LINAC2026 - 33rd Linear Accelerator Conference

RF design of broadband high-power coaxial HOM extractors for the FCC-ee 400 MHz cavities

Not scheduled

2h

Daejeon Convention Center

Poster Presentation MC4.A08: Superconducting RF Poster Session

Speaker

Shahnam Gorgi Zadeh (European Organization for Nuclear Research)

Description

The higher-order mode (HOM) power generated in the 2-cell 400 MHz superconducting cavities and associated auxiliary components of the FCC-ee at the Z working point, with a beam current of 1.28 A, is estimated to reach approximately 60 kW per four-cavity cryomodule. Efficient extraction of this power is essential to ensure stable operation and to limit the thermal load on the cryogenic system. In this work, the HOM damping requirements for Z operation are reviewed, and the RF design of broadband high-power coaxial HOM extractors is presented. The proposed extractors are normal-conducting devices located in the inter-cavity regions of the cryomodule, each capable of handling kilowatts of HOM power while keeping the heat load to the cryogenic system within acceptable limits. The extracted HOM energy is taken outside the cryomodule and dissipated in RF loads at room temperature. A ceramic window is used to isolate the load from the beam vacuum, with optimized RF matching to minimize reflections. The performance of the proposed design is evaluated and compared with alternative HOM damping schemes, such as beamline absorbers and waveguide dampers.