Beam Position Monitor for the PAL-XFEL Laser Heater

A beam position monitor (BPM) has been developed to monitor the position of an electron beam in the laser heater of the X-ray free electron laser at the Pohang Accelerator Laboratory (PALXFEL). The BPM for the laser heater (LH-BPM) is based on a strip-line type. The LH-BPM consists of a pair of upper and lower blocks. Two strip-lines are in each block. In this paper, we report on the physical motivation, design considerations, cold tests, and typical results for the LH-BPM currently in use at the PAL-XFEL.