IBIC2013 - List of Keywords (feedback)

Paper	Title	Other Keywords	Page
MOAL4	First Results from the Bunch Arrival-Time Monitor at the SwissFEL Test Injector	pick-up, laser, gun, electron	8
	V.R. Arsov, M.M. Dehler, S. Hunziker, M.G. Kaiser, V. Schlott PSI, Villigen PSI, Switzerland
	Non-destructive electron bunch arrival-time monitors (BAMs) with resolution <10 fs, sensitivity down to 10 pC and high intrinsic bandwidth for double bunch detection are required for reliable operation of SwissFEL. To achieve this ultimate goal, such a monitor based on a Mach-Zehnder electro-optical intensity modulator has been under development at the SwissFEL Test Injector. The high timing precision is derived by a stable pulsed optical reference system. The first BAM is located before the bunch compressor where the bunch energy is 230 MeV and the pulse length is approximately 3 ps. At this position, the bunch arrival time is sensitive to the laser- and gun timing. In this paper, we report on the commissioning of the RF- and optical front ends, the first arrival-time jitter and drift measurements with the entire system, as well as correlation of the arrival-time with different machine and environmental parameters. We achieve a resolution of 20 fs down to 60 pC.
	Slides MOAL4 [1.228 MB]

MOCL1	Beam Instrumentation at the Accelerator Test Facility 2	laser, electron, OTR, emittance	26
	S.T. Boogert JAI, Egham, Surrey, United Kingdom S.T. Boogert Royal Holloway, University of London, Surrey, United Kingdom
	The Accelerator Test Facility 2 (ATF2) is a scaled demonstrator system for final focus beam lines of linear high energy colliders. Four OTR (Optical Transition Radiation) monitors have been installed at the ATF2. Major characteristics is the fast measurement of projected (2D) and intrinsic (4D) emittances and the coupling corrections with skew quadrupole magnets at the upstream. The high resolution cavity beam position monitor (BPM) system is a part of the ATF2 diagnostics. Two types of cavity BPMs are used, C-band operating at 6.426 GHz, and S-band at 2.888 GHz with an increased beam aperture. The resolution of the C-band system with attenuators was determined to be approximately 250 nm and 1 μm for the S-band system. Without attenuation the best recorded C-band cavity resolution was 27 nm. A laser-wire transverse electron beam size measurement system has been constructed and operated at the ATF2 beam line at KEK. A special set of electron beam optics was developed to generate an approximately 1μm vertical focus at the laser-wire location. Systematic measurements of a micron beam size have been successfully executed.
	Slides MOCL1 [6.059 MB]

MOPC16	FPGA Based Fast Orbit Feedback Data Acquisition System for Electron and Hadron Storage Rings	hadron, COSY, storage-ring, BPM	82
	G. Schünemann, P. Hartmann, D. Schirmer, G. Schmidt, P. Towalski, T. Weis DELTA, Dortmund, Germany
	In the course of a BMBF supported development of a fast orbit feedback system for electron and hadron storage rings, in prospect of the upcoming FAIR facility, this paper presents the developed data acquisition system, based on Field Programmable Gateway Array (FPGA) technology, as well as the first results of in-situ measurements. Data was successfully taken at the TU-Dortmunds synchrotron light source DELTA as well as hadron storage rings COSY of the Forschungszentrum Jülich (FZJ) and SIS18 of the GSI Helmholtzzentrum für Schwerionenforschung GmbH (GSI).

MOPC26	Optimization of Bunch-to-Bunch Isolation in Instability Feedback Systems	coupling, pick-up, kicker, FIR	116
	D. Teytelman Private Address, San Jose, USA
	Bunch-by-bunch feedback formalism is a powerful tool for combating coupled-bunch instabilities in circular accelerators. Imperfections in the analog front and back ends lead to coupling between neighboring bunches. Such coupling limits system performance in both feedback and diagnostic capacities. In this paper, techniques for optimizing bunch-to-bunch isolation within the system will be presented. A new method for improving the performance of the existing systems will be described. The novel approach uses a "shaper" filter in the digital signal processor to compensate for the imperfect response of the power amplifier and kicker combination. An objective optimization method to derive the optimal back end configuration will be presented and illustrated with measurements from several accelerators.
	Poster MOPC26 [0.851 MB]

MOPC28	The Hardware Implementation of the CERN SPS Ultrafast Feedback Processor Demonstrator	controls, SPS, FIR, CERN	124
	J.E. Dusatko, J.M. Cesaratto, J.D. Fox, J.J. Olsen, C.H. Rivetta SLAC, Menlo Park, California, USA W. Höfle CERN, Geneva, Switzerland
	Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515 and the US LHC Accelerator Research program ( LARP) An ultrafast 4GSa/s transverse feedback processor has been developed for proof-of-concept studies of feedback control of e-cloud driven and transverse mode coupled intra-bunch instabilities in the CERN SPS. This system consists of a high-speed ADC on the front end and equally fast DAC on the back end. All control and signal processing is implemented in FPGA logic. This system is capable of taking up to 16 sample slices across a single SPS bunch and processing each slice individually within a reconfigurable signal processor. This demonstrator system is a rapidly developed prototype, consisting of both commercial and custom-design components. It can stabilize the motion of a single particle bunch using closed loop feedback. The system can also run open loop as a high-speed arbitrary waveform generator and contains diagnostic features including a special ADC snapshot capture memory. This paper describes the overall system, the feedback processor and focuses on the hardware architecture, design and implementation.
	Poster MOPC28 [1.684 MB]

MOPC29	Realization of Transverse Feedback System for SIS18/100 using FPGA	BPM, transverse, controls, FIR	128
	T. Rueckelt Technische Universität Darmstadt (TU Darmstadt), Signal Processing Group, Darmstadt, Germany M. Alhumaidi, T. Rueckelt, A.M. Zoubir TU Darmstadt, Darmstadt, Germany
	Higher beam intensities in particle accelerator are usually prevented by beam instabilities. To cure these instabilities, additional active system must be used besides passive damping. For this purpose, we have developed a distributed low-latency Transverse Feedback System (TFS) using FPGAs. Data acquisition takes place on multiple BPMs with individual FPGAs and ADCs around the accelerator ring. Acquired data is compressed and sent over broadband fiber optic wires to a central unit. For synchronization, data is tagged using timestamps from a reference time, which is distributed by a specially constrained network time protocol to obtain cycle accuracy. The central unit provides an FIR filter for system bandwidth limitation, and an adaptive IIR filter for stable beam signal rejection. Feedback is given using a linear combination of the pre-processed BPM signals. The system provides substantial flexibility, due to the possibility to configure most parameters online. Filters, feedback sources and parameters, compression rate and more can be adapted via Ethernet interface, which also supplies analysis data. First results are shown.
	Poster MOPC29 [1.842 MB]

MOPC31	Streak Camera Imaging at ELSA	ELSA, longitudinal, transverse, synchrotron	132
	M.T. Switka, W. Hillert, M. Schedler, S. Zander ELSA, Bonn, Germany
	Funding: Funded by the DFG within SFB/TR 16 The Electron Stretcher Facility ELSA provides polarized electrons with energies up to 3.2 GeV for external hadron experiments. In order to suffice the need of stored beam currents towards 200 mA, studies of instabilities and the effect of adequate countermeasures are essential for appropriate machine settings. For this purpose a new diagnostic beamline has been constructed. It is optimized for transverse and longitudinal streak camera measurements with time resolution down to one picosecond. Operation of the diagnostic beamline has recently started and first measurements are presented.

MOPC39	Commissioning of a New Streak Camera at TLS for TPS Project	laser, synchrotron, storage-ring, longitudinal	159
	C.Y. Liao, M.C. Chou, K.T. Hsu, K.H. Hu, C.H. Kuo, C.-C. Kuo, W.K. Lau, C.Y. Wu NSRRC, Hsinchu, Taiwan
	Taiwan Photon Source (TPS) is a 3 GeV synchrotron light source which is being construction at campus of National Synchrotron Radiation Research Center (NSRRC) in Taiwan. A new streak camera equipped with a 125/250 MHz synchroscan unit, a fast/slow single sweep unit, and a dual-time sweep unit is prepared for beam diagnostics, especially for the TPS. An ultra short femtosecond Ti-Sapphire laser was used to evaluate the sub-picosecond temporal resolution of the streak camera and the first beam measurements of the streak camera using synchrotron light from the existing 1.5 GeV Taiwan Light Source (TLS) were performed. The commissioning results are summarized in this report.

MOPF02	The Wire Scanner Control Sytem for C-ADS Injector-II	controls, emittance, linac, diagnostics	197
	M. Li, X.C. Kang, R.S. Mao, J.X. Wu, Y.J. Yuan, J. Zhang, Y. Zhang, G. Zhu IMP, Lanzhou, People's Republic of China
	The C-ADS project is a strategic plan to solve the nuclear waste problem and the resource problem for nuclear power plants in China. The first step of this project is to build two 5-MeV test CW linac. The institute of Modern physics (IMP) is in charge of designing one of them. In order to measure the beam profile in this linac, a wire scanner system was designed and tested. In this paper, the mechanical design and control system of this wire scanner system are introduced. A real-time, closed loop control system is being developed and tested for more repeatable and accurate positioning of beam sense wires. All of the electronic and computational duties are handled in one the National Instruments compact RIO real-time chassis with a Field-Programmable Gate Array (FPGA). The beam test result of this system in IMP 320 KV beam line was present. The test result of this system and the measured beam profile result are discussed in this paper.

MOPF03	Laser Diode Velocimeter-Monitor Based on Self-Mixing Technique	target, laser, scattering, radiation	200
	A.S. Alexandrova, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom A.S. Alexandrova, C.P. Welsch The University of Liverpool, Liverpool, United Kingdom
	Funding: Work supported within LA3NET which is funded by the European Commission under contract PITN-GA-2011-289191 and STFC under the Cockcroft Institute Core Grant No.ST/G008248/1. Gas targets are important for a number of accelerator-based applications, in particular as cold targets for collision experiments and beam diagnostics purposes where gas jets have been successfully used as least intrusive beam profile monitors, however, detailed information about the gas jet is important for its optimization and the quality of the beam profile that can be measured with it. A laser velocimeter shall be used for an in-detail characterization of atomic and molecular gas jets and allow investigations into the jet dynamics. Existing methods are currently not efficient enough, hard to build, and rather expensive. A laser velocimeter based on the self-mixing technique can provide unambiguous measurements from a single interferometric channel, realizable in a compact experimental setup that can be installed even in radiation-exposed environments. In this contribution, an introduction to the underlying theory of self-mixing is given, before the design and functioning principle of the velocimeter is described in detail. Finally, preliminary experimental results with different solid targets are presented and an outlook on measurements with fluid and gaseous targets is given.
	Poster MOPF03 [1.045 MB]

TUBL1	NSLS-II BPM and Fast Orbit Feedback System Design and Implementation	BPM, storage-ring, controls, linac	316
	O. Singh, B. Bacha, A. Blednykh, W.X. Cheng, J.H. De Long, A.J. Della Penna, K. Ha, Y. Hu, B.N. Kosciuk, M.A. Maggipinto, J. Mead, D. Padrazo, I. Pinayev, Y. Tian, K. Vetter, L.-H. Yu BNL, Upton, Long Island, New York, USA
	The National Synchrotron Light Source II is a third generation light source under construction at Brookhaven National Laboratory. The project includes a highly optimized, ultra-low emittance, 3 GeV electron storage ring, linac pre-injector and full energy booster synchrotron. The low emittance requires high performance beam position monitor systems, providing measurement to better than 200 nm resolution; and fast orbit feedback systems, holding orbit to similar level of orbit deviations. The NSLS-II storage ring has 30 cells, each deploying up to 8 RF BPMs and 3 fast weak correctors. Each cell consists of a "cell controller", providing fast orbit feedback system infrastructure. This paper will provide a description of system design and summarize the implementation and status for these systems.
	Slides TUBL1 [5.225 MB]

TUBL2	A 4 GS/s Feedback Processing System for Control of Intra-Bunch Instabilities	SPS, controls, kicker, injection	323
	J.D. Fox, J.M. Cesaratto, J.E. Dusatko, J.J. Olsen, K.M. Pollock, C.H. Rivetta, O. Turgut SLAC, Menlo Park, California, USA W. Höfle CERN, Geneva, Switzerland
	Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515 and the US LHC Accelerator Research program ( LARP) We present the architecture and implementation overview of a digital signal processing system developed to study control of Electron-Cloud and Transverse Mode coupling instabilities in the CERN SPS. The system is based on a reconfigurable processing architecture which samples vertical bunch motion and applies correction signals at a 4 GS/s rate, allowing 16 samples across a single 5 ns SPS RF bucket. The system requires wideband beam pickups and a vertical kicker structure with GHz bandwidth. This demonstration system implements a general purpose 16 tap FIR control filter for each sample. We present results from SPS machine studies showing the impact of wideband feedback to excite/damp internal modes of vertical motion as well as stabilize an unstable beam. These results highlight the challenges of intra-bunch feedback and show proof of principle feasibility of the architecture.
	Slides TUBL2 [12.154 MB]

TUPC08	Design and Impedance Optimization of the LNLS-UVX Longitudinal Kicker Cavity	longitudinal, kicker, impedance, synchrotron	369
	L. Sanfelici, H.O.C. Duarte, S.R. Marques LNLS, Campinas, Brazil
	Performance evolution of parameters achieved during the electromagnetic design of the longitudinal kicker cavity for the LNLS UVX storage ring is presented. The effort on the electromagnetic optimization process of the heavily loaded cavity has been made to reach the required electrodynamic parameters of the kicker. The results for three different geometries are compared and a good compromise between the longitudinal shunt impedance and the effect of the longitudinal Higher Order Modes (HOM’s) on beam stability has been found.
	Poster TUPC08 [1.365 MB]

TUPC16	Bunch-by-Bunch Feedback and Diagnostics at BESSY II	longitudinal, beam-losses, injection, kicker	399
	A. Schälicke, F. Falkenstern, R. Müller HZB, Berlin, Germany
	At the light source BESSY II new digital bunch-by-bunch feedback systems have been put into operation in January 2013, replacing the existing analog as well as the obsolete digital systems. From the first days of operation the new system successfully suppresses transverse and longitudinal beam instabilities in wide range of machine parameters. The system offers also many new diagnostics opportunities, these include the analysis of instability modes, measurement of the feedback loop gain, and determination of the transfer function. A method to systematically optimise the output amplifier response function with the help of shaper coefficients for the optimal bunch separation has been developed. In addition the analysis of the input data stream allows a passive determination of machine properties like betatron and synchrotron frequencies as well as the longitudinal phases for every bunch. The integration of external triggers permits the analysis of postmortem data, the characterisation of beam-loss events, and monitoring of the injection process. In this contribution first operational experience, the developed data analysis techniques and experimental data will be presented.
	Poster TUPC16 [56.767 MB]

TUPC22	Cavity Beam Position Monitor in Multiple Bunch Operation for the ATF2 Interaction Point Region	beam-position, BPM, collider, single-bunch	419
	Y.I. Kim, D.R. Bett, N. Blaskovic Kraljevic, S.T. Boogert, P. Burrows, G.B. Christian, M.R. Davis, A. Lyapin, C. Perry JAI, Oxford, United Kingdom J.C. Frisch, D.J. McCormick, J. Nelson, G.R. White SLAC, Menlo Park, California, USA Y. Honda, T. Tauchi, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan
	The Accelerator Test Facility 2 (ATF2) at KEK, Japan, is a scaled test beam line for the international linear collider (ILC) final focus system. There are two goals: firstly, to demonstrate focusing to 37 nm vertical beam size; secondly, to achieve a few nanometer level beam orbit stability at the focus point (the Interaction Point (IP)) in the vertical plane. High-resolution beam position monitors around the IP area (IPBPMs) have been developed in order to measure the electron beam position in that region with a resolution of a few nanometers in the vertical plane. Currently, the standard operation mode at ATF2 is single bunch, however, multiple bunch operation with a bunch spacing similar to the one foreseen for the ILC (around 300 ns) is also possible. IPBPMs have a low Q value resulting in a decay time of about 30 ns, and so should be able to measure the beam position of individual bunches without any significant performance degradation. The IPBPMs in the ATF2 extraction beam line have been tested in multibunch regime. This paper analyses the signals, processing methods and results for this mode.
	Poster TUPC22 [1.050 MB]

TUPC24	The Design Strategy of Orbit Feedback System in the TPS	BPM, controls, power-supply, storage-ring	423
	C.H. Kuo, J. Chen, Y.-S. Cheng, P.C. Chiu, K.T. Hsu, K.H. Hu, C.Y. Wu NSRRC, Hsinchu, Taiwan
	TPS (Taiwan Photon Source) is a 3 GeV synchrotron light source which is being constructed at NSRRC. The BPM electronic is based on uTCA platform, is used for various request and function reasons. The orbit feedback system design is based on open structure, modularization and highly integration. There are many advantages that orbit feedback system is embedded in the BPM crate with FPGA modules. High throughput backplane, data transfer and processing support rich function for waveform record, diagnostic, beam study and transient analysis. The design and implementation result of the system will be reported in this conference.

TUPC28	Strip Line Monitor design for the ISIS Proton Synchrotron using the FEA program HFSS	coupling, kicker, impedance, scattering	435
	S.J. Payne STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	This paper reports the development of a strip line monitor for the ISIS accelerator main ring. The strip line is still in the design phase and the work reported here is the results of the FEA programme HFSS. The strip line will eventually form part of a beam instability feedback system and will be used to control instabilities both in the current ISIS machine and for all future ISIS upgrades where higher intensities and energies could be realised. The strip line consists of two pairs of 550mm by 160mm broad flat electrodes configured to allow damping in both the horizontal and vertical planes. The paper describes the efforts to achieve a bandwidth of >260MHz which will allow the feedback system deal with instabilities such as those caused by electron clouds. Design of the electrodes including matching of the feed throughs to the electrodes , concerns of materials for the electrode supports are considered. Also considered are methods used to improved inter-electrode decoupling (to better than -30db) . Results in the form of scattering parameters, smith charts, time domain reflectivity and shunt impedances will be presented.

TUPC34	Precision Synchronization of Optical Lasers Based on MTCA.4 Electronics	laser, DESY, monitoring, XFEL	451
	U. Mavrič, L. Butkowski, H.T. Duhme, M. Felber, M. Fenner, C. Gerth, P. Peier, H. Schlarb, B. Steffen DESY, Hamburg, Germany T. Kozak, P. Predki TUL-DMCS, Łódź, Poland
	Optical laser have become an integral part of free-electron laser facilities for the purposes of electron bunch generation, external seeding, diagnostics and pump-probe experiments. The ultra-short electron bunches demand a high timing stability and precision synchronization of the optical lasers. In this paper, we present the proof-of-principle for a laser locking application implemented on a MTCA.4 platform. The system design relies on existing MTCA.4 compliant off-the-shelf modules that are available on the market or have been developed for other applications within the particle accelerator community. Besides performance and cost, we also tried to minimize the number of out-of-crate components. Preliminary measurements of laser locking at the FLASH and REGAE particle accelerators are presented, and an outlook for further system development in the area of laser-to-RF synchronization is given.

TUPC36	First Realization and Performance Study of a Single-Shot Longitudinal Bunch Profile Monitor Utilizing a Transverse Deflecting Structure	longitudinal, FEL, kicker, electron	456
	M. Yan, C. Behrens, C. Gerth, R. Kammering, A. Langner, F. Obier, V. Rybnikov DESY, Hamburg, Germany J. Wychowaniak TUL-DMCS, Łódź, Poland
	For the control and optimization of electron beam parameters at modern free-electron lasers (FEL), transverse deflecting structures (TDS) in combination with imaging screens have been widely used as robust longitudinal diagnostics with single-shot capability, high resolution and large dynamic range. At the free-electron laser in Hamburg (FLASH), a longitudinal bunch profile monitor utilizing a TDS has been realized. In combined use with a fast kicker magnet and an off-axis imaging screen, selection and measurement of a single bunch out of the bunch train with bunch spacing down to 1us can be achieved without affecting the remaining bunches which continue to generate FEL radiation during user operation. Technical obstacles have been overcome such as suppression of coherent transition radiation from the imaging screen, the continuous image acquisition and processing with the bunch train repetition rate of 10Hz. The monitor, which provides the longitudinal bunch profile and length, has been used routinely at FLASH. In this paper, we present the setup and operation of the longitudinal bunch profile monitor as well as the performance during user operation.

TUPF29	Tune Measurement from Transverse Feedback Signals in LHC	transverse, LHC, damping, CERN	579
	F. Dubouchet, W. Höfle, G. Kotzian, T.E. Levens, D. Valuch CERN, Geneva, Switzerland P. Albuquerque HES-SO//Geneva, Geneva, Switzerland
	We show how bunch-by-bunch position data from the LHC transverse feedback system can be used to determine the transverse tunes. Results from machine development experiments are presented and compared with theoretical predictions. In the absence of external beam excitations the tune is visible in the spectra of the position data with the feedback loop as a dip, while with external excitation a peak is visible. Both options, observation with and without excitation, are demonstrated to be complementary. Periodic excitation and observation of the free oscillation can also be used to determine the damping time of the feedback in addition to the coherent tune. Plans are outlined for hardware upgrades of the LHC transverse feedback system that will enable fast online processing of bunch-by-bunch, turn-by-turn data using Graphical Processing Units (GPU). By using GPUs we gain the ability to compute and store the spectrum of all bunches in real-time and the possibility to reconfigure test and deploy algorithms. This data acquisition and analysis architecture also allows changes to be made without disturbing the operation.
	Poster TUPF29 [1.052 MB]

WEBL2	Applications of Stripline and Cavity Beam Position Monitors in Low-Latency, High-Precision, Intra-Train Feedback Systems	BPM, kicker, beam-position, extraction	630
	M.R. Davis, D.R. Bett, N. Blaskovic Kraljevic, P. Burrows, G.B. Christian, Y.I. Kim, C. Perry JAI, Oxford, United Kingdom
	Two, low-latency, sub-micron beam position monitoring (BPM) systems have been developed and tested with beam at the KEK Accelerator Test Facility (ATF2). One system (‘upstream’), based on stripline BPMs uses fast analogue front-end signal processing and has demonstrated a position resolution as low as 400nm for beam intensities of ~1 nC, with single-pass beam. The other (‘IP’) system, based on low-Q cavity BPMs and utilising custom signal processing electronics designed for low latency, provides a single pass resolution of approximately 100nm. The BPM position data are digitised by fast ADCs on a custom FPGA-based feedback controller and used in three modes: 1) the upstream BPM data are used to drive a pair of local kickers nominally orthogonal in phase in closed-loop feedback mode; 2) the upstream BPM data are used to drive a downstream kicker in the ATF2 final focus region in feedforward mode; 3) the IP cavity BPM data are used to drive a local downstream kicker in the ATF2 final focus region in closed-loop feedback mode. In each case the beam jitter is measured downstream of the final focus system with the IP cavity BPMs. The relative performance of these systems is compared.
	Slides WEBL2 [1.934 MB]

WEPC08	Vibration Measurement and its Effect on Beam Stability at NSLS2	storage-ring, BPM, ground-motion, damping	674
	W.X. Cheng, A.K. Jain, S. Krinsky, S.K. Sharma, C.J. Spataro BNL, Upton, Long Island, New York, USA
	Vibration measurements have been carried out at NSLS2. The floor has more than 100nm RMS vertical motion during workdays (>1Hz). This motion reduces to 30nm RMS during night and weekends. Traffic on the nearby expressway is considered to be the major source of ground motion. Weather (wind) and utility system induced vibrations are other possible factors on floor motion. Vibrations have been measured at various locations, like the tunnel and experiment floor, HXN long beamline satellite building floor, high stability BPMs, Quadrupole magnets etc. Assume a typical un-correlated motion of Quadrpole magnets of 100nm, beam orbit jitter is around 4-7 microns. Fast orbit feedback will control the orbit stability within 10% of beam size.

WEPC10	Capability Upgrade of the Diamond Transverse Multibunch Feedback	DIAMOND, controls, transverse, FIR	682
	M.G. Abbott, G. Rehm, I.S. Uzun Diamond, Oxfordshire, United Kingdom
	We describe an upgrade to the Transverse Multi-Bunch Feedback processor used at Diamond for control of multi-bunch instabilities and measurement of betatron tunes. The new system will improve both feedback and diagnostic capabilities. Bunch by bunch selectable control over feedback filters, gain and excitation will allow finer control over feedback, allowing for example the single bunch in a hybrid or camshaft fill pattern to be controlled independently from the bunch train. It will also be possible to excite all bunches at a single frequency while simultaneously sweeping the excitation for tune measurement of a few selected bunches. The single frequency excitation can be used for bunch cleaning or continuous measurement of the beta-function. A simple programmable event sequencer will provide support for up to 8 steps of programmable sweeps and changes to feedback and excitation, allowing a variety of complex and precisely timed beam characterisation experiments including grow-damp measurements in unstable conditions.
	Poster WEPC10 [0.427 MB]

WEPC12	Evaluation of Strip-line Pick-up System for the SPS Wideband Transverse Feedback System	pick-up, SPS, transverse, coupling	690
	G. Kotzian, W. Höfle, R.J. Steinhagen, D. Valuch, U. Wehrle CERN, Geneva, Switzerland
	The proposed SPS Wideband Transverse Feedback system requires a wide-band pick-up system to be able to detect intra-bunch motion within the SPS proton bunches, captured and accelerated in a 200 MHz bucket. We present the electro-magnetic design of transverse beam position pick-up options optimised for installation in the SPS and evaluate their performance reach with respect to direct time domain sampling of the intra-bunch motion. The analysis also discusses the achieved subsystem responses of the associated cabling with new low dispersion smooth wall cables, wide-band generation of intensity and position signals by means of 180 degree RF hybrids as well as passive techniques to electronically suppress the beam offset signal, needed to optimise the dynamic range and position resolution of the planned digital intra-bunch feedback system.

WEPC13	Optimisation of the SVD Treatment in the Fast Orbit Correction of the ESRF Storage Ring	BPM, ESRF, storage-ring, injection	694
	E. Plouviez, F. Epaud, L. Farvacque, J.M. Koch ESRF, Grenoble, France
	The ESRF fast orbit correction system has been in operation since May 2012. The orbit correction scheme relies classically on the calculation of a correction orbit based on the SVD analysis of the response matrix of our 224 BPMs to each of our 96 correctors. The rate of the calculation of the corrections is 10 KHz; we use a PI loop achieving a bandwidth of 150Hz completed with a narrow band pass filter with extra gain at 50Hz. In order to make the best use of the correctors dynamic range and of the resolution of the calculation, it can be useful to limit the bandwidth of loop for the highest order vectors of the SVD, or even to totally remove some of these vectors from the correction down to DC. Removing some of the eigen vectors while avoiding that the loop becomes unstable usually increases a lot the complexity of the matrix calculations: we have developed an algorithm which overcomes this problem; The test of this algorithm is presented. We present also the beneficial effect at high frequency of the limitation of the gain of the correction of the highest SVD eigen vectors on the demand of the peak strength of the correctors and on the resolution of the correction calculation.
	Poster WEPC13 [0.974 MB]

WEPC22	First Steps Towards a Fast Orbit Feedback at ALBA	DIAMOND, ESRF, brilliance, simulation	727
	A. Olmos, S. Blanch-Torné, Z. Martí, J. Moldes, M. Muñoz, R. Petrocelli, X. Serra-Gallifa CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain A. Gutierrez-Milla UAB, Barcelona, Spain
	An optimum performance of the ALBA facility requires a beam orbit stability on the sub-micron level up to frequencies in the 100 Hz range. The Fast Orbit FeedBack system (FOFB) is designed to achieve such a stability. After investigation of possible system architecture, a decision has been taken that exploits the available in-house hardware. This “low-cost” first stage FOFB will be an ideal test-bench to learn about beam stabilization and find possible problems and improvements on it. This report explains the current lay-out and status of the FOFB at ALBA.
	Poster WEPC22 [3.107 MB]

WEPC38	Current Status of Development of Optical Synchronization System for PAL XFEL	XFEL, laser, FEL, LCLS	772
	C.-K. Min, I. Eom, H.-S. Kang, B.R. Park, S.J. Park PAL, Pohang, Kyungbuk, Republic of Korea K. Jung, J. Kim, J. Lim KAIST, Daejeon, Republic of Korea
	Optical synchronization system has been developed for higher quality PAL XFEL with low timing jitter since 2011. In last two years, laboratory test was successfully performed, and test in our accelerator environment is ongoing. In laboratory, we tested the synchronization of RF master oscillator and optical master oscillator, the stabilization of 610 m optical fiber link, and the remote optical-to-RF conversion. We report recent our development results and summarize on-going optical timing project.
	Poster WEPC38 [3.366 MB]

WEPF07	Profile Grid Monitor and First Measurement Results at the MedAustron Accelerator	controls, CERN, ion, beam-transport	822
	M. Repovz, A. Gyorgy, A. Kerschbaum, F. Osmic, S.M. Schwarz EBG MedAustron, Wr. Neustadt, Austria G. Burtin CERN, Geneva, Switzerland
	MedAustron is an ion beam therapy center located in Wiener Neustadt, Austria. The design is based on CERN’s Proton-Ion Medical Machine Study and the project is currently in the installation and commissioning phase. This paper summarizes the design, production and commissioning of MedAustron’s beam profile grid monitor. This monitor measures the beam profile in the low and medium energy beam transfer line where the beam dimensions can be as large as 100 mm. Reasonable position resolution is achieved with a harp consisting of 64 wires per plane and a pitch of up to 1.7 mm. Special effort was needed to produce such harps and bring the signal cables out of the vacuum. As the readout electronics has to cope with DC as well as pulsed beam all 128 wires are acquired simultaneously. This is achieved by integrating the charge during the “flat-top” of the beam pulse and storing it for serial transmission to the back end electronics for conversion. The high accuracy requires calibration of offset and amplification errors for every single channel. A NI PXI FPGA card controls the readout chain. The code for controlling the readout, including the graphical interface, is written in NI LabView.

Paper

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Other Keywords

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MOAL4

First Results from the Bunch Arrival-Time Monitor at the SwissFEL Test Injector

pick-up, laser, gun, electron

8

V.R. Arsov, M.M. Dehler, S. Hunziker, M.G. Kaiser, V. Schlott
PSI, Villigen PSI, Switzerland

Non-destructive electron bunch arrival-time monitors (BAMs) with resolution <10 fs, sensitivity down to 10 pC and high intrinsic bandwidth for double bunch detection are required for reliable operation of SwissFEL. To achieve this ultimate goal, such a monitor based on a Mach-Zehnder electro-optical intensity modulator has been under development at the SwissFEL Test Injector. The high timing precision is derived by a stable pulsed optical reference system. The first BAM is located before the bunch compressor where the bunch energy is 230 MeV and the pulse length is approximately 3 ps. At this position, the bunch arrival time is sensitive to the laser- and gun timing. In this paper, we report on the commissioning of the RF- and optical front ends, the first arrival-time jitter and drift measurements with the entire system, as well as correlation of the arrival-time with different machine and environmental parameters. We achieve a resolution of 20 fs down to 60 pC.

Slides MOAL4 [1.228 MB]

MOCL1

Beam Instrumentation at the Accelerator Test Facility 2

laser, electron, OTR, emittance

26

S.T. Boogert
JAI, Egham, Surrey, United Kingdom
S.T. Boogert
Royal Holloway, University of London, Surrey, United Kingdom

The Accelerator Test Facility 2 (ATF2) is a scaled demonstrator system for final focus beam lines of linear high energy colliders. Four OTR (Optical Transition Radiation) monitors have been installed at the ATF2. Major characteristics is the fast measurement of projected (2D) and intrinsic (4D) emittances and the coupling corrections with skew quadrupole magnets at the upstream. The high resolution cavity beam position monitor (BPM) system is a part of the ATF2 diagnostics. Two types of cavity BPMs are used, C-band operating at 6.426 GHz, and S-band at 2.888 GHz with an increased beam aperture. The resolution of the C-band system with attenuators was determined to be approximately 250 nm and 1 μm for the S-band system. Without attenuation the best recorded C-band cavity resolution was 27 nm. A laser-wire transverse electron beam size measurement system has been constructed and operated at the ATF2 beam line at KEK. A special set of electron beam optics was developed to generate an approximately 1μm vertical focus at the laser-wire location. Systematic measurements of a micron beam size have been successfully executed.

Slides MOCL1 [6.059 MB]

MOPC16

FPGA Based Fast Orbit Feedback Data Acquisition System for Electron and Hadron Storage Rings

hadron, COSY, storage-ring, BPM

82

G. Schünemann, P. Hartmann, D. Schirmer, G. Schmidt, P. Towalski, T. Weis
DELTA, Dortmund, Germany

In the course of a BMBF supported development of a fast orbit feedback system for electron and hadron storage rings, in prospect of the upcoming FAIR facility, this paper presents the developed data acquisition system, based on Field Programmable Gateway Array (FPGA) technology, as well as the first results of in-situ measurements. Data was successfully taken at the TU-Dortmunds synchrotron light source DELTA as well as hadron storage rings COSY of the Forschungszentrum Jülich (FZJ) and SIS18 of the GSI Helmholtzzentrum für Schwerionenforschung GmbH (GSI).

MOPC26

Optimization of Bunch-to-Bunch Isolation in Instability Feedback Systems

coupling, pick-up, kicker, FIR

116

D. Teytelman
Private Address, San Jose, USA

Bunch-by-bunch feedback formalism is a powerful tool for combating coupled-bunch instabilities in circular accelerators. Imperfections in the analog front and back ends lead to coupling between neighboring bunches. Such coupling limits system performance in both feedback and diagnostic capacities. In this paper, techniques for optimizing bunch-to-bunch isolation within the system will be presented. A new method for improving the performance of the existing systems will be described. The novel approach uses a "shaper" filter in the digital signal processor to compensate for the imperfect response of the power amplifier and kicker combination. An objective optimization method to derive the optimal back end configuration will be presented and illustrated with measurements from several accelerators.

Poster MOPC26 [0.851 MB]

MOPC28

The Hardware Implementation of the CERN SPS Ultrafast Feedback Processor Demonstrator

controls, SPS, FIR, CERN

124

J.E. Dusatko, J.M. Cesaratto, J.D. Fox, J.J. Olsen, C.H. Rivetta
SLAC, Menlo Park, California, USA
W. Höfle
CERN, Geneva, Switzerland

Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515 and the US LHC Accelerator Research program ( LARP)
An ultrafast 4GSa/s transverse feedback processor has been developed for proof-of-concept studies of feedback control of e-cloud driven and transverse mode coupled intra-bunch instabilities in the CERN SPS. This system consists of a high-speed ADC on the front end and equally fast DAC on the back end. All control and signal processing is implemented in FPGA logic. This system is capable of taking up to 16 sample slices across a single SPS bunch and processing each slice individually within a reconfigurable signal processor. This demonstrator system is a rapidly developed prototype, consisting of both commercial and custom-design components. It can stabilize the motion of a single particle bunch using closed loop feedback. The system can also run open loop as a high-speed arbitrary waveform generator and contains diagnostic features including a special ADC snapshot capture memory. This paper describes the overall system, the feedback processor and focuses on the hardware architecture, design and implementation.

Poster MOPC28 [1.684 MB]

MOPC29

Realization of Transverse Feedback System for SIS18/100 using FPGA

BPM, transverse, controls, FIR

128

T. Rueckelt
Technische Universität Darmstadt (TU Darmstadt), Signal Processing Group, Darmstadt, Germany
M. Alhumaidi, T. Rueckelt, A.M. Zoubir
TU Darmstadt, Darmstadt, Germany

Higher beam intensities in particle accelerator are usually prevented by beam instabilities. To cure these instabilities, additional active system must be used besides passive damping. For this purpose, we have developed a distributed low-latency Transverse Feedback System (TFS) using FPGAs. Data acquisition takes place on multiple BPMs with individual FPGAs and ADCs around the accelerator ring. Acquired data is compressed and sent over broadband fiber optic wires to a central unit. For synchronization, data is tagged using timestamps from a reference time, which is distributed by a specially constrained network time protocol to obtain cycle accuracy. The central unit provides an FIR filter for system bandwidth limitation, and an adaptive IIR filter for stable beam signal rejection. Feedback is given using a linear combination of the pre-processed BPM signals. The system provides substantial flexibility, due to the possibility to configure most parameters online. Filters, feedback sources and parameters, compression rate and more can be adapted via Ethernet interface, which also supplies analysis data. First results are shown.

Poster MOPC29 [1.842 MB]

MOPC31

Streak Camera Imaging at ELSA

ELSA, longitudinal, transverse, synchrotron

132

M.T. Switka, W. Hillert, M. Schedler, S. Zander
ELSA, Bonn, Germany

Funding: Funded by the DFG within SFB/TR 16
The Electron Stretcher Facility ELSA provides polarized electrons with energies up to 3.2 GeV for external hadron experiments. In order to suffice the need of stored beam currents towards 200 mA, studies of instabilities and the effect of adequate countermeasures are essential for appropriate machine settings. For this purpose a new diagnostic beamline has been constructed. It is optimized for transverse and longitudinal streak camera measurements with time resolution down to one picosecond. Operation of the diagnostic beamline has recently started and first measurements are presented.

MOPC39

Commissioning of a New Streak Camera at TLS for TPS Project

laser, synchrotron, storage-ring, longitudinal

159

C.Y. Liao, M.C. Chou, K.T. Hsu, K.H. Hu, C.H. Kuo, C.-C. Kuo, W.K. Lau, C.Y. Wu
NSRRC, Hsinchu, Taiwan

Taiwan Photon Source (TPS) is a 3 GeV synchrotron light source which is being construction at campus of National Synchrotron Radiation Research Center (NSRRC) in Taiwan. A new streak camera equipped with a 125/250 MHz synchroscan unit, a fast/slow single sweep unit, and a dual-time sweep unit is prepared for beam diagnostics, especially for the TPS. An ultra short femtosecond Ti-Sapphire laser was used to evaluate the sub-picosecond temporal resolution of the streak camera and the first beam measurements of the streak camera using synchrotron light from the existing 1.5 GeV Taiwan Light Source (TLS) were performed. The commissioning results are summarized in this report.

MOPF02

The Wire Scanner Control Sytem for C-ADS Injector-II

controls, emittance, linac, diagnostics

197

M. Li, X.C. Kang, R.S. Mao, J.X. Wu, Y.J. Yuan, J. Zhang, Y. Zhang, G. Zhu
IMP, Lanzhou, People's Republic of China

The C-ADS project is a strategic plan to solve the nuclear waste problem and the resource problem for nuclear power plants in China. The first step of this project is to build two 5-MeV test CW linac. The institute of Modern physics (IMP) is in charge of designing one of them. In order to measure the beam profile in this linac, a wire scanner system was designed and tested. In this paper, the mechanical design and control system of this wire scanner system are introduced. A real-time, closed loop control system is being developed and tested for more repeatable and accurate positioning of beam sense wires. All of the electronic and computational duties are handled in one the National Instruments compact RIO real-time chassis with a Field-Programmable Gate Array (FPGA). The beam test result of this system in IMP 320 KV beam line was present. The test result of this system and the measured beam profile result are discussed in this paper.

MOPF03

Laser Diode Velocimeter-Monitor Based on Self-Mixing Technique

target, laser, scattering, radiation

200

A.S. Alexandrova, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
A.S. Alexandrova, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom

Funding: Work supported within LA3NET which is funded by the European Commission under contract PITN-GA-2011-289191 and STFC under the Cockcroft Institute Core Grant No.ST/G008248/1.
Gas targets are important for a number of accelerator-based applications, in particular as cold targets for collision experiments and beam diagnostics purposes where gas jets have been successfully used as least intrusive beam profile monitors, however, detailed information about the gas jet is important for its optimization and the quality of the beam profile that can be measured with it. A laser velocimeter shall be used for an in-detail characterization of atomic and molecular gas jets and allow investigations into the jet dynamics. Existing methods are currently not efficient enough, hard to build, and rather expensive. A laser velocimeter based on the self-mixing technique can provide unambiguous measurements from a single interferometric channel, realizable in a compact experimental setup that can be installed even in radiation-exposed environments. In this contribution, an introduction to the underlying theory of self-mixing is given, before the design and functioning principle of the velocimeter is described in detail. Finally, preliminary experimental results with different solid targets are presented and an outlook on measurements with fluid and gaseous targets is given.

Poster MOPF03 [1.045 MB]

TUBL1

NSLS-II BPM and Fast Orbit Feedback System Design and Implementation

BPM, storage-ring, controls, linac

316

O. Singh, B. Bacha, A. Blednykh, W.X. Cheng, J.H. De Long, A.J. Della Penna, K. Ha, Y. Hu, B.N. Kosciuk, M.A. Maggipinto, J. Mead, D. Padrazo, I. Pinayev, Y. Tian, K. Vetter, L.-H. Yu
BNL, Upton, Long Island, New York, USA

The National Synchrotron Light Source II is a third generation light source under construction at Brookhaven National Laboratory. The project includes a highly optimized, ultra-low emittance, 3 GeV electron storage ring, linac pre-injector and full energy booster synchrotron. The low emittance requires high performance beam position monitor systems, providing measurement to better than 200 nm resolution; and fast orbit feedback systems, holding orbit to similar level of orbit deviations. The NSLS-II storage ring has 30 cells, each deploying up to 8 RF BPMs and 3 fast weak correctors. Each cell consists of a "cell controller", providing fast orbit feedback system infrastructure. This paper will provide a description of system design and summarize the implementation and status for these systems.

Slides TUBL1 [5.225 MB]

TUBL2

A 4 GS/s Feedback Processing System for Control of Intra-Bunch Instabilities

SPS, controls, kicker, injection

323

J.D. Fox, J.M. Cesaratto, J.E. Dusatko, J.J. Olsen, K.M. Pollock, C.H. Rivetta, O. Turgut
SLAC, Menlo Park, California, USA
W. Höfle
CERN, Geneva, Switzerland

Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515 and the US LHC Accelerator Research program ( LARP)
We present the architecture and implementation overview of a digital signal processing system developed to study control of Electron-Cloud and Transverse Mode coupling instabilities in the CERN SPS. The system is based on a reconfigurable processing architecture which samples vertical bunch motion and applies correction signals at a 4 GS/s rate, allowing 16 samples across a single 5 ns SPS RF bucket. The system requires wideband beam pickups and a vertical kicker structure with GHz bandwidth. This demonstration system implements a general purpose 16 tap FIR control filter for each sample. We present results from SPS machine studies showing the impact of wideband feedback to excite/damp internal modes of vertical motion as well as stabilize an unstable beam. These results highlight the challenges of intra-bunch feedback and show proof of principle feasibility of the architecture.

Slides TUBL2 [12.154 MB]

TUPC08

Design and Impedance Optimization of the LNLS-UVX Longitudinal Kicker Cavity

longitudinal, kicker, impedance, synchrotron

369

L. Sanfelici, H.O.C. Duarte, S.R. Marques
LNLS, Campinas, Brazil

Performance evolution of parameters achieved during the electromagnetic design of the longitudinal kicker cavity for the LNLS UVX storage ring is presented. The effort on the electromagnetic optimization process of the heavily loaded cavity has been made to reach the required electrodynamic parameters of the kicker. The results for three different geometries are compared and a good compromise between the longitudinal shunt impedance and the effect of the longitudinal Higher Order Modes (HOM’s) on beam stability has been found.

Poster TUPC08 [1.365 MB]

TUPC16

Bunch-by-Bunch Feedback and Diagnostics at BESSY II

longitudinal, beam-losses, injection, kicker

399

A. Schälicke, F. Falkenstern, R. Müller
HZB, Berlin, Germany

At the light source BESSY II new digital bunch-by-bunch feedback systems have been put into operation in January 2013, replacing the existing analog as well as the obsolete digital systems. From the first days of operation the new system successfully suppresses transverse and longitudinal beam instabilities in wide range of machine parameters. The system offers also many new diagnostics opportunities, these include the analysis of instability modes, measurement of the feedback loop gain, and determination of the transfer function. A method to systematically optimise the output amplifier response function with the help of shaper coefficients for the optimal bunch separation has been developed. In addition the analysis of the input data stream allows a passive determination of machine properties like betatron and synchrotron frequencies as well as the longitudinal phases for every bunch. The integration of external triggers permits the analysis of postmortem data, the characterisation of beam-loss events, and monitoring of the injection process. In this contribution first operational experience, the developed data analysis techniques and experimental data will be presented.

Poster TUPC16 [56.767 MB]

TUPC22

Cavity Beam Position Monitor in Multiple Bunch Operation for the ATF2 Interaction Point Region

beam-position, BPM, collider, single-bunch

419

Y.I. Kim, D.R. Bett, N. Blaskovic Kraljevic, S.T. Boogert, P. Burrows, G.B. Christian, M.R. Davis, A. Lyapin, C. Perry
JAI, Oxford, United Kingdom
J.C. Frisch, D.J. McCormick, J. Nelson, G.R. White
SLAC, Menlo Park, California, USA
Y. Honda, T. Tauchi, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan

The Accelerator Test Facility 2 (ATF2) at KEK, Japan, is a scaled test beam line for the international linear collider (ILC) final focus system. There are two goals: firstly, to demonstrate focusing to 37 nm vertical beam size; secondly, to achieve a few nanometer level beam orbit stability at the focus point (the Interaction Point (IP)) in the vertical plane. High-resolution beam position monitors around the IP area (IPBPMs) have been developed in order to measure the electron beam position in that region with a resolution of a few nanometers in the vertical plane. Currently, the standard operation mode at ATF2 is single bunch, however, multiple bunch operation with a bunch spacing similar to the one foreseen for the ILC (around 300 ns) is also possible. IPBPMs have a low Q value resulting in a decay time of about 30 ns, and so should be able to measure the beam position of individual bunches without any significant performance degradation. The IPBPMs in the ATF2 extraction beam line have been tested in multibunch regime. This paper analyses the signals, processing methods and results for this mode.

Poster TUPC22 [1.050 MB]

TUPC24

The Design Strategy of Orbit Feedback System in the TPS

BPM, controls, power-supply, storage-ring

423

C.H. Kuo, J. Chen, Y.-S. Cheng, P.C. Chiu, K.T. Hsu, K.H. Hu, C.Y. Wu
NSRRC, Hsinchu, Taiwan

TPS (Taiwan Photon Source) is a 3 GeV synchrotron light source which is being constructed at NSRRC. The BPM electronic is based on uTCA platform, is used for various request and function reasons. The orbit feedback system design is based on open structure, modularization and highly integration. There are many advantages that orbit feedback system is embedded in the BPM crate with FPGA modules. High throughput backplane, data transfer and processing support rich function for waveform record, diagnostic, beam study and transient analysis. The design and implementation result of the system will be reported in this conference.

TUPC28

Strip Line Monitor design for the ISIS Proton Synchrotron using the FEA program HFSS

coupling, kicker, impedance, scattering

435

S.J. Payne
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

This paper reports the development of a strip line monitor for the ISIS accelerator main ring. The strip line is still in the design phase and the work reported here is the results of the FEA programme HFSS. The strip line will eventually form part of a beam instability feedback system and will be used to control instabilities both in the current ISIS machine and for all future ISIS upgrades where higher intensities and energies could be realised. The strip line consists of two pairs of 550mm by 160mm broad flat electrodes configured to allow damping in both the horizontal and vertical planes. The paper describes the efforts to achieve a bandwidth of >260MHz which will allow the feedback system deal with instabilities such as those caused by electron clouds. Design of the electrodes including matching of the feed throughs to the electrodes , concerns of materials for the electrode supports are considered. Also considered are methods used to improved inter-electrode decoupling (to better than -30db) . Results in the form of scattering parameters, smith charts, time domain reflectivity and shunt impedances will be presented.

TUPC34

Precision Synchronization of Optical Lasers Based on MTCA.4 Electronics

laser, DESY, monitoring, XFEL

451

U. Mavrič, L. Butkowski, H.T. Duhme, M. Felber, M. Fenner, C. Gerth, P. Peier, H. Schlarb, B. Steffen
DESY, Hamburg, Germany
T. Kozak, P. Predki
TUL-DMCS, Łódź, Poland

Optical laser have become an integral part of free-electron laser facilities for the purposes of electron bunch generation, external seeding, diagnostics and pump-probe experiments. The ultra-short electron bunches demand a high timing stability and precision synchronization of the optical lasers. In this paper, we present the proof-of-principle for a laser locking application implemented on a MTCA.4 platform. The system design relies on existing MTCA.4 compliant off-the-shelf modules that are available on the market or have been developed for other applications within the particle accelerator community. Besides performance and cost, we also tried to minimize the number of out-of-crate components. Preliminary measurements of laser locking at the FLASH and REGAE particle accelerators are presented, and an outlook for further system development in the area of laser-to-RF synchronization is given.

TUPC36

First Realization and Performance Study of a Single-Shot Longitudinal Bunch Profile Monitor Utilizing a Transverse Deflecting Structure

longitudinal, FEL, kicker, electron

456

M. Yan, C. Behrens, C. Gerth, R. Kammering, A. Langner, F. Obier, V. Rybnikov
DESY, Hamburg, Germany
J. Wychowaniak
TUL-DMCS, Łódź, Poland

For the control and optimization of electron beam parameters at modern free-electron lasers (FEL), transverse deflecting structures (TDS) in combination with imaging screens have been widely used as robust longitudinal diagnostics with single-shot capability, high resolution and large dynamic range. At the free-electron laser in Hamburg (FLASH), a longitudinal bunch profile monitor utilizing a TDS has been realized. In combined use with a fast kicker magnet and an off-axis imaging screen, selection and measurement of a single bunch out of the bunch train with bunch spacing down to 1us can be achieved without affecting the remaining bunches which continue to generate FEL radiation during user operation. Technical obstacles have been overcome such as suppression of coherent transition radiation from the imaging screen, the continuous image acquisition and processing with the bunch train repetition rate of 10Hz. The monitor, which provides the longitudinal bunch profile and length, has been used routinely at FLASH. In this paper, we present the setup and operation of the longitudinal bunch profile monitor as well as the performance during user operation.

TUPF29

Tune Measurement from Transverse Feedback Signals in LHC

transverse, LHC, damping, CERN

579

F. Dubouchet, W. Höfle, G. Kotzian, T.E. Levens, D. Valuch
CERN, Geneva, Switzerland
P. Albuquerque
HES-SO//Geneva, Geneva, Switzerland

We show how bunch-by-bunch position data from the LHC transverse feedback system can be used to determine the transverse tunes. Results from machine development experiments are presented and compared with theoretical predictions. In the absence of external beam excitations the tune is visible in the spectra of the position data with the feedback loop as a dip, while with external excitation a peak is visible. Both options, observation with and without excitation, are demonstrated to be complementary. Periodic excitation and observation of the free oscillation can also be used to determine the damping time of the feedback in addition to the coherent tune. Plans are outlined for hardware upgrades of the LHC transverse feedback system that will enable fast online processing of bunch-by-bunch, turn-by-turn data using Graphical Processing Units (GPU). By using GPUs we gain the ability to compute and store the spectrum of all bunches in real-time and the possibility to reconfigure test and deploy algorithms. This data acquisition and analysis architecture also allows changes to be made without disturbing the operation.

Poster TUPF29 [1.052 MB]

WEBL2

Applications of Stripline and Cavity Beam Position Monitors in Low-Latency, High-Precision, Intra-Train Feedback Systems

BPM, kicker, beam-position, extraction

630

M.R. Davis, D.R. Bett, N. Blaskovic Kraljevic, P. Burrows, G.B. Christian, Y.I. Kim, C. Perry
JAI, Oxford, United Kingdom

Two, low-latency, sub-micron beam position monitoring (BPM) systems have been developed and tested with beam at the KEK Accelerator Test Facility (ATF2). One system (‘upstream’), based on stripline BPMs uses fast analogue front-end signal processing and has demonstrated a position resolution as low as 400nm for beam intensities of ~1 nC, with single-pass beam. The other (‘IP’) system, based on low-Q cavity BPMs and utilising custom signal processing electronics designed for low latency, provides a single pass resolution of approximately 100nm. The BPM position data are digitised by fast ADCs on a custom FPGA-based feedback controller and used in three modes: 1) the upstream BPM data are used to drive a pair of local kickers nominally orthogonal in phase in closed-loop feedback mode; 2) the upstream BPM data are used to drive a downstream kicker in the ATF2 final focus region in feedforward mode; 3) the IP cavity BPM data are used to drive a local downstream kicker in the ATF2 final focus region in closed-loop feedback mode. In each case the beam jitter is measured downstream of the final focus system with the IP cavity BPMs. The relative performance of these systems is compared.

Slides WEBL2 [1.934 MB]

WEPC08

Vibration Measurement and its Effect on Beam Stability at NSLS2

storage-ring, BPM, ground-motion, damping

674

W.X. Cheng, A.K. Jain, S. Krinsky, S.K. Sharma, C.J. Spataro
BNL, Upton, Long Island, New York, USA

Vibration measurements have been carried out at NSLS2. The floor has more than 100nm RMS vertical motion during workdays (>1Hz). This motion reduces to 30nm RMS during night and weekends. Traffic on the nearby expressway is considered to be the major source of ground motion. Weather (wind) and utility system induced vibrations are other possible factors on floor motion. Vibrations have been measured at various locations, like the tunnel and experiment floor, HXN long beamline satellite building floor, high stability BPMs, Quadrupole magnets etc. Assume a typical un-correlated motion of Quadrpole magnets of 100nm, beam orbit jitter is around 4-7 microns. Fast orbit feedback will control the orbit stability within 10% of beam size.

WEPC10

Capability Upgrade of the Diamond Transverse Multibunch Feedback

DIAMOND, controls, transverse, FIR

682

M.G. Abbott, G. Rehm, I.S. Uzun
Diamond, Oxfordshire, United Kingdom

We describe an upgrade to the Transverse Multi-Bunch Feedback processor used at Diamond for control of multi-bunch instabilities and measurement of betatron tunes. The new system will improve both feedback and diagnostic capabilities. Bunch by bunch selectable control over feedback filters, gain and excitation will allow finer control over feedback, allowing for example the single bunch in a hybrid or camshaft fill pattern to be controlled independently from the bunch train. It will also be possible to excite all bunches at a single frequency while simultaneously sweeping the excitation for tune measurement of a few selected bunches. The single frequency excitation can be used for bunch cleaning or continuous measurement of the beta-function. A simple programmable event sequencer will provide support for up to 8 steps of programmable sweeps and changes to feedback and excitation, allowing a variety of complex and precisely timed beam characterisation experiments including grow-damp measurements in unstable conditions.

Poster WEPC10 [0.427 MB]

WEPC12

Evaluation of Strip-line Pick-up System for the SPS Wideband Transverse Feedback System

pick-up, SPS, transverse, coupling

690

G. Kotzian, W. Höfle, R.J. Steinhagen, D. Valuch, U. Wehrle
CERN, Geneva, Switzerland

The proposed SPS Wideband Transverse Feedback system requires a wide-band pick-up system to be able to detect intra-bunch motion within the SPS proton bunches, captured and accelerated in a 200 MHz bucket. We present the electro-magnetic design of transverse beam position pick-up options optimised for installation in the SPS and evaluate their performance reach with respect to direct time domain sampling of the intra-bunch motion. The analysis also discusses the achieved subsystem responses of the associated cabling with new low dispersion smooth wall cables, wide-band generation of intensity and position signals by means of 180 degree RF hybrids as well as passive techniques to electronically suppress the beam offset signal, needed to optimise the dynamic range and position resolution of the planned digital intra-bunch feedback system.

WEPC13

Optimisation of the SVD Treatment in the Fast Orbit Correction of the ESRF Storage Ring

BPM, ESRF, storage-ring, injection

694

E. Plouviez, F. Epaud, L. Farvacque, J.M. Koch
ESRF, Grenoble, France

The ESRF fast orbit correction system has been in operation since May 2012. The orbit correction scheme relies classically on the calculation of a correction orbit based on the SVD analysis of the response matrix of our 224 BPMs to each of our 96 correctors. The rate of the calculation of the corrections is 10 KHz; we use a PI loop achieving a bandwidth of 150Hz completed with a narrow band pass filter with extra gain at 50Hz. In order to make the best use of the correctors dynamic range and of the resolution of the calculation, it can be useful to limit the bandwidth of loop for the highest order vectors of the SVD, or even to totally remove some of these vectors from the correction down to DC. Removing some of the eigen vectors while avoiding that the loop becomes unstable usually increases a lot the complexity of the matrix calculations: we have developed an algorithm which overcomes this problem; The test of this algorithm is presented. We present also the beneficial effect at high frequency of the limitation of the gain of the correction of the highest SVD eigen vectors on the demand of the peak strength of the correctors and on the resolution of the correction calculation.

Poster WEPC13 [0.974 MB]

WEPC22

First Steps Towards a Fast Orbit Feedback at ALBA

DIAMOND, ESRF, brilliance, simulation

727

A. Olmos, S. Blanch-Torné, Z. Martí, J. Moldes, M. Muñoz, R. Petrocelli, X. Serra-Gallifa
CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain
A. Gutierrez-Milla
UAB, Barcelona, Spain

An optimum performance of the ALBA facility requires a beam orbit stability on the sub-micron level up to frequencies in the 100 Hz range. The Fast Orbit FeedBack system (FOFB) is designed to achieve such a stability. After investigation of possible system architecture, a decision has been taken that exploits the available in-house hardware. This “low-cost” first stage FOFB will be an ideal test-bench to learn about beam stabilization and find possible problems and improvements on it. This report explains the current lay-out and status of the FOFB at ALBA.

Poster WEPC22 [3.107 MB]

WEPC38

Current Status of Development of Optical Synchronization System for PAL XFEL

XFEL, laser, FEL, LCLS

772

C.-K. Min, I. Eom, H.-S. Kang, B.R. Park, S.J. Park
PAL, Pohang, Kyungbuk, Republic of Korea
K. Jung, J. Kim, J. Lim
KAIST, Daejeon, Republic of Korea

Optical synchronization system has been developed for higher quality PAL XFEL with low timing jitter since 2011. In last two years, laboratory test was successfully performed, and test in our accelerator environment is ongoing. In laboratory, we tested the synchronization of RF master oscillator and optical master oscillator, the stabilization of 610 m optical fiber link, and the remote optical-to-RF conversion. We report recent our development results and summarize on-going optical timing project.

Poster WEPC38 [3.366 MB]

WEPF07

Profile Grid Monitor and First Measurement Results at the MedAustron Accelerator

controls, CERN, ion, beam-transport

822

M. Repovz, A. Gyorgy, A. Kerschbaum, F. Osmic, S.M. Schwarz
EBG MedAustron, Wr. Neustadt, Austria
G. Burtin
CERN, Geneva, Switzerland

MedAustron is an ion beam therapy center located in Wiener Neustadt, Austria. The design is based on CERN’s Proton-Ion Medical Machine Study and the project is currently in the installation and commissioning phase. This paper summarizes the design, production and commissioning of MedAustron’s beam profile grid monitor. This monitor measures the beam profile in the low and medium energy beam transfer line where the beam dimensions can be as large as 100 mm. Reasonable position resolution is achieved with a harp consisting of 64 wires per plane and a pitch of up to 1.7 mm. Special effort was needed to produce such harps and bring the signal cables out of the vacuum. As the readout electronics has to cope with DC as well as pulsed beam all 128 wires are acquired simultaneously. This is achieved by integrating the charge during the “flat-top” of the beam pulse and storing it for serial transmission to the back end electronics for conversion. The high accuracy requires calibration of offset and amplification errors for every single channel. A NI PXI FPGA card controls the readout chain. The code for controlling the readout, including the graphical interface, is written in NI LabView.