ad-hoc BLM Thresholds Meeting (IR3 MBW/MQW power deposition limits)

Thursday 13 Feb 2025, 14:00 → 15:00 Europe/Zurich

CERN

Participants: A.Lechner, B.Salvachua, P.A.Thonet, D.Mirarchi, R.Bruce, S.Morales, P.Schwarz

• BLM dumps during Run 3 due to off-momentum losses in IR3 at the start of the ramp
• Could be a performance limitation for HL-LHC
• Aim to increase thresholds by a factor of 2-3 -> power loss of around 200kW
  • Need to understand how much power loss can be allowed in IR3
• Power loss over a certain period
  • Different thresholds for different time durations
• Non-negligible fraction of the power loss goes to the warm magnets
• Relative power deposition higher in the warm magnets in IR3 with respect to IR7 due to different layout (from simulations)
• At injection energy, most loaded MB in IR3 would receive ~12% of the power deposition
  • 24kW if we allow for 200kW in IR3
• Power deposition limits date back from Run 1
  • 49kW max allowed power deposition in a single MQW 
    • Nominal current from Run 1, not updated
    • Now we could allow less at top energy
  • Idea to update these assumptions
  • Magnet running at less than 60 degrees C
  • Water flow ok for MQW
  • Same exercise can be done for MBW
    • Add present current for operation of the two magnets
    • Is it lower at injection? Can we have more margin then?
• Magnets cooled in parallel
  • Possibility to increase the water flow locally for specific magnets

 

• Action: More detailed profile to see how power is deposited in MBW. Which part goes to the yoke and which part to the coil.
• Action: Confirmation that the assumptions shown by Anton are still up to date. Repeat calculations for MBW and MQW.
• Action: Check possibility to increase water flow locally for specific magnets. 
• Action: Check magnet current at injection. 
• Action: Collection of steady-state losses during Run 3
  • HL-LHC specifications 1MW for 10s

 

• Worries about expected power deposition in IR7 with HL-LHC expected maximum allowed loss rate of 1MW
  • Possibility to log temperature on the most critical magnets
    • Stickers on magnets to see the maximum temperature achieved on magnets
      • They should be radiation-hard
    • Measure from power converters the voltages during operation or quench test
  • We hit the yoke of the magnets, but not directly in contact to the coils

14:00 → 14:30 Power load to IR3 warm magnets due to beam losses

Speaker: Anton Lechner (CERN)

BLMTWG_powerloadwarmmagnetsIR3_13022025.pdf