ad-hoc BLMTWG discussion RS11-RS12

Monday 15 May 2023, 11:30 → 12:30 Europe/Zurich

Anton Lechner (CERN), Belen Maria Salvachua Ferrando (CERN)

Participants:

B.Salvachua SY-BI

A.Lechner SY-STI

F.Carra BE-MME

R.Bruce BE-ABT

M.D'Andrea BE-ABT

S.Redaelli BE-ABT

D.Mirarchi BE-OP

J.Wenninger BE-OP

M.Solfaroli BE-OP

D.Wollmann TE-MPE

C.Hernalsteens TE-MPE

We discussed the possible limitation of RS11 and RS12 from Collimation losses in IR7.

Collimation specs were reviewed in LS2:

• for long RS the limit of 0.2 h lifetime for maximum of 10 seconds was used for RS08-RS11, this corresponds to
• 500 kW for 10 seconds.
  • RS11 is then set to maximum of 250 kW , or 5000 kJ over the 20.9 seconds 
• for > 10 seconds losses, the limit used is the 1 h lifetime for infinite time
  • RS12 is then set to maximum of 100kW over the 83.8 seconds
• This is implemented as Master Thresholds. The final BLM thresholds are a combinatio of :
  • Master Threshod x Monitor Factor
  • Monitor factor is a number between 0 to 1. We choose to operate the machine at 0.4 MF for collimation losses.
  • This seems to be too tight for RS11 and RS12 which are already showing up with warnings from constant losses.

After discussions on several options, we agreed that the BLM threshold model for collimation losses is still valid and adecuate. In order not to limit operation we propose to rise the Monitor Factor from 0.4 to 0.6, giving more margin for RS12 and rising the limit for RS08-RS10 to 300kW.