Keyword: feedback
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MOPAB085 Introduction of Beam Position Monitor System in the HLS II Storage Ring storage-ring, closed-orbit, quadrupole, brilliance 319
 
  • F.F. Wu, L. Lin, X.Y. Liu, P. Lu, B.G. Sun, L.L. Tang, J.G. Wang, J.H. Wei, K. Xuan, Y.L. Yang, T.Y. Zhou, Z.R. Zhou
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  
  Funding: Supported by the National Key Research and Development Program of China (No. 2016YFA0402000) Supported by the National Science Foundation of China (11575181, 11605202)
Beam position monitor(BPM) system for the HLS II storage ring were designed in the HLS II upgrade project. This system is composed of BPM, BPM processor embedded with IOC and OPI. Every component of BPM system is introduced in this paper. BPM processors have different modes of data, such as ADC data, turn-by-turn(TBT) data, fast acquirement(FA) data and slow acquirement(SA) data. Different modes of data are used to different applications. Two applications based on SA data of the BPM system, such as BBA for quadrupole magnet center measurement and beam closed orbit feedback, are described in detail. The result of BBA shows that most magnetic centers of quadrupole magnets are in the range of [-1 mm, 1 mm] with respect to BPM electric centers. The result of beam closed orbit feedback shows that beam orbit stability when the closed orbit feedback system is on is far better than that when the closed orbit feedback system is off. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB085  
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MOPAB091 Transverse Beam Instability Observation and Investigation Using Bunch by Bunch on-Line DAQ System experiment, storage-ring, vacuum, data-acquisition 335
 
  • N. Zhang, L.W. Lai, Y.B. Leng
    SSRF, Shanghai, People's Republic of China
  
  Funding: supported by National Natural Foundation of China (11375255 and 11375254)
Tank impedance of in-vacuum insertion device is one important source of beam transverse instability, which was expected to be suppressed by transverse feedback system (TFB). For the observation and study of transverse instability affected by insertion device and TFB, sets of an in-vacuum undulator narrow gap setting and TFB gain setting were operated in a beam-based experiment. A bunch-by-bunch (BYB) position on-line DAQ system was employed in the measurement to characterize frequencies of individual bunches. Bunch-train transverse oscillation amplitude variation were curved by harmonic analysis. In this paper, we will introduce the BTB ADQ system, and report on the measurement experiment and related data analysis. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB091  
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MOPAB117 Online Bunch by Bunch Transverse Instability Detection in LHC operation, pick-up, network, injection 397
 
  • M.E. Söderén, G. Kotzian, M. Ojeda Sandonís, D. Valuch
    CERN, Geneva, Switzerland
  
  Reliable detection of developing transverse instabilities in the Large Hadron Collider is one of the main operational challenges of the LHC's high intensity proton run. A full machine snapshot provided from the moment of instability is a crucial input to develop and fine tune instability models. The transverse feedback system (ADT) is the only instrument in LHC, where a full rate bunch by bunch transverse position information is available. Together with a sub-micron resolution it makes it a perfect place to detect transverse beam motion. Very large amounts of data, at very high data rates (8 Gb/s) need to be processed on the fly to detect onset of transverse instability. A very powerful computer system (so called ADTObsBox) was developed and put into operation by the CERN RF group, which is capable of processing the full rate data streams from ADT and perform an on the fly instability detection. The output of this system is a timing event with a list of all bunches developing instability, which is then sent to the LHC-wide instability trigger network to freeze other observation instruments. The device also provides buffers with raw position data for offline analysis.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB117  
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MOPAB151 Techniques for Transparent Lattice Measurement and Correction lattice, operation, betatron, storage-ring 483
 
  • W.X. Cheng, K. Ha, Y. Li
    BNL, Upton, Long Island, New York, USA
  
  Funding: Work supported by DOE contract No: DE-SC0012704
NSLS-II storage ring started top off operation since Oct 2015. It has been noticed during the user operation that machine lattice was affected by insertion devices (ID). The storage ring coupling, emittance and lifetime vary when ID gap changes. Lattice characterization was typically carried out with dedicated machine study time with low storage current. Due to collective effect, the lattice at high operation current is different. To characterize the machine lattice during normal user operation with little disturbance, a small portion of beam (~1%) filled in the ion gap can be excited by the bunch by bunch feedback system near betatron frequency. Recent development on BPM electronics enables the gate function to detect partial beam motion in the ring. With the gated BPM turn by turn data from excited bunches, storage ring lattice can be measured and corrected with the well-developed tools. We present in the paper preliminary test results with these tools to characterize the lattice and how it improves the machine performance during user operation. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB151  
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MOPIK033 The Development of a New Low Field Septum Magnet System for Fast Extraction in Main Ring of J-PARC septum, operation, extraction, power-supply 573
 
  • T. Shibata, K. Ishii, H. Matsumoto, N. Matsumoto, T. Sugimoto
    KEK, Ibaraki, Japan
  • K.J. Kuanjun
    HUST, Wuhan, People's Republic of China
  
  The J-PARC Main Ring (MR) is being upgraded to improve its beam power to the design goal of 750 kW. One important way is to reduce the repetition period from 2.48 s to 1.3 s so that the beam power can be nearly doubled. We need to improve the septum magnets for fast extraction. We are improving the magnets and their power supplies. The present magnets which is conventional type have problem in durability of septum coil by its vibration, and large leakage field. The new magnets are eddy current type. The eddy current type does not have septum coil, but has a thin plate. We expect that there is no problem in durability, we can construct the thin septum plate, the leakage field can be reduced. The output of the present power supply are pattern current which of flat top is 10 ms width, the new one is short pulse which of one is 10 us. The short pulse consists of 1st and 3rd higher harmonic. We can expect that the flatness and reproducibility of flat top current can be improved. The calorific power can be also reduced. This paper will report the field measurement results with the eddy septum magnet systems.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK033  
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MOPIK080 Research of the Electro-Gravitational Induction by Using COD Signals in Charged Particle Storage Rings storage-ring, induction, positron, electron 719
 
  • D. Dong
    IHEP, Beijing, People's Republic of China
  • J.Y. Dong
    Binghamton University, State University of New York, Binghamton, New York, USA
  
  Funding: The project was supported by the National Natural Science Foundation of China under Grant No. 11575215, partly.
Form the beam instability in the charged particle storage ring; researchers have known that one kinds of long term beam instability, the period of 12 hours, comes from the gravity changes, the change of acceleration of gravity g, delta g caused by the moon and sun moving relative to the earth, so called the terrestrial tidal forces. Phenomenology, we would say that the gravity changes caused by the moon and sun moving at the storage ring have caused the beam energy changes in the storage ring. If it is true, then it may be the electro-gravitational induction (EGI). In this paper, we will discuss the possibility of EGI, and estimate the maximum value of the gravity coefficient of the induced electromotive force by using the existing beam data from the storage rings. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK080  
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MOPVA060 Fabrication and Treatment of the ESS Medium Beta Prototype Cavities cavity, controls, operation, vacuum 1003
 
  • L. Monaco, A. Bellandi, M. Bertucci, A. Bignami, A. Bosotti, J.F. Chen, P. Michelato, R. Paparella, D. Sertore
    INFN/LASA, Segrate (MI), Italy
  • C. Pagani
    Università degli Studi di Milano & INFN, Segrate, Italy
  • S. Pirani
    ESS, Lund, Sweden
  
  In view of the Medium Beta series cavities production at the industry for the European Spallation Source project, INFN Milano - LASA design prototypes have been fully produced at Ettore Zanon S.p.A. with our supervision. Based on our experience on the production of 1.3 GHz and 3.9 GHz E-XFEL series cavities, we set-up and applied an external quality control activity of the overall production of the prototype cavity, starting from the row materials to the ready to be tested cavity. In this paper, we report the strategy we have adopted on the overall production, mechanical and surface treatments, frequency measurement of subcomponents and cavities and the obtained results.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA060  
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MOPVA094 ESS Spoke Cavity Conditioning at FREIA cavity, vacuum, software, controls 1074
 
  • H. Li, K.J. Gajewski, L. Hermansson, M. Jobs, R.J.M.Y. Ruber, R. Santiago Kern
    Uppsala University, Uppsala, Sweden
  
  The first ESS double spoke cavity installed with RF power coupler was tested in the HNOSS cryostat at the FREIA Laboratory. Power coupler and cavity conditioning have been optimized in order to reach high efficiency and high availability by reducing the time and effort of the overall conditioning process. Meanwhile, an optimal procedure for ESS conditioning is studied. This paper presents the study result and experience of the RF conditioning procedure for the first ESS double spoke cavity.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA094  
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MOPVA146 Optimization of Carbon Treatments at CNAO dipole, extraction, acceleration, ion 1197
 
  • L. Falbo, E. Bressi, C. Priano
    CNAO Foundation, Milan, Italy
  
  CNAO facility is treating patients with carbon ion beams since 2012. Often carbon ions are used to treat tumors with great volumes that causes long time irradiations: this represents a complaint for the patient, a limit in the number of treatable patients per day and an increase in the cost of the treatment itself. An effort has been done in the last year to increase the particle intensity in order to reduce the irradiation time for the carbon treatments: this article illustrates the changes in the machine done to achieve this goal.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA146  
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TUPAB026 Status of the Cryogenic Undulator CPMU-17 for EMIL at BESSY II / HZB vacuum, undulator, Windows, permanent-magnet 1372
 
  • J. Bahrdt, J. Bakos, W. Frentrup, S. Gottschlich, C. Kuhn, G. Pfeiffer, C. Rethfeldt, A. Rogosch-Opolka, M. Scheer, B. Schulz, L. Ziemann
    HZB, Berlin, Germany
  
  The CPMU-17 is the hard X-ray radiation source of a canted double undulator system for the Energy Materials In-situ Laboratory EMIL at BESSY II [1]. Various ambitious concepts are realized in this undulator such as Dy-hardened PrFeB-magnets, direct liquid Nitrogen cooling, dual loop feedback gap drive based on an optical micrometer and a low permeability stainless steel In-Vacuum(IV)-girder without keepers. The magnets are sorted according to Helmholtz coil and stretched wire data. Reproducibility and accuracy measurements of two IV-measurement tools needed for the CPMU-17 are presented: an IV-Hall probe bench and an IV-Moving Wire.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB026  
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TUPAB103 Orbit Correction With Path Length Compensation Based on Rf Frequency Adjusments in TPS operation, electron, site, photon 1553
 
  • P.C. Chiu, K.T. Hsu, K.H. Hu, C.H. Huang, C.-C. Kuo, C.C. Liang, Y.-C. Liu, H.-J. Tsai, F.H. Tseng
    NSRRC, Hsinchu, Taiwan
  
  The 3 GeV Taiwan Photon Source has been routinely operated for public users since September 2016. Orbit reproducibility and stability are critical for the quality of user experiments. Ambient temperature variations and earth tides can cause a change in circumference, changing in turn the beam energy, and orbit drift. Therefore both, orbit correction and rf frequency adjustments are necessary to keep the ring circumference constant. A Fast Orbit Feedback (FOFB) system combined with rf frequency correction deduced from the fast corrector strengths is applied to the FOFB routine. The correlation between the measured frequency variation with ambient temperature and earth tides is also reported in this article.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB103  
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TUPIK040 Commissioning of the Fast Orbit Feedback System at the Australian Synchrotron FPGA, synchrotron, controls, insertion-device 1770
 
  • Y.E. Tan, S. Chen, T.D. Cornall, A. Michalczyk, A. C. Starritt, E.J. Vettoor
    SLSA, Clayton, Australia
  • B. Dickson
    Arrayware Pty Ltd, Scoresby, Australia
  • D.J. Peake
    DETECT Australia, Bundoora, Australia
  • D.O. Tavares
    LNLS, Campinas, Brazil
  
  An FPGA based fast orbit feedback system developed at the Australian Synchrotron aims to improve the stability of the electron beam by reducing the impact of moving insertion devices and targeting orbit perturbations at the mains frequency (50 Hz, 100 Hz and 300 Hz). The feedback system uses a PI controller with harmonic suppressors in parallel to specifically target perturbations at the mains frequency and its harmonics. This report will present the results of the commissioning of the FOFB system demonstrating a reduction in the integrated RMS motion up to 300 Hz by 75% to 90%.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK040  
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TUPIK045 Closed Orbit Feedback for FAIR - Prototype Tests at SIS18 controls, software, closed-orbit, distributed 1784
 
  • B.R. Schlei, H. Liebermann, D. Ondreka, P.J. Spiller, R.J. Steinhagen
    GSI, Darmstadt, Germany
  
  A new steering software for cycle-to-cycle closed orbit as well as trajectory control is currently under development for FAIR's planned control system. It has been successfully tested with beam at the SIS18 in 2016. COAT (i.e., Controlling Orbits And Trajectories) has been realized as a distributed, Java-based application. It consists of a background daemon process that handles the actual beam-based feedback logic, and independent clients that provide visualization and various user-interaction capabilities. Built on top of the LSA settings management system, code-shared and also used at CERN, the system is kept generic. Furthermore, it is designed to support multiple accelerators, transfer lines and users in parallel. In particular, it can handle continuously changing optics and other in advance known changing beam parameters. The COAT computer program is part of a set of newly developed beam-based feedback tools* for FAIR. Preliminary results of our proof-of-concept prototype studies indicate, e.g., in view of the observed SIS18 machine reproducibility, that such a cycle-to-cycle feedback control scheme may be adequate also for the other FAIR accelerators and transfer lines.
*see separate contribution by R. J. Steinhagen et al. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK045  
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TUPIK046 Beam-Based Feedbacks for FAIR - Prototyping at the SIS18 controls, extraction, proton, injection 1787
 
  • R.J. Steinhagen, J. Fitzek, H.C. Hüther, H. Liebermann, R. Müller, D. Ondreka, H. Reeg, B.R. Schlei, P.J. Spiller
    GSI, Darmstadt, Germany
  
  The 'Facility for Anti-Proton and Ion Research' (FAIR) presently under construction, extends and supersedes GSI's existing infrastructure. Its core challenges include the precise control of highest proton and uranium ion beam intensities, the required extreme high vacuum conditions, machine protection and activation issues while providing a high degree of multi-user mode of operation with facility reconfiguration on time-scales of a few times per week. To optimise turn-around times and to establish a safe and reliable machine operation, a comprehensive suite of semi-automated measurement applications, as well as fully-automated beam-based feedbacks will be deployed, covering the control of orbit, Q/Q', spill structure, optics, and other machine parameters. These systems are based on the LSA settings management framework, code-shared with and also used at CERN. The concepts, software architecture and first prototype beam tests at the SIS18 in 2016 are presented. As an initial proof-of-concept, a cycle-to-cycle orbit* and macro-spill feedback, as well as a semi-automated magnetic quadrupole- and sextupole-centre measurement tool have been selected.
*results presented in separate contribution 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK046  
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TUPIK050 COSY Slow Orbit Feedback System controls, closed-orbit, EPICS, dipole 1802
 
  • M. Simon, M. Bai, C. Böhme, F. Hinder, B. Lorentz, C. Weidemann
    FZJ, Jülich, Germany
  • J. Bobnar, J. Malec, R. Modic, K. Žagar
    Cosylab, Ljubljana, Slovenia
  • A. Marusic
    BNL, Upton, Long Island, New York, USA
  
  The Cooler Synchrotron (COSY) at Forschungszentrum Jülich is currently carrying out the preparation for a direct measurement of the electric Dipole Moment (EDM) of the deuteron using an RF Wien filter*,**. In a magnetic storage ring with the spin vector aligned along the direction of motion, the EDM manifests in a buildup of the vertical spin component. Besides this signal, radial magnetic fields due to a distortion of the vertical closed orbit can produce a similar signal. This signal is a systematic limit of the proposed measurement procedure. Based on simulation studies***, a vertical closed orbit distortion with a RMS smaller than 0.1 mm is required to achieve a sensitivity of 10-19 e.cm or better. In order to accomplish this challenging goal, a slow orbit feedback system was proposed and recently commissioned at COSY. The design and commissioning results will be presented, and the future plan will also be discussed.
* A. Lehrach et. al, arXiv:1201.5773 [hep-ex].
** W. M. Morse, Y. F. Orlov and Y. K. Semertzidis, PRSTAB 16, no.11, 114001 (2013).
*** M. Rosenthal, Ph.D. thesis, RWTH Aachen University, 2016, available from http://collaborations.fz-juelich.de/ikp/jedi/publicfiles/theses/ThesisMRosenthal.pdf 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK050  
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TUPIK052 Fast Automatic Ramping of High Average Power Guns cavity, gun, resonance, operation 1809
 
  • Y. Renier
    DESY Zeuthen, Zeuthen, Germany
  • M.K. Grecki, O. Hensler, S. Pfeiffer
    DESY, Hamburg, Germany
  
  The electron guns at PITZ, FLASH and European XFEL are standing wave structures which operate at high average power (>40 kW) to produce long trains of high quality beams. This amount of power heats the cavity surface enough to change signi'cantly the gun resonance frequency. As consequence, to keep the re'ection low, the RF power ramp must be enough slow to permit the water cooling system to keep the gun temperature close to the set-point. Also, as the temperature probe sits close to the surface of the iris, the required gun temperature set-point to maintain the gun on resonance is a function of the average power. The RF power ramping is a difficult process in which temperature and re'ection must be monitored to adjust accordingly the temperature set-point and the ramping speed of the RF power. An automatic software to adjust the RF frequency and the temperature set-point of the PITZ gun in parallel to the RF power ramping has been developed. The use of this software has signi'cantly reduced the time spent to start up the gun or to recover from interlocks, increasing the time spent at nominal parameters which would also be very important for user facilities.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK052  
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TUPIK053 A Broadband Transverse Kicker Prototype for Intra-Bunch Feedback in the CERN SPS kicker, impedance, simulation, coupling 1812
 
  • M. Wendt, I.A. Alonso Romero, S.J. Calvo, W. Höfle, O.R. Jones, E. Montesinos
    CERN, Geneva, Switzerland
  
  A transverse intra-bunch feedback system is currently under study at CERN for the SPS, to mitigate beam instabilities caused by electron clouds and coupled transverse modes (TMCI). This feedback system is designed for a bandwidth of 1 GHz, and based on a digital feedback controller and broadband power amplifiers. For the kicker, a periodic, quasi-TEM slotted transmission-line structure is foreseen which promises to meet the bandwidth requirements. This paper discusses the electromagnetic design and the mechanical implementation of a prototype kicker, demonstrating its performance and limitations based on numerical simulations.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK053  
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TUPIK059 Recent Progress of Dithering System at SuperKEKB luminosity, background, optics, electronics 1827
 
  • Y. Funakoshi, H. Fukuma, T. Kawamoto, M. Masuzawa, S. Nakamura, K. Ohmi, T. Oki, S. Uehara
    KEK, Ibaraki, Japan
  • P. Bambade, D. El Khechen, D. Jehanno, V. Kubytskyi, C. Rimbault
    LAL, Orsay, France
  • A.S. Fisher
    SLAC, Menlo Park, California, USA
  • U. Wienands
    ANL, Argonne, Illinois, USA
  
  Recent progress of the dithering system at SuperKEKB is described. Some details of the system layout are shown. Beam orbit and optics related issues are discussed. Preliminary tests of the some components in the Phase 1 beam commissioning or in the bench are described.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK059  
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TUPIK077 Main Achievements of the PACMAN Project for the Alignment at Micrometric Scale of Accelerator Components alignment, quadrupole, target, collider 1872
 
  • H. Mainaud Durand, K. Artoos, M.C.L. Buzio, D. Caiazza, N. Catalán Lasheras, A. Cherif, I.P. Doytchinov, J.-F. Fuchs, A. Gaddi, N. Galindo Munoz, J. Gayde, S.W. Kamugasa, M. Modena, P. Novotny, S. Russenschuck, C. Sanz, G. Severino, D. Tshilumba, V. Vlachakis, M. Wendt, S. Zorzetti
    CERN, Geneva, Switzerland
  • A. Faus-Golfe
    LAL, Orsay, France
  
  Funding: The research leading to these results has received funding from the European Union's 7th Framework Programme Marie Curie actions, grant agreement PITN-GA-2013-606839.
The objectives of the PACMAN* project are to improve the precision and accuracy of the alignment of accelerator components. Two steps of alignment are concerned: the fiducialisation, i.e. the determination of the reference axis of components w.r.t alignment targets, and the initial alignment of components on a common support assembly. The main accelerator components considered for the study are quadrupoles, 15 GHz BPM and RF structures from the Compact LInear Collider (CLIC) project. Different methods have been developed to determine the reference axis of these components with a micrometric accuracy, as well as to determine the position of this reference axis in the coordinate frame of the common support assembly. The tools and methods developed have been validated with success on dedicated test setups using CLIC components. This paper will provide a compilation of the main achievements and results obtained.
* PACMAN is an acronym for a study on Particle Accelerator Components' Metrology and Alignment to the Nanometre scale. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK077  
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TUPIK091 Simulation Tools for the Design and Performance Evaluation of Transverse Feedback Systems framework, simulation, interface, pick-up 1912
 
  • J. Komppula, W. Höfle, K.S.B. Li
    CERN, Geneva, Switzerland
  
  Transverse feedback systems are used in synchrotrons and storage rings to damp injection oscillations and suppress transverse instabilities. Especially instabilities driven by high intensity beams in future circular colliders such as the FCC set challenging requirements for transverse feedback systems. In order to develop a transverse feedback system able to meet those requirements, sophisticated simulation tools are required. For this purpose, a new modular framework for modeling a transverse feedback system has been developed in Python. The framework can be used as a transverse feedback module in the macro-particle beam dynamics simulation code PyHEADTAIL or as a separate tool for studying a feedback model from a control theory point of view by using a simple signal models for the beam. The main principle of the code is presented and simulation methods used for the conceptual design of the FCC are discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK091  
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TUPIK093 Sensitivity of the LHC Transverse Feedback System to Intra-Bunch Motion pick-up, simulation, hardware, impedance 1916
 
  • G. Kotzian, W. Höfle, D. Valuch
    CERN, Geneva, Switzerland
  
  The LHC Transverse Feedback System is designed to damp and counteract all possible coupled bunch modes between the lowest betatron frequency and 20 MHz. The present study reveals that the analogue frontend processing scheme based on down converting the pick-up signal at the LHC RF frequency to baseband considerably extends the detected bunch movements visible to the feedback system to beyond 1 GHz. We develop an analytical model of the signal processing chain to explore the impact of even-symmetric and odd-symmetric intra-bunch movements on the detected beam position as a function of the longitudinal bunch shape. A set of equations is derived suitable for numerical simulations, or as a complement in particle tracking codes to further refine the behaviour of the LHC transverse feedback system.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK093  
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TUPIK094 Transverse Feedback Parameter Extraction from Excitation Data kicker, pick-up, damping, operation 1920
 
  • G. Kotzian
    CERN, Geneva, Switzerland
  
  In this paper we present a simple and fast approach to extract essential parameters of a transverse feedback system such as phase advances between pick-ups and kickers, fractional tune, kicker delay, or per-bunch transverse activity from discrete-time samples of position signals. In this approach the beam is excited and subsequent beam oscillations are recorded. Given that any number of pick-ups can be evaluated at once with only a marginal increase of transverse beam size this method is suitable for regular health checks of a transverse feedback system, e.g., for every injection. The fundamental idea relies on the reconstruction of the transverse phase space by means of digital filters. We sketch a simple mathematical model to illustrate the underlying method. Examples are given together with a set of filter kernels for the fractional tunes of the LHC transverse feedback system.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK094  
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TUPIK095 Possibilities for Transverse Feedback Phase Adjustment by Means of Digital Filters pick-up, kicker, betatron, damping 1924
 
  • G. Kotzian
    CERN, Geneva, Switzerland
  
  In transverse feedback systems a phase adjustment is generally required to convert a beam position signal from a pick-up into a momentum correction signal used by a transverse kicker. In this paper we outline several possibilities for phase adjustments using only single pick-ups or the vector combination of two pick-ups. Analytical expressions are given as a function of the fractional tune and the betatron phase advance between the pick-up location and the kicker. The shortest possible digital filter is formulated, including a notch for closed orbit suppression and a free parameter to adjust for betatron phase. We introduce a novel, fully parametrized digital filter with the feature to be insensitive to variations in fractional tune. Examples are given for the SPS transverse feedback system and compared with measurements.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK095  
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TUPIK097 Improving the Performance of an Orbit Feed-forward Based on Quadrupole Motion at the KEK ATF quadrupole, kicker, ground-motion, collider 1931
 
  • D.R. Bett, C. Charrondière, M. Patecki, J. Pfingstner, D. Schulte, R. Tomás
    CERN, Geneva, Switzerland
  • P. Burrows, G.B. Christian, C. Perry
    JAI, Oxford, United Kingdom
  • A. Jeremie
    IN2P3-LAPP, Annecy-le-Vieux, France
  • K. Kubo, S. Kuroda, T. Naito, T. Okugi, T.T. Tauchi, N. Terunuma
    KEK, Ibaraki, Japan
  
  The high luminosity requirement for a future linear collider sets a demanding limit on the beam quality at the Interation Point (IP). Even the natural motion of the ground could misalign the quadrupole magnets to such an extent that the resulting dipole kicks would require compensation. The novel technique described in this paper uses seismometers to measure the positions of the quadrupole magnets in real time and a kicker to counteract the effect of their misalignment. The prototype system deployed at the Accelerator Test Facility (ATF) at KEK in Japan has already demonstrated a reduction in the pulse-to-pulse vertical position jitter of the beam by about 10%. Based on the observed correlation of the beam position to the quadrupole positions the maximum possible jitter reduction from such a system is estimated to be about 25%. This paper details the latest improvements made to the system with the aim of achieving this limit.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK097  
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TUPIK110 Optimisation of a High-Resolution, Low-Latency Stripline Beam Position Monitor System for Use in Intra-Train Feedback electron, extraction, cavity, collider 1979
 
  • N. Blaskovic Kraljevic, R.M. Bodenstein, T. Bromwich, P. Burrows, G.B. Christian, C. Perry, R.L. Ramjiawan
    JAI, Oxford, United Kingdom
  • D.R. Bett
    CERN, Geneva, Switzerland
  
  A high-resolution, low-latency beam position monitor (BPM) system has been developed for use in feedback systems at particle accelerators and beamlines that operate with trains of particle bunches with bunch separations as low as several tens of nanoseconds, such as future linear electron-positron colliders and free-electron lasers. The system was tested with electron beams in the extraction line of the Accelerator Test Facility at the High Energy Accelerator Research Organization (KEK) in Japan. The fast analogue front-end signal processor is based on a single-stage RF down-mixer, with a measured latency of 15.6 ± 0.1 ns. The processor has been optimised, doubling the maximum operating beam intensity up to 1.6 nC, and the signal processing in the custom digital acquisition board has been upgraded in order to improve the resolution beyond the 300 nm level measured previously. The latest results, demonstrating a position resolution of order 150 nm with single-pass beam, will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK110  
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TUPIK111 IP Feedback Ground Motion Simulation Studies for the ILC luminosity, ground-motion, simulation, collider 1983
 
  • R.M. Bodenstein, N. Blaskovic Kraljevic, T. Bromwich, P. Burrows, G.B. Christian, C. Perry, R.L. Ramjiawan
    JAI, Oxford, United Kingdom
  • J. Pfingstner
    CERN, Geneva, Switzerland
  
  The International Linear Collider (ILC), as described in its Technical Design Report (TDR), must maintain strict control of its electron and positron beams in order to achieve the desired luminosity at each of its proposed center-of-mass energies. Controlling the beam parameters requires a dynamic system, capable of adjusting to a myriad of perturbations and errors. One of the components used to control the beam is the Interaction Point (IP) feedback system, which is used to dynamically steer the beams back into collision within nanoseconds. This work will show the simulation of the IP Feedback system's compensation for ground motion model K at the ILC.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK111  
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TUPIK112 Progress Towards Nanometre-Level Beam Stabilisation Using a Cavity BPM System at ATF2 cavity, dipole, kicker, electronics 1986
 
  • T. Bromwich, N. Blaskovic Kraljevic, R.M. Bodenstein, P. Burrows, G.B. Christian, C. Perry, R.L. Ramjiawan
    JAI, Oxford, United Kingdom
  
  A low-latency feedback system has been designed and tested to achieve inter-bunch position stabilisation at the final focus of the Accelerator Test Facility (ATF2) at KEK. This system has now been enhanced through the use of position information from two cavity beam position monitors (BPMs) to enable beam stabilisation at a third, intermediate location where a witness BPM measures the correction. Low-Q cavity BPMs were used, along with custom signal processing electronics designed for low latency and optimal position resolution. A custom stripline kicker, power amplifier and digital feedback board were used to provide beam correction and feedback control. The system was tested in single-pass, multi-bunch mode with the aim of providing inter-bunch beam stabilisation on electron bunches of charge ~1 nC separated in time by 280 ns. In 2015 a single BPM feedback system demonstrated beam stabilisation to below 75 nm. To date the two BPM input feedback system has demonstrated beam stabilisation to 83 ± 6 nm. This performance is limited by the current understanding of the cavity BPM resolution. Work will be described with the aim of improving this result.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK112  
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TUPIK113 Performance of the Fast Orbit Feedback System with the Double-Double Bend Achromat Installed in Diamond Light Source storage-ring, sextupole, controls, vacuum 1989
 
  • S. Gayadeen, G. Rehm
    DLS, Oxfordshire, United Kingdom
  
  At Diamond Light Source, the Double-Double Bend Achromat (DDBA) lattice upgrade involved the conversion of one cell of the storage ring from a double bend achromat (DBA) structure to a double-DBA (DDBA). The new cell includes corrector magnets that are different in design to the DBA corrector magnets. The DDBA vacuum chamber cross section is also different from the DBA cells and includes both stainless steel and copper sections over which corrector magnets are fitted. The performance of the Fast Orbit Feedback (FOFB) used for electron beam stabilisation with the DDBA cell installed is presented in this paper. Firstly the different corrector magnet dynamic responses are characterised and secondly the closed loop performance of the FOFB is measured and analysed for the upgraded lattice.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK113  
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TUPIK114 First Experiences with the Longitudinal Feedback System at Diamond Light Source cavity, kicker, simulation, hardware 1992
 
  • A.F.D. Morgan, M.G. Abbott, G. Rehm
    DLS, Oxfordshire, United Kingdom
  
  In order to avoid longitudinal multibunch instabilities potentially caused by the addition of normal conducting RF cavities into the Diamond storage ring, a longitudinal feedback was installed. The main components are newly developed feedback electronics, in-house built modulator and amplifier, and a low Q kicker cavity. This paper describes the performance of the cavity as well as the full longitudinal feedback system as it is installed on the machine and tested before the installation of the normal conducting RF cavities.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK114  
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TUPIK115 Control System Developments for the Diamond Light Source DDBA Upgrade controls, storage-ring, vacuum, software 1996
 
  • W.A.H. Rogers, M.G. Abbott, K.A.R. Baker, N.W. Battam, M.J. Furseman, I.J. Gillingham, P. Hamadyk, M.T. Heron, D.G. Hickin, S.C. Lay, I.P.S. Martin, A.J. Rose
    DLS, Oxfordshire, United Kingdom
  
  Upgrading one Double Bend Achromat cell to a Double Double Bend Achromat (DDBA) cell in the Diamond Light Source storage ring* necessitated a broad range of changes to the overall control system. These changes covered developments to the interface layer of the controls system to incorporate changes to the underlying instrumentation, associated development of user interface, changes to real-time feedback and feed-forward processes and to the online accelerator model. Given the pressures to minimise the shutdown length, the control system developments were optimised for time effective installation and commissioning. This paper outlines the control system developments for DDBA, the management process and lessons learnt from this process.
* R.P. Walker et al., The Double-Double Bend Achromat (DDBA) Lattice Modification for the Diamond Storage Ring, Proc. IPAC 2014, MOPRO103, (2014) 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK115  
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TUPIK119 Control of Intra-Bunch Vertical Instabilities at the SPS - Measurements and Technology Demonstration controls, injection, kicker, optics 2005
 
  • J.D. Fox, J.E. Dusatko, C.H. Rivetta, O. Turgut
    SLAC, Menlo Park, California, USA
  • H. Bartosik, W. Höfle, K.S.B. Li, E. Métral, B. Salvant, U. Wehrle
    CERN, Geneva, Switzerland
  • S. De Santis
    LBNL, Berkeley, California, USA
  
  Funding: Work supported by the U.S. Department of Energy under contract # DOE-AC02-76SF00515, the US LHC Accelerator Research Program ( LARP), the FP7 High Luminosity LHC Project and the US-Japan Cooperative Program in High Energy Physics
We present recent measurements demonstrating control of unstable beam motion in single bunch and bunch train configurations at the SPS. The work is motivated by anticipated intensity increases from the LIU and HL-LHC upgrade programs, and has included the development of a GHz bandwidth reconfigurable 4 GS/S signal processor with wideband kickers and associated amplifiers. The system was operated at 3.2GS/s with 16 samples across a 5 ns RF bucket (4.2 ns bunch at injection). The experimental results confirm damping of intra-bunch instabilities in both Q20 and Q26 optics configurations for intensities of 2x1011 P/bunch. Instabilities with growth times of 200 turns are well-controlled from injection, consistent with the achievable gains for the 2 installed stripline kickers with 1 kW broadband power. Measurements from multiple studies in single-bunch and bunch train configurations show achieved damping rates, control of multiple intra-bunch modes, behavior of the system at injection and final damped noise floor. We present an analysis method to study the relative phase of slice motion during a transient to discriminate between TMCI and other types of Head-Tail instabilities. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK119  
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TUPIK122 Bunch-by-Bunch Feedback Kickers for SPEAR3 kicker, impedance, ion, vacuum 2012
 
  • K. Tian, W.J. Corbett, J.D. Fox, S.M. Gierman, R.O. Hettel, X. Huang, A.K. Krasnykh, N. Kurita, D.J. Martin, J.A. Safranek, J.J. Sebek
    SLAC, Menlo Park, California, USA
  • Q. Lin
    DongHua University, Songjiang, People's Republic of China
  • D. Teytelman
    Dimtel, San Jose, USA
  
  SPEAR3 operates with a large cross-section copper vacuum chamber, mode-damped RF cavities and low-impedance insertion devices. As a result, the beam is passively stable for 280-bunch circulating beam current up to 500ma when the background gas pressure is low. In the future, more small-gap insertion devices will be installed and plans are underway to implement resonant bunch-crabbing for the ultrafast x-ray research program. These requirements drive the need for a fast, bunch-by-bunch feedback system to control beam instabilities, remove unwanted satellite bunches and resonantly crab select bunches on demand. In this paper we present a conceptual design for the transverse bunch-by-bunch stripline kickers.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK122  
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TUPVA154 Project-Based Cooperative Learning in Accelerator Science and Technology Education dipole, FEL, quadrupole, cavity 2458
 
  • G. Burt
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • R.B. Appleby, G.X. Xia
    UMAN, Manchester, United Kingdom
  • I.R. Bailey
    Lancaster University, Lancaster, United Kingdom
  • J.A. Clarke, O.B. Malyshev, N. Marks, B.D. Muratori, M.W. Poole, Y.M. Saveliev, B.J.A. Shepherd
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • C.P. Welsch, A. Wolski
    The University of Liverpool, Liverpool, United Kingdom
  
  Funding: The work is funded by STFC via the Cockcroft Institute core grant.
The next generation of particle accelerators will require the training of greater numbers of specialist accelerator physicists and engineers . These physicists and engineers should have a broad understanding of accelerator physics as well as the technology used in particle accelerators as well as a specialist in some area of accelerator science and technology . Such specialists can be trained by combining a University based PhD, in collaboration with national laboratory training with a broad taught accelerator lecture program. In order to have a faster start we decided to run an intensive two week school to replace the basic course at the Cockcroft Institute. At the same time we decided to investigate the use of problem based learning to simulate the way accelerator science tends to work in practice. In this exercise he students worked in groups of 5 to design a 3rd generation light source from scratch based on photon light specifications. In comparison to similar design exercises we stipulate that all students must do all parts and students are not allowed to specialise. A comparison with a standard lecture based education programme is discussed in this paper. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA154  
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WEPAB073 First Measurements of Pulse Picking by Resonant Excitation (PPRE) at the MAX IV 3 GeV Storage Ring emittance, storage-ring, diagnostics, timing 2750
 
  • T. Olsson, Å. Andersson
    MAX IV Laboratory, Lund University, Lund, Sweden
  
  At synchrotron light storage rings there is demand for serving high-brilliance users requesting multibunch operation while simultaneously serving timing users who require single-bunch operation. One method to accomplish this is PPRE developed and currently in user operation at BESSY-II. In the method, the transverse emittance of one of the bunches in the bunch train is increased by an incoherent betatron excitation. Part of the light from this bunch can then be separated from the multibunch light by an aperture in the beamline, resulting in single-bunch light for the experiment. Methods such as this expand the scope of storage rings without requiring special fill patterns. This is of growing interest due to the upgrade trend towards diffraction-limited storage rings where it becomes more challenging to operate with inhomogeneous fill patterns. Measurements of PPRE were performed at the MAX IV 3 GeV storage ring utilizing the bunch-by-bunch feedback system both for excitation and as a diagnostic. Furthermore, measurements involving direct beam imaging at the diagnostics beamline allowed quantifying the effect of this excitation on the horizontal and vertical emittance.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB073  
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WEPAB096 Diamond Light Source: A 10-year View of the Past and Vision of the Future cavity, vacuum, operation, emittance 2804
 
  • R.P. Walker, R. Bartolini, C. Christou, P. Coll, M.P. Cox, M.T. Heron, J. Kay, V.C. Kempson, S. Milward, G. Rehm
    DLS, Oxfordshire, United Kingdom
  • R. Bartolini
    JAI, Oxford, United Kingdom
  
  Diamond Light Source has been in regular operation for users for 10 years and so it is an appropriate moment to review the successes and challenges of the past, and also consider the vision for the next 10 years.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB096  
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WEPIK071 Resistive-Wall Impedance Effects for the New KEK Light Source impedance, vacuum, betatron, storage-ring 3095
 
  • N. Nakamura
    KEK, Ibaraki, Japan
  
  KEK Light Source (KEK-LS) is a 3-GeV storage ring of 20-cell HMBA (Hybrid Multi-Bend Achromat) lattice*, which is planned to be constructed as a successor of the two existing Photon Factory storage rings (PF ring and PF-AR) in the KEK Tsukuba Campus. In this ring, a lot of in-vacuum undulators with a small magnetic gap (4 mm at minimum) will be installed and the vacuum pipe of a small aperture (25 mm in diameter) will be used. In addition, NEG coating, having a low electric conductivity, will be utilized for the vacuum pipe to ensure a sufficient beam lifetime early in the machine commissioning. In this paper, the heating power due to the longitudinal RW impedance and the growth rate of coupled-bunch instability caused by the transverse RW impedance are calculated and the effects of the RW impedance on KEK-LS are presented.
* K. Harada et al., Proc. of IPAC2016, Busan, Korea, pp.3251-3253; K. Harada et al., these proceedings. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK071  
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WEPIK077 Shielding of Beam Pipe on Rapidly Varying Magnetic Field simulation, vacuum, shielding, emittance 3107
 
  • N. Wang, J. Chen, S.K. Chen, P. He, G. Xu
    IHEP, Beijing, People's Republic of China
  
  In low emittance rings, beam is quite sensitive to orbit oscillations. Fast correctors will be used to correct the beam orbit. The fast varying magnetic field will generate eddy current on the beam pipe, which will in turn change the phase and the amplitude of the magnetic field. The shielding effect of the beam pipe on a fast varying magnetic field is simulated for different frequencies. The results are also benchmarked with the measurements in the lab.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK077  
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WEPIK078 Development of the Impedance Model in HEPS impedance, vacuum, kicker, injection 3110
 
  • N. Wang, Z. Duan, X.Y. Li, H. Shi, S.K. Tian, G. Xu
    IHEP, Beijing, People's Republic of China
  
  The High Energy Photon Source (HEPS) is a new designed photon source at beam energy of 6 GeV. Due to the small beam pipe aperture and a large number of insertion devices in the machine, the impedance can drive collective instabilities and limit the machine performance. Therefore, a thorough estimation of the coupling impedance is necessary in controlling the total impedance of the whole machine. A primary impedance model is obtained for the storage ring.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK078  
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WEPVA057 High-Stability Magnet Power Supplies for SuperKEKB controls, power-supply, operation, wiggler 3391
 
  • T. Oki, T. Adachi, S. Nakamura
    KEK, Ibaraki, Japan
  
  For the SuperKEKB, over 2,000 of magnet power supplies were recycled and around 300 of power supplies were newly fabricated. The newly fabricated power supplies include high performance power supplies: the main bending/wiggler magnet power supplies and the power supplies for final-focus superconducting magnets installed around an interaction point. High power tests were performed and the results are reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA057  
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WEPVA130 Simulation the Iterative Learing Control Applied to the TPS Booster Ring Quadruple Magnet Power Supply controls, booster, power-supply, simulation 3574
 
  • B.S. Wang, Y.-C. Chien, C.Y. Liu, K.-B. Liu, Y.S. Wong
    NSRRC, Hsinchu, Taiwan
  
  In the newly built TPS (Taiwan Photon Source), the AC power supplies of the Booster ring are required to operate in DC and AC mode with accuracy. Especially in AC mode, during the booster ramping process, the current ramping profiles of the Quadruple Magnets have to track that of the Dipole AC power supply with precise phase and amplitude to maximize the beam energy boost efficiency. At the present time, analog controllers are used for all the booster supplies and the tracking waveforms are generated externally in an EPICS control unit, converted to analog signals with precision Digital-to-Analog Converters (DACs) and then distributed to all the booster power supplies with differential signal pairs. In this paper, here we propose a hybrid iterative learning control algorithm combined with discrete PID feedback controller with the objective to eliminate the signal integrity problem inherent in analogue signals, so that boosting the beam energy might become more reliable. The proposed digital controller algorithm for the TPS booster ring magnet power supply and quadruple magnet load has been simulated with success.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA130  
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THPAB022 Ion Instability in SuperKEKB Phase I Commissioning ion, simulation, betatron, vacuum 3741
 
  • K. Ohmi, H. Fukuma, Y. Suetsugu, M. Tobiyama
    KEK, Ibaraki, Japan
  
  Ion instability has been observed in SuperKEKB phase I commissioning. Unstable modes, their growth rates, tune shift were measured. Frequency of the unstable modes is slower than theoretical prediction and the growth rate is also slower. We discuss possible model to explain the measurements.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB022  
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THPAB093 Synchronization of a Photo-Injector and a High Power Laser With Independent Clocks laser, electron, plasma, gun 3935
 
  • N. Delerue, C. Bruni, K. Cassou, V. Chaumat, R. Chiche, D. Douillet, N. ElKamchi, S. Jenzer, V. Kubytskyi, P. Lepercq, H. Purwar, H. Roesch
    LAL, Orsay, France
  • E. Baynard, M. Pittman
    CLUPS, Orsay, France
  • J. Demailly, O. Guilbaud, S. Kazamias, G. Maynard, O. Neveu, D. Ros
    CNRS LPGP Univ Paris Sud, Orsay, France
  • D. Garzella
    CEA, Gif-sur-Yvette, France
  • R. Prazeres
    LCP/CLIO, Orsay, Cedex, France
  
  Funding: LAL/IN2P3/CNRS and Université Paris-Sud
The plasma acceleration project ESCULAP (ElectronS CoUrts pour L'Acc\'el\'eration Plasma) aims at studying electrons injection into a laser plasma accelerator. This requires the injection of short electron bunches generated by the photo injector PHIL (Photo injector at LAL) into a plasma wave by the high power femtosecond Laser LASERIX. As a first step we have studied how to synchronize PHIL and LASERIX. As these two machines had not been initially designed to work together, simple synchronization solutions were not available. We detail here the synchronisation scheme that we have tested and the experimental results obtained. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB093  
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THPAB106 Experience with Single Cavity and Piezo Controls for Short, Long Pulse and CW Operation cavity, operation, controls, experiment 3966
 
  • K.P. Przygoda, V. Ayvazyan, R. Rybaniec, H. Schlarb, Ch. Schmidt, J.K. Sekutowicz
    DESY, Hamburg, Germany
  • P. Echevarria
    HZB, Berlin, Germany
  
  We present a compact RF control system for SCRF single cavities based on MicroTCA.4 equipped with specialized advanced mezzanine cards (AMCs) and rear transition modules (RTMs). To sense the RF signals from the cavity and to drive the high power source, a DRTM-DWC8VM1 module is used equipped with 8 analog field detectors and one RF vector modulator. Fast cavity frequency tuning is achieved by piezo-actuators attached to the cavity and a RTM piezo-driver module (DRTM-PZT4). Data processing of the RF signals and the real-time control algorithms are implemented on a Virtex-6 FPGA and a Spartan FPGAs within two AMCs (SIS8300-L2V2 and DAMC-FMC20). The compact single cavity control system was tested at Cryo Module Test Bench (CMTB) at DESY. Software and firmware were developed to support all possible modes, the short pulse (SP), the long pulse (LP) and CW operation mode with duty cycles ranging from 1 % to 100%. The SP mode used a high power multi-beam klystron at low QL ~3·106. For the LP mode (up to 50% duty cycle) and the CW mode a 120 kW IOT tube was used at QL up to 1.5·107. Within this paper we present the achieved performance and report on the operation experience on such system.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB106  
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THPAB124 DSP Frame and Algorithm of LLRF of IR-FEL LLRF, FEL, controls, target 4017
 
  • B. Du, G. Huang, L. Lin, W. Liu, Z.R. Zhou
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  
  Infrared Free Electron Laser (IR-FEL) use linear accelerator to accelerate electron to relative speed and then generate simulated radiation of infrared wavelength by periodic magnetic field of undulator. The amplitude and phase of microwave field need to be controlled precisely by low level RF control system (LLRF) to meet the high quality demand of electron from undulator. This paper mainly introduce the digital signal processing frame and feedback algorithm. Four times frequency sampling can realize IQ demodulation precisely and reduce DC offset, amplitude sampling error is less than 0.075% and phase sampling error is less than 0.1°. Pipeline CORDIC can calculate amplitude and phase by parallel processing and shift operation. Phase calculating accuracy reach 0.0005° when iteration count is 18. FIR filter is used to improve frequency selected performance. Feedback loop use digital PI controller to adjust system output.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB124  
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THPAB131 Test of the Feedback and Feedforward Control Loop for Digital LLRF System of 1 MeV/n RFQ LLRF, controls, rfq, FPGA 4028
 
  • H.S. Jeong, Y.-S. Cho, H.S. Kim, J.H. Kim, S.G. Kim, H.-J. Kwon, Y.G. Song
    Korea Atomic Energy Research Institute (KAERI), Gyeongbuk, Republic of Korea
  
  Funding: This work has been supported through KOMAC (Korea of Multi-purpose Accelerator Complex) operation fund of KAERI by MSIP (Ministry of Science, ICT and Future Planning)
KOMAC (Korea Multi-purpose Accelerator Complex) has a plan to develop the multipurpose ion irradiation system. This system includes the ion source, LEBT, RFQ and MEBT systems to transport ion particles to the target. In particular, the RFQ (Radio Frequency Quadrupole) system should receive 200 MHz RF within 1 % amplitude error stability. To supply stable 200 MHz RF signal to the RFQ cavity, the LLRF (Low-Level Radio Frequency) system should be controlled through a control system which implemented using commercial digital board. This 1 MeV/n RFQ LLRF system has a concept to minimize the number of the analog components for minimizing the control error. For this, the FPGA (Field Programmable Gate Array) in the digital board will control the frequency of the output sinusoidal signal. In addition, this LLRF system applied the direct sampling, Non-IQ sampling, direct RF generation and fast IQ set update rate algorithm. In this presentation, the LLRF PI control and feed-forward control logic test using 200 MHz dummy cavity will be described.
LLRF, direct sampling, Non-IQ, RFQ, control loop, feedback, feedforward 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB131  
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THPAB148 DIGITAL LOW LEVEL RF CONTROL SYSTEM FOR THE TAIWAN PHOTON SOURCE controls, cavity, FPGA, booster 4077
 
  • F.Y. Chang, L.-H. Chang, M.H. Chang, L.J. Chen, F.-T. Chung, M.-C. Lin, Z.K. Liu, C.H. Lo, C.L. Tsai, Ch. Wang, M.-S. Yeh, T.-C. Yu
    NSRRC, Hsinchu, Taiwan
  
  The Taiwan Photon Source (TPS) is a 3 GeV, 500 mA, 499.65 MHz, 3rd generation synchrotron light source at NSRRC. To achieve the requirements of system flexibil-ity, fault diagnosis, precise control and high noise reduc-tion, a digital low level RF (DLLRF) control system based on Field Programmable Gate Array (FPGA) was developed. The communication interface is based on Raspberry Pi. The feedback loop performance of the control system was tested on the booster of the Taiwan Photon Source (TPS) with 950 kV gap voltage.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB148  
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THPIK016 Status of the SIS100 RF Systems cavity, status, synchrotron, power-supply 4136
 
  • H. Klingbeil, R. Balß, M. Frey, P. Hülsmann, A. Klaus, H.G. König, U. Laier, D.E.M. Lens, K.-P. Ningel
    GSI, Darmstadt, Germany
  
  Four different types of RF cavities are realized for the heavy-ion synchrotron SIS100 which is built in the scope of the FAIR (Facility for Antiproton and Ion Research) project. The standard acceleration is performed by ferrite cavities. Barrier bucket cavities will allow a pre-compression of the beam by means of moving barriers. Bunch compressor cavities are used to realize a rotation in longitudinal phase space by 90 degrees, thereby reducing the bunch length. Finally, a longitudinal feedback system reduces undesired beam oscillations. In contrast to the ferrite-loaded accelerating cavities, the last-mentioned three cavity types are based on magnetic alloy (MA) material. Depending on the type of the cavity system, the realization is done by - or in close collaboration with - different industrial companies and institutions. In this contribution, the realization status of all these synchrotron RF systems is summarized.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK016  
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THPIK048 Design of Rapid Tuning System for a Ferrite-Loaded Cavity with Heavy Beam Loading cavity, controls, beam-loading, LLRF 4203
 
  • X. Li, H. Sun, F.C. Zhao, J.Y. Zhu
    IHEP, Beijing, People's Republic of China
  
  A high power, broadband and rapid frequency sweeping RF system was developed to satisfy the demand of China Spallation Neutron source (CSNS)/ Rapid Cycling Synchrotron (RCS). The cavity tuning is the key issue which has great impact on the performance of the whole RF system. In order to satisfy the requirement of cavity dynamic tuning caused by the nonlinear characteristics of the ferrite material, some new technologies were developed and applied. In this paper, the overall design of the tuning system will be introduced. The ensuing discussion will be focused on the choice of different types bias current supplies, the control algorithm of LLRF system and the beam loading compensation issues.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK048  
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THPIK086 Design and Implementation of Stripline Feedback Kickers in the MAX IV 3 GeV Ring kicker, impedance, storage-ring, cavity 4285
 
  • D. Olsson, L. Malmgren, K. Åhnberg
    MAX IV Laboratory, Lund University, Lund, Sweden
  
  The commissioning of a bunch-by-bunch feedback system for the MAX IV 3 GeV storage ring was started in early 2016. At date, the actuators are two stripline kickers oriented in the horizontal and in the vertical plane, respectively. Apart from providing feedback in the transverse plane, the horizontal stripline is simultaneously operating as a longitudinal kicker. This is done by upconverting the longitudinal 0 - 50 MHz baseband signal to the 150 MHz - 250 MHz range where the longitudinal shunt impedance of the stripline is higher. This signal is then fed to the stripline electrodes in common-mode. The design of the stripline kickers and the layout of the bunch-by bunch feedback system in the 3 GeV ring are presented in this report. Results from instability studies in this ring are also discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK086  
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THPIK087 A Waveguide Overloaded Cavity Kicker for the MAX IV Bunch-by-Bunch Feedback System cavity, kicker, impedance, storage-ring 4289
 
  • D. Olsson, L. Malmgren, K. Åhnberg
    MAX IV Laboratory, Lund University, Lund, Sweden
  
  The higher-order modes (HOMs) in the main and the 3:rd harmonic cavities are driving longitudinal coupled-bunch mode instabilities (CBMIs) in the MAX IV 3 GeV storage ring. This far, negative feedback has been applied in the longitudinal plane by a stripline kicker at lower ring currents. However, the maximum longitudinal feedback voltage provided by the stripline is rather weak, and a waveguide overload cavity was therefore designed in order to suppress CBMIs at higher ring currents as well. Due to the long bunch length in the MAX IV storage rings, a relatively low center frequency of 625 MHz is selected. The new cavity kicker has been manufactured, and will be installed in the 3 GeV ring during the summer shut-down of 2017. In this paper, the RF and mechanical design of the cavity is presented. Simulation results are also compared with measurements of the manufactured cavity.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK087  
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THPVA029 Study of Single Bunch Instabilities with Transverse Feedback at Diamond operation, storage-ring, coupling, controls 4489
 
  • E. Koukovini-Platia, R. Bartolini, A.F.D. Morgan, G. Rehm
    DLS, Oxfordshire, United Kingdom
  • R. Bartolini
    JAI, Oxford, United Kingdom
  
  Single bunch instability studies have been carried out at Diamond with and without the transverse multi-bunch feedback (TMBF) system. Single bunch instability thresholds were measured for zero, positive and negative chromaticity values by increasing the current till the instability onset. The bunch-by-bunch feedback system was then used to suppress the motion of the bunch centroid and the new thresholds were measured in all chromaticity regimes. The feedback loop phase of the TMBF was changed from resistive to reactive as well as intermediate to find the optimal feedback settings that maximize the single bunch instability thresholds.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA029  
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THPVA046 Thermo Mechanical Study of the ESS DTL DTL, simulation, quadrupole, linac 4537
 
  • P. Mereu, M. Mezzano, C. Mingioni, M. Nenni
    INFN-Torino, Torino, Italy
  • F. Grespan, A. Palmieri, A. Pisent
    INFN/LNL, Legnaro (PD), Italy
  
  The Drift Tube Linac (DTL) of the European Spallation Source (ESS) is designed to operate at 352.2 MHz with a duty cycle of 4 % (3 ms pulse length, 14 Hz repetition period) and will accelerate a proton beam of 62.5 mA pulse peak current from 3.62 to 90 MeV. In this paper the main issues regarding the thermo-mechanical 3D details of the DTL are addressed and a Computational Fluid Dynamics (CFD) model is proposed and validated against the experimental data. The results of these simulations are used to properly design the DTL cooling system.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA046  
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THPVA060 Technical Overview of Inter-Undulator Support System for PAL XFEL undulator, cavity, quadrupole, controls 4579
 
  • H.-G. Lee, S.-H. Jeong, Y.G. Jung, H.-S. Kang, D.E. Kim, S.B. Lee, B.G. Oh, K.-H. Park, H.S. Suh
    PAL, Pohang, Kyungbuk, Republic of Korea
  
  Pohang Accelerator Laboratory (PAL) has been developing a SASE X-ray Free Electron Laser based on 10 GeV linear accelerator. The inter-Undulator (IU) support system was developed to be used in the intersections of the Undulator Systems. The IU supports consist of phase shifter, quadrupole magnet with mover, beam loss monitor, cavity BPM with mover, two corrector magnets and vacuum components. The adjusting mechanism of IU Support has manual alignment system to be easily adjusting the component. The mover of quadruple magnet and cavity BPM with submicron repeatability has auto-adjusting systems with stepping motor. The mover main specifications include compact dimensions and a ±1.5 mm stroke in the vertical and horizontal direction. Linear motion guide based on 5-phase stepping motors have been chosen. This paper describes the design of the stages used for precise movement and results of mechanical measurements including reproducibility will be reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA060  
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