cryogenic systems juan casas (te-crg-ci) in behalf of the crg team r2e and availability workshop -...

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

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



ColdCompressor

box

UpperCold Box

Interconnection Box

Cold Box

WarmCompressor

Station

LowerCold Box



ColdCompressor

box

Sha

ftS

urfa

ceC

ave

rnT

unne

l


1.8 KRefrigeration

Unit

New4.5 K

Refrigerator

Existing4.5 K

Refrigerator

1.8 KRefrigeration

Unit

WarmCompressor

Station

WarmCompressor

Station

WarmCompressor

Station

ColdCompressor

box



UpperCold Box

Interconnection Box

Cold Box

WarmCompressor

Station

LowerCold Box



ColdCompressor

box

UpperCold Box

Cold Box

WarmCompressor

Station

LowerCold Box


ColdCompressor

box

Sha

ftS

urfa

ceC

ave

rnT

unne

l


1.8 KRefrigeration

Unit

New4.5 K

Refrigerator

Existing4.5 K

Refrigerator

1.8 KRefrigeration

Unit

WarmCompressor

Station

WarmCompressor

Station

WarmCompressor

Station

ColdCompressor

box



UpperCold Box

Interconnection Box

Cold Box

WarmCompressor

Station

LowerCold Box



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%


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


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


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.


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


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


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:


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


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


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.


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

cryogenic systems juan casas (te-crg-ci) in behalf of the crg team r2e and availability workshop -...

Documents

average availability

cryogenic equipment

new challenges availability

users overall availability

sensitive equipment

sensible equipment

runs slide

cryo issues