LHC Cryogenics HWC day 19 March 2009

LHC CryogenicsHWC day 19 March 2009

Serge Claudet TE-CRG-OA

(LHC Cryo OP)

S. Claudet LHC Cryogenics - LHC HWC day - Mar'09

Content

• Introduction: experience gained so far

• Consolidations and re-commissioning

• Calorimetry

• Organisation and staff matters

• Summary


First cool-down of LHC sectors

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Temperature [K]

ARC56_MAGS_TTAVG.POSST ARC78_MAGS_TTAVG.POSST ARC81_MAGS_TTAVG.POSST ARC23_MAGS_TTAVG.POSST

ARC67_MAGS_TTAVG.POSST ARC34_MAGS_TTAVG.POSST ARC12_MAGS_TTAVG.POSST ARC45_MAGS_TTAVG.POSST

Christmas and water maintenance shut-down

Short in connection

cryostats and repairs

Ope

n Da

ys

Cooling sectors + Cryo tuning + Powering activities

UX85 Ph1

works

All sectors at nominal

temperature

Simultaneous Cryo start/maintain

First beams around LHC

8 sectors - 8 months

Tuning: ≈ 6 wks / sector


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LHC Cryo Maintain

LHC Cryogenics: towards beamsTarget for global (8 sectors)

“Cryo OK for Powering”

UX85 Ph1

worksElectrical

Transformers

Cool-down and commissioning

(systems, instrumentation, logic)

Beams !!!

19 Sept’08Cryo conditions for 3 months of intense HWC


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LHC Cryo Maintain

LHC Cryogenics: just after beams

Target for 4 sectors tested with calorimetry

A bit frustrating !!!

19 Sept’08

Switch EL network

Rather good stability without specific efforts

A dream for HWC w.r.t Spring’08 !!!


Experience gained so far

• All cryo-subsystems were tuned and put into service (if it has worked once, it will come back)

• Procedures established and teams trained

• Weak points identified and consolidation programs established:– Already visible in 2008 for EL, CV, CO, Cryo– Continued since with many support teams


Tuning LSS components• Electrical Feed Boxes (DFBs):

– We could operate all of them close to nominal conditions (maximum scenario required so far during HWC)

– Few delicate cases (heat loads, levels measurements, levelling of sc link to magnets, valves for cooling current leads, thermometers and noise, High Voltage perturbation on instrumentation cards)

• Stand alone Magnets (SAM):– Difficult Level measurements due to Cold GHe capillary with too

small diameter and possible low points, most delicate cases being treated

• Triplets:– DFBX: Commissionned with moderate ramp rates on some leads

(Cu)– NC found on some Q1 (Missing Cu braid), being treated on critical

cases in R1 and 5L

• Superconducting links (DSLs):– No problem encountered on four DSLs (<80m),

except for DSLC_P3– DSLC design/installation weak point being treated

Might come back !

Nothing special expected for re-testing of Y-lines or DSLC


Electrical feed boxes (DFB’s)

QRL

• On-going work on valve positioners (and plugs ?)

=> Expected gain in stability

- Rangeability of all valves tuned - Filters installed ahead of all valves

=> Effects already confirmed @ P8

Current leads

control

Filling valve


Levels for stand-alone magnets

2008: Case by case lengthy tuning AND global QRL_line_D pressure stability required

LSD0809: Pipe work being consolidated for most cases

2009: At least first sector to be re-assessed with complete boil-off tests, should become more straight forward once consolidation validated

Reference: P6 already conform, due to specific design due to beam dump line

Old small diameter capillary


Calorimetry• Operation:

– Establish global stable conditions, with specific settings for cooling and filling valves

– Almost on-line assessment of temperature drifts (mK/hr) mostly to validate the test or identify possible non-standard zones

• Analysis (off-line so far):– Evaluation of the power deposited in helium (internal

energy) to define the total resistance of a cryo sub-sector, and by comparison quantify singularities.

– Specific studies required to confirm the origin of the singularities

Manual tuning

So far manual, drifts to be

included in supervision

So far manual

(Timber & XL)

Many specific cases (cryo cells, instrumentation, operation facts and accuracy) being considered, so far with success


Standard cells (≈27/sector)

QRLFilling valve

Q D DD

• Preparation from 1.9K operation: 2-3 days to set-up conditions

• Test configuration: 4-5 hours before ramping current

Q D DDQ D DDQ D DD

Magnets 1.9K control

Beam screen T control


Arc sub-sector resistance variation assessed by calorimetry

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Sub-sector resistance variation w/r to baseline [nΩ]

(5 )Dipole arcs (4 )Quadrupole arcs

NNXN: Confirmed by electrical measurements

23R3

15R131

R6, 3

1R1

31R7

~ 2 W @ 7 kA

Although we try to reduce our uncertainty, we feel that specific behaviour of DS zones would be of greater interest!

Triplets: being tested right now @P8


“Cryo view” of tasks ahead this year

Challenges for this year:

Completion of consolidations (like others!)Cooling 4 sectors + filling/tuning 8 sectors in four months !!!


Affectations LHC Cryo CRG-OA

Ing. OP référents experts académiques

Ing. production Encadrement site

Opérateurs Sites + ShiftsCCC

interface

Site coordination

HWC


LHC Cryo shifts 2009: 15 Avril

Final adjustments being implemented

Timing:6h - 14h - 22h

(+/- 1/4h over-lap)

Tel Cryo CCC:70463-70464

+ Additional support am/pm (2x2 pers.) for CCC or LN2 logistics

+ Double on-call service for interventions + Eng. Support via “Best Effort”


Proposal for definition of tasks site/shifts

We will adapt to reality and needs for global efficiency

Winter’09 Spring’09 Summer’09 Aut’09

CCC for Cryo Start/Maintain Direct interface for BE/OP

Local CCR for support and site periodic activities

CCC for global overview and continuity of activities

Local CCR for cool-down, tuning and HWC activities

PP BeamsCooling-Tuning-HWC

Cryo shifts in CCC

Being reviewed and more closely precised


Summary• LHC Cryogenic system has been put in operation with

success in 2008 and was “ready” for 5 Tev operation

• Since september 2008, test programs were conducted and improved our understanding and tuning of sub-systems (calorimetry, 1 refrigerator on two sectors)

• Consolidation programs were launched to improve safety and to increase availability (to be completed)

• We should manage foreseen program with less stress, but we know we have about 500 PID control loops per sector to be active simultaneously, and we will have surprises and temporary down-time to be dealt with!

Complements


Cryo conditions for powering

Cryo Start: set of conditions to allow powering of concerned sub-sector (rather strict = good stability of process)

Cryo Maintain: Few important conditions checking integrity of HW, with slow power abort in case this signal is lost CM: No adjustment possible

during operation

CS: Adjustments within pre-set limits


Recovery Time after Limited Resistive Transitions

• More than 14 cells or full sector: recovery up to 48 hours• In case of fast discharge (even w/o quench): 2 h recovery (heating due to

eddy currents).

(Predictions at design stage)

Achieved or achievable

From x3 down to x1.5 w.r.t design values

Without loosing helium, and powering permit on other powering subsectors


St Genis-PouillyFerney VoltaireGexGenevaPoint 2Point 4Point 5Point 6Point 7Point 8P 1P 1.8Point 32 forCMS(R)

Helium storage

50 t: 50 x 250 m3 + 40 x 76 m3

30 t: 2 x 15 t for Spring 2008 !

Now completed by (Ph. 1):

A good basis, but “rather long” logistics

7832

10 5 5

Cold massesQRL, header CQRL, other headersCryoplantsStorage tanks

LHC: 130t


Two sectors on one cryoplant

Distribution Line Distribution Line

Magnet Cryostats Magnet Cryostats

Cold Compressorbox

Warm CompressorStation

Cold Compressorbox


Shaft

Sur

face

Cav

ern

Tun

nel

LHC Sector (3.3 km) LHC Sector (3.3 km)

1.8 K Refrigeration Unit Ex-LEP 4.5 K Refrigerator New 4.5 K refrigerator 1.8 K Refrigeration Unit

Upper Cold Box


Lower Cold Box


Cold Box

Interconnection Box

Powering tests Powering tests

4.5K 15 mbar

4.5K Ref.: ≈10% capacity left per sector for dynamic loads, after specific adjustments made

≈ 5MW of power input, instead of 8MW (2x4MW)

Competitive for recovery after stops (<10hrs for CC, <24hrs after power failure for 2 sectors)

Not valid for large transients, but an interesting feature for low beam loads, or validated fall-back scenario if serious problems with a refrigerator

OK P6, possible P8 (3Qx) P4 ? (RF/DSLC),

P2/P18 ?!? (ex-LEP, 3Qx)

Documents

LHC Cryogenics HWC day 19 March 2009