LHC Cryogenics Status and Perspectives Serge Claudet, on behalf of the LHC Cryogenics group LHC - MAC22 05 Dec 2007

Content Introduction Main facts from sector 7-8 (January to July 2007) Last projects towards completion Identified weak points (@MAC21) and status Cryo HWC activities since Mid 2007 Action plans Summary S. Claudet - 06Dec'07 LHC-MAC22 - Cryogenics

S. Claudet - 06Dec'07 LHC-MAC22 - Cryogenics

LHC Sector 4-5 scheme 4.5 K 1.9 K 3.3 km 4’700 t @ 1.9K ≈ 10t/15tHe S. Claudet - 06Dec'07 LHC-MAC22 - Cryogenics

Content Introduction Main facts from sector 7-8 (January to July 2007) Last projects towards completion Identified weak points (@MAC21) and status Cryo HWC activities since Mid 2007 Action plans Summary S. Claudet - 06Dec'07 LHC-MAC22 - Cryogenics

LHC sector 7-8 - First cool-down S. Claudet - 06Dec'07 LHC-MAC22 - Cryogenics

Availability for HWC: From 7-8 to others Cryo Maintain LSS: 85% (Since 1st May) Cryo Maintain ARC: 66% (Since 1st June) DFBMs DFBAs Availability for the powering phase for sector 7-8 and expected one for the coming sectors Target LSS: 90% (incl. time lost for quench recovery) Target ARC: 80% (incl. time lost for quench recovery) + Cryogenic tuning to be minimised ?!? S. Claudet - 06Dec'07 LHC-MAC22 - Cryogenics

Heat inleaks Average distributed heat inleak at 1.9 K: 0.2 W/m 20 % of cells operating with degraded insulation vacuum Average distributed heat inleak of cells with good vacuum: 0.14 W/m 33 % below the design estimation Average global thermal shield heat inleak: 6.6 W/m 15 % below the design estimation S. Claudet - 06Dec'07 LHC-MAC22 - Cryogenics

LHC Cryogenics: duration of cool-down phases Design LHC 7-8 Final 9 d 21 d 3 d 14 d 1 d 80 K 20 K 4.5 K 1.9 K Total 14 d / 2 wks 70 d / 10 wks ELQA 4 d 7 d 28 d / 4 wks Excluding ELQA or extra-works : Sketches intended to illustrate achievements and medium term expectations S. Claudet - Jul’07 Proposed for schedule: 8wks-6wks-4wks S. Claudet - 06Dec'07 LHC-MAC22 - Cryogenics

Content Introduction Main facts from sector 7-8 (January to July 2007) Last projects towards completion Identified weak points (@MAC21) and status Cryo HWC activities since Mid 2007 Action plans Summary S. Claudet - 06Dec'07 LHC-MAC22 - Cryogenics

Superconducting links (DSL) Few hundred meters link between DFBL’s and stand-alone magnets S. Claudet - 06Dec'07 LHC-MAC22 - Cryogenics

Many non conformities from contractor, repaired by CERN Problems with leaks at the factory-made welds on belows Many non conformities from contractor, repaired by CERN => Impact on sector 3-4 S. Claudet - 06Dec'07 LHC-MAC22 - Cryogenics

Global pressure test of magnets and cryolines Sector 7-8, 25 Nov 2006 Six sectors May’07 to Nov’07 Remaining 1 sector in Dec’07 S. Claudet - 06Dec'07 LHC-MAC22 - Cryogenics

Content Introduction Main facts from sector 7-8 (January to July 2007) Last projects towards completion Identified weak points (@MAC21) and status Cryo HWC activities since Mid 2007 Action plans Summary S. Claudet - 06Dec'07 LHC-MAC22 - Cryogenics

On-going actions & plans @ MAC21 LN2 logistics to be continued; turbine and flow controls to be improved for 20 K phase Heat loads to be further checked and analysed JT valves to be checked and replaced (8x27) LHe level / anti-condensation for DFB’s to be finalised Instrumentation & controls to be available & more reliable Test of specific tool QUI to separate installation/operation Helium inventory & strategy to be confirmed OK, Faster at sector 4-5, to be continued When conditions OK Done for 8 arcs, singularities being treated OK, to be continued OK, to be continued Done, no longer required Defined, to be implemented S. Claudet - 06Dec'07 LHC-MAC22 - Cryogenics

DFB Commissioning: levels and anti-condensation LT836 LT837 LT864 LT865 LT866 LT867 ≈ 5 m S. Claudet - 06Dec'07 LHC-MAC22 - Cryogenics

Dry air protection of 600A chimneys of DFBAH Consolidation of DFBs Protective box Liquid helium level gauges Installation of calibrated level gauges. Installation of a protective box around the level gauges Anti-condensation system 6 kA, 13 kA, 600 A dry air protection: current lead insulating flange + top of chimney flange, connected in series. Interim solution for sector 4-5 120A active heating system + dry air (depending on tests) Configuration of LG 6 kA, 13 kA (322) 600 A (178) 120 A (36) Dry air protection of 600A chimneys of DFBAH LHC-MAC22 - Cryogenics S. Claudet - 06Dec'07

Commissioning DFBs of sector 4-5 IR4R IR5L DFBMK: boil-off cross-check to be finalized DFBML: released for ELQA DFBMG: released for powering DFBAH LCM: liquid level confirmed abnormal behaviour of several control valves for 600A CL DFBAH HCM: liquid level confirmed - abnormal reading of temperature sensors of 13kA CL #1 DFBAI HCM: liquid level cross-checking in progress Liquid level control to be tuned. DFBAI LCM: liquid level confirmed abnormal behaviour of several control valves for 600A CL. Several valves had to be replaced by caps! DFBLD: boil-off performed - Liquid level control to be tuned. LHC-MAC22 - Cryogenics S. Claudet - 06Dec'07

S. Claudet - 06Dec'07 LHC-MAC22 - Cryogenics

Content Introduction Main facts from sector 7-8 (January to July 2007) Last projects towards completion Identified weak points (@MAC21) and status Cryo HWC activities since Mid 2007 Action plans Summary S. Claudet - 06Dec'07 LHC-MAC22 - Cryogenics

Flushing sectors before cool-down Dust Debris Kapton Reports And possible shorts in diodes ! But the sooner the best !!! S. Claudet - 06Dec'07 LHC-MAC22 - Cryogenics

LHC - 1st cool-down sector 4-5 Cool-down stopped twice due to leaks during cool-down P5 P4 Two hoses in DFBA’s became leaky during cool-down 6 weeks stand-by: looks promising S. Claudet - 06Dec'07 LHC-MAC22 - Cryogenics

LHC Sector 4-5: 1st cool-down (2007) Cool-down to 1.9K Cryogenic tuning 1st leak and repair Powering tests 2nd leak and repair S. Claudet - 06Dec'07 LHC-MAC22 - Cryogenics

LHC 45: Cryogenic tuning toward 1.9K With contractor Cryogenic tuning at 1.9K Stops due to external sources Stops due to 1.8K units with small air leak in cold sub-atmospheric circuit Last 4 weeks (6Nov’07 to 5Dec’07) S. Claudet - 06Dec'07 LHC-MAC22 - Cryogenics

Cool-down of other sectors 7-8 & 4-5: 1st cool-down in 2007 5-6: 300K-80K Nov-Dec 2007 Short in diode and repair 7-8 & 8-1: start wk51 for Jan’08 5-6 & 6-7: Restart wk05 2008 And four remaining sectors Feb’08 to Apr’08 S. Claudet - 06Dec'07 LHC-MAC22 - Cryogenics

Content Introduction Main facts from sector 7-8 (January to July 2007) Last projects towards completion Identified weak points (@MAC21) and status Cryo HWC activities since Mid 2007 Action plans Summary S. Claudet - 06Dec'07 LHC-MAC22 - Cryogenics

On-going actions & plans Cool-down process & Heat loads to be further checked and analysed Refrigeration: Ex-LEP upgrade consolidations and 1.8K units Instrumentation & controls to be terminated and consolidated LHe level / anti-condensation for DFB’s to be deployed He guard along sectors to be consolidated Few other consolidations to be evaluated Operation procedures and teams know-how to be re-inforced Strategy for Helium inventory defined, to be implemented S. Claudet - 06Dec'07 LHC-MAC22 - Cryogenics

Summary The LHC cryogenic system is progressively being commissioned, with signs of “learning curve” Consolidation program started (JT valves, DFB’s, controls, helium) and to be continued 2007 has been a difficult year of commissioning, and most likely 2008 will be a difficult year towards the expected first beams and collisions Looking forward to “routine” operation !!! S. Claudet - 06Dec'07 LHC-MAC22 - Cryogenics