LINAC2026 - 33rd Linear Accelerator Conference

Simulation of DC bias-based multipacting supression in FCC-ee fundamental power couplers

Not scheduled

2h

Daejeon Convention Center

Poster Presentation MC4.A06: RF power sources and power couplers Poster Session

Speaker

Ana Durdevic (European Organization for Nuclear Research)

Description

In fundamental power couplers for RF accelerators, secondary electron emission can give rise to multipacting (MP), leading to RF losses, heating, and performance degradation. A mitigation technique consists of superimposing an electrostatic DC field onto the RF field by applying a bias voltage between the inner and outer conductors of the coaxial power coupler. This approach alters electron trajectories and disrupts the resonant conditions required for MP. This work investigates the effectiveness of DC bias in suppressing MP in FPCs designed for the Future Circular Collider (FCC-ee) accelerating cavities operating at 400.79 MHz and 801.58 MHz. Two baseline coaxial FPC designs are analyzed, with nominal maximum power levels of 382 kW and 195 kW, respectively, extended to 500 kW and 250 kW to account for operational margins. Using the Spark3D MP simulation tool, the required DC bias voltage for MP suppression is systematically evaluated across the full power range. The study also examines the influence of different secondary electron yield (SEY) models for copper surfaces in the coaxial structure and ceramic materials in the RF window on the required DC bias voltage.