Upgrade of beam position diagnostics System at FELiChEM

The FELiChEM is a user facility dedicated for energy chemistry research, developed at University of Science and Technology of China in Hefei. The beam position diagnostics system at FELiChEM are upgraded recently. The facility operates with a special mode: macropulses at 1 Hz repetition rate with microsecond duration, each containing micropluses at 59.5 MHz repetition rate. The key advancement of beam position monitor (BPM) system lies in the upgraded which now achieves micropluse-level resolution. This enhancement enables real-time measurement of transverse position deviations for individual micropluses, providing essential diagnostics for investigating intra-macropulse instabilities. Post-upgrade characterization demonstrates a transverse position resolution better than 20 μm, satisfying design specifications. The upgraded BPM system has been successfully integrated into routine beam tuning operations.