lhc cryogenics status and perspectives serge claudet, on behalf of the lhc cryogenics group lhc -...

LHC CryogenicsStatus and Perspectives

Serge Claudet, on behalf of the LHC Cryogenics group

LHC - MAC22 05 Dec 2007

LHC-MAC22 - CryogenicsS. Claudet - 06Dec'07

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


LHC Sector 4-5 scheme

4.5 K1.9 K

3.3 km4’700 t @ 1.9K≈ 10t/15tHe


LHC sector 7-8 - First cool-down


Availability for HWC: From 7-8 to others

DFBMs

Cryo Maintain LSS: 85% (Since 1st May)

DFBAs

Cryo Maintain ARC: 66% (Since 1st June)

Target LSS: 90%(incl. time lost for quench recovery)

Target ARC: 80%(incl. time lost for quench recovery)

+ Cryogenic tuning to be minimised ?!?


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

0

0.5

1

1.5

2

2.5

3

0 20 40time [h]

[K],

[kP

a],

[MP

a]

0

10

20

30

40

50

60

[g/s

]

Average temperature at HX outlet[K]Pressure at HX outlet [MPa]

Saturated helium pressure [kPa]

Pumping mass-flow [g/s]


LHC Cryogenics: duration of cool-down phasesDesignLHC 7-8Final

9 d21 d

3 d14 d

1 d14 d

1 d21 d

80 K

20 K

4.5 K

1.9 K

Total

DesignLHC 7-8Final

DesignLHC 7-8Final

DesignLHC 7-8Final

DesignLHC 7-8Final

14 d / 2 wks70 d / 10 wksELQA

14 d

4 d

3 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


Superconducting links (DSL)Few hundred meters link between DFBL’s and stand-alone magnets


Problems with leaks at the factory-made welds on belows

Many non conformities from contractor, repaired by CERN

=> Impact on sector 3-4


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


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


LT836LT837

LT864LT865

LT866LT867

DFB Commissioning: levels and anti-condensation

≈ 5 m

Consolidation of DFBs

Anti-condensation system6 kA, 13 kA, 600 A- dry air protection: current lead insulating flange + top of chimney

flange, connected in series. Interim solution for sector 4-5120A - active heating system + dry air (depending on tests)

6 kA, 13 kA (322) 600 A (178) 120 A (36)

Liquid helium level gauges- Installation of calibrated level gauges. - Installation of a protective box around the level gauges

Protective box

Dry air protection of 600A chimneys of DFBAH

Configuration of LG

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

Commissioning DFBs of sector 4-5

report date: 04.12.2007 ← Point 4 Point 5 →

DFBMK DFBML DFBMG DFBAH-L DFBAH-H DFBAI-H DFBAI-L DFBLD DFBXE

Monitoring tasks

Current lead temperature readings n.a.

Current lead head heating system n.a.

DFB liquid level readings n.a.

DFB pressure readings n.a.

DFB temperature readings n.a.

All instrumentation functional n.a.

Commissioning-specific tasks

Lead flow control tuning at 50 K n.a.

Insulator + CL free of condensation at 50 K for 24 hours n.a.

Liquid level control tuning n.a.

Boiloff test to verify LL probe calibration and calculate heat load n.a.

Level gauges set points confirmed n.a.

ELQA passed n.a.

Cryo Start/Cryo Maintain n.a.

Authorization for pow ering n.a.

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.

completed

in progress / scheduled

IR4R IR5L

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 !!!


LHC - 1st cool-down sector 4-5

04-Jul11-Jul

18-Jul25-Jul

01-Aug08-Aug

15-Aug22-Aug

29-Aug05-Sep

12-Sep19-Sep

26-Sep03-Oct

10-Oct17-Oct

A7R4

A7L5

60

80

100

120

140

160

180

200

220

240

260

280

300

320

Temperature [K]

Date

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

P4

P5

6 weeks stand-by: looks promising

Two hoses in DFBA’s became leaky during

cool-down

Cool-down stopped twice due to leaks during cool-down


LHC sector 4-5: 1st Cool-down (2007)

0

50

100

150

200

250

300

350

29-Jun-07

13-Jul-07

27-Jul-07

10-Aug-07

24-Aug-07

07-Sep-07

21-Sep-07

05-Oct-07

19-Oct-07

02-Nov-07

16-Nov-07

30-Nov-07

14-Dec-07

Time [days]

Tem

pe

ratu

re [

K]

Return Temperature to 4.5K Refrigerator Magnet Temperature (average over sector)

4.5K Refrigerator Supply Temperature

LHC Sector 4-5: 1st cool-down (2007)

1st leak and repair 2nd leak

and repair

Cool-down to 1.9K

Powering tests

Cryogenic tuning


0

12

3

45

6

7

89

10

1-Jan-04 19-Jul-04 4-Feb-05 23-Aug-05 11-Mar-06

Tem

pe

ratu

re [

K]

4.5K Refrigerator supply temperature

Magnet temperature (average over sector)

1.8K Refrigeration unit cooling temperature

LHC 45: Cryogenic tuning toward 1.9K

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)

With contractor


LHC sector 5-6: 1st Cool-down (2007)

0

50

100

150

200

250

300

350

16-Nov-07 23-Nov-07 30-Nov-07 07-Dec-07 14-Dec-07

Time [days]

Tem

pe

ratu

re [

K]

4.5K Refrigerator Supply TemperatureMagnet Return Temperature to 4.5K Refrigerator

Temperature (average over sector)

Cool-down of other sectors

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

7-8 & 4-5: 1st cool-down in 2007

5-6: 300K-80K Nov-Dec 2007

Short in diode and repair


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


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 !!!

lhc cryogenics status and perspectives serge claudet, on behalf of the lhc cryogenics group lhc -...

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