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

3.3 km 4’700 t @ 1.9K

≈ 10t/15tHe

LHC Sector 4-5 scheme

4.5 K 1.9 K 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

DFBMs Cryo Maintain LSS: 85% (Since 1st May) Cryo Maintain ARC: 66% (Since 1st June) DFBAs Target LSS: 90% (incl. time lost for quench recovery) S. Claudet - 06Dec'07 Target ARC: 80% (incl. time lost for quench recovery) + Cryogenic tuning to be minimised ?!?

LHC-MAC22 - Cryogenics

Heat inleaks

60 3 2.5

2 1.5

1 0.5

50 40 30 20 10 Average temperature at HX outlet [K] Pressure at HX outlet [MPa] Saturated helium pressure [kPa] Pumping mass-flow [g/s] 0 0 0 20 time [h] 40 • 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

9 d 80 K Design LHC 7-8 Final 21 d 14 d 20 K Design LHC 7-8 Final 3 d 7 d 14 d Sketches intended to illustrate achievements and medium term expectations 1 d 4.5 K Design LHC 7-8 Final 14 d S. Claudet - Jul’07 1 d 3 d 1.9 K Design LHC 7-8 Final 21 d 4 d 14 d / 2 wks

Excluding ELQA or extra-works :

Total Design LHC 7-8 Final ELQA 70 d / 10 wks 28 d / 4 wks S. Claudet - 06Dec'07 Proposed for schedule: 8wks-6wks-4wks 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

S. Claudet - 06Dec'07

Problems with leaks at the factory-made welds on belows

Many non conformities from contractor, repaired by CERN => Impact on sector 3-4 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 S. Claudet - 06Dec'07 LHC-MAC22 - Cryogenics

DFB Commissioning: levels and anti-condensation

LT836 LT837 ≈ 5 m LT866 LT867 LT864 LT865 S. Claudet - 06Dec'07 LHC-MAC22 - Cryogenics

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 Configuration of LG 120A - active heating system + dry air (depending on tests) 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 DFBAI HCM: liquid level cross-checking in progress -Liquid level control to be tuned.

DFBML: released for ELQA DFBMG: released for powering DFBAH LCM: liquid level confirmed - abnormal behaviour of several control valves for 600A CL DFBAI LCM: liquid level confirmed - abnormal behaviour of several control valves for 600A CL. Several valves had to be replaced by caps!

DFBAH HCM: liquid level confirmed - abnormal reading of temperature sensors of 13kA CL #1

report date: 04.12.2007

← Point 4

DFBMK DFBML DFBMG

Monitoring tasks

Current lead temperature readings Current lead head heating system DFB liquid level readings DFB pressure readings DFB temperature readings All instrumentation functional

Commissioning-specific tasks

Lead flow control tuning at 50 K Insulator + CL free of condensation at 50 K for 24 hours Liquid level control tuning Boiloff test to verify LL probe calibration and calculate heat load Level gauges set points confirmed ELQA passed Cryo Start/Cryo Maintain Authorization for pow ering S. Claudet - 06Dec'07 DFBLD: boil-off performed - Liquid level control to be tuned.

DFBAH-L DFBAH-H DFBAI-H DFBAI-L DFBLD

Point 5 →

DFBXE n.a.

n.a.

n.a.

n.a.

n.a.

n.a.

n.a.

n.a.

n.a.

n.a.

n.a.

n.a.

com pleted

n.a.

in progress / scheduled

n.a.

LHC-MAC22 - Cryogenics

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 S. Claudet - 06Dec'07 And possible shorts in diodes !

But the sooner the best !!!

LHC-MAC22 - Cryogenics

P4 P5

LHC - 1st cool-down sector 4-5

Cool-down stopped twice due to leaks during cool-down 04-Jul 11-Jul 18-Jul 25-Jul 01-Aug 08-Aug 15-Aug 22-Aug

Date

29-Aug 05-Sep 12-Sep 6 weeks stand-by: looks promising 19-Sep 26-Sep 03-Oct 10-Oct 17-Oct A7R4 S. Claudet - 06Dec'07 320 300 280 260 240 220 200 180 160 140 120 100 80 60

Temperature [K]

A7L5

Arc Cells

300-320 280-300 260-280 240-260 220-240 200-220 180-200 160-180 140-160 120-140 100-120 80-100 60-80 Two hoses in DFBA’s became leaky during cool-down LHC-MAC22 - Cryogenics

350 300 250 Cool-down to 1.9K

200 150 Cryogenic tuning 100 50 1st leak and repair 2nd leak and repair Powering tests 0 29 Jun 07 13 Jul-07 27 Jul-07 10 Aug 07 24 Aug 07 07 Sep 07 21 Sep 07 05 Oct 07

Time [days]

Return Temperature to 4.5K Refrigerator 19 Oct 07 02 Nov 07 16 Nov 07 30 Nov 07 14 Dec 07 Magnet Temperature (average over sector) 4.5K Refrigerator Supply Temperature S. Claudet - 06Dec'07 LHC-MAC22 - Cryogenics

LHC 45: Cryogenic tuning toward 1.9K

10 9 8 7 6 5 4 3 2 1 0 1-Jan-04 S. Claudet - 06Dec'07 With contractor Stops due to external sources Cryogenic tuning at 1.9K

4-Feb-05 Stops due to 1.8K units with small air leak in cold sub-atmospheric circuit 23-Aug-05 11-Mar-06 4.5K Refrigerator supply temperature Magnet temperature (average over sector) 1.8K Refrigeration unit cooling temperature LHC-MAC22 - Cryogenics

350 300 250 200 150 100 50 0 16-Nov-07

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 23-Nov-07 30-Nov-07

Time [days]

07-Dec-07 14-Dec-07 4.5K Refrigerator Supply TemperatureMagnet Temperature (average over sector) S. Claudet - 06Dec'07 Return Temperature to 4.5K Refrigerator 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