MicroTCA.4-Based Low-Level RF for Continuous Wave Mode Operation at the ELBE Accelerator

At the ELBE Center for High-Power Radiation Sources, electrons are accelerated to an energy of up to 40 MeV in a superconducting linear accelerator that is operated in continuous wave (CW) mode. The acceleration is achieved using superconducting radio frequency (RF) cavities, which are driven by an analog low-level RF (aLLRF) system and solid-state-based RF amplifiers. The analog aLLRF system was transformed to a digital system based on the MicroTCA standard. It is in user operation since 2020. Here, the new digital system and its integration in the ELBE control system are described. Furthermore, the system is characterized by noise measurements and shows rms field stability of the digital LLRF (dLLRF) system of 0.01° in phase and 0.005% in amplitude. In addition, an algorithm for compensating long-term drifts is presented and characterized.