RF Electronics for the Measurement of Beam Induced Higher Order Modes (HOM) Implemented in the MICROTCA.4 Form Factor

Higher order modes (HOM) excited in RF accelerating cavities by a particle beam can be used for electron beam diagnostics. Phase of a monopole HOM provides infor-mation about the beam phase relative to the externally induced RF field in a cavity (BPhM) [1] . Furthermore, the amplitude of a dipole mode is proportional to the beam position in the cavity, hence it can be used for beam position monitoring (BPM). In this paper we present a proto-type of an instrument implemented in the MicoTCA.4 form factor for the measurement of the HOMs at FLASH and Eu-XFEL. The prototype consists of an analog module, which is used for filtering and conditioning of the selected modes, and a digital module responsible for digitization and signal processing. We present the instruments performance and discuss its influence on the precision of the HOM-based diagnostics