Cold Compressor
box
Distribution Line
Distribution Line
Magnet Cryostats
Magnet Cryostats
LHC Sector (3.3 km)
S.Claudet
Interconnection Box
Tunnel
Cold Compressor
box
Cavern
Lower Cold Box
LHC Sector (3.3 km)
•
Running two sectors with one cryoplant was tested during
powering
•
Not valid for large transients, but an interesting alternative for low
beam loads. It is a validated fall-back scenario if serious problems
with a refrigerator
R.Saban Feb 24th , 2009
LHC Performance Workshop Chamonix - What did we learn without beam in 2008?
14
Cryogenics: from cool-down to first beams
Non conformities were detected, workarounds found
during the run and consolidations actions ongoing level
gauges on stand alone magnets, DFBLC heat load, valves on current leads, heat
loads on the triplet, etc.
Stability was achieved
stable services, global refrigeration mastered,
15mbar established, DFB, current lead and beam screen cooling loops stabilised
Recovery from quenches or failures
a lot of experience gained
and results obtained
Towards more stable services
insulation vacuum
electricity, cooling water controls,
S.Claudet
Getting ready for round the clock operation
R.Saban Feb 24th , 2009
LHC Performance Workshop Chamonix - What did we learn without beam in 2008?
15
What else did we learn?
The Procedures
The Tools which implemented the procedures and assisted the
operators during the execution and the analysis
Sequencer
Post-Mortem browser
PIC supervision
QPS supervision
Powering to Nominal (P2N)
Databases
… others were developed during the hc
efficiency,
automation and
no compromise
Some teething problems were identified and were corrected or
are being corrected remote resets, communications problems, timing, coherence
M.Pojer
between time stamps, etc.
R.Saban Feb 24th , 2009
LHC Performance Workshop Chamonix - What did we learn without beam in 2008?
16
What else did we learn?
Hardware problems
600A-10V LHC type power converters
QPS requires a smooth change in current,
otherwise it trips
LHC 600A-10V: 0V-crossing distortion
The power converters generate some distortion
when crossing through zero voltage with
current in the load  QPS trips
600 A-10 V Crowbar Issue
Some PCs don’t have the crowbar and are not
safe under certain conditions
Reduced dI/dt
and d2I/dt2
which could
limit operation
and physics
ECR to add crowbar
on those circuits
M.Pojer
Frequent clogging of water filters installed on cables and converters lines
 flow reduction and stop of the converter
A decision was taken to change all filters around the
machine from the present 50 μ to 100 μ mesh
R.Saban Feb 24th , 2009
LHC Performance Workshop Chamonix - What did we learn without beam in 2008?
17
Conclusions
Many surprises: training & sector 34
During the commissioning the equipment owners and
the operation crews gathered the experience which
they expected to re-commission, run and debug the
equipment
The incident in sector 34 requires modifications of the
hardware, upgrade of protection systems and the
development of additional test procedures
While during most of the commissioning campaign the
observations matched what was expected; in a few
cases however, they revealed non-conformities
some of which remain to be understood, followed and
corrected or coped with
R.Saban Feb 24th , 2009
LHC Performance Workshop Chamonix - What did we learn without beam in 2008?
18