How can we reduce the “no beam„ time?

Walter Venturini Delsolaro

D. Arnoult, S. Claudet, G. Cumer, K. Dahlerup Petersen, R. Denz, F. Duval, V.

Montabonnet, D. Nisbet, H. Thiesen

LHC Performance Workshop – Chamonix 2011

Outline

• Beam statistics for the 2010 run, H factor• How to reduce the no beam time:

– Faults statistics of top 4 systems (mitigation actions)

– Review of technical stops – Possible gains in setup time without

beam

Machine statistics 2010

Stable beams16%

Fault25%

beam setup40%

Technical stop/ HC10%

setup no beam9%

Machine statistics along the run

1 3 5 7 9 110.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00

90.00

Availability

Month

% o

f to

tal ti

me

1 3 5 7 9 110.00

10.00

20.00

30.00

40.00

50.00

60.00Beam setup Setup no beam

Month

% o

f to

tal ti

me

1 3 5 7 9 110.00

5.00

10.00

15.00

20.00

25.00

30.00

35.00

40.00Technical stop

Faults

Month

% o

f to

tal ti

me

1 3 5 7 9 110.00

5.00

10.00

15.00

20.00

25.00

30.00

35.00

Stable b...

Month

% o

f to

tal ti

me

physics oriented operation0.2 < H < 0.3

August

beam setup32%

setup no beam6%

Technical stop/ HC

7%

Fault26%

Stable beams29%

0 1 2 3 4 5 6

QPSCryogenics

PCEL+UPS

InjectorsAccess system

LBDSCol l imators

ControlsRFOP

BLMCV

Q, Qp FeedbacksExperiments

NOFMKI

VacuumBICPIC

Alarm-fi re IT

IQCsetti ngs

BPMTiming

SoftQuench

Faults downtime distribution

% of total time

70% of all faults downtime

Covered in Verena’s talk

QPS detailed statistics and mitigation actions

R .Denz

Equipment type Faults

Qty. Availability [%]

MTBF [hours]

Quench heater power supplies

26 6076 99.998 1145760

Quench detection systems 19 10438 99.999 3362135

DAQ caused by radiation (SEU)

12 1624 99.997 828240

DAQ other causes than radiation

8 2532 99.999 1936980

DAQ all faults combined 20 2532 99.997 774792

Equipment type

Mitigation

Quench heater power supplies

Replacement of faulty switches (1000), additional software interlocks allowing to continue to run MB systems with 3 out of 4 quench heater power supplies and postpone intervention to a convenient time e.g. technical stop

Quench detection systems

Removal of obsolete systems (global bus-bar detector), increase EMC immunity for Q9 and Q10, try to improve noise immunity of RU.L4 (re-cabling of current sensor)

DAQ caused by radiation (SEU)

Firmware upgrade in hot spots, i.e. point 3, point 7, L2, R8

Cryogenics downtime and perspectives (S. Claudet)

Major causes in 2010 Forecasts 2011

Cold Compressors (bearings, drives)Consolidation done at Xmas, and new diagnostics

Less failures (1 or 2)

Sub-atm filter clogging:Last leaks (P4) identified at Xmas and treated

No perturbations (possible surprise at Beg. of the run)

Valves for flow control of current leads:50% of valves changed with new type (flex bearings)

Almost no failure, existing mitigation program continued

Instrumentation:Fuses, old FPGA cards, non-conformity treated at Xmas

Less failures (max. 10?)

24V power supply units:Checks done all sites, long term repair under investigation

Few failures (1 or 2)

+ 2-5 failures due to minimal preventive maintenance

Detailed analysis fault statistics of power supplies in EDMS 1109277

PC detailed statistics and mitigation actions

Target MTBF 80000 hours

0

10

20

30

40

50

60

70

80

QD-QF IPD-IPQ Main IT 600A-10V

WarmMagnetsPoint 3 &

7

COD 120A-10V

RB WarmMagnetsexcept

Point 3 &7

Faul

ts n

umbe

r

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

Faul

ts/c

onve

rter

Faults

Faults/ converter

Check of connector contacts during winter

technical stop,ADC-DCCT Calibration

Spurious fault? Change of internal logic, being

tested

Most faults in RBA78, solved

Redesign of the earth current monitoring card in 2011-2012

In general, sensitive to Electrical perturbations

ALICE dipole: Expertise on going on the transformer, U CAPA OVER RIPPLE fault

threshold revisited 

SPA reference to be revisited during 2011

HWC campaign 

Spurious faults due to bad contact during the first part of 2010

                3x ERD fuse blown without any problem observed on the converters (no

explanation YET)

AUG18 kV prot

UPS

Ext non RTE

RTE

EL-UPS (LHC downtime)

Electrical network perturbations

-45%

-40%

-35%

-30%

-25%

-20%

-15%

-10%

-5%

0%

0 20 40 60 80 100 120 140 160

time (ms)

Vari

ation

LHC stop

EN-EL

Zone defined in EDMS 113154

Technical Stops• In 2010 we had 6, as scheduled, starting on March 15• Pattern: 4-36-3-31-4-45-5-37-4-45-4-40+• After TS, an increment in faults was observed. Effect is

decreasing along the run

-15

-10

-5

0

5

10

15

20

25

30

1 2 3 4 5 6

TS progressive number

Faul

ts (a

fter

- be

fore

) [%

of t

otal

tim

e]

Expressed needs for TS in 2011

• Cryo: “3 TS equally spaced, 4 days each”• QPS: “at least two, first one not too late. 4

days too short”• EPC: “none, see how it goes with 60A”• EL: “frequency is not important, but 4 days too

short. Can reduce during the run but must recuperate during the Xmas break”

• CV: same as EL• Experiments?• …

0

5

10

15

20

25

30

35

40

0.0E+00 1.0E-04 2.0E-04 3.0E-04 4.0E-04 5.0E-04 6.0E-04 7.0E-04

Resistance [Ohm]

Tim

e to

ram

p do

wn

[min

utes

]

148 mH74 mHTexp 148 mHTexp 74 mH

Setup without beam: Q4 ramp down time is the bottleneck,

due to converter topology and warm cables resistances

How to ramp down faster1) Ramp down “open loop” (less precision on current with no beam)

IT becomes the bottleneck IT min time from 3.5 TeV to I min op ~ 25 minutes (H. Thiesen)

2) Add an extra cable on the mid lead:allows faster ramp down with beam (squeeze) (already studied for TOTEM high β* optics)

Would bring advantages in controllability, optics flexibility (and gain time when squeezing to low β*)

IT warm cables section “over sized”, reducing it could gain ~30% in time constant while keeping reasonable margin

Hardware changes not possible before next long shutdown

D. Nisbet at LMC 10

Access recovery

• Normal Ramp down/pre cycle

• Proposed Ramp down for short access (EDMS 1076139)

5890 A

350 A 500 A760 A

5890 A

100 A (access here)760 A

Today: need to pre cycle after access, as the main magnets are put off. A new procedure (under approval) proposes to leave them at 100 A

Magnetically almost equivalent, small effect on static b3 (Q’)

-30

-10

10

30

50

70

90

110

0 500 1000 1500 2000

Current (A)

b 3 (u

nits

)

Standby current (100 A)

End of ramp down current (350 A)

Between 350 A and 760 A:

ΔB in the bore ~ 280 mT

Penetration field is ~ 150 mT

But b3 comes from detailed distribution of magnetic moments in the cross section

Easy to solve!

Injection current

Conclusions: how can we reduce....

• Reduce fault numbers: mitigation QPS, Cryo, PC

• Review frequency and duration of TS • Faster turnaround:

– IPQs, IT: gain 10 mins with no hardware changes

– Hw changes (with gains for squeeze duration and optics flexibility) possible during long shutdown

• No pre cycle after short access (needs approval of new prodedure)

Backup slides

0

10

20

30

40

50

60

70

80

90

100

25 01 22 02 22 03 19 04 17 05 14 06 12 07 09 08 06 09 04 10 01 11 29 11

Ava

ila

bil

ity

Daily "Global LHC Cryo" weekly AVG Monthly AVG Scheduled Stops

LHC Cryo global availability

Powering tests

Perturbations: clogging sub-atm circuits-CV891-instrumentation-Shaft seals-VFD/MB-24V

Learning spring Fantastic since summer !

Results for 2010 above expectations, thanks as well to periodic technical stops

S. Claudet

Availability

90.0

91.0

92.0

93.0

94.0

95.0

96.0

97.0

98.0

99.0

100.0

12 23 34 45 56 67 78 81 Average

%

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

%

12 23 34 45 56 67 78 81 Average

Supply

Cryo

Users

ScheduledStops

Availability, as percent of the time since 1st beams

Unavailability, per origin

3.47

0.12

0.940.48

95.0

No visible impact of “1 Ref. for 2 sectors”

RF emptied during technical stops

Cryogenics detailed statistics

S. Claudet

Measurement in MBP2O1 - Aperture 1

-30

-20

-10

0

10

20

30

0 500 1000 1500current (A)

b3

(u

nits

@ 1

7 m

m)

injection -10

-8

-6

-4

-2

0

0 200 400 600 800

minimum current (A)

b3 (

units

@ 1

7 m

m)

0.2

0.4

0.6

0.8

1

1.2

b5 (

units

@ 1

7 m

m)

L. Bottura