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Joint BLMTWG meeting with ColUSM (IR3 studies)

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864/1-B04 (CERN)

864/1-B04

CERN

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Anton Lechner (CERN), Belen Maria Salvachua Ferrando (CERN), Daniele Mirarchi (CERN), Sara Morales Vigo
Joint BLMTWG meeting with ColUSM (IR3 studies)
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63164783124
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Sara Morales Vigo
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Participants in person: A.Lechner, L.Puddu, D.Wollmann, B.Salvachua, S.Morales

  • Arjan Verweij - Considerations on Q6 quench level
    • RQ6 -> 8 circuits in LHC
    • Each ciruits with 6 MQTLH magnets operated at 4.5K 
    • Why are the MQTL quench levels so much lower than other magnets?
      1. At short heat deposition, at injection similar value to other magnets, at nominal a bit more margin
      2. At long heat deposition, MQP governed by the cooling from the coild to the helium bath
        1. QP3 model predicts the cooling for the MQTL is worse
    • No experimental data of the MQE for MQTL 
      1. Theoretically calculated MQE correct for short durations (<1 ms), might be quite wrong for intermediate and long durations
    • Quench tests can be safely done for the MQTL when operated at low current (<50A)
      1. Suggests starting with an energy power deposition equal to the calculated theoretical value, if no quench is observed, increase the power in steps of maximum a factor 2
      2. If a quench is observed, if needed, add intermediate powers to improve accuracy
    • No spares -> Should still be ok for a quench test (D.Wollmann)
    • Sandrine will also give an update on the spares and possible concerns for this test

 

  • Sara Morales - Overview of operational IR3 losses - Start of ramp

 

  • Anton Lechner - IR3 power load studies
    • Need to update the beam loss specifications for IR3 
      • Aim to increase the thresholds by at least a factor of 2-3 compared to now -> 200kW or higher
      • In IR7, power loss 500kW, up to 1 MW for HL-LHC, but leakage to magnets is lower
    • TCPs and TCSGs thresholds more or less well aligned with Run 1 values -> 500kW master thresholds
    • TCLAs and Q6 thresholds dumping at a much lower power loss
    • Key aspects for IR3 power loss specifications
      • Power load to collimators (TCP, TCSG, TCLA)
      • Power load to warm magnets (mBWs and MQWs)
      • Power load to cold magnets (Q6 and DS)
    • FLUKA power deposition estimates for three different loss rates -> 200kW, 300kW, 500kW -> 0.6-20s range
      • Assuming present collimator settings
      • Difference between simulation and data around 10%
      • In IR3, 35-45% of power deposited in warm magnets, <20% in IR7 
      • Max power deposition in TCPs/TCSGs -> Power load seems acceptable even for 500kW 
      • Max power deposition in TCLAs -> acceptable at 450GeV, even for 500kW losses, for top energy, load is more critical
      • Max power deposition in MBWs/MQWs -> power load might pose a limitation at 450 GeV, although 300kW could probably be feasible
        • More detailed assessment needed
        • MBWs -> Most of the power deposited in the yoke
          • Have to see with magnet experts what the limit in power deposition is for
        • Power deposition limits for MBW and MQW
          • Max allowed power deposition from beam losses in a single MQW = 49 kW at nominal 3.5 TeV magnet current
      • Power deposition in Q6 
        • Exposed to showers from the second last TCLA on the outgoing beam
        • Q6 in 6L3 receives a 2x higher power load than the Q6R3 due to asymmetric arrangement of corrector
        • Larger simulation uncertainty, up to a factor of 2
        • Large uncertainty on quench level as well
        • Highly desirable to probe the quench margin in an MD!
      • Power deposition in DS
        • First preliminary results show power density below 2mW/cm3 
        • Needs benchmark with BLM signals
    • Stefano Redaelli asks to review distribution of collimators in IR3 for simulations at injection and top energy

 

  • Luisa Puddu - Allowed power load on TCLA
    • Case analyzed for ion collision last year for TCTP collimators
    • Evaluation of TCLA thermo-mechanical thresholds in the context of proton beam losses
      • TCLA same design as TCTPs -> As first approximation, allowed deposited power can be compared
    • Case 1a -> Most conservative
    • Scraping scenario also analyzed 
    • Considering the safety margins on the critical elements, TCLAs are not expected to face thermo-mechanical issues with protons if they experience the same integral power deposited
    • Belen says it would be useful to have the simulations also for protons
    • Priority is to get the MD

 

  • Daniele's presentation postponed for next meeting
  • Next meeting also joint with ColUSM - to be discussed offline
    • RF busy at the moment, better for the week of 5th of May

 

  • Belen says we put the interlock on BLMs on crystals in IR3 and IR7, with thresholds to the maximum value

 

 

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