Keyword: SRF
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MOOC03 The Removal of Interference Noise of ICT using the PCA Method FEL, experiment, electron, Windows 22
 
  • J. Chen, Y.B. Leng, L.Y. Yu
    SINAP, Shanghai, People's Republic of China
  • N. Zhang
    SSRF, Shanghai, People's Republic of China
 
  The measurement of beam charge is a fundamental re-quirement to all particle accelerators facility. Shanghai soft X-ray free-electron laser (SXFEL) started construc-tion in 2015 and is now in the commission phase. Al-though integrated current transformer (ICT) were installed in the entire FEL for the measurement of the absolute beam charge, the accurate measurement becomes difficult in the injector and the main accelerator section due to the noise interference from external factors such as klystron modulator. The evaluation of the source of noise signals and the procession of noise reduction using the principal component analysis (PCA) are proposed in this paper. Experiment results show that PCA method can effectively remove the interference of lower frequency noise from the klystron modulator and it can also improve the resolution of the ICT system. Detailed experiment results and data analysis will be mentioned as well.  
slides icon Slides MOOC03 [2.520 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-MOOC03  
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MOPA17 Momentum Compaction Measurement Using Synchrotron Radiation radiation, electron, photon, experiment 66
 
  • L. Torino, N. Carmignani, A. Franchi
    ESRF, Grenoble, France
 
  The momentum compaction factor of a storage ring can be obtained by measuring how the beam energy changes with the RF frequency. Direct measurement of the beam energy can be difficult, long or even not possible with acceptable accuracy and precision in some machines such as ESRF. Since the energy spectrum of the Synchrotron Radiation (SR) depends on the beam energy, it is indeed possible to relate the variation of the beam energy with a variation of the produced SR flux. In this proceeding, we will present how we obtain a measurement of the momentum compaction using this dependence.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-MOPA17  
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MOPB13 Active Magnetic Field Compensation System for SRF Cavities cavity, controls, electron, electronics 101
 
  • L.H. Ding
    Laboratory GREYC, Caen, France
  • J. Liang, H. Liu, Z.P. Xie
    Hohai University, Nanjing, People's Republic of China
  • Z.P. Xie
    IMP/CAS, Lanzhou, People's Republic of China
 
  Abstract: Superconducting Radio Frequency (SRF) cavities are becoming popular in modern particle accelerators. When the SRF cavity is transitioning from the non-conducting to the Superconducting state at the critical temperature (Tc), the ambient magnetic field can be trapped. This trapped flux may lead to an increase in the surface resistance of the cavity wall, which can reduce the Q-factor and efficiency of the cavity. In order to increase the Q-factor, it is important to lower the surface resistance by reducing the amount of magnetic flux trapped in the cavity wall to sub 10mG range during the Tc transition. In this paper, we present a 3-axis automatic active magnetic field compensation system that is capable of reducing the earth magnetic field and any local disturbance field. Design techniques are described to enhance the system stability while utilizing the flexibility of embedded electronics. This paper describes the system implementation and concludes with initial results of tests. Experimental results demonstrate that the proposed magnetic field compensation system can reduce the earth magnetic field to around 2.5 mG even without shielding.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-MOPB13  
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MOPB14 SSRF Beam Operation Stability Evaluation Using Bunch by Bunch Beam Position Method* injection, damping, operation, storage-ring 104
 
  • N. Zhang
    SSRF, Shanghai, People's Republic of China
  • Y.B. Leng, Y.M. Zhou
    SINAP, Shanghai, People's Republic of China
 
  Funding: * Work supported by National Natural Science Foundation of China (No.11575282 No.11375255 No.11305253)
In order to improve the efficiency and quality of light in top-up mode at SSRF, disturbance caused by leakage fields mismatch during injection should be minimized and stable. This could be evaluated by analysis of bunch by bunch residual betatron oscillation data, using this method, instability of tune distribution and damping repeatability could also be calculated. So we could evaluate the beam operation stability by the data analysis and discuss in the paper.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-MOPB14  
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MOPC02 Identification of Faulty Beam Position Monitor Based Clustering by Fast Search and Find of Density Peaks storage-ring, electron, operation, experiment 114
 
  • R. Jiang, Y.B. Leng
    SSRF, Shanghai, People's Republic of China
  • F.Z. Chen, Z.C. Chen, Y.B. Leng
    SINAP, Shanghai, People's Republic of China
 
  The accuracy and stability of beam position moni-tors(BPMs) are important for all kinds of measurement systems and feedback systems in particle accelerator field. A proper method detecting faulty beam position monitor or monitoring their stability could optimize accel-erator operating conditions. With development in ma-chine learning methods, a series of powerful analysis approaches make it possible for detecting beam position monitor's stability. Here, this paper proposed a clustering analysis approach to detect the defective BPMs. The method is based on the idea that cluster centres are char-acterized by a higher density than their neighbours and by a relatively large distance from points with higher densi-ties. The results showed that clustering by fast search and find of density peaks could classify beam data into dif-ferent clusters on the basis of their similarity. And that, aberrant data points could be detected by decision graph. So the algorithm is appropriate for BPM detecting and it could be a significant supplement for data analysis in accelerator physics.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-MOPC02  
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MOPC16 The Development and Applications of Digital BPM Signal Processor on SSRF brilliance, controls, FEL, storage-ring 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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TUPB02 Complete Test Results of New BPM Electronics for the ESRF New LE-Ring electron, electronics, controls, MMI 257
 
  • K.B. Scheidt
    ESRF, Grenoble, France
 
  Among the 320 BPMs in the ESRF new low emittance ring, a set of 128 units will be equipped with new electronics, while the other set (192) will be served by the existing Libera-Brilliance electronics. These new electronics are an upgraded version of the low-cost Spark electronics originally developed 3 years ago for the ESRF Injector complex. All these 128 units have been installed in the first half of 2018 on existing BPM signals (through duplication with RF-splitters) and subsequently been tested thoroughly for performance characteristics like stability, resolution and reliability. It will be shown that while these Sparks have a very straightforward and simple concept, i.e. completely omitting calibration schemes like RF-cross-bar switching, pilot-tone introduction or active temperature control, that they are fully compatible with all the beam position measurement requirements of this new ring.  
poster icon Poster TUPB02 [1.577 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-TUPB02  
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WEOB01 New Beam Loss Detector System for EBS-ESRF detector, injection, operation, vacuum 346
 
  • L. Torino, K.B. Scheidt
    ESRF, Grenoble, France
 
  In view of the construction and the commissioning of the new Extremely Brilliant Source (EBS) ring, a new Beam Loss Detector (BLDs) system has been developed, installed and tested in the present European Synchrotron Radiation Facility (ESRF) storage ring. The new BLD system is composed of 128 compact PMT-scintillator based BLDs, distributed evenly and symmetrically at 4 BLDs per cell, controlled and read out by 32 Libera Beam Loss Monitors (BLMs). The detectors fast response and the versatility of the read-out electronics allow to measure fast losses with an almost bunch-by-bunch resolution, as well as integrated losses useful during the machine operation. In this paper the different acquisition modes will be explained and results obtained during injection and normal operation will be presented.  
slides icon Slides WEOB01 [8.727 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEOB01  
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WEPB03 First Prototype of a Coronagraph-based Halo Monitor for BERLinPro diagnostics, operation, linac, gun 434
 
  • J.G. Hwang, J. Kuszynski
    HZB, Berlin, Germany
 
  Since particle losses by beam halo induced by space charge force and scattering of trapped ions are critical issues for superconducting-linac based high power machines such as BERLinPro, a halo monitor is demanded to monitor and control particle distribution at the level of 10-4 ~ 10-5 of the core intensity. A coronagraph-based halo monitor was adopted and the first prototype has been designed as a demonstrator system aimed at resolving a halo-core contrast in the 10-3 to 10-4 range. This monitor was tested at BESSY II with various operation modes such as Transverse Resonance Island Buckets (TRIBs) and Pulse-Picking by Resonant Excitation (PPRE). We show our design parameters, experimental criterion, and experimental results.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEPB03  
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WEPC15 Machine Learning Applied to Predict Transverse Oscillation at SSRF diagnostics, injection, network, storage-ring 512
 
  • B. Gao, J. Chen, Y.B. Leng, Y.M. Zhou
    SINAP, Shanghai, People's Republic of China
 
  A fast beam size diagnostic system has been developed at SSRF (Shanghai Synchrotron Radiation Facility) storage ring for turn-by-turn and bunch-by-bunch beam transverse oscillation study. This system is based on visible synchrotron radiation direct imaging system. Currently, this system already has good experimental results. However, this system still has some limitations, the resolution is subject to the point spread function and the speed of online data processing is limited by the complex algorithm. We present a technique that applied machine learning tools to predict transverse oscillation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEPC15  
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THOB01 Injection Transient Study Using 6-Dimensional Bunch-by-bunch Diagnostic System at SSRF* injection, extraction, kicker, diagnostics 542
 
  • Y.M. Zhou, Y.B. Leng, N. Zhang
    SSRF, Shanghai, People's Republic of China
  • B. Gao
    SINAP, Shanghai, People's Republic of China
 
  Beam instability often occurs in the accelerator and even causes beam loss. The beam injection transient process provides an important window for the study of beam instability. Measurement of the bunch-by-bunch dynamic parameters of the storage ring is useful for accelerator optimization. A 6-dimensional bunch-by-bunch diagnostic system has been successfully implemented at SSRF. The measurements of transverse position and size and longitudinal phase and length are all completed by the system. Button BPM is used to measure beam position, phase, and length, and the synchrotron radiation light is used to beam size measurement. Signals are sampled simultaneously by a multi-channel acquisition system with the same clock and trigger. Different data processing methods are used to extract the 6-dimensional information, where the delta-over-sum algorithm for beam position extraction, the Gaussian fitting algorithm for beam size extraction, zero-crossing detection algorithm for beam phase extraction and the two-frequency method for bunch length extraction. The system set up and performance will be discussed in more detail in this paper.  
slides icon Slides THOB01 [7.413 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-THOB01  
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