Discussion on HOM Power Limitation and Beam Current Issues
Dive into the challenges related to Higher Order Modes (HOM) affecting beam current at TTC2025(WG3) on April 9, 2025. Explore topics like ferrite dampers, copper duct temperatures, power considerations, and discrepancies compared to simulations with a focus on resolving concerns for the future.
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Presentation Transcript
Do you have issues related to HOM? April 9, 2025 TTC2025(WG3), Open Discussion-HOM 1
HOM power can limit the beam current HOM power can limit the beam current Limits of ferrite dampers Temperature of copper duct 60 The ferrite is HIPped on copper duct. To prevent ferrite cracking SiC SiC Water flow speed (flow rate) 8 L/min To avoid the erosion-corrosion of cooling pipe 2.6A 12 kW for SBP 18 kW for LBP Installation of additional SiC dampers are expected to reduce the load on downstream ferrite dampers. LBP 18kW SBP 12kW More R&D Build-up Effect depending on bunch spacing Effect of crack of ferrite Improvement of the cooling capacity Monitoring erosion-corrosion (Can we increase the flow rate?) etc LBP SBP April 9, 2025 TTC2025(WG3), Open Discussion-HOM 2
Discrepancies compared to CST 2 ??mA ?? ????kHz ????kW = ??? V pC LF from CST Power Flow Calc. ( z= 5 mm) SBP ferrite damper eqLF [V/pC] 0.35 LBP ferrite damper 0.45 Possible reason : Difference of HOM freq. of cavity Errors of power measurement individuality of Dampers LBP SBP Investigation is on going. April 9, 2025 TTC2025(WG3), Open Discussion-HOM 3
Questions about HOM issues Are there any discrepancies compared to simulations? What are the actual power levels? Are there any concerns for the future? April 9, 2025 TTC2025(WG3), Open Discussion-HOM 4
Facility HOM dampers or couplers Ib HOM Load /module Ib HOM Load /module Expected HOM Load /module from act. meas. Measures note achieved design, simulation SuperKEKB Beam Pipe, Ferrite, RT 1.4 A 16 kW (absorbed by SBP+LBP) 2.6 A 21 kW (absorbed by SBP+LBP) 30-40 kW (absorbed by SBP+LBP) add. dampers add. cooling Recheck freq. &Q values LBP is more severe. BEPCII HEPS TPS EIC April 9, 2025 TTC2025(WG3), Open Discussion-HOM 5
