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MOPB13 Active Magnetic Field Compensation System for SRF Cavities cavity, SRF, 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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MOPC11 Data Acquisition System for Beam Instrumentation of SXFEL and DCLS FEL, laser, data-acquisition, instrumentation 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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MOPC12 The Radial Detector in the Cyclotron of HIMM cyclotron, target, detector, extraction 140
 
  • M. Li, Y.C. Chen, Y.C. Feng, X.C. Kang, S. Li, W.L. Li, W.N. Ma, R.S. Mao, Y.G. Nie, H.H. Song, Y. Wang, Y. Yin, T.C. Zhao
    IMP/CAS, Lanzhou, People's Republic of China
 
  The cyclotron is designed as the injector of the Heavy Ion Medical Machine (HIMM) in Wuwei city, China. It provides 10 uA carbon beams to fulfill the requirement of the accumulation in the following syn-chrotron. The Radial detector is used to measure the beam current and beam turn motion in this Cyclotron. The beam current signal gathered by radial detector is acquired by four picoammeters, meanwhile the beam time structure is measured with FPGA and real time operating system. This paper introduces the design of radial detector, the motion control and data acquisition system for it of the cyclotron. Finally, the beam current and turn pattern measurement results at HIMM are presented in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-MOPC12  
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MOPC14 The Design of Dose Parameter Acquisition and Control System for a Pencil Beam Scanning System in HUST-PTF proton, monitoring, software, EPICS 143
 
  • Y.Y. Hu, H.D. Guo, H. Lei, X.Y. Li, Y.J. Lin, P. Tan, Y.C. Yu
    HUST, Wuhan, People's Republic of China
 
  Pencil beam scanning (PBS) technology is a flexible and accurate dose delivery technology in proton therapy, which can deliver beams adapting to irregularly shaped tumors, while it requires precise diagnostic and real-time control of the beam dose and position. In this paper,a dose parameter acquisition and control system for the pencil beam scanning system based on the EPICS and LabVIEW is designed for HUST-PTF. The EPICS environment is built to realize the data exchange function between the front-end devices and control system. A channel access server(CAS)is designed to convert treatment parameters into the process variables (PVs) and expose them to the network for data sharing. Under current experimental conditions, the simulated beam current is generated according to the dose parameters in the treatment plan file. The current are processed by a digital electrometer and transmitted to the EPICS database in real time. Then the control system user interface based on LabVIEW is realized for displaying and parameter analysis.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-MOPC14  
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MOPC16 The Development and Applications of Digital BPM Signal Processor on SSRF SRF, brilliance, 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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MOPC19 Virtual Signal Spectrum Analyzer Development Based On RedPitaya and EPICS for Tune Measurement in BEPCII EPICS, synchrotron, collider, interface 159
 
  • Y.H. Lu, J. He
    IHEP, Beijing, People's Republic of China
 
  An independent tune measurement system was developed in BEPCII with Direct Diode Detect (3D) technique. The system includes two diagonal electrode signals of a set of BPM, a self-developed board based on Direct Diode Detect (3D) technique, and a commercial virtual spectrum analyzer with a proprietary GUI client. Based on the open source digital electronics RedPitaya and open source software Spectrum, a device driver was developed based on EPICS and ASYN support for replacement of the commercial virtual spectrum analyzers and integration with the central system EPICS. According to the application requirements of tune measurement in BEPCII, the device driver finds the frequency point and power value corresponding to the X&Y tune between 631 to 800 kHz. The spectral resolution is 119 Hz. An EPICS IOC was built and run on RedPitaya for accessing the device driver. A CSS-based user interface shows the signal's power spectra and the tune frequency directly.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-MOPC19  
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TUOA02 Application of Machine Learning to Beam Diagnostics network, optics, diagnostics, simulation 169
 
  • E. Fol, J.M. Coello de Portugal, R. Tomás
    CERN, Geneva, Switzerland
 
  Machine learning techniques are used in various scientific and industry fields as a powerful tool for data analysis and automatization. The presentation is devoted to exploration of relevant machine learning methods for beam diagnostics. The target is to provide an insight into modern machine learning techniques, which can be applied to improve current beam diagnostics and general applications in accelerators. Possible concepts for future applications are also presented.  
slides icon Slides TUOA02 [2.497 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-TUOA02  
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TUOC01 Integration of a Pilot-Tone Based BPM System Within the Global Orbit Feedback Environment of Elettra FPGA, electron, Ethernet, feedback 190
 
  • G. Brajnik, S. Bassanese, G. Cautero, S. Cleva, R. De Monte
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
 
  In this contribution, we describe the advantages of the pilot tone compensation technique that we implemented in a new BPM prototype for Elettra 2.0. Injecting a fixed reference tone upstream of cables allows for a continuous calibration of the system, compensating the different behaviour of every channel due to thermal drifts, variations of cable properties, mismatches and tolerances of components. The system ran successfully as a drop-in substitute for a Libera Electron not only during various machine shifts, but also during a user dedicated beamtime shift for more than 10 hours, behaving in a transparent way for all the control systems and users. The equivalent RMS noise (at 10 kHz data rate) for the pilot tone position was less than 200 nm on a 19 mm vacuum chamber radius, with a long-term stability better than 1 um in a 12-hour window. Two main steps led to this important result: firstly, the development of a novel RF front end that adds the pilot tone to the signals originated by the beam, secondly, the realisation of an FPGA-based double digital receiver that demodulates both beam and pilot amplitudes, calculating the compensated X and Y positions.  
slides icon Slides TUOC01 [6.468 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-TUOC01  
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TUOC03 Commissioning of the Open Source Sirius BPM Electronics electron, electronics, FPGA, Ethernet 196
 
  • S.R. Marques, G.B.M. Bruno, L.M. Russo, H.A. Silva, D.O. Tavares
    LNLS, Campinas, Brazil
 
  The new Brazilian 4th generation light source, Sirius, have already started and commissioning is planned to start in 2018. This paper will report on the manufacturing, deployment and production batch testing of the in-house developed BPM electronics. The latest performance and reliability achievements will be presented.  
slides icon Slides TUOC03 [14.606 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-TUOC03  
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TUPA01 Pin Diode in a Medical Accelerator - a Proof of Principle and Preliminary Measurements extraction, diagnostics, beam-diagnostic, proton 208
 
  • A. Pozenel, M. Eichinger, S. Enke, M. Fürtinger, C. Kurfürst, M. Repovž
    EBG MedAustron, Wr. Neustadt, Austria
 
  The MedAustron Ion Therapy Center located south of Vienna, Austria, is a cancer treatment facility utilizing a particle therapy accelerator optimized for protons and carbon ions. The beam is injected into the synchrotron, accelerated to the desired speed and extracted to be guid-ed into one of four irradiation rooms. During extraction a certain amount of particles is lost which is measured with a PIN diode. In this paper the measurement method of this system is presented, as well as some measurement attempts documented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-TUPA01  
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TUPA03 Test of New Beam Loss Monitors for SOLEIL storage-ring, detector, electron, shielding 215
 
  • N. Hubert, M. El Ajjouri, D. Pédeau
    SOLEIL, Gif-sur-Yvette, France
 
  Soleil is currently testing new beam loss monitors to replace its pin-diode based existing system. The new detectors are made of plastic scintillators associated with photomultiplier and connected to Libera BLM dedicated electronics. This new detector should provide both fast (turn by turn) and slow (averaged) loss measurements, post mortem capabilities and should be less sensitive to the beam directivity compared to the pin-diodes. Different methods for a relative calibration of the modules are under investigation, either using a diode (LED) or a cesium radioactive source. Calibration results and first measurements with beam are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-TUPA03  
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TUPA07 Collimator for Beam Position Measurement and Beam Collimation for Cyclotron target, cyclotron, vacuum, collimation 224
 
  • L.X. Hu, Y. Chen, K.Z. Ding, J. Li, Y. Song, Q. Yang
    ASIPP, Hefei, People's Republic of China
  • Y.C. Wu, K. Yao
    HFCIM, HeFei, People's Republic of China
 
  Funding: This work is supported in part by grants 1604b0602005 and 1503062029.
In order to restrict the beam dispersion and diffusion at the extraction area of the cyclotron and to detect abnormal beam loss, a beam collimator system has been designed to collimate the beam and to measure its transverse positions. The collimator system is composed of a vacuum cavity, two pairs of beam targets, a set of driving and supporting mechanism, and a measurement and control unit. The beam target with the size determined by the diameter of the beam pipe, the particle energy and beam intensity, will generate current signal during particle deposition. Each pair of beam targets has bilateral blocks which forms a slit in either horizontal or vertical direction. Servo motor and screw rod are used so that the target can reciprocate with the repeatability of less than 0.1mm. The measurement and control system based on LabVIEW can realize the motion control and current measurement of the targets and then calculate the beam transverse positions.
 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-TUPA07  
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TUPA14 Beam Loss Monitoring in the ISIS Synchrotron Main Dipole Magnets dipole, detector, synchrotron, radiation 236
 
  • D.M. Harryman, S.A. Fisher, W.A. Frank, B. Jones, A. Pertica, D.W. Posthuma de Boer, C.C. Wilcox
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
 
  Beam loss monitoring at the ISIS Neutron and Muon Source is primarily carried out with the use of gas ionisation chambers filled with argon. These chambers are 3 to 4m long and are positioned around the inside of the synchrotron as well as along the ISIS Linac and Extracted Proton Beamlines (EPBs). To achieve finer spatial resolution a programme has been implemented to install six scintillator Beam Loss Monitors (BLMs), each 300 mm long, inside each of the ten main dipole magnets. Using these scintillator BLMs the accelerator can be fine-tuned during set-up to reduce areas of beam loss that were previously unseen or hard to characterise. As the installation programme comes to an end, this paper will review: the installation of the scintillator BLMs, the electronic hardware and software used to control them, and the initial measurements that have been taken using them.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-TUPA14  
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TUPA16 Signal Processing for Beam Loss Monitor System at Jefferson Lab machine-protect, FPGA, operation, diagnostics 245
 
  • J. Yan, T.L. Allison, S. Bruhwel, W. Lu
    JLab, Newport News, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Ion Chamber and Photomultiplier Tube (PMT) were both used for beam loss monitor in the Machine Protection System (MPS) at Jefferson Lab. The requirements of signal processing of these detectors are different, so two VME-based signal processing boards, Beam Loss Monitor (BLM) board and Ion-Chamber board, were developed. The BLM board has fast response (< 1us) and 5 decades dynamic range from 10nA to 1 mA, while the Ion-Chamber board has 8 decades dynamic range from 100 pA to 10 mA and slower response. Both of boards provide functions of machine protection and beam diagnostics, and have features of fast shutdown (FSD) interface, beam sync interface, built-in-self-test, remotely controlled bias signals, and on-board memory buffer.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-TUPA16  
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TUPB02 Complete Test Results of New BPM Electronics for the ESRF New LE-Ring electron, electronics, SRF, 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.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-TUPB02  
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TUPB13 Stability Tests with Pilot-Tone Based Elettra BPM RF Front End and Libera Electronics electron, electronics, pick-up, ISOL 289
 
  • M. Cargnelutti, P. Leban, M. Žnidarčič
    I-Tech, Solkan, Slovenia
  • S. Bassanese, G. Brajnik, S. Cleva, R. De Monte
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
 
  Long-term stability is one of the most important properties of the BPM readout system. Recent developments on pilot tone capable front end have been tested with an established BPM readout electronics. The goal was to demonstrate the effectiveness of the pilot tone compensation to varying external conditions. Simulated cable attenuation change and temperature variation of the readout electronics were confirmed to have no major effect to position data readout. The output signals from Elettra front end (carrier frequency and pilot tone frequency) were processed by a Libera Spark with the integrated standard front end which contains several filtering, attenuation and amplification stages. Tests were repeated with a modified instrument (optimized for pilot tone) to compare the long-term stability results. Findings show the pilot tone front end enables great features like self-diagnostics and cable-fault compensation as well as small improvement in the long-term stability. Measurement resolution is in range of 10 nanometers RMS in 5 Hz bandwidth.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-TUPB13  
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TUPC04 BPM System Upgrade at COSY EPICS, electron, operation, electronics 303
 
  • V. Kamerdzhiev, I. Bekman, C. Böhme, B. Lorentz, S. Merzliakov, P. Niedermayer, K. Reimers, M. Simon, M. Thelen
    FZJ, Jülich, Germany
 
  The beam position monitoring system of the Cooler Synchrotron (COSY) has been upgraded in 2017. The upgrade was driven by the requirement of the JEDI collaboration to significantly improve the orbit control and by the electronics approaching end-of-life. The entire signal processing chain has been replaced. The new low noise amplifiers, mounted directly on the BPM vacuum feedthroughs, were developed in-house and include adjustable gain in 80 dB rage and in-situ test and calibration capabilities. The signals are digitized and processed by means of commercial BPM signal processing units featuring embedded EPICS IOC. The decision path, technical details of the upgrade and performance of the new system are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-TUPC04  
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TUPC10 The Design of Scanning Control System for Proton Therapy Facility at CIAE proton, feedback, cyclotron, interface 319
 
  • L.C. Cao, T. Ge, F.P. Guan, S.G. Hou, X.T. Lu, Y. Wang, L.P. Wen
    CIAE, Beijing, People's Republic of China
 
  A new proton therapy facility is being construted at CIAE. As a part of whole control system, the scanning control system is designed to scan the beam for the access of required tumor therapy field. The origin data plan comes from treatment control system. Two set of dipole magnet is driven for changing the beam path. Meanwhile, interfaces between scanning system and other systems is built for beam control and safe considering. In order to acquire high precise feedback control, the beam position and dose monitor ionization chambers will be constructed in the nozzle. Once accident occurs, the scanning system should be able to response instantly to cut off beam and inform safe interlock system simultaneously. The response time of scanning system is at tens of microsecond level, so the scanning controller, feedback controller and the monitor electronics is built in fast mode. Detailed description will be presented in this paper.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-TUPC10  
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TUPC13 Early Commissioning of the Luminosity Dither Feedback for SuperKEKB luminosity, feedback, MMI, electron 328
 
  • M. Masuzawa, Y. Funakoshi, T. Kawamoto, S. Nakamura, T. Oki, M. Tobiyama, S. Uehara
    KEK, Ibaraki, Japan
  • P. Bambade, S. Di Carlo, D. Jehanno, C.G. Pang
    LAL, Orsay, France
  • D.G. Brown, A.S. Fisher, M.K. Sullivan
    SLAC, Menlo Park, California, USA
  • D. El Khechen
    CERN, Geneva, Switzerland
  • U. Wienands
    ANL, Argonne, Illinois, USA
 
  SuperKEKB is an electron-positron collider, which aims to achieve a peak luminosity of 8×1035 cm-2 s−1 using what is known as the "nano-beam" scheme. This paper reports on the commissioning and performance of a luminosity dither feedback. The system, based on one previously used at SLAC for PEP-II, is employed for collision orbit feedback in the horizontal plane. Twelve air-core Helmholtz coils drive the positron beam sinusoidally at a frequency near 80 Hz, forming a closed bump at the interaction point. A lock-in amplifier detects the amplitude and phase of the corresponding frequency component of the luminosity signal. When the beams are aligned for peak luminosity, the magnitude of the luminosity component at the dithering frequency becomes zero. The magnitude grows as the beams are offset, and the phase shifts by 180 degrees when the direction of the necessary correction reverses. The hardware and algorithm were tested during SuperKEKB Phase II run. The electron beam orbit was successfully adjusted to minimize the amplitude of the dither frequency component of the luminosity signal, and the optimal condition was maintained by continuously adjusting the electron beam orbit.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-TUPC13  
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WEOB03 The European XFEL Beam Loss Monitor System FEL, electron, high-voltage, undulator 357
 
  • T. Wamsat, T. Lensch
    DESY, Hamburg, Germany
 
  The European XFEL MTCA based Beam Loss Monitor System (BLM) is composed of about 470 monitors, which are part of the Machine Protection System (MPS). The BLMs detect losses of the electron beam, in order to protect accelerator components from damage and excessive activation, in particular the undulators, since they are made of permanent magnets. Also each cold accelerating module is equipped with a BLM to measure the sudden onset of field emission (dark current) in cavities. In addition some BLMs are used as detectors for wire- scanners. Experience from the already running BLM system in FLASH2 which is developed for XFEL and tested here, led to a fast implementation of the system in the XFEL. Further firmware and server developments related to alarm generation and handling are ongoing. The BLM systems structure, the current status and the different possibilities to trigger alarms which stop the electron beam will be presented.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEOB03  
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WEPA01 A MicroTCA.4 Timing Receiver for the Sirius Timing System timing, feedback, interface, hardware 375
 
  • J.L. Brito Neto, G.B.M. Bruno, S.R. Marques, L.M. Russo, D.O. Tavares
    LNLS, Campinas, Brazil
 
  The AMC FMC carrier (AFC) is a MicroTCA.4 AMC board which has a very flexible clock circuit that enables any clock source to be connected to any clock input, including telecom clock, FMC clocks, programmable VCXO oscillator and FPGA. This paper presents the use of the AFC board as an event receiver connected to the Sirius timing system to provide low jitter synchronized clocks and triggers for Sirius BPM electronics and other devices.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEPA01  
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WEPA06 Thermal Coefficient of Delay Measurement of the New Phase Stable Optical Fiber * detector, laser, operation, ISOL 383
 
  • L. Liu, X. Ma, G. Pei
    IHEP, Beijing, People's Republic of China
 
  The Thermal Coefficient of Delay (TCD) is an essen-tial parameter of optical fiber which determines a fiber's phase transfer stability due to temperature variation. The TCD of a new phase stable single mode optical fiber (YPSOC) from Yangtze Optical Fibre and Cable Compa-ny (YOFC) is measured. The radio frequency (RF) signal is modulated to optical wave by a laser module which is transmitted through the 400-meter long YPSOC to be measured. The returned optical wave is demodulated to RF signal by the photodetector. A phase detector and a data acquisition module (DAQ) are used to acquire the phase difference between the forward and returned sig-nals. Two temperature-stabilized cabinets are designed to maintain and control the ambient temperature of the measurement system. The TCD of less than 10ps/km/K at room temperature is obtained. YPSOC and the meas-urement platform can be applied on signal transmission or measurement system that need to compensate the temperature drift.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEPA06  
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WEPA09 Long Term Beam Phase Monitoring Based on HOM Signals in SC Cavities at FLASH HOM, cavity, electron, FEL 388
 
  • J.H. Wei
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  • N. Baboi
    DESY, Hamburg, Germany
  • L. Shi
    PSI, Villigen PSI, Switzerland
 
  The accelerating RF fields in superconducting cavities must be controlled precisely in FEL (Free Electron Laser) facilities to avoid beam energy spread and arrival time jitter. Otherwise the beam quality is degraded. The LLRF (Low Level Radio Frequency) system controls the RF field and provides a highly stable RF reference. A new type of beam phase determination technique based on beam-excited HOMs (Higher Order Modes) in cavities has been implemented. The two special couplers installed at both ends of each cavity, pick up the signals containing both the leakage of the accelerating field and the HOM signals. Therefore the signals can be used to calculate the beam phase directly with respect to the RF phase. We analysed the factors which may affect the result of the beam phase on a long-term based on an experimental platform at FLASH. Some phase drifts between the HOM-BPhM (Beam Phase Monitor) and the LLRF system phase measurement were observed and the reason will be further studied.  
poster icon Poster WEPA09 [1.720 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEPA09  
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WEPA15 Development of BAM Electronics in PAL-XFEL electron, electronics, pick-up, FEL 400
 
  • D.C. Shin, J.H. Hong, H.-S. Kang, C. Kim, G. Kim, C.-K. Min
    PAL, Pohang, Republic of Korea
 
  We describe an electronics for electron bunch arrival time monitor (BAM) with a less than 10 femtosecond resolution, which was developed in 2017 and is currently in use at PAL-XFEL. When electron bunches go through an S-band monopole cavity, about 1 us long RF signal can be obtained to compare with a low phase noise RF reference. The differential phase jitter corresponds to the arrival time jitter of electron bunches. RF front-end (F/E) which converts the S-band pickup signal to intermediate frequency (IF) signal, is the essential part of a good time resolution. The digitizer and the signal processor of the BAM electronics are installed in an MTCA platform. This paper presents the design scheme, test results of the BAM electronics and future improvement plans.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEPA15  
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WEPB06 Time-Synchronous Measurements of Transient Beam Dynamics at Spear3* feedback, diagnostics, experiment, injection 441
 
  • Q. Lin, Z.H. Sun
    Donghua University, Shanghai, People's Republic of China
  • W.J. Corbett, D.J. Martin, K. Tian
    SLAC, Menlo Park, California, USA
 
  Funding: Work supported by the China Scholarship Council and the US Department of Energy Contract DE-AC03-76SF00515, Office of Basic Energy Sciences.
Multi-bunch beam instabilities can often be controlled with high-speed digital bunch-by-bunch feedback systems. The detected motion is based on charge centroid measurements that, for short bunches, cannot resolve intrabunch charge dynamics. To compliment the BxB data, we installed a fast-gated camera with a rotating mirror to sweep visible-light synchrotron radiation across the camera CCD. The SR measurements present a complimentary view of the motion. For this work we generated transient beam events in SPEAR3 using the BxB feedback system and synchronously observed the motion on the camera. Results are presented for a high-order multibunch beam instability and for single bunch drive-damp experiments.

 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEPB06  
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WEPB09 Wire Scanner Measurements at the PAL-XFEL undulator, FEL, electron, emittance 445
 
  • G. Kim, H.-S. Kang, C. Kim, B.G. Oh, D.C. Shin
    PAL, Pohang, Kyungbuk, Republic of Korea
 
  The PAL-XFEL, an X-ray Free electron laser user facility based on a 10 GeV normal conducting linear accelerator, have been operational at Pohang, South Korea. The wire scanners are installed for transverse beam profile measurement of the Linac and the Hard X-ray undulator section. The wire scanner is a useful device for emittance measurements in the Hard X-ray undulator section. In this paper, we describe the details of the wire scanner and the results of the measurements.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEPB09  
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THOA02 High-Speed Direct Sampling FMC for Beam Diagnostic and Accelerator Protection Applications interface, FEL, diagnostics, timing 534
 
  • J. Zink, M.K. Czwalinna, M. Fenner, S. Jabłoński, J. Marjanovic, H. Schlarb
    DESY, Hamburg, Germany
 
  The rapid development in the field of digitizers is leading to Analog-to-Digital Converters (ADC) with ever higher sampling rates. Nowadays many high-speed digitizers for RF applications and radio communication are available, which can sample broadband signals, without the need of down converters. These ADCs fit perfectly into beam instrumentation and diagnostic applications, e.g. Bunch Arrival time Monitor (BAM), klystron life-time management or continuous wave synchronization. To cover all these high-frequency diagnostic applications, DESY has developed a direct sampling FMC digitizer board based on a high-speed ADC with an analog input bandwidth of 2.7 GHz. A high-speed data acquisition system capable of acquiring 2 channels at 800 MSP/s will be presented. As first model application of the versatile digitizer board is the coarse bunch arrival time diagnostics in the free electron laser FLASH at DESY.  
slides icon Slides THOA02 [5.817 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-THOA02  
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