1 / 22

TIDVG Issue

TIDVG Issue. R. Losito, EN/STI LMC, 09/07/2014. Content. Introduction to TIDVG The problem Video of the endoscopy Discussion on dangerous beams Strategy for replacement and protection Conclusions and decisions. Introduction to TIDVG.

olaf
Download Presentation

TIDVG Issue

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. TIDVG Issue R. Losito, EN/STI LMC, 09/07/2014

  2. Content • Introduction to TIDVG • The problem • Video of the endoscopy • Discussion on dangerous beams • Strategy for replacement and protection • Conclusions and decisions

  3. Introduction to TIDVG • TIDVG stands for Target Internal Dump Vertical Graphite • Used to dump the high energy beams in the SPS: • Follows a vertical+horizontal kicker able to paint beams on its core between 105 to 450 GeV • Beams up to 37 GeV are dumped on the TIDH • Beams between 37 and 105 GeV cannot be dumped.

  4. Introduction to TIDVG Copper jackets (OFE, C10100 H02) Iron Shielding (EN-GJL-200) Tungsten blocks (Densimet 180) 0.3 m Copper blocks (OFE, C10100 H02) 0.5 m Beam direction Aluminum blocks (EN AW 6082 T6) 1 m Graphite blocks (2020 PT) + Titanium coating 2.5 m

  5. Introduction to TIDVG • Painting is used to reduce the internal stress of the internal blocks • Stresses and temperatures can become extremely high for repeated impact • Cooling of the blocks rely on contact between the blocks and surrounding copper. Not a clearly defined value, so impossible to correlate precisely with external temperature. • Temperature probes originally not positioned close to the Al blocks

  6. Introduction to TIDVG • Painting is used to reduce the internal stress of the internal blocks • Stresses can become extremely high anyway for small size beams or repeated impact • Cooling of the blocks rely on contact between the blocks and surrounding copper. Not a clearly defined value, so impossible to correlate precisely with external temperature. • Temperature probes originally not positioned close to the Al blocks

  7. Introduction to TIDVG Vacuum Issue Radioprotection issue • TIDVG contains a lot of graphite: porous material, releasing big quantities of water vapour and other gases when impacted. • Because of it design can only be baked in situ at 150°C. During operation can easily reach 300°C. • Requires therefore long commissioning with beam to get to a satisfactory vacuum level • Becomes extremely radioactive • Today (after more than 1 year cooldown) we can still measure about 15 mSv/h at contact. • Even taking a picture inside requires ALARA approach

  8. Introduction to TIDVG Operational observations Conclusion • No disruptive vacuum peak, nor complete beam loss was observed during Run 1 • Measurement of aperture before closure of the machines did not show any limitation of aperture on the TIDVG • When disconnected last summer, the TIDVG was immediately closed and put under vacuum to try not to lose commissioning.

  9. The problem • At reconnection, the VSC team had to look inside and this is what they saw looking upstream • Big “stones” of Al laying here and there • A probable deformation of the Al blocks. • Analysis of one of the stones confirmed it is Al.

  10. The problem • It was decided to conduct asap an endoscopy • The endoscopy confirmed destructive damage to the first Al block and partial damage to the second one. • It has been decided to replace the TIDVG with a spare one

  11. Video of the endoscopy

  12. Discussion on Dangerous Beams • During Run I the SPS has seen powerful operational beams (CNGS, FT, LHC) as well as test beams during MD • The damage has certainly been caused by continuous energy deposition rather than by an incidental grazing impact. • Al is clearly the weakest material in the TIDVG, having a melting point of about 580 °C. • A simplified approach has been used in 2009 to determine limits for beams to be dumped on the TIDVG.

  13. Discussion on Dangerous Beams • Beams considered in 2009

  14. Discussion on Dangerous Beams TIDVG #2 (damaged) TIDVG #3 (spare to be installed) • Graphite : 2.5 m • Aluminum : 1.0 m • Copper : 0.5 m • Tungsten : 0.3 m • Graphite : 2.7 m • Aluminum : 0.8 m • Copper : 0.5 m • Tungsten : 0.3 m

  15. Discussion on Dangerous Beams • Simulations assumes beams damped until 450 degrees are reached in the Al block, then switch off for 5 minutes • Only 5 cycles, then assumes steady state is reached (thanks to water cooling).

  16. Discussion on Dangerous Beams • Results in this table will be crossed checked again • 20 cm more graphite (and less Al) are effective in reducing temperature in the Al block. • Of course, one loses in dumping efficiency (already only 150 GeV/c are absorbed for every p+ at 450 GeV/c ) • In practice, we have lower temperatures also because we deposit less energy in the dump (increase dose downstream?)

  17. Discussion on Dangerous Beams Can we simplify with a steady state analysis? • Simplified steady state analysis can provide a rough figure for max number of p+/sec that can be dumped on the TIDVG. • Assuming 400°C as max Al temperature, we get a limit of around 3.5 1012 p+/sec • At present, no operational beam has dramatically passed this limit, so this analysis is clearly too optimistic. • Dynamic effects certainly play a role, detailed simulations are necessary.

  18. Strategy For Replacement

  19. Strategy for replacement • The TIDVG is basically made of two parts: • The core containing the absorbing blocks • The external shielding (24 Tons of Iron) • We have a spare core, almost identical to the installed one. • It has to be baked out before installation in the shielding (2 weeks) • The shielding has to be recovered from an old one, used until 2004, stored in the Radioactive storage in B954 (2 mSv at contact outside, certainly more inside). • Being optimistic it can be reinstalled mid August, then aligned and baked just before the restart of the SPS: • schedule has not been checked vs availability of resources, just put tasks in series one after the other

  20. Strategy for replacement and protection • Because the spare is identical to the present one, we have to understand better the limitations to be imposed to operation. • A “crisis” effort is being launched to determine how many consecutive times we can dump the beams on both TIDVG and TED. • Priority given to the following: • LHC – 25 nsec • LHC – 25 nsec (doublet) • LHC – 50 nsec • OP will set software interlocks to block injections after a predefined number of consecutive dumps for each beam

  21. Strategy for replacement • We have to immediately launch the manufacturing of a new spare (TIDVG #4). • Earliest date for its availability (my guess): Winter stop 2015/2016 if we do not modify dramatically its design. • We’ll profit to crosscheck whether Al can be avoided and replaced with something else. What is the next bottleneck? • Definition of new series of materials by Dec. 2014, to have the spare ready in Dec. 2015. • Will probably need to significantly change the design for LIU/HL-LHC era if higher intensity beams are to be produced in the SPS.

  22. Conclusions • A big yellow card for (us and) LHC beams in the SPS… • We need to understand better the limitations in terms of beam intensity, brightness, repetition rate etc… • We need to work on improving the spare for winter stop 2015/2016 • In the immediate: • Decide on priority of beams to be studied • Acknoeledgement to RP, VSC, MME, HE for immediate reaction

More Related