vacuum system how to get ready for beam ?

V. Baglin - Chamonix 2009 1

Vacuum SystemHow to Get Ready for Beam ?

V. Baglinon behalf of the team in charge of cleanning the beam vacuum in sector 3-4

CERN TE-VSC, Geneva

1. Final numbers2. Status of sector 3-4 cleanning

3. Conclusions


1. Final Numbers


Sector 3-4 : Final numbers

• All beam lines in the tunnel have been inspected• All visual and endoscopic inspections of the beam tubes and interconnects are documented

V1 V2 V1 V2 Total

Ok 54 39 26 % 18 % 22 %

MLI 124 129 58 % 61 % 59 %

Soot 35 45 16 % 21 % 19 %

To be done 0 0 0 % 0 % 0 %

Total 213 213 100 % 100 % 100 %


• MLI :DFBAR3 => A10R3

• ~ OK :B10R 3 => A19R3

• Soot : B19R3 => Q31R3

MLI

~ OK

SOOT

SOOT ~ OK


• ~ OK :

A32R 3 => B34L4

• MLI : A34L4 => DFBAL4

~ OK

MLIMLI

MLI


Beam Screens of 3-4 Declared Cleaned

C20L4.V1 Q13L4.V2

B8L4.V2C14R3.V1


Beam Screens with MLI and Fibers

QBQI 8L4.V2 A10L4.V2

A13L4.V1QBQI 14L4.V2 QBQI 12L4.V1

B9R3.V1

• Different types of results

Traces left by the endoscope

8V. Baglin - Chamonix 2009

Beam Screens with Soot

Electron Microscopy

QBBI-21R3 - V2

• Investigation report SEM-EDS analysis of particles (EDMS 972804)

QBBI.21R3 line V2: Abundant presence of particles, they aggregate in macroscopic clusters. Sizes range from less than 1 µm up to 80 µm. Many have droplet shape. A “dust” of sub micrometric particles covers the bigger ones. The composition corresponds to the materials melted in the interconnect; two main groups of particles can be established:- Cu-rich particles with mainly Cu and some Sn and Si (possibly from brazing filler and glass fibre in the G11 around the busbar junction?) - Stainless steel-like particles, with mainly Fe, Cr, Ni, Mo but usually also Cu that could be due to submicrometric particles covering the bigger ones. In the overall analysis the Cu is the major element.



2. Status of Cleaning in Sector 3-4


What remains to be cleanned in the tunnel ?

• 53 cold masses are back to the surface from Q20R3 to Q33R3 (14 MQ, 39 MB)

• V2 line : 6 cold masses with soot (B19R3 -> C20R3)

V1 V2 V1 V2 Total

Ok 49 30 31 % 19 % 25%

MLI 111 124 69 % 78 % 73 %

Soot 0 6 0 % 4 % 2 %

Total 160 160 100 % 100 % 100 %


Soot Removal


Beam screens with soot in tunnel : Cleanning Method

Example of C19R3.V2

• Two plugs : one for horizontal and one for vertical parts of the beam screen

• Use of a foam-plug wet with alcohol• Use of a dry foam-plug

• Up to 50 passages in each direction with wet foam-plug• Up to 15 passages with dry plug


Beam screens with soot in tunnel : C19R3

C19R3.V2 before cleanning

entrance mid end

After cleanning


Beam screens with soot in tunnel : Q19R3

Q19R3.V2 before cleanning

entrance mid end

After cleanning


Beam screens with soot in tunnel : C20R3

C20R3.V2 before cleanning

entrance mid end

After cleanning


Beam screens with soot in tunnel : Summary

• B19R3, C19R3, Q19R3, A20R3, B20R3 and C20R3 have been sweept

• Two vacuum systems are oxydised (C19R3 & Q19R3). The oxyde layer cannot be removed by the mechanical process. However, it is expected to have negligible impact on the vacuum performance since the outgassing rate scales like ~ exp(1/T)

• Four vacuum systems have been mechanically cleanned (see samples circulating in the room).

• Now, these 6 vacuum chambers will follow the protocol for the MLI removal (see next slides)


MLI Removal


• Based on automatic pumping/venting of a half-cell (52 m)

• A cycle : 20 s pumping, 18 s plateau, 2 second vent

• The pressure in the beam tube is reduced from 1 atm to 0.8 atm in 2 s (to be compared to the arc pump down of 200 mbar/h)

• Air speed of 20 m/s

• This process is applied for 30 min (40 pumping/venting cycles)

MLI removal : 1st step


MLI removal : 1st step

• This procedure give good results i.e no more MLI are observable by endoscopy inside the beam screen

• Example :- Q8R4 till Q13R4 line V1 (~ 250 m)

3.2 g i.e 0.4 m2 1.2 g i.e 0.1 m2 ~ 100 bits


MLI removal : 2nd step

• Time : 5 min per PIM, speed of 3 m/min along the beam screen

• A passage along a beam tube in a half-cell requires about half an hour

• Based on aspiration with local pertubation controlled by endoscope• A nozzle blows filtered air, the MLI residues left behind the beam screen and the RF fingers are directed towards the beam aperture where they are aspired away.


Nozzle demonstration : QQEI.11L4


MLI Harvest : Beam Screen AloneExample of A8L4.V2

1st passage~ 100 bits

2nd passage~ 100 bits

3rd passage~ 20 bits

• The efficiency decrease with the number of passages

• The 1st method is not efficient anymore

• Debris size range from 1 x 1 to 2 x 2 mm2


MLI Harvest : PIM AloneExample of QBBI.8L4.V2

1st passage~ Too many bits (500)

• Debris size range from 1 x 1 to 5 x 5 mm2

• Time ~ 5 min / PIM

• Most of the debris recovered by the nozzle are coming from the PIM

QBQI 12L4.V1


MLI Harvest : A8L4+QBBI+B8L4

2 passages~ 250 bits

5 passages20 bits

9 passages4 bits

• The tooling efficiency decrease with the number of passages

2 per dipole !


MLI Harvest : Tooling Efficieny

• 4-5 passages will allow to remove 95 % of what can be removed by the tool

• 8-10 passages will allow to remove 99 % of what can be removed by the tool

Preliminary


MLI Harvest : How many and where remain the debris ? • Statistic was performed in the lab on 20 PIM from sector 3-4. Under analysis.• The nozzle allows to remove 90 to 99 % of the MLI debris

• The remaining MLI debris are located in « corners » … probably for ever !

• We can expect the same situation for the beam screen / cold bore case• A MLI particle will probably find its place for ever in the coaxial space


Tunnel Work


Organisation

• Two fronts : removal of MLI, removal of soot

• Two teams

• Cleaning activities started beginning of January

• Procedure for MLI and soot removal have been set up

• All QQBI interconnects have been open to allow MLI removal and perform PIM’s consolidation in the meantime


Procedure

• Soot front :- mechanical cleanning- aspiration/ venting for 30 min- 5 to 10 passages of aspiration under nozzle perturbation- final endoscopy for qualification

• MLI front :- aspiration/ venting for 30 min- 5 to 10 passages of aspiration under nozzle perturbation- final endoscopy for qualification

• All steps are documented


Status

• The 6 magnets with soot have been sweeped

• MLI 1st step :DFBAR3 => Q16R3 is doneQ27L4 => DFBAR4 is done30 % remain to be done

• MLI 2nd step :A8L4 => Q8L4 is done99 % remain to be doneStill to be defined if 5, 10 or 15 passages are requiredRate of progress :

- < 1h per passage and per beam line and half-cell- about 4 (2) half-cell per week and per team for 5 (10) passages


Vacuum Sectors at

Room Temperature

(A7R3, A7L4)

V. Baglin - Chamonix 2009

Recovery of room temperature vacuum sectors• Sectors A7R3.R and A7R3.B were at 1 mbar after the incident• Sectors A7L4.R and A7L4.B were at 5 10-2 mbar

• After 3 days of pumping down, the sector A7R3.B is at 6 10-11 mbar • So, these vacuum sectors are under pure He atmosphere (as expected)

33

Inspections• Opening parts of the vacuum sector A7R3.R&B and the sectors A7L4.R&B did not revealed any traces of debris, only normal contamination could be identified by electron microscopy (EDMS 974970, 985095)

• Endoscopy of magnet Q6R3 and Q6L4 did not show any traces of debris


Vacuum sectors A7L4.R&B are activated this week and ready for operation

Vacuum sectors A7R3.R&B will be activated in two weeks


Magnets at the surface


Surface Front

• Some magnets to be installed in sector 3-4 are « new »- Insertion of new beam screens

• Other magnets are « re-used »- Cutting and insertion of new beam screen- Soot sweeping and cleanning with the SMI2 washing machine

Give very good results for the inner beam screen

Inspection of the outer coaxial space is under way


Conclusions• Systematic inpections revealed debris of soot and MLI all along the arc

• Soot is removed by a mechanical action with a foam-plug• MLI is removed first by a pumping/venting mechanism and second by a combination of a nozzle and pumping mechanism

• No traces of debris have been found outside the arc• Room temperature vacuum sectors are under commissioning

• On the MLI front : still a lot of work to do in the tunnel• The objective of the coming weeks is to release sectors for PIMs interconnection


Acknowledgments• A. Mongelluzzo; M. Thiebert; L. Leggiero; I. Wevers; J-F Ecarnot; H. Neupert; J. Cave; W. Vollenberg; B. Teissandier; M. Malabaila; H. Kos for the endoscopic inspections

• B. Jenninger, A. Sinturel, E. Mahner for the design, procurement and validation of the pumping/venting systems and nozzle systems

• B. Henrist, A Vidal, G. Schneider, E. Page, J. Finelle for their comittement to the repair of sector 3-4

• Industrial support : FSU and AL43 teams

• HNINP collaboration for the endoscopies after cleanning

• J-M Jimenez for his constant support

vacuum system how to get ready for beam ?

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