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Vacuum System How to Get Ready for Beam ?

Vacuum System How to Get Ready for Beam ?. V. Baglin on behalf of the team in charge of cleanning the beam vacuum in sector 3-4. CERN TE-VSC, Geneva. 1. Final numbers 2. Status of sector 3-4 cleanning 3. Conclusions. 1. Final Numbers. Sector 3-4 : Final numbers.

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Vacuum System How to Get Ready for Beam ?

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  1. Vacuum System How to Get Ready for Beam ? V. Baglin on behalf of the team in charge of cleanning the beam vacuum in sector 3-4 CERN TE-VSC, Geneva 1. Final numbers 2. Status of sector 3-4 cleanning 3. Conclusions V. Baglin - Chamonix 2009

  2. 1. Final Numbers V. Baglin - Chamonix 2009

  3. 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 V. Baglin - Chamonix 2009

  4. MLI • MLI : • DFBAR3 => A10R3 • ~ OK : • B10R 3 => A19R3 • Soot : • B19R3 => Q31R3 SOOT ~ OK ~ OK V. Baglin - Chamonix 2009 SOOT

  5. ~ OK MLI • ~ OK : • A32R 3 => B34L4 • MLI : • A34L4 => DFBAL4 MLI MLI V. Baglin - Chamonix 2009

  6. Beam Screens of 3-4 Declared Cleaned C20L4.V1 Q13L4.V2 C14R3.V1 B8L4.V2 V. Baglin - Chamonix 2009

  7. Beam Screens with MLI and Fibers QBQI 8L4.V2 A10L4.V2 B9R3.V1 QBQI 14L4.V2 A13L4.V1 QBQI 12L4.V1 V. Baglin - Chamonix 2009

  8. Beam Screens with Soot Traces left by the endoscope • Different types of results V. Baglin - Chamonix 2009

  9. Electron Microscopy • 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. QBBI-21R3 - V2 V. Baglin - Chamonix 2009

  10. 2. Status of Cleaning in Sector 3-4 V. Baglin - Chamonix 2009

  11. 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) V. Baglin - Chamonix 2009

  12. Soot Removal V. Baglin - Chamonix 2009

  13. Beam screens with soot in tunnel : Cleanning Method • 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 V. Baglin - Chamonix 2009 Example of C19R3.V2

  14. Beam screens with soot in tunnel : C19R3 C19R3.V2 before cleanning After cleanning end entrance mid V. Baglin - Chamonix 2009

  15. Beam screens with soot in tunnel : Q19R3 Q19R3.V2 before cleanning After cleanning end entrance mid V. Baglin - Chamonix 2009

  16. Beam screens with soot in tunnel : C20R3 C20R3.V2 before cleanning After cleanning end entrance mid V. Baglin - Chamonix 2009

  17. 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) V. Baglin - Chamonix 2009

  18. MLI Removal V. Baglin - Chamonix 2009

  19. MLI removal : 1st step • 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) V. Baglin - Chamonix 2009

  20. 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 V. Baglin - Chamonix 2009

  21. MLI removal : 2nd step • 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. • Time : 5 min per PIM, speed of 3 m/min along the beam screen • A passage along abeam tube in a half-cell requires about half an hour V. Baglin - Chamonix 2009

  22. Nozzle demonstration : QQEI.11L4 V. Baglin - Chamonix 2009

  23. MLI Harvest : Beam Screen Alone Example 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 V. Baglin - Chamonix 2009

  24. MLI Harvest : PIM Alone Example of QBBI.8L4.V2 QBQI 12L4.V1 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 V. Baglin - Chamonix 2009

  25. MLI Harvest : A8L4+QBBI+B8L4 2 passages ~ 250 bits 5 passages 20 bits 9 passages 4 bits 2 per dipole ! • The tooling efficiency decrease with the number of passages V. Baglin - Chamonix 2009

  26. MLI Harvest : Tooling Efficieny Preliminary • 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 V. Baglin - Chamonix 2009

  27. 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 V. Baglin - Chamonix 2009

  28. Tunnel Work V. Baglin - Chamonix 2009

  29. 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 V. Baglin - Chamonix 2009

  30. 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 V. Baglin - Chamonix 2009

  31. Status • The 6 magnets with soot have been sweeped • MLI 1st step : • DFBAR3 => Q16R3 is done • Q27L4 => DFBAR4 is done • 30 % remain to be done • MLI 2nd step : • A8L4 => Q8L4 is done • 99 % remain to be done • Still to be defined if 5, 10 or 15 passages are required • Rate 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 V. Baglin - Chamonix 2009

  32. Vacuum Sectors at Room Temperature (A7R3, A7L4) V. Baglin - Chamonix 2009

  33. 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) V. Baglin - Chamonix 2009

  34. 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 V. Baglin - Chamonix 2009

  35. Magnets at the surface V. Baglin - Chamonix 2009

  36. 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 V. Baglin - Chamonix 2009

  37. 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 V. Baglin - Chamonix 2009

  38. 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 V. Baglin - Chamonix 2009

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