2014.10.15
Cryogenic SystemsJuan Casas (TE-CRG-CI)
In behalf of the CRG team
R2E and Availability Workshop - Cryogenic Systems - JCC
2014.10.15
UpperCold Box
Interconnection Box
Cold Box
WarmCompressor
Station
LowerCold Box
Distribution Line Distribution Line
Magnet Cryostats, DFB, ACS Magnet Cryostats, DFB, ACS
ColdCompressor
box
Sha
ftS
urfa
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ave
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LHC Sector (3.3 km) LHC Sector (3.3 km)
1.8 KRefrigeration
Unit
New4.5 K
Refrigerator
Existing4.5 K
Refrigerator
1.8 KRefrigeration
Unit
WarmCompressor
Station
WarmCompressor
Station
WarmCompressor
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ColdCompressor
box
Even pointOdd point Odd point
MP StorageMP Storage MP Storage
UpperCold Box
Interconnection Box
Cold Box
WarmCompressor
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LowerCold Box
Distribution Line Distribution Line
Magnet Cryostats, DFB, ACS Magnet Cryostats, DFB, ACS
ColdCompressor
box
UpperCold Box
Interconnection Box
Cold Box
WarmCompressor
Station
LowerCold Box
Distribution Line Distribution Line
Magnet Cryostats, DFB, ACS Magnet Cryostats, DFB, ACS
ColdCompressor
box
Sha
ftS
urfa
ceC
ave
rnT
unne
l
LHC Sector (3.3 km) LHC Sector (3.3 km)
1.8 KRefrigeration
Unit
New4.5 K
Refrigerator
Existing4.5 K
Refrigerator
1.8 KRefrigeration
Unit
WarmCompressor
Station
WarmCompressor
Station
WarmCompressor
Station
ColdCompressor
box
Even pointOdd point Odd point
MP StorageMP Storage MP Storage
UpperCold Box
Interconnection Box
Cold Box
WarmCompressor
Station
LowerCold Box
Distribution Line Distribution Line
Magnet Cryostats, DFB, ACS Magnet Cryostats, DFB, ACS
ColdCompressor
box
UpperCold Box
Cold Box
WarmCompressor
Station
LowerCold Box
Magnet Cryostats, DFB, ACS Magnet Cryostats, DFB, ACS
ColdCompressor
box
Sha
ftS
urfa
ceC
ave
rnT
unne
l
LHC Sector (3.3 km) LHC Sector (3.3 km)
1.8 KRefrigeration
Unit
New4.5 K
Refrigerator
Existing4.5 K
Refrigerator
1.8 KRefrigeration
Unit
WarmCompressor
Station
WarmCompressor
Station
WarmCompressor
Station
ColdCompressor
box
Even pointOdd point Odd point
MP StorageMP Storage MP Storage
UpperCold Box
Interconnection Box
Cold Box
WarmCompressor
Station
LowerCold Box
Distribution Line Distribution Line
Magnet Cryostats, DFB, ACS Magnet Cryostats, DFB, ACS
ColdCompressor
box
R2E and Availability Workshop - Cryogenic Systems - JCC
Cryogenic Systems: outline of the talk• Availability• Relocation of commercial equipment: status and plans• Cryo-tunnel sensors & actuators: qualification campaign & remaining issues• Radiation tolerant custom electronics: expected radiation performance & long-term issues• NOT IN THIS TALK:
• Refrigeration Units, Interconnection boxes & controls: well established maintenance procedures• Materials ageing for gaskets, diaphragms, cable insulation, etc.
2014.10.15R2E and Availability Workshop - Cryogenic Systems - JCC
Cryogenic Systems: AvailabilityAvailability of Cryogenic Cooling operation is/WAS impaired by:• 26.9 %: Utilities (Electrical supply, water cooling, networks, etc)• 14.0 %: Radiation effects• 54.1 %: Cryogenic equipment failures• 5.0 %: Users
Overall availability is better than 91.9 %; it is already an excellent performance.Cryogenics team is continuously looking for optimizing operation, SEU shall disappearHowever next runs may result in new challenges
LHCCryo - Average of 8 sectors (except TechStops)
91.4789.68
94.8
5.21 4.20
3.62.66 3.51
0.4
0.66
0.15
0.9
2.46
0.3
86
88
90
92
94
96
98
100
2010 2011 2012
Pe
rce
nt
[%]
Supply (EL, CV, IT)CryoCryo SEUUsersGlobal availability
0
10
20
30
40
50
60
70
80
90
100
0 100 200 300 400 500 600 700 800 900
Operation for beams [Cumulated
Availab
ilit
y [
%]
Avai
labi
lity
[%] 2010
Nice learning curve! mostly Cryo
issues treated “on the fly”
2011
Good start before beam induced issues
(energetic neutrons), 1st
corrections
2012
Effective treatment of beam induced
issues,
A global success !
2013
830 cumulated days with an average availability of 91.9%
2014.10.15R2E and Availability Workshop - Cryogenic Systems - JCC
Cryogenic Systems: Availability & LHC Radiation EventsSingle Events is the only type of observed perturbation induced by the LHC radiation
All the affected components were supposed to be located in radiation free areas
“Radtol” refers to the custom electronics measuring the leads temperatureSensitive digital-insulator consolidated by end to 2011 => No events in 2012
Availability increases with experience and by applying corrective actions (hardware, software or relocation)During 2012 most of the SEE/SEU were transparent to the LHC availability
Commercial equipment was relocated => SEU on commercial equipment not expected for next runs
2014.10.15R2E and Availability Workshop - Cryogenic Systems - JCC
Cryogenic Systems: Instrumentation & Controls• Industrial electronics shall always be located in protected areas
• Exception: split valve-actuator designed for CERN and qualified in TCC2• Sensors & actuators: qualified during LHC design phase• Cryo Rad-Tol electronics: designed for Arc & DSS
2014.10.15R2E and Availability Workshop - Cryogenic Systems - JCC
Cryogenic Systems: Industrial equipmentIndustrial/commercial equipment is not qualified for radiation and shall be removed from exposed areas.
=> relocation campaigns of the most sensible equipment like:• Remote IO (Siemens ET200), profibus DP/PA couplers, 24 Vdc
power supplies, Sipart valve actuator in UJ14, UJ16, UJ56, UJ67, P4 & P8
• Power electronics for the cold-compressor magnetic bearings controller and variable frequency drives in P4 & P8.
Note that potentially sensitive equipment like intelligent signal conditioners still remain in P4 & P8• Detailed list to be prepared and commented• Commercial electronics shall be relocated along with the rest of
the equipment
Nothing is planned yet for P2 and P6. Radiation field calculations shall indicate whether yes or no, a relocation is required.
Similar equipment also exist in the underground areas of P18, but in a location that is deemed to be free of radiation.
2014.10.15R2E and Availability Workshop - Cryogenic Systems - JCC
Cryogenic Systems: sensors/actuators
Non exchangeable: thermometers and electrical heaters.=> Duplication exist for some critical thermometers=> No duplication for beam-screen heaters
=> 100% availability unlikely for about 300 channels!
Exchangeable: pressure sensors, liquid helium level gauges, valves motors, etc
Qualified for radiation:• Split valve positioner
piezoresistive valve and feedback potentiometer installed in radiation areaIntelligent part integrated profibus interface and controlller installed in protected area
• Pressure sensor• Temperature sensor: next slideMay still fail as any industrial device!
Assumed to be rad-hard or adequate procedure for maintenance:• Superconducting level gauge: identical technology as for magnets• Pressure sensors with metallic membranes (new 50 mbar devices)
Similar devices used in other radiation areasQualification <= rad-hard reference => too complicated & not worth
Cold-mass thermometeron magnetic yoke
Replacing a liquidHe superconducting
Level gauge
2014.10.15R2E and Availability Workshop - Cryogenic Systems - JCC
Cryogenic Systems: Temperature sensorsMost of the sensors were qualified for radiation in nominal operational conditions:Arc: 10 year dose 1.5 1013 n/cm2, 300 Gy=> OK for HL-LHC apart of ITInner-Triplet: neutron dose will it exceed the qualification dose? Probably yes• Saturation of drift: probably true above 1015 n/cm2, it is an amorphous structure,
however….• Radiation qualification above 1014 n/cm2: too complicated, it has to be done @ 1.8 K• INVESTIGATE ALTERNATIVE SOLUTIONS:
• Exchangeability: insertion capillaries but superfluid helium complicates the design• Foresee additional thermometer supports in the vacuum envelope
Drawback: IT need to be opened• Combine several type of sensors
Thermometer @ end-plate of IT
2014.10.15R2E and Availability Workshop - Cryogenic Systems - JCC
Cryogenic Systems: Tunnel ElectronicsDesign target 1 kGy on single components, compatible with HL-LHC dose estimationComponent selection and tests started by 1998.
Most sensitive components during “short” IC qualification campaigns:• Micro-FIP CC131 & ADC failed by respectively 800 Gy and 500 Gy
Annealing repaired the faults => LHC total withstand radiation is certainly higher• Some not “properly” qualified dc/dc converter in use for several type of cards
NOTE that no problems up to 500 Gy in CNGS tests
Thermal design has margin for additional dissipation due to radiation.
Crates:Under Dipole:
2014.10.15R2E and Availability Workshop - Cryogenic Systems - JCC
Cryogenic Systems: New Tunnel Electronics
New electrical power supply:• Designed to satisfy baking requirements for the LHC beam-screen• Good opportunity to consolidate all 500 W heaters
relied in a SEE sensitive signal conditioner used for the heater element protection thermometer• New components were qualified in CNGS and PSI
• MOSFET ac switch (FCA36N60NF)• Analog multiplexer (SW06GSZ Quad SPST JFET Analog Switch, Analog Devices)
• Overall radiation performance should be improved with respect to previous design:No DC-DC converter or any other “complicated” IC
New insulated temperature card for the current leads• Designed to withstand the 1.2 kV test voltage applied during ELQA• Adapted for use in the tunnel in order to read temperature sensors with a short-circuit to ground• Digital-insulator SEU sensitivity consolidated by implementing a periodical reset
NEXT:• Final check for new electronic cards in CHARM
Tests planned from November 2014
Analog multiplexer: radiation test
2014.10.15R2E and Availability Workshop - Cryogenic Systems - JCC
Cryogenic Systems: Tunnel Electronics & Availability
The LHC readouts and actuators are not only affected by radiation but also by:• Ambient temperature and humidity• Electromagnetic interference• Ageing• Mechanical issues due to corrosion, reliability of contacts, …• …………………..
Losses of “cryo-maintain” are caused not only by SEU but also by intermittent losses of electrical continuity when it affects a critical channelFurthermore there are thousands of channels with several electrical interfaces each.
About 3 such events are observed each year of operation
2014.10.15R2E and Availability Workshop - Cryogenic Systems - JCC
Cryogenic Systems: Tunnel electronics spare parts & issues
The LHC cryo radtol electronics are based on a library components qualified before 2005.For new designs radiation tests are performed if the part is not in our stock of components
Some of the components have become obsolete or replaced by new parts, in most cases (but not always) the replacement parts can be expected to have similar radiation performance.Cross-checked by radiation test.
New commercial COTS may become available with promising characteristics for radiation:Example is the analog multiplexer selected for new cards.This part simplified significantly the design of the new power supply for the beam screen.
LHC spare cards: typically at least 15% of installed base
Replacement cards can be produced within 6 month compatible if end-of-life warningRAD-HARD ASIC: more than 12 k pieces in stock => sufficient for future needs
Exception: micro-FIP CC-131 communication card that is not any more availableÞ Spare cards and spare CC-131 modules should permit to cope with MTBF issuesÞ Foresee for 2020 development of new communication interface compatible with the existing
crates and cardsnanoFIP but a development is required for the handling of the backpanel signals.
2014.10.15R2E and Availability Workshop - Cryogenic Systems - JCC
Conclusions
Availability of LHC cryogenics is a complex issue, it is certainly affected not only by the radiation effects on the tunnel electronics, but also by common issues that do exist in any industrial complex (fuses, open electrical connections, interference, etc.).
Long term issues of concern:• Obsolescence of microFIP CC-131 imposes the development of a new interface to be ready
when MTBF issues become a problematic issue• Maintenance of reception automated test-benches for new cards manufacturing
• Existing production test bench is based in LabView and any modification require updating the OS and/or LabView version => lots of effort
• Last development used the PVSS/CIET environment for automating the testBased on a platform maintained by CERN as it is based in the CERN SCADAs
Radiation doses expected in the inner triplets => foresee insertion thermometersProbably not required, but dose exceed qualification parameters
Electromagnetic noise:• Noise appear when grounding locally some leads• What happen when the power converters will not be alongside the lead temperature cards?
Until now there is no evidence of increased rate of failuresWithout personnel in the tunnel failure rate is close to nil