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Description
PERLE (Powerful Energy Recovery Linac for Experiments) is designed to demonstrate multi-turn, high-current operation of an Energy Recovery Linac (ERL). Achieving this demanding operating regime requires effective management of propagating higher-order-mode (HOM) power in order to limit beam instabilities and minimize the associated cryogenic heat load. The PERLE main cryomodule comprises four 5-cell superconducting cavities operating at 801.58 MHz. Each cavity is equipped with two HOM hook couplers, while cold beamline absorbers operating at 40 K are positioned between neighboring cavities, with tapered transitions at both ends of the cavity string. This work presents updated results of the HOM power spectrum of the complete multi-cavity string under the nominal PERLE beam current and filling pattern. The resulting dielectric losses in the cold beamline absorbers are also evaluated. The analysis provides the distribution of HOM power among the different ports of the string and supports the assessment of the HOM damping scheme for high-current operation.