BPM System Development and Applications in Commission of SXFEL-UF
B. Gao
SARI-CAS, Pudong, Shanghai, People’s Republic of China
J. Chen, Y.B. Leng
SSRF, Shanghai, People’s Republic of China
SXFEL is a soft X-ray free electron laser user facility that is current being commissioned in Shanghai. It is based on a 1.5 GeV normal conducting high gradient C-band (linear accelerator) LINAC and contains two FEL beamline, a seeded FEL beamline and a SASE beamline, and five experimental stations. The performance of X-ray FEL depends strongly on the quality of the electron beam and single shot stability. We have developed a BPM system including SBPM and CBPM. The resolution of SBPM is better than 4μmeters, and the resolution of CBPM is better than 176 nm. Because of its excellent position resolution, it plays an important role in the SASE beamline commissioning. The beam adjusters rely on this system to find and maintain an ideal track, and complete the debugging of the SBP beamline within 21 days. This paper presents the system design, methods used to determine the resolution, the performance, and the applications of those BPMs.
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Research on the Optimal Amplitude Extraction Algorithm for Cavity BPM
48
J. Chen, Y.B. Leng, T. Wu, Y.M. Zhou
SSRF, Shanghai, People’s Republic of China
S.S. Cao, B. Gao
SARI-CAS, Pudong, Shanghai, People’s Republic of China
The wake field of different modes of cavity BPM carries different bunch information, the amplitude and phase of the signals of different modes can be extracted through the signal processing method to obtain the characteristic parameters of the source bunch. In the application of bunch charge and position measurement, the accurate amplitude extraction method for cavity BPM signal is the primary issue to be considered when designing the data acquisition and processing system. In this paper, through theoretical analysis and numerical simulation, it is proved that the optimal algorithm of amplitude extraction for CBPM exists, and the dependence between the data processing window size and the decay time of the cavity BPM under the optimal design is given. In addition, the relationship between the optimized amplitude extraction uncertainty and the noise-to-signal ratio, sampling rate of data acquisition and processing system, and the decay time of the cavity BPM is also proposed, which can also provide clear guidance for the design and optimization of the CBPM system.
Bunch Arrival Time Measurement System Test for SHINE
396
Y.M. Zhou, J. Chen, Y.B. Leng
SSRF, Shanghai, People’s Republic of China
S.S. Cao
SARI-CAS, Pudong, Shanghai, People’s Republic of China
To achieve high-precision synchronization between electron bunches and seeded lasers, a femto-second resolution bunch arrival time measurement system (BAM) is required at SHINE (Shanghai High repetition rate XFEL aNd Extreme light facility). The bunch signal from a GHz-bandwidth cavity monitor is mixed with a reference signal from the device synchronization clock in the RF front-end. Then, the generated IF signal is collected by the digital acquisition system. In the pre-research stage, four sets of cavity monitors with different frequencies and load quality factors and three sets of analog front-ends with different schemes were performed, but now only one monitor with the attenuation time constant of 200 ns was installed for beam experiment testing. The system can measure the bunch charge, bunch arrival time, and bunch flight time. The first results will be presented in this paper.
