Expert discussion on scenarios for operating with sparking RF Fingers

Thursday 21 Mar 2024, 09:15 → 10:30 Europe/Zurich

874/R-018 - salle de réunion activité CCC (CERN)

09:15 → 09:30 Bunch length blow-up

Speaker: Helga Timko (CERN)

Bunch_length_ramp_Timko.pdf

Bunch_length_ramp_Timko.pptx

09:30 → 09:35 Discussion

09:35 → 09:45 Estimate energy deposition in the triplet before the repair the warm module with full beam - TBC

Speaker: Anton Lechner (CERN)

BLMTHR_RFfingerFLUKA_20032024.pdf

09:45 → 10:00 Further input from Giuseppe

Iis there any danger of additional damage if we run with sparking RF fingers (under the condition that we do not quench). Anything that can get worse from a vacuum point of view?:
Answer: We could open a leak and then intervene to exchange the damaged part but in any case this need to be done sooner or later. In case the damaged RF fingers is located in a cryogenic sector at that moment we should analyse more in details the impact, but as said during last meeting this situation will imply a complete warm up to perform the intervention with a huge downtime.

Do we see a conditioning effect of the vacuum after the first sparks by cleaning/conditioning of the surface? If yes, how long would this take? What reduction could be expected? What beam intensities do we need to condition?
Answer: We can not talk of any conditioning effects, maybe with time if the RF fingers get open more and more we could have less sparks but heating from impedance will be always present and the damage is always there. From last year issue, even with a very low intensity and juts one beam we have the same pressure spikes intensity. So, if we want to be conservative, and I think we should, we must consider to have on each fills always some sparks happening and do not think that the situation will improve with time.

Speakers: Daniel Wollmann (CERN), Josef Sestak (CERN)

10:00 → 10:15 Draft procedure

Speaker: Daniel Wollmann (CERN)

Procedure in case of issues with sparking RF fingers