The Joint Accelerator Conferences Website (JACoW) is an international collaboration that publishes the proceedings of accelerator conferences held around the world.
TY - CONF AU - Wei, J.H. AU - Baboi, N. AU - Shi, L. ED - Schaa, Volker RW TI - Stability Study of Beam Position Measurement Based on Higher Order Mode Signals at FLASH J2 - Proc. of IBIC2018, Shanghai, China, 09-13 September 2018 CY - Shanghai, China T2 - International Beam Instrumentation Conference T3 - 7 LA - english AB - FLASH is a free-electron laser driven by a supercon-ducting linac at DESY in Hamburg. It generates high-brilliance XUV and soft X-ray pulses by SASE (Self Amplified Spontaneous Emission). Many accelerating cavities are equipped with HOMBPMs (Higher Order Mode based Beam Position Monitors) to align the beam and monitor the transverse beam position. However, these lose their position prediction ability over time. In this paper, we applied an efficient measurement and signal analysis with various data process methods including PLS (Partial Least Square) and SVD (Singular Value Decomposition) to determine the transverse beam position. By fitting the HOM signals with a genetic algorithm, we implemented a new HOMBPM calibration procedure and obtained reliable beam prediction positions over a long time. A stable RMS error of about 0.2 mm by using the spectra of signals and 0.15 mm by using the new method over two months has been observed. PB - JACoW Publishing CP - Geneva, Switzerland SP - 273 EP - 277 KW - HOM KW - cavity KW - dipole KW - electron KW - higher-order-mode DA - 2019/01 PY - 2019 SN - 978-3-95450-201-1 DO - DOI: 10.18429/JACoW-IBIC2018-TUPB07 UR - http://jacow.org/ibic2018/papers/tupb07.pdf ER -