Cao, S. S.; Yuan, R. X.; Leng, Y. B.; Yang, L.

IEEE TRANSACTIONS ON NUCLEAR SCIENCE

2022, 69, 0018-9499

Cao, S. S.; Yuan, R. X.; Leng, Y. B.; Yang, L.

High repetition rates are considered essential to meet the anticipated new demands of the free-electron laser (FEL) facility. To offer precise beam handling for high-repetition-rate FEL facilities operating in a multi-bunch mode, an ultralow quality factor (Q) cavity beam position monitor (CBPM) is studied to distinguish nanosecond spaced electron bunches, enabling the independent position measurement of each bunch and reducing the contamination between hunch signals. The low-Q CBPM consists of two cavities: a reference cavity and a position cavity. The reference cavity is mainly used for bunch charge normalization, and the position cavity can measure the beam position vertically and horizontally. This article studies the method to attain a low loaded quality factor for the CBPM and presents the design and preliminary test results. The test results show that both the loaded quality factors of the reference cavity and the position cavity can reach 13, which enables bunch position monitoring for those high repetition rate FEL facilities.