Update on MKI Performance:TS3 to 02/10/2012

M.J. Barnes

Acknowledgements: P. Adraktas, V. Baglin, A. Bertarelli, G. Bregliozzi, S. Calatroni, F. Caspers, H. Day,

L. Ducimetière, M. Garlasche, A. Gérardin, B. Goddard, J.M. Jimenez, V. Mertens, E. Métral, B. Salvant, M. Taborelli, B. Teissandier, J. Uythoven, W. Vollenberg, W. Weterings

02/10/2012 1M.J. Barnes

Motivation for exchanging MKI8D

Motivation for changing MKI8D during TS3 was to gain valuable experience of the improved MKI beam screen, installed in the LHC, prior to LS1 (in view of a bulk upgrade of all MKIs during LS1), – especially reduced beam induced power deposition (MKI8D was limiting the availability of the LHC – see LMC 27/06/2012), while maintaining the HV performance.

4 MKIs in RA87

MKI8D

MKI8CMKI8BMKI8A

Injected Beam

02/10/2012 2M.J. Barnes

MKI8D Exchange (TS3)

New ceramic tube & 19 (c.f. 15) beam screen conductors, each with stretched spheres.

MKI#5 has an expected power deposition of one-half to one-

third of installed MKIs.

New NEG coated bypass tubes

Removal of “old” MKI8D (no jacket)

Transport of “new” MKI8D (with jacket)

MKI8D exchange completed in 4.5 days, teams working around the clock, and MKI8 handed back to the CCC several hours in advance of the ambitious planning.Sincere thanks to all teams for excellent preparation and extraordinary efforts throughout TS3 which made this operation possible.Plus: measures to ensure

that emissivity of inside of MKI5 tank was ≥ 0.1.

Exchange envisaged, at Chamonix 2012, during 2012. Preparation very tight for improvements: worked with available

components, e.g. ceramic tube.

02/10/2012 3M.J. Barnes

MKI2 and MKI8 Temperatures: 29/09-01/10

The “old” MKI8D had the highest measured temperature of all the MKIs, prior to TS3. Since TS3, the “new” MKI8D has the lowest measured temperature (it is estimated that the “old” MKI8D would have been at ~60˚C, at 02:00hrs on 01/10/2012).Note: measurements are not absolute, because of thermal contacts, etc.

02/10/2012 4M.J. Barnes

01/10/2012: MKI8D measured temperatures lowest of all MKI8s!

25

40

25

40

Breakdown (@ ~23:20hrs): No precursor to breakdown of MKI8D: occurred at Q5 end (beam screen suspected). Possibly related to transport and relatively short HV re-conditioning (magnet was OK in lab).

Vacuum Activity: B1: 4e13 max charge.Anti-ecloud solenoids initially at 3A.Relatively high pressure close to MKI8s when B1 injected.When solenoid current was increased from 3A to 5A large reduction in pressure in C-D interconnect and thus in MKI8C and MKI8D: SIS interlock level increased for MKI8 solenoids.Significant vacuum activity on VGPB.192.5R8.R during subsequent MKI8 SoftStart.

MKI8. 24/09/2012

02/10/2012 5M.J. Barnes

B1 intensity

VGPB.192.5R8.R (Q5 side of MKI8D)

VGPB.192.5R8.R(SoftStart): B1 circulating

Solenoid: 3A

Solenoid: 5A

C-D interconnect

Spark

MKI8C

MKI8D

NO BEAM

4E13 Pressure FS: 1E-9

Anti-Ecloud solenoids on MKI interconnects did not effect pressure near MKI8s (unlike 24/09 evening). Also B1 does not effect pressure near MKI8s. Good part of pressure rise originates in ceramic tube - strong surface conditioning occurred.

MKI8. Initial Intensity Ramp-up, 26/09/2012

02/10/2012 6M.J. Barnes

6+36

8.5e-8mbar (Q5 side of 8D)

6+2*36

6e-8mbar (C-D interconnect)

2e-8mbar (MKI8D)

2e-8mbar (Q5 side of 8D)

3e-8mbar (Q5 side of 8D)

6+36

Pressure FS: 9E-81.4E13

Definite surface conditioning effect – which would be even more dramatic if normalized to charge.Note: a time delay of 1-3 mins between injection of B2 and onset of pressure rise.

MKI8. Initial Intensity Ramp-up, 26-27/09/2012

02/10/2012 7M.J. Barnes

B2: 6+2*144

6+2*144+72 6+3*144

6+4*144

6+5*144 6+5*1444.5e-8mbar (Q5 side of MKI8d)

2.5e-8mbar

5e-9mbar (MKI8D)

1.2E14 Pressure FS: 6E-8

1hour/div

~2mins

B2

~2mins

1.2E13

Vacuum Pressure Oscillations07:30h improved beam screen temperature tuning

Courtesy: B. Holzer, J. Wenninger

02/10/2012 8M.J. Barnes

Vacuum pressure oscillations in phase with Q5 beam screen temperature.

Spent 13 hrs “scrubbing only”, without going to stable beams: this was very efficient, with high vacuum levels.Then spent further 25 hrs scrubbing while providing in parallel physics to the experiments, from the first fill with 452 bunches up to the fill with 1374 bunches with reduced bunch intensity. The vacuum during this period was roughly a factor of 2 to 3 better than during the “scrubbing only”.

MKI8. 50ns, 26/09/2012 – 01/10/2012

1374b, 1.4e11p/b(FBCT prob.)

1E-8 2E-8 2E-82.2E14

6+2*144+72

1374b, 1.5e11p/b7e33 cm-2s-1.

Q5 side of MKI8D

~5e-9 (Q5 side of 8D)

6+36

3.6e-9 (MKI8D)

02/10/2012 9M.J. Barnes

Effect of MKI PressureHigh pressure in both the kicker magnet tank and near to the capacitively coupled end of the beam screen, when pulsing the kickers, increases the probability of an electrical breakdown. Tank pressure SIS vacuum threshold for injection is 2e-9 mbar (temporarily increased to 2.5e-9 mbar, for 25 ns beam, during October 2011).“Ceramic tube” SIS vacuum interlock threshold for injection is 5e-9 mbar (NEW interlock). Pressure is measured on interconnects, just outside the kicker tanks.

On the new MKI8D, in the lab, the probability of sparking increased with increasing pressure (>~5e-9mbar).A risk of sparking is deposition of metal on a ceramic surface – further increasing risk of sparking, even with lower pressure, and possibly requiring the exchange of an MKI (interruption of normal program – most likely more than 5 days).

Occasional sparks at end of screen conductors, at

bottom LHS (lab).

02/10/2012 10M.J. Barnes

Recall: MKI8, UFO MD – 50ns. 22/06/2012

After switching off interconnect solenoids, pressure in C-D interconnect increased by a factor of ~70 !! Solenoids of Q4 & Q5 also effect MKI8D (and MKI8C) pressure.Spark in MKI8C (probably at end of beam screen) after 11 pulses – [MD: pulsing MKIs in beam gap]. To minimize probability of beam screen spark, recently interlocked injection (SIS) on pressure of (kicked beam) interconnects: threshold of 5e-9 mbar.

02/10/2012 11M.J. Barnes

Q5 side of MKI8D

Solenoids on interconnectsSolenoids by Q4 & Q5

Pressure rise in MKI8C-D interconnect

MKI8CMKI8DMKI8C spark

Q4 & Q5

solenoids OFF

Interconnect

solenoids OFF

Pressure rise on Q5 side of MKI8D

1

2

Pressure FS: 1E-8

~6.5e-9

MKI Sparks - 2011Reason for vacuum integrals - “Old” MKI8-D sparked on: April 17, 2011: @51.3kV and 7800ns – following a period of “high” pressure (50ns beam); Oct. 25, 2011: @54.3kV and 1200ns (SS) – following a period of pressure of ~9e-9 mbar (25 ns beam, Anti-ecloud solenoids off).

02/10/2012 12M.J. Barnes

8 Feb 2011 to 18 Apr 2011 (Spark on 17/04)Pressure.Time Integral: MKI8D: 4.7*10^-7 mbar.hours

March April

8 Feb 2011 to 18 Apr 2011 (Spark on 17/04)Pressure.Time Integral: C-D interconnect: 1.1*10^-6 mbar.hours

1 Sept 2011 to 26 Oct 2011 (Spark on 25/10)Pressure.Time Integral: MKI8D: 2.9*10^-7 mbar.hours

Oct.

1 Sept 2011 to 26 Oct 2011 (Spark on 25/10)Pressure.Time Integral: C-D interconnect: 7*10^-7 mbar.hours

5x10-7 5x10-7

1.2x10-64x10-8

1x10-81x10-8

4x10-8 1.2x10-6

1x10-8 1x10-8

MKI Sparks - 2012“Old” MKI8-D also sparked on: April 9, 2012: @51.3kV and 7800ns – following a period of “high” pressure (50ns beam); Apr. 15, 2012: @51.3kV and 7800ns (SS). Vacuum

Threshold Setpoints (mbar.hours) (mbar.s)MKI8-D 2.88E-07 1.04E-03MKI8-C 1.23E-07 4.43E-04MKI8-B 2.51E-07 9.04E-04MKI8-A 3.12E-07 1.12E-03MKI2-D 2.24E-07 8.06E-04MKI2-C 1.31E-07 4.72E-04MKI2-B 1.51E-07 5.44E-04MKI2-A 2.55E-07 9.18E-04

• Vacuum Integral threshold for new MKI8D set to same value as previous MKI8D.

• As of 08:00hrs on 01/10/2012 MKI8C/D at 10%/70% of thresholds – these magnets were sublimated in the shadow of another intervention, and integrals subsequently reset to zero.

02/10/2012 13M.J. Barnes

3.5410 10 9 3.5415 10 9 3.5420 10 9 3.5425 10 9 3.5430 10 9 3.5435 10 90.

2. 10 9

4. 10 9

6. 10 9

8. 10 9

0.

3.8 10 8

7.5 10 8

1.1 10 7

1.5 10 7

Timestamp UTC_TIME

Pres

surembar

Pressure and Integrated pressure vs Time for ValueMKI8D: 13/03/2012 to 15/04/20128x10-9

2x10-9

Preliminary UFO Observations for new MKI8D magnet

02/10/2012 14M.J. Barnes

• In total 53 candidate MKI UFOs in Pt.8 since TS#3.

Low statsistics but reduced UFO activity in new MKI.D5R8 so far.

44 MKI UFOs in Pt.8 since TS#3. Signal RS04 > 2∙10-4 Gy/s. No correction for new BLM positioning.

502 MKI UFOs in Pt.8 from April 2012 until TS#3 . Signal RS04 > 5∙10-4 Gy/s.

since TS#3

until TS#3

Courtesy: T. Baer

3mm gap between ceramic tube and conducting cylinder

1mm gap between ceramic tube and conducting cylinder

Screen conductors

On-going R&D• Working closely with VSC to devise a method to apply

Cr2O3 to inside of (~3m long) ceramic tube: literature shows that ceramic insulators treated with Cr2O3 had a voltage hold-off of the surface of the alumina increased by ~50%. In addition the peak measured SEY of 95% alumina of ~6.4 was reduced to ~1 after treatment.• Author of paper located and contacted….

• VSC also looking at other coatings (e.g. Carbon).• Studying means of reducing electric field gradient on

surface of ceramic tube to permit 24 screen conductors to be used without HV breakdown!

• Intention is to bring as many of these improvements to fruition, as possible, during LS1 (for all MKIs).

02/10/2012 15M.J. Barnes

Remarks Significant surface conditioning of new MKI8D ceramic tube has taken place (required 13 hrs scrubbing without going to stable beams. 25 hrs scrubbing while providing physics to the experiments). High pressure in the kicker magnet tank, and near the capacitively coupled end of the beam screen, when pulsing the kickers, increases the probability of an electrical breakdown.

SIS interlocks prevents injection with pressure >2e-9 mbar in an MKI tank; SIS interlock now implemented for pressure in the beam-pipes immediately around the MKIs

>5e-9 mbar. Pressure threshold will be adjusted based on experience: it is presently considered to be safe but not unduly conservative.

The pressure in the MKI tanks is presently integrated w.r.t. time and SIS interlock thresholds are defined for each integral.

If the integral exceeds the SIS threshold a sublimation should be carried out on MKI8D, and possibly MKI8C: last carried out 01/10/2012. To minimize HV de-conditioning of the MKIs, and the need for a sublimation, it is recommended that the MKI anti-ecloud solenoids are kept on throughout both normal operation and, in general, during MDs.

Anti-ecloud solenoids: SIS interlock prevents injection if current of solenoids, around MKIs, < threshold. Have MKI anti-ecloud solenoids (and maybe those next to Q4 & Q5) ON during the 25ns

scrubbing run: ‘probe’ the effect of changing the coil current.

02/10/2012 16M.J. Barnes

Conclusions Significant scrubbing and surface conditioning of new MKI8D has taken place, total scrubbing time 13 + 25 hours.Initial analysis of “new” MKI8D measured temperatures indicates that beam induced power deposition is significantly reduced in comparison with the “old” MKI8D, as per design – further operational data with high beam intensities required for more quantitative conclusions. Preliminary data indicates that new cleaning procedures have significantly reduced the number of UFOs at the replaced magnet. The present SIS vacuum interlocks in the kicker tank and interconnects are based on experience in the lab and the machine following magnet breakdowns after being exposed to bad vacuum. Working towards a bulk upgrade of MKIs during LS1.

02/10/2012 17M.J. Barnes

Spare Slides ….

25/09/2012 18M.J. Barnes

Note: Anti-Ecloud Solenoids installation as follows:TS 2010-2011: Q4 & Q5 sides of both MKI2 and MKI8 06-Jul-11: MKI8 B-C & C-D Interconnects (B1 & B2) TS 2011-2012: MKI2 All Interconnects

02/10/2012 19M.J. Barnes

Pressure FS: 4E-81.4E14

MKI2 Interconnects Following Exchange of MKI2B (Dec. 2010)

POINT 8 (Anticlockwise Inj.): Vacuum & BLM Systems

Capacitive C

oupling

Capacitive C

oupling

Capacitive C

oupling

Capacitive C

oupling(D

ouble foot)

TMR

TMR

TMR

TMR

(Single foot)

BEAM 2

VG

PB.176.5R

8.R

VG

P.158.5R8.C

VG

PB.138.5R

8.R

VG

P.118.5R8.C

VG

PB.98.5R

8.R

VG

P.78.5R8.C

VG

PB.59.5R

8.R

VG

P.39.5R8.C

VG

PB.4.5R

8.R

VG

PB.14.5R

8.RBLM

2346

0.82

m

B

LMQ

I.04R

8.B

1I30

_MQ

Y

BLM

2346

9.8m

BLM

EI.0

5R8.

B2E

20_M

KI.C

5R8.

B2

BLM

2347

3.34

mB

LMEI

.05R

8.B

2E10

_MK

I.D5R

8.B

2

2347

3.89

m

2347

7.31

m

2346

5.41

m

2346

5.96

m

2346

9.93

m

2347

9.12

m to

234

79.2

0m

VV

GST

.I5R

8.R

Distance:

2346

2.00

m

B

LMI.5

R8.

B2

2348

1.60

m

B

LMQ

I.C5R

8

BMKI.B5R8.B2

CMKI.C5R8.B2

DMKI.D5R8.B2

AMKI.A5R8.B2

BLM

2346

0.11

m to

234

60.1

9m

VV

GST

.A5R

8.R

2345

7.68

m

BLM

QI.F

4R8

2346

5.70

m

VG

PB.D

5R8.

R

2346

9.66

m

VG

PB.E

5R8.

R

2347

3.63

m

VG

PB.F

5R8.

R

2347

7.46

m

VG

PB.G

5R8.

R

2347

9.04

m

VG

PB.H

5R8.

R

2346

3.71

m

VG

P.A

5R8.

C

2346

7.67

m

VG

P.B

5R8.

C

2347

1.63

m

VG

P.C

5R8.

C

2347

5.60

m

VG

P.D

5R8.

C

2346

1.2m

V

GPB

.C5R

8.R

VG

PB.4

.5R

8.B

VG

PB.6

0.5R

8.B

VG

PB.9

9.5R

8.B

VG

PB.1

39.5

R8. B

VG

PB.1

92.5

R8. B

VG

PB.1

95.5

R8. B

VG

PB.2

.6R

8.B

VG

PB.2

.5R

8.B

VG

PB.2.5R

8.R

VG

PB.195.5R

8.R

VG

PB.2.6R

8.R

Q4R8 side

VG

I.36.5R8.C

VG

I.75.5R8.C

VG

I.115.5R8.C

VG

I.155.5R8.C

VIE

SA.1

93.5

R8.

CPS

: VR

PMB

.21.

5R8

2347

8.8m

. Cct

12

VIE

SA.3

.5R

8.C

PS: V

RPM

B.2

1.5R

823

459.

8m. C

ct 1

2

Q5R8 side

Interaction Point

BLM

2347

7.63

m

BLM

QI.0

5R8.

B2E

30_M

QY

2347

8.8m

B

TV

SI.C

5R8.

B2

(BT

VSI

084)

Anti-Ecloud solenoids installed: on Q4 side and Q5 side during TS 2010/2011;B-C and C-D interconnects 6/07/2011A-B interconnects?? (after 22/09/2011)

25/09/2012 20M.J. Barnes

Ecloud solenoid layout Courtesy of V. Baglin

Q5Q4

MKI8DMKI8CMKI8BMKI8A

Anti-Ecloud Solenoids at MKI, LSS8

25/09/2012 21M.J. Barnes

MKI8. 25ns, 24/10/2011

B2: 9e13 max charge.Anti-elcoud solenoids switched between 0A and 5A.Max pressure on B2 close to MKI8s: 6e-8mbar on VGPB.192.5R8.R (Q5 side of MKI8D).Pressure on VGPB.192.5R8.R not sensitive to Ecloud solenoid current (in this case)…..Pressure in C-D interconnect, and thus magnet, is sensitive to Ecloud solenoid being on or off. Max. C-D interconnect pressure during injection ~6e-9, with several injections > 4e-9 mbar.

VGPB.192.5R8.R

MKI8D

C-D interconnect

Switching solenoids off results in an increase in pressure, on C-D interconnect, and thus MKI8D by factor of ~3.

25/09/2012 22M.J. Barnes

During MKI8 SoftStart, following breakdown of MKI8D, considerable vacuum activity seen on VGPB.192.5R8.R: vacuum activity reduces for subsequent SoftStarts…..

25/09/2012 23M.J. Barnes

MKI8. 50ns, 24/09/2012B1 intensity

VGPB.192.5R8.R

VGPB.192.5R8.R(SoftStart): B1 circulating

Solenoid: 3A

Solenoid: 5A

C-D interconnect

VGPB.192.5R8.R(SoftStart)

B2 intensity

VGPB.192.5R8.R(SoftStart)

Spark

LHC Injection Kicker: Maximum Temperatures During Oct. 2011

Magnet PT100’s are mounted on ground plates: these plates contact the ground busbar and magnet capacitors; Ground busbar does not contact ferrites – hence heat conduction to magnet PT100’s is mainly via magnet capacitors. Hence Mag_Up would be expected to measure a higher temperature than Mag_Dn, but …. Tube_Up temperature > Tube_Dn temperature, maybe because of more cooling at “Dn” end (due to SS tube and “cage” around ferrites??).The Power (W/m) shown is derived from impedance measurements – measured magnet temperature does not correlate with the power….

Kicked Beam

TMR connection

entrance box connection

capacitor

ferrite yoke

ground plateground

plate HV plate

HV plate

PT100Tube_Dn

Beam impedance reduction ferrite

(lossy + low-loss)

Beam impedance reduction ferrites

(lossy + low-loss)

PT100Mag_Dn

PT100Tube_Up

PT100Mag_Up

Screen conductors soldered to “ground”

(Ferrites mounted on SS tube)

Screen conductors capacitively coupled to “ground”

(metallization on ceramic tube)

NO Capacitor

here

MKI2 Mag_Up Mag_Dn Tube_Up Tube_Dn Tank Power (W/m)A 42.2 38.8 76 51.1 8 60B 44.1 40.9 70.3 50.2 10 97C 38.8 41.6 66.5 58.6 4 76D NC NC NC NC 9 89

MKI8 Mag_Up Mag_Dn Tube_Up Tube_Dn Tank Power (W/m)A 36.6 NC 73.1 35.4 1 88B 40.9 57.7 88.3 56.7 3 Not meas.C 45.2 40.9 102.1 64.7 2 Not meas.D 43.1 68.3 72.4 67.9 6 Not meas.

18/04/2012 24M.J. Barnes: LMC

Planning for TS3• The exchange of MKI8D will take ~4.5 days with shifts, requiring full commitment from all

teams involved to achieve this optimized intervention time.

25M.J. Barnes: LMC27/06/2012

Courtesy: G. Bregliozzi & V. Baglin

Duration (hours) Activity ManpowerStart Time End Time

2 8:00

Consign MKI8. Demount 3 BLMs (BI) - 30mins. Remove entry box & TMR (FPS) - 90mins. Note: - De 7h30 à 9h15 patrouille RP RA87: Les intervenants ont accès à la zone dès 8h00 accompagnés de RP, dès 9h15 lever du véto radiation: EN-HE : ouverture du blindage

5 8:00 Finish VSC activity at 13:00Materials transport to the tunnel + Remove solenoids + Venting to

N2 vacuum sectors + Mechanical opening of 2 vacuum sectors (VSC).

Mechanics 2+ 2,bakeout 2+1

5 8:00 Finish preparation activity at 13:00

Preparation, transport from surface to underground for tank #5 + handling vehicles

5 13:00 18:00 Installation of MKI tank #5. Re-install entry box & TMR (FPS) - 90mins.

2 (maybe up to 4) 18:00 20:00 Alignment4 20:00 0:00 Mechanical installation + Pump Down + First leak detection Mechanics 2+ 2

12 0:00 12:00 Install bake-out equipment for adjacent interconnects & adjacent beampipes & test at 50˚C

bake out 2+1

48 12:00 continue Start bake-out for 48 h activation 2

Check bake-out. Note: Maintenance ascenseur PM85 : mercredi 19.09 de 6h30 à 9h30

activation 2

8 12:00 20:00 Degassing, cooling down of sectors, final leak detection. Fermeture du blindage ?

activation 2

8 20:00 4:00 Remove bake-out + mechanical installation and clear area Mechanics 2+ 2, bake out 2+1

12 4:00 16:00 Re-install anti-ecloud solenoids. bake out 2+12 16:00 17:00 Remount 3 BLMs (BI) - 60mins.

5 17:00 22:00 Deconsign MKI8. Mini high voltage conditioning of MKI8 kicker magnets - FPS.

Wednesday 19/09/2012

Date and Time

Monday 17/09/2012

End of the dayTuesday 18/09/2012

End of the day

continue

End of the dayThursday 20/09/2012

End of activityFriday 21/09/2012