Keyword: feedback
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MOMAU008 Integrated Management Tool for Controls Software Problems, Requests and Project Tasking at SLAC software, controls, status, HOM 59
  • D. Rogind, W. Allen, W.S. Colocho, G. DeContreras, J.B. Gordon, P. Pandey, H. Shoaee
    SLAC, Menlo Park, California, USA
  The Controls Department at SLAC, with its service center model, continuously receives engineering requests to design, build and support controls for accelerator systems lab-wide. Each customer request can vary in complexity from installing a minor feature to enhancing a major subsystem. Departmental accelerator improvement projects, along with DOE-approved construction projects, also contribute heavily to the work load. These various customer requests and projects, paired with the ongoing operational maintenance and problem reports, place a demand on the department that usually exceeds the capacity of available resources. An integrated, centralized repository - comprised of all problems, requests, and project tasks - available to all customers, operators, managers, and engineers alike - is essential to capture, communicate, prioritize, assign, schedule, track progress, and finally, commission all work components. The Controls software group has recently integrated its request/task management into its online problem tracking "Comprehensive Accelerator Tool for Enhancing Reliability" (CATER ) tool. This paper discusses the new integrated software problem/request/task management tool - its work-flow, reporting capability, and its many benefits.  
slides icon Slides MOMAU008 [0.083 MB]  
poster icon Poster MOMAU008 [1.444 MB]  
MOMMU005 Stabilization and Positioning of CLIC Quadrupole Magnets with sub-Nanometre Resolution quadrupole, controls, luminosity, simulation 74
  • S.M. Janssens, K. Artoos, C.G.R.L. Collette, M. Esposito, P. Fernandez Carmona, M. Guinchard, C. Hauviller, A.M. Kuzmin, R. Leuxe, R. Morón Ballester
    CERN, Geneva, Switzerland
  Funding: The research leading to these results has received funding from the European Commission under the FP7 Research Infrastructures project EuCARD, grant agreement no.227579
To reach the required luminosity at the CLIC interaction point, about 2000 quadrupoles along each linear collider are needed to obtain a vertical beam size of 1 nm at the interaction point. Active mechanical stabilization is required to limit the vibrations of the magnetic axis to the nanometre level in a frequency range from 1 to 100 Hz. The approach of a stiff actuator support was chosen to isolate from ground motion and technical vibrations acting directly on the quadrupoles. The actuators can also reposition the quadrupoles between beam pulses with nanometre resolution. A first conceptual design of the active stabilization and nano positioning based on the stiff support and seismometers was validated in models and experimentally demonstrated on test benches. Lessons learnt from the test benches and information from integrated luminosity simulations using measured stabilization transfer functions lead to improvements of the actuating support, the sensors used and the system controller. The controller electronics were customized to improve performance and to reduce cost, size and power consumption. The outcome of this R&D is implemented in the design of the first prototype of a stabilized CLIC quadrupole magnet.
slides icon Slides MOMMU005 [1.046 MB]  
poster icon Poster MOMMU005 [1.551 MB]  
MOPKS001 Diamond Light Source Booster Fast Orbit Feedback System booster, controls, storage-ring, synchrotron 160
  • S. Gayadeen, S. Duncan
    University of Oxford, Oxford, United Kingdom
  • C. Christou, M.T. Heron, J. Rowland
    Diamond, Oxfordshire, United Kingdom
  The Fast Orbit Feedback system that has been installed on the Diamond Light Source Storage ring has been replicated on the Booster synchrotron in order to provide a test bed for the development of the Storage Ring controller design. To realise this the Booster is operated in DC mode. The electron beam is regulated in two planes using the Fast Orbit Feedback system, which takes the beam position from 22 beam position monitors for each plane, and calculates offsets to 44 corrector power supplies at a sample rate of 10~kHz. This paper describes the design and realization of the controller for the Booster Fast Orbit Feedback, presents results from the implementation and considers future development.  
poster icon Poster MOPKS001 [0.597 MB]  
MOPKS006 Application of Integral-Separated PID Algorithm in Orbit Feedback controls, closed-orbit, simulation, storage-ring 171
  • K. Xuan, X. Bao, C. Li, W. Li, G. Liu, J.G. Wang, L. Wang
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  The algorithm in the feedback system has important influence on the performance of the beam orbit. PID algorithm is widely used in the orbit feedback system; however the deficiency of PID algorithm is big overshooting in strong perturbations. In order to overcome the deficiencies, Integral Separated PID algorithm is developed. When the closed orbit distortion is too large, it cancels integration action until the closed orbit distortions are lower than the threshold value. The implementation of Integral Separated PID algorithm with MATLAB is described in this paper. The simulation results show that this algorithm can improve the control precision.  
poster icon Poster MOPKS006 [0.091 MB]  
MOPKS007 Design of a Digital Controller for ALPI 80 MHz Resonators cavity, FPGA, controls, resonance 174
  • S.V. Barabin
    ITEP, Moscow, Russia
  • G. Bassato
    INFN/LNL, Legnaro (PD), Italy
  We discuss the design of a resonator controller completely based on digital technology. The controller is currently operating at 80 MHz but can be easily adapted to frequencies up to 350MHz; it can work either in "Generator Driven" and in "Self Excited Loop" mode. The signal processing unit is a commercial board (Bittware T2-Pci) with 4 TigerSharc DSPs and a Xilinx Virtex II-Pro FPGA. The front-end board includes five A/D channels supporting a sampling rate in excess of 100M/s and a clock distribution system with a jitter less than 10ps, allowing direct sampling of RF signals with no need of analog downconversion. We present the results of some preliminary tests carried out on a 80 MHz quarter wave resonator installed in the ALPI Linac accelerator at INFN-LNL and discuss possible developments of this project.  
poster icon Poster MOPKS007 [0.931 MB]  
MOPKS010 Fast Orbit Correction for the ESRF Storage Ring FPGA, controls, operation, diagnostics 177
  • J.M. Koch, F. Epaud, E. Plouviez, K.B. Scheidt
    ESRF, Grenoble, France
  Up to now, at the ESRF, the correction of the orbit position has been performed with two independent systems: one dealing with the slow movements and one correcting the motion in a range of up to 200Hz but with a limited number of fast BPMs and steerers. These latter will be removed and one unique system will cover the frequency range from DC to 200Hz using all the 224 BPMs and the 96 steerers. Indeed, thanks to the procurement of Libera Brilliance units and the installation of new AC power supplies, it is now possible to access all the Beam positions at a frequency of 10 kHz and to drive a small current in the steerers in a 200Hz bandwidth. The first tests of the correction of the beam position have been performed and will be presented. The data processing will be presented as well with a particular emphasis on the development inside the FPGA.  
MOPKS013 Beam Spill Structure Feedback Test in HIRFL-CSR extraction, controls, power-supply, FPGA 186
  • R.S. Mao, P. Li, L.Z. Ma, J.X. Wu, J.W. Xia, J.C. Yang, Y.J. Yuan, T.C. Zhao, Z.Z. Zhou
    IMP, Lanzhou, People's Republic of China
  The slow extraction beam from HIRFL-CSR is used in nuclear physics experiments and heavy ion therapy. 50Hz ripple and harmonics are observed in beam spill. To improve the spill structure, the first set of control system consisting of fast Q-magnet and feedback device based FPGA is developed and installed in 2010, and spill structure feedback test also has been started. The commissioning results with spill feedback system are presented in this paper.  
poster icon Poster MOPKS013 [0.268 MB]  
MOPKS015 Diagnostics Control Requirements and Applications at NSLS-II controls, diagnostics, injection, emittance 192
  • Y. Hu, L.R. Dalesio, K. Ha, O. Singh
    BNL, Upton, Long Island, New York, USA
  To measure various beam parameters such as beam position, beam size, circulating current, beam emittance, etc., a variety of diagnostic monitors will be deployed at NSLS-II. The Diagnostics Group and the Controls Group are working together on control requirements for the beam monitors. The requirements are originated from and determined by accelerator physics. An attempt of analyzing and translating physics needs into control requirements is made. The basic functionalities and applications of diagnostics controls are also presented.  
poster icon Poster MOPKS015 [0.142 MB]  
MOPKS020 Low Level RF Control System for Cyclotron 10 MeV controls, cyclotron, low-level-rf, cavity 199
  • J. Huang, D. Li, K.F. Liu
    Huazhong University of Science and Technology (HUST), Wuhan, People's Republic of China
  • T. Hu
    HUST, Wuhan, People's Republic of China
  The low level RF control system consists of a 101MHz signal generator, three feedback loops, an interlock and a protection system. The stability of control system is one of the most important indicators in the cyclotron design, especially when the whole system has a high current. Due to the hugeness of the RF system and the complexity of control objects, the low level RF control system must combine the basic theory with the electronic circuit to optimize the whole system. The major obstacles in the research, which rarely exist in other control systems, lay in the coupling of beam and resonant cavity, requiring to be described by the transfer function between beam and cavity, the complex coupling between microwave devices and the interference signals of all loops. By introducing the three feedback loops (tuning loop, amplitude loop and phase loop) and test results from some parts of electric circuits, this paper unfolds the performance index and design of low level RF control system, which may contribute to the design of cyclotron with a high and reliable performance.  
MOPKS021 High-speed Data Handling Using Reflective Memory Thread for Tokamak Plasma Control controls, real-time, plasma, power-supply 203
  • S.Y. Park, S.H. Hahn, W.C. Kim
    NFRI, Daejon, Republic of Korea
  • R.D. Johnson, B.G. Penaflor, D.A. Piglowski, M.L. Walker
    GA, San Diego, California, USA
  The KSTAR plasma control system (PCS) is defined as a system consisting of electronic devices and control software that identifies and diagnoses various plasma parameters, calculates appropriate control signals to each actuator to keep the plasma sustained in the KSTAR operation regime. Based on the DIII-D PCS, the KSTAR PCS consists of a single box of multiprocess Linux system which can run up to 8 processes, and both digital and analog data acquisition methods are adapted for fast real-time data acquisition up to 20 kHz. The digital interface uses a well-known shared memory technology, the reflective memory (RFM), which can support data transmission up to 2Gbits/s. An RFM technology is adopted for interfacing the actuators, 11 PF power supplies and 1 IVC power supply, and the data acquisition system for plasma diagnostics. To handle the fast control of the RFM data transfer, the communication using the RFM with the actuators and diagnostics system is implemented as thread. The RFM thread sends commands like target current or voltage which is calculated by the PCS to the actuators area of RFM for plasma control and receives measured data by the magnet power supply. The RFM thread also provides the method for monitoring signal in real time by sharing data of diagnostics system. The RFM thread complete all data transfer within 50us so that data process can be completed within the fastest control cycle time of the PCS. This paper will describe the design, implementations, performances of RFM thread and applications to the tokamak plasma controls utilizing the technique.  
poster icon Poster MOPKS021 [1.745 MB]  
MOPKS022 BPM System And Orbit Feedback System Deisgn For the Taiwan Photon Source controls, FPGA, EPICS, power-supply 207
  • C.H. Kuo, J. Chen, Y.-S. Cheng, P.C. Chiu, K.T. Hsu, K.H. Hu, C.Y. Wu
    NSRRC, Hsinchu, Taiwan
  Taiwan Photon Source (TPS) is a 3 GeV synchrotron light source which is in construction at NSRRC. Latest generation BPM electronics with FPGA enhanced functionality of current generation products was adopted. The prototype is under testing. To achieve its design goal of the TPS and eliminate beam motions due to various perturbation sources, orbit feedback is designed with integration of BPM and corrector control system . The design and implementation of the BPM system will be summarized in this report.  
MOPKS024 A Digital System for Longitudinal Emittance Blow-Up in the LHC controls, FPGA, software, synchrotron 215
  • M. Jaussi, M. E. Angoletta, P. Baudrenghien, A.C. Butterworth, J. Sanchez-Quesada, E.N. Shaposhnikova, J. Tückmantel
    CERN, Geneva, Switzerland
  In order to preserve beam stability above injection energy in the LHC, longitudinal emittance blowup is performed during the energy ramp by injecting band-limited noise around the synchrotron frequency into the beam phase loop. The noise is generated continuously in software and streamed digitally into the DSP of the Beam Control system. In order to achieve reproducible results, a feedback system on the observed average bunch length controls the strength of the excitation, allowing the operator to simply set a target bunch length. The frequency spectrum of the excitation depends on the desired bunch length, and as it must follow the evolution of the synchrotron frequency spread through the ramp, it is automatically calculated by the LHC settings management software from the energy and RF voltage. The system is routinely used in LHC operation since August 2010. We present here the details of the implementation in software, FPGA firmware and DSP code, as well as some results with beam.  
poster icon Poster MOPKS024 [0.467 MB]  
MOPKS027 Operational Status of theTransverse Multibunch Feedback System at Diamond FPGA, damping, controls, operation 219
  • I. Uzun, M.G. Abbott, M.T. Heron, A.F.D. Morgan, G. Rehm
    Diamond, Oxfordshire, United Kingdom
  A transverse multibunch feedback (TMBF) system is in operation at Diamond Light Source to damp coupled-bunch instabilities up to 250 MHz in both the vertical and horizontal planes. It comprises an in-house designed and built analogue front-end combined with a Libera Bunch-by-Bunch feedback processor and output stripline kickers. FPGA-based feedback electronics is used to implement several diagnostic features in addition to the basic feedback functionality. This paper reports on the current operational status of the TMBF system along with its characteristics. Also discussed are operational diagnostic functionalities including continuous measurement of the betatron tune and chromaticity.  
poster icon Poster MOPKS027 [1.899 MB]  
MOPMU002 Progress of the TPS Control System Development controls, EPICS, interface, power-supply 425
  • J. Chen, Y.-T. Chang, Y.K. Chen, Y.-S. Cheng, P.C. Chiu, K.T. Hsu, S.Y. Hsu, K.H. Hu, C.H. Kuo, D. Lee, C.Y. Liao, Y.R. Pan, C.-J. Wang, C.Y. Wu
    NSRRC, Hsinchu, Taiwan
  The Taiwan Photon Source (TPS) is a low-emittance 3-GeV synchrotron light source which is in construction on the National Synchrotron Radiation Research Center (NSRRC) campus. The control system for the TPS is based upon EPICS framework. The standard hardware and software components have been defined. The prototype of various subsystems is on going. The event based timing system has been adopted. The power supply control interface accompanied with orbit feedback support have also been defined. The machine protection system is in design phase. Integration with the linear accelerator system which are installed and commissioned at temporary site for acceptance test has already been done. The interface to various systems is still on going. The infrastructures of high level and low level software are on going. Progress will be summarized in the report.  
MOPMU036 Upgrade of the CLS Accelerator Control and Instrumentation Systems booster, controls, linac, EPICS 518
  • E. D. Matias, L. Baribeau, S. Hu, C.G. Payne, H. Zhang
    CLS, Saskatoon, Saskatchewan, Canada
  The Canadian Light Source is undertaking a major upgrade to it's accelerator system in preparation for the eventual migration to top-up and to meet the increasing demanding needs of it's synchrotron user community. These upgrades on the Linac include the development of software for new modulators, RF sections, power supplies and current monitors. On the booster ring the upgrades include the development of new improved BPM instrumentation and improved diagnostics on the extracted beam. For the storage ring these upgrades include fast orbit correct, instrumentation for use by the safety systems and a new transverse feedback system.  
TUDAUST04 Status of the Control System for the European XFEL controls, hardware, distributed, device-server 597
  • K. Rehlich
    DESY, Hamburg, Germany
  DESY is currently building a new 3.4 km-long X-ray free electron laser facility. Commissioning is planned in 2014. The facility will deliver ultra short light pulses with a peak power up to 100 GW and a wavelength down to 0.1 nm. About 200 distributed electronic crates will be used to control the facility. A major fraction of the controls will be installed inside the accelerator tunnel. MicroTCA was chosen as an adequate standard with state-of-the-art connectivity and performance including remote management. The FEL will produce up to 27000 bunches per second. Data acquisition and controls have to provide bunch-synchronous operation within the whole distributed system. Feedbacks implemented in FPGAs and on service tier processes will implement the required stability and automation of the FEL. This paper describes the progress in the development of the new hardware as well as the software architecture. Parts of the control system are currently implemented in the much smaller FLASH FEL facility.  
slides icon Slides TUDAUST04 [6.640 MB]  
WEPMN032 Development of Pattern Awareness Unit (PAU) for the LCLS Beam Based Fast Feedback System timing, operation, controls, software 954
  • K.H. Kim, S. Allison, D. Fairley, T.M. Himel, P. Krejcik, D. Rogind, E. Williams
    SLAC, Menlo Park, California, USA
  LCLS is now successfully operating at its design beam repetition rate of 120 Hz, but in order to ensure stable beam operation at this high rate we have developed a new timing pattern aware EPICS controller for beam line actuators. Actuators that are capable of responding at 120 Hz are controlled by the new Pattern Aware Unit (PAU) as part of the beam-based feedback system. The beam at the LCLS is synchronized to the 60 Hz AC power line phase and is subject to electrical noise which differs according to which of the six possible AC phases is chosen from the 3-phase site power line. Beam operation at 120 Hz interleaves two of these 60 Hz phases and the feedback must be able to apply independent corrections to the beam pulse according to which of the 60 Hz timing patterns the pulse is synchronized to. The PAU works together with the LCLS Event Timing system which broadcasts a timing pattern that uniquely identifies each pulse when it is measured and allows the feedback correction to be applied to subsequent pulses belonging to the same timing pattern, or time slot, as it is referred to at SLAC. At 120 Hz operation this effectively provides us with two independent, but interleaved feedback loops. Other beam programs at the SLAC facility such as LCLS-II and FACET will be pulsed on other time slots and the PAUs in those systems will respond to their appropriate timing patterns. This paper describes the details of the PAU development: real-time requirements and achievement, scalability, and consistency. The operational results will also be described.  
poster icon Poster WEPMN032 [0.430 MB]  
WEPMS007 Backward Compatibility as a Key Measure for Smooth Upgrades to the LHC Control System controls, software, operation, Linux 989
  • V. Baggiolini, M. Arruat, D. Csikos, R. Gorbonosov, P. Tarasenko, Z. Zaharieva
    CERN, Geneva, Switzerland
  Now that the LHC is operational, a big challenge is to upgrade the control system smoothly, with minimal downtime and interruptions. Backward compatibility (BC) is a key measure to achieve this: a subsystem with a stable API can be upgraded smoothly. As part of a broader Quality Assurance effort, the CERN Accelerator Controls group explored methods and tools supporting BC. We investigated two aspects in particular: (1) "Incoming dependencies", to know which part of an API is really used by clients and (2) BC validation, to check that a modification is really backward compatible. We used this approach for Java APIs and for FESA devices (which expose an API in the form of device/property sets). For Java APIs, we gather dependency information by regularly running byte-code analysis on all the 1000 Jar files that belong to the control system and find incoming dependencies (methods calls and inheritance). An Eclipse plug-in we developed shows these incoming dependencies to the developer. If an API method is used by many clients, it has to remain backward compatible. On the other hand, if a method is not used, it can be freely modified. To validate BC, we are exploring the official Eclipse tools (PDE-API tools), and others that check BC without need for invasive technology such as OSGi. For FESA devices, we instrumented key components of our controls system to know which devices and properties are in use. This information is collected in the Controls Database and is used (amongst others) by the FESA design tools in order to prevent the FESA class developer from breaking BC.  
WEPMS022 The Controller Design for Kicker Magnet Adjustment Mechanism in SSRF controls, software, kicker, injection 1021
  • R. Wang, R. Chen, Z.H. Chen, M. Gu
    SINAP, Shanghai, People's Republic of China
  The kicker magnet adjustment mechanism controller in SSRF is to improve the efficiency of injection by changing the magnet real-time, especially in the top-up mode. The controller mainly consists of Programmable Logic Controller (PLC), stepper motor, reducer, worm and mechanism. PLC controls the stepper motors for adjusting the azimuth of the magnet, monitors and regulates the magnet with inclinometer sensor. It also monitors the interlock. In addition, the controller is provided with local and remote working mode. This paper mainly introduces related hardware and software designs for this device.  
poster icon Poster WEPMS022 [0.173 MB]  
WEPMS028 Online Evaluation of New DBPM Processors at SINAP injection, betatron, electronics, hardware 1041
  • Y.B. Leng, G.Q. Huang, L.W. Lai, Y.B. Yan, X. Yi
    SSRF, Shanghai, People's Republic of China
  In this paper, we report our online evaluation results for new digital BPM signal processors, which are developed for the SSRF and the new Shanghai SXFEL facility. Two major prototypes have been evaluated. The first algorithm evaluation prototype is built using commercial development toolkits modules in order to test various digital processing blocks. The second prototype is designed and fabricated from chips level in order to evaluate the hardware performances of different functional modules and assembled processor.  
poster icon Poster WEPMS028 [0.546 MB]  
THBHAUST04 jddd, a State-of-the-art Solution for Control Panel Development controls, operation, software, status 1189
  • E. Sombrowski, A. Petrosyan, K. Rehlich, W. Schütte
    DESY, Hamburg, Germany
  Software for graphical user interfaces to control systems may be developed as a rich or thin client. The thin client approach has the advantage that anyone can create and modify control system panels without specific skills in software programming. The Java DOOCS Data Display, jddd, is based on the thin client interaction model. It provides "Include" components and address inheritance for the creation of generic displays. Wildcard operations and regular expression filters are used to customize the graphics content at runtime, e.g. in a "DynamicList" component the parameters have to be painted only once in edit mode and then are automatically displayed multiple times for all available instances in run mode. This paper will describe the benefits of using jddd for control panel design as an alternative to rich client development.  
slides icon Slides THBHAUST04 [0.687 MB]  
THBHMUST04 The Software Improvement Process – Tools and Rules to Encourage Quality software, operation, controls, FEL 1212
  • K. Sigerud, V. Baggiolini
    CERN, Geneva, Switzerland
  The Applications section of the CERN accelerator controls group has decided to apply a systematic approach to quality assurance (QA), the "Software Improvement Process", SIP. This process focuses on three areas: the development process itself, suitable QA tools, and how to practically encourage developers to do QA. For each stage of the development process we have agreed on the recommended activities and deliverables, and identified tools to automate and support the task. For example we do more code reviews. As peer reviews are resource-intensive, we only do them for complex parts of a product. As a complement, we are using static code checking tools, like FindBugs and Checkstyle. We also encourage unit testing and have agreed on a minimum level of test coverage recommended for all products, measured using Clover. Each of these tools is well integrated with our IDE (Eclipse) and give instant feedback to the developer about the quality of their code. The major challenges of SIP have been to 1) agree on common standards and configurations, for example common code formatting and Javadoc documentation guidelines, and 2) how to encourage the developers to do QA. To address the second point, we have successfully implemented 'SIP days', i.e. one day dedicated to QA work to which the whole group of developers participates, and 'Top/Flop' lists, clearly indicating the best and worst products with regards to SIP guidelines and standards, for example test coverage. This paper presents the SIP initiative in more detail, summarizing our experience since two years and our future plans.  
slides icon Slides THBHMUST04 [5.638 MB]  
THCHMUST03 A New Fast Data Logger and Viewer at Diamond: the FA Archiver network, FPGA, electron, target 1244
  • M.G. Abbott, G. Rehm, I. Uzun
    Diamond, Oxfordshire, United Kingdom
  At the Diamond Light Source position data from 168 Electron Beam Position Monitors (BPMs) and some X-Ray BPMs is distributed over the Fast Acquisition communications network at an update rate of 10kHz; the total aggregate data rate is around 15MB/s. The data logger described here (the FA Archiver) captures this entire data stream to disk in real time, re-broadcasts selected subsets of the live stream to interested clients, and allows rapid access to any part of the saved data. The archive is saved into a rolling buffer allowing retrieval of detailed beam position data from any time in the last four days. A simple socket-based interface to the FA Archiver allows easy access to both the stored and live data from a variety of clients. Clients include a graphical viewer for visualising the motion or spectrum of a single BPM in real time, a command line tool for retrieving any part of the stored data by time of day, and Matlab scripts for exploring the dataset, helped by the storage of decimated minimum, maximum, and mean data.  
slides icon Slides THCHMUST03 [0.482 MB]  
FRBHAULT01 Feed-forward in the LHC software, real-time, controls, database 1302
  • M. Pereira, X. Buffat, K. Fuchsberger, M. Lamont, G.J. Müller, S. Redaelli, R.J. Steinhagen, J. Wenninger
    CERN, Geneva, Switzerland
  The LHC operational cycle is comprised of several phases such as the ramp, the squeeze and stable beams. During the ramp and squeeze in particular, it has been observed that the behaviour of key LHC beam parameters such as tune, orbit and chromaticity are highly reproducible from fill to fill. To reduced the reliance on the crucial feedback systems, it was decided to perform fill-to-fill feed-forward corrections. The LHC feed-forward application was developed to ease the introduction of corrections to the operational settings. It retrieves the feedback system's corrections from the logging database and applies appropriate corrections to the ramp and squeeze settings. The LHC Feed-Forward software has been used during LHC commissioning and tune and orbit corrections during ramp have been successfully applied. As a result, the required real-time corrections for the above parameters have been reduced to a minimum.  
slides icon Slides FRBHAULT01 [0.961 MB]  
FRBHAULT02 ATLAS Online Determination and Feedback of LHC Beam Parameters database, detector, monitoring, experiment 1306
  • J.G. Cogan, R. Bartoldus, D.W. Miller, E. Strauss
    SLAC, Menlo Park, California, USA
  The High Level Trigger of the ATLAS experiment relies on the precise knowledge of the position, size and orientation of the luminous region produced by the LHC. Moreover, these parameters change significantly even during a single data taking run. We present the challenges, solutions and results for the online luminous region (beam spot) determination, and its monitoring and feedback system in ATLAS. The massively parallel calculation is performed on the trigger farm, where individual processors execute a dedicated algorithm that reconstructs event vertices from the proton-proton collision tracks seen in the silicon trackers. Monitoring histograms from all the cores are sampled and aggregated across the farm every 60 seconds. We describe the process by which a standalone application fetches and fits these distributions, extracting the parameters in real time. When the difference between the nominal and measured beam spot values satisfies threshold conditions, the parameters are published to close the feedback loop. To achieve sharp time boundaries across the event stream that is triggered at rates of several kHz, a special datagram is injected into the event path via the Central Trigger Processor that signals the pending update to the trigger nodes. Finally, we describe the efficient near-simultaneous database access through a proxy fan-out tree, which allows thousands of nodes to fetch the same set of values in a fraction of a second.  
slides icon Slides FRBHAULT02 [7.573 MB]  
FRBHAULT03 Beam-based Feedback for the Linac Coherent Light Source network, timing, linac, controls 1310
  • D. Fairley, K.H. Kim, K. Luchini, P. Natampalli, L. Piccoli, D. Rogind, T. Straumann
    SLAC, Menlo Park, California, USA
  Funding: Work supported by the U. S. Department of Energy Contract DE-AC02-76SF00515
Beam-based feedback control loops are required by the Linac Coherent Light Source (LCLS) program in order to provide fast, single-pulse stabilization of beam parameters. Eight transverse feedback loops, a 6x6 longitudinal feedback loop, and a loop to maintain the electron bunch charge were successfully commissioned for the LCLS, and have been maintaining stability of the LCLS electron beam at beam rates up to 120Hz. In order to run the feedback loops at beam rate, the feedback loops were implemented in EPICS IOCs with a dedicated ethernet multicast network. This paper will discuss the design, configuration and commissioning of the beam-based Fast Feedback System for LCLS. Topics include algorithms for 120Hz feedback, multicast network performance, actuator and sensor performance for single-pulse control and sensor readback, and feedback configuration and runtime control.
slides icon Slides FRBHAULT03 [1.918 MB]  
FRBHAULT04 Commissioning of the FERMI@Elettra Fast Trajectory Feedback controls, real-time, linac, Ethernet 1314
  • G. Gaio, M. Lonza, R. Passuello, L. Pivetta, G. Strangolino
    ELETTRA, Basovizza, Italy
  Funding: The work was supported in part by the Italian Ministry of University and Research under grants FIRB-RBAP045JF2 and FIRB-RBAP06AWK3
FERMI@Elettra is a new 4th-generation light source based on a single pass Free Electron Laser (FEL). In order to ensure the feasibility of the free electron lasing and the quality of the produced photon beam, a high degree of stability is required for the main parameters of the electron beam. For this reason a flexible real-time feedback framework integrated in the control system has been developed. The first implemented bunch-by-bunch feedback loop controls the beam trajectory. The measurements of the beam position and the corrector magnet settings are synchronized to the 50 Hz linac repetition rate by means of the real-time framework. The feedback system implementation, the control algorithms and preliminary close loop results are presented.
slides icon Slides FRBHAULT04 [2.864 MB]