Author: Lai, L.W.
Paper Title Page
TUPB09 The Evaluation of Beam Inclination Angle on the Cavity BPM Position Measurement 278
 
  • J. Chen, L.W. Lai, Y.B. Leng, L.Y. Yu, R.X. Yuan
    SINAP, Shanghai, People's Republic of China
 
  Cavity beam position monitor (CBPM) is widely used to measure the transverse position in free-electron laser (FEL) and international linear collider (ILC) facilities due to the characteristic of high sensitive. In order to study the limiting factors of the position resolution of cavity BPM, the influence of beam inclination angle on the measure-ment of CBPM position and the direction of beam deflec-tion was analyzed. The simulation results show that the beam inclination angle is an important factor limiting the superiority of CBPM with extremely high position resolu-tion. The relative beam experiments to change the relative inclination angle between the cavity and the electron beam based on a 4-dimension moveable platform were performed in Shanghai Soft X-ray FEL (SXFEL) facility, the experiment results will also be mentioned as well.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-TUPB09  
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TUPC05 Influence of Sampling Rate and Passband on the Performance of Stripline BPM 307
 
  • T. Wu, S.S. Cao, F.Z. Chen, Y.B. Leng, Y.M. Zhou
    SSRF, Shanghai, People's Republic of China
  • J. Chen, L.W. Lai
    SINAP, Shanghai, People's Republic of China
 
  It is obviously that the property of SBPM is influenced by data acquisition system, but how the procedure of data acquisition and processing takes effect is still room for enquiring into it. This paper will present some data simulation and experiment results to discuss the function between resolution and pass band, sampling rate or other influence factor. We hope that this paper would give some advice for building up data acquisition system of SBPM.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-TUPC05  
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WEPA13 Electro-Optic Modulator Based Beam Arrival Time Monitor for SXFEL* 396
 
  • X.Q. Liu, L.F. Hua, L.W. Lai, Y.B. Leng, R.X. Yuan
    SINAP, Shanghai, People's Republic of China
  • N. Zhang
    SSRF, Shanghai, People's Republic of China
 
  Beam arrival time monitor (BAM) is an important tool to investigate the temporal characteristic of elec-tron bunch in free electron laser (FEL) like Shanghai soft X-ray Free Electron Laser (SXFEL). Since the timing jitter of electron bunch will affect the FEL's stability and the resolution of time-resolved experi-ment at FELs, it is necessary to precisely measure the electron bunch arrival time so as to reduce the timing jitter of the electron bunch with beam based feedback. The beam arrival time monitor based on electro-optic modulator (EOM) is already planned and will be de-veloped and tested at SXFEL in the next three years. Here the design and preliminary results of the EOM based beam arrival time monitor will be introduced in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEPA13  
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MOPC11 Data Acquisition System for Beam Instrumentation of SXFEL and DCLS 137
 
  • Y.B. Yan
    SINAP, Shanghai, People's Republic of China
  • J. Chen, L.W. Lai, Y.B. Leng, C.L. Yu, L.Y. Yu, H. Zhao, W.M. Zhou
    SSRF, Shanghai, People's Republic of China
 
  The high-gain free electron lasers have given scientists hopes for new scientific discoveries in many frontier research areas. The Shanghai X-Ray Free-Electron Laser (SXFEL) test facility is commissioning at the SSRF campus. The Dalian Coherent Light Source (DCLS) has successfully commissioned in the northeast of China, which is the brightest vacuum ultraviolet free electron laser facility. The data acquisition system for beam instrumentation is based on EPICS platform. The field programmable gate array (FPGA) and embedded controller are adopted for the signal processing and device control. The high-level applications are developed using Python. The details of the data acquisition system will be reported in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-MOPC11  
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MOPC16 The Development and Applications of Digital BPM Signal Processor on SSRF 147
 
  • L.W. Lai, F.Z. Chen, Y.B. Leng, Y.B. Yan, N. Zhang, W.M. Zhou
    SSRF, Shanghai, People's Republic of China
 
  The development of Digital BPM Signal Processors (DBPM) for SSRF started from 2008. The first prototype for SSRF storage ring was completed in 2012, with turn-by-turn resolution better than 1μm. From 2016 to 2017, SSRF successively constructed two FEL facilities in China, DCLS and SXFEL test facilities. The second ver-sion DBPM was developed and used in large scale during this period to meet the requirements of signal processing for stripline BPMs and cavity BPMs. After that, we turned to the development of DBPM for SSRF storage ring based on the second version hardware, including FPGA firmware, EPICS IOC, EDM control panel. The development was completed and tests were carried out in early 2018. Test results showed that the position data is accurate and can monitor beam movement correctly, and online turn-by-turn position data resolution reaches 0.46μm. This paper will introduce the design of DBPM for the SSRF storage ring and the tests carried out to verify the data accuracy and evaluate the system performance.  
poster icon Poster MOPC16 [1.372 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-MOPC16  
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MOPC17 On-line Crosstalk Measurement and Compensation Algorithm Study of SXFEL Digital BPM System 150
 
  • F.Z. Chen, L.W. Lai, Y.B. Leng, T. Wu, L.Y. Yu
    SSRF, Shanghai, People's Republic of China
  • J. Chen, R.X. Yuan
    SINAP, Shanghai, People's Republic of China
 
  Shanghai soft X-ray Free Electron Laser (SXFEL) has acquired the custom designed Digital BPM processor used for signal processing of cavity BPMs and stripline BPMs. In order to realize monitor the beam position accurately, it has high demand for DBPM system performance. Considering the crosstalk may introduce distortion and influence beam position resolution, it is important to analyze and compensate the crosstalk to improve the resolution. We choose the CBPM signal to study the crosstalk for its narrowband and sensitive for phase. The main experiment concept is successive accessing four channels to form a signal transfer matrix, which including amplitude frequency response and phase response information. And the compensation algorithm is acquire four channel readouts, then using the signal transfer matrix to reverse the true signal to ensure the accurate beam position measurement. This concept has already been tested at SXFEL and hopeful to compensate the crosstalk sufficiently.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-MOPC17  
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TUPB12 Machine Studies with Libera Instruments at the SLAC Spear3 Accelerators 284
 
  • S. Condamoor, W.J. Corbett, D.J. Martin, S. C. Wallters
    SLAC, Menlo Park, California, USA
  • M. Cargnelutti, P. Leban
    I-Tech, Solkan, Slovenia
  • L.W. Lai
    SSRF, Shanghai, People's Republic of China
  • Q. Lin
    Donghua University, Shanghai, People's Republic of China
 
  Turn-by-turn BPM readout electronics were tested on the SPEAR3 booster synchrotron and storage ring to identify possible improvements for the booster injection process and to characterize processor performance in the storage ring. For this purpose, Libera Spark and Libera Brilliance+ instruments were customized for the booster (358.4 MHz) and storage ring (476.3 MHz) radio-frequencies, respectively, and tested during machine studies. Even at low single-bunch booster beam current, the dynamic range of the Libera Spark readout electronics provided excellent transverse position measurement capability during the linac-to-booster injection process, the energy ramp-up phase and during beam extraction. Booster injection efficiency was also analyzed as a function of linac S-band bunch train arrival time. In the SPEAR3 storage ring turn-by-turn Libera Brilliance+ measurement capability was evaluated for single and multi-bunch fill patterns as a function of beam current. The single-turn measurement resolution was found to be better than 10 microns for a single 3 mA bunch. The horizontal single-bunch damping time was then determined with the 238 MHz bunch-by-bunch feedback system on and off.  
poster icon Poster TUPB12 [1.531 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-TUPB12  
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