IPAC2017 - Classification: 06 Beam Instrumentation, Controls, Feedback and Operational Aspects / T05 Beam Feedback Systems

Paper	Title	Page
TUPAB103	Orbit Correction With Path Length Compensation Based on Rf Frequency Adjusments in TPS	1553
	P.C. Chiu, K.T. Hsu, K.H. Hu, C.H. Huang, C.-C. Kuo, C.C. Liang, Y.-C. Liu, H.-J. Tsai, F.H. Tseng NSRRC, Hsinchu, Taiwan
	The 3 GeV Taiwan Photon Source has been routinely operated for public users since September 2016. Orbit reproducibility and stability are critical for the quality of user experiments. Ambient temperature variations and earth tides can cause a change in circumference, changing in turn the beam energy, and orbit drift. Therefore both, orbit correction and rf frequency adjustments are necessary to keep the ring circumference constant. A Fast Orbit Feedback (FOFB) system combined with rf frequency correction deduced from the fast corrector strengths is applied to the FOFB routine. The correlation between the measured frequency variation with ambient temperature and earth tides is also reported in this article.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB103
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK040	Commissioning of the Fast Orbit Feedback System at the Australian Synchrotron	1770
	Y.E. Tan, S. Chen, T.D. Cornall, A. Michalczyk, A. C. Starritt, E.J. Vettoor SLSA, Clayton, Australia B. Dickson Arrayware Pty Ltd, Scoresby, Australia D.J. Peake DETECT Australia, Bundoora, Australia D.O. Tavares LNLS, Campinas, Brazil
	An FPGA based fast orbit feedback system developed at the Australian Synchrotron aims to improve the stability of the electron beam by reducing the impact of moving insertion devices and targeting orbit perturbations at the mains frequency (50 Hz, 100 Hz and 300 Hz). The feedback system uses a PI controller with harmonic suppressors in parallel to specifically target perturbations at the mains frequency and its harmonics. This report will present the results of the commissioning of the FOFB system demonstrating a reduction in the integrated RMS motion up to 300 Hz by 75% to 90%.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK040
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK041	Cleaning of Parasitic Bunches for Time Structured Filling of the ESRF Storage Ring During Top Up Operation	1774
	E. Plouviez, L. Farvacque, J.M. Koch, T.P. Perron, B. Roche, K.B. Scheidt, R. Versteegen, S.M. White ESRF, Grenoble, France
	In order to generate time structured synchrotron radiation the 6GeV ESRF storage ring can be operated with 16 buckets filled with 15nC separated by 16 gaps of 61 nearly perfectly empty buckets. The contrast required by some users between the population of the main and empty buckets is 10¹¹. In order to obtain these empty buckets some RF knock out (cleaning) of the parasitic bunches is needed. Until now this cleaning was performed on the beam stored in the storage ring. Recently we have started to deliver this 16 bunches filling in a so called top up mode, drastically increasing the rate of the storage ring refills. In this top up mode it is very penalizing to perform the cleaning in the storage ring so we are now performing it in the booster synchrotron which accelerates the 200MeV beam coming from the linac up to 6GeV. We describe the set up used to perform the cleaning in the booster and all the measurement and experiments performed in order to correctly understand the origin of the unwanted electrons populating buckets of the gaps separating the 16 main bunches.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK041
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK045	Closed Orbit Feedback for FAIR - Prototype Tests at SIS18	1784
	B.R. Schlei, H. Liebermann, D. Ondreka, P.J. Spiller, R.J. Steinhagen GSI, Darmstadt, Germany
	A new steering software for cycle-to-cycle closed orbit as well as trajectory control is currently under development for FAIR's planned control system. It has been successfully tested with beam at the SIS18 in 2016. COAT (i.e., Controlling Orbits And Trajectories) has been realized as a distributed, Java-based application. It consists of a background daemon process that handles the actual beam-based feedback logic, and independent clients that provide visualization and various user-interaction capabilities. Built on top of the LSA settings management system, code-shared and also used at CERN, the system is kept generic. Furthermore, it is designed to support multiple accelerators, transfer lines and users in parallel. In particular, it can handle continuously changing optics and other in advance known changing beam parameters. The COAT computer program is part of a set of newly developed beam-based feedback tools* for FAIR. Preliminary results of our proof-of-concept prototype studies indicate, e.g., in view of the observed SIS18 machine reproducibility, that such a cycle-to-cycle feedback control scheme may be adequate also for the other FAIR accelerators and transfer lines. *see separate contribution by R. J. Steinhagen et al.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK045
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK046	Beam-Based Feedbacks for FAIR - Prototyping at the SIS18	1787
	R.J. Steinhagen, J. Fitzek, H.C. Hüther, H. Liebermann, R. Müller, D. Ondreka, H. Reeg, B.R. Schlei, P.J. Spiller GSI, Darmstadt, Germany
	The 'Facility for Anti-Proton and Ion Research' (FAIR) presently under construction, extends and supersedes GSI's existing infrastructure. Its core challenges include the precise control of highest proton and uranium ion beam intensities, the required extreme high vacuum conditions, machine protection and activation issues while providing a high degree of multi-user mode of operation with facility reconfiguration on time-scales of a few times per week. To optimise turn-around times and to establish a safe and reliable machine operation, a comprehensive suite of semi-automated measurement applications, as well as fully-automated beam-based feedbacks will be deployed, covering the control of orbit, Q/Q', spill structure, optics, and other machine parameters. These systems are based on the LSA settings management framework, code-shared with and also used at CERN. The concepts, software architecture and first prototype beam tests at the SIS18 in 2016 are presented. As an initial proof-of-concept, a cycle-to-cycle orbit* and macro-spill feedback, as well as a semi-automated magnetic quadrupole- and sextupole-centre measurement tool have been selected. *results presented in separate contribution
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK046
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK048	Longitudinal Beam Stabilization at FAIR by Means of a Derivative Estimation	1795
	B.R. Reichardt, D. Domont-Yankulova Technische Universität Darmstadt (TU Darmstadt, RMR), Darmstadt, Germany D. Domont-Yankulova, H. Klingbeil TEMF, TU Darmstadt, Darmstadt, Germany H. Klingbeil, D.E.M. Lens GSI, Darmstadt, Germany
	Funding: Supported by the GSI During acceleration in SIS18/SIS100 at GSI/FAIR longitudinal beam-oscillations are expected to occur. To reduce emittance blow-up, dedicated LLRF beam feedback systems are planned. To date longitudinal beam oscillations have been damped in machine experiments with a finite-impulse-response (FIR) filter controller with 3 filter taps[1]. An alternative approach implementing the FIR filter as a derivative estimator controller is simulated and tested. This approach shares the same controller topology and can therefore be easily integrated in the system. It exploits the fact that the sampling rate of the feedback hardware is considerably higher than the frequency of the beam oscillations. It is therefore capable of damping oscillations without overshoot within one oscillation period.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK048
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK050	COSY Slow Orbit Feedback System	1802
	M. Simon, M. Bai, C. Böhme, F. Hinder, B. Lorentz, C. Weidemann FZJ, Jülich, Germany J. Bobnar, J. Malec, R. Modic, K. Žagar Cosylab, Ljubljana, Slovenia A. Marusic BNL, Upton, Long Island, New York, USA
	The Cooler Synchrotron (COSY) at Forschungszentrum Jülich is currently carrying out the preparation for a direct measurement of the electric Dipole Moment (EDM) of the deuteron using an RF Wien filter,. In a magnetic storage ring with the spin vector aligned along the direction of motion, the EDM manifests in a buildup of the vertical spin component. Besides this signal, radial magnetic fields due to a distortion of the vertical closed orbit can produce a similar signal. This signal is a systematic limit of the proposed measurement procedure. Based on simulation studies*, a vertical closed orbit distortion with a RMS smaller than 0.1 mm is required to achieve a sensitivity of 10^-19 e.cm or better. In order to accomplish this challenging goal, a slow orbit feedback system was proposed and recently commissioned at COSY. The design and commissioning results will be presented, and the future plan will also be discussed. A. Lehrach et. al, arXiv:1201.5773 [hep-ex]. W. M. Morse, Y. F. Orlov and Y. K. Semertzidis, PRSTAB 16, no.11, 114001 (2013). * M. Rosenthal, Ph.D. thesis, RWTH Aachen University, 2016, available from http://collaborations.fz-juelich.de/ikp/jedi/public_files/theses/Thesis_MRosenthal.pdf
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK050
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK053	A Broadband Transverse Kicker Prototype for Intra-Bunch Feedback in the CERN SPS	1812
	M. Wendt, I.A. Alonso Romero, S.J. Calvo, W. Höfle, O.R. Jones, E. Montesinos CERN, Geneva, Switzerland
	A transverse intra-bunch feedback system is currently under study at CERN for the SPS, to mitigate beam instabilities caused by electron clouds and coupled transverse modes (TMCI). This feedback system is designed for a bandwidth of 1 GHz, and based on a digital feedback controller and broadband power amplifiers. For the kicker, a periodic, quasi-TEM slotted transmission-line structure is foreseen which promises to meet the bandwidth requirements. This paper discusses the electromagnetic design and the mechanical implementation of a prototype kicker, demonstrating its performance and limitations based on numerical simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK053
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK059	Recent Progress of Dithering System at SuperKEKB	1827
	Y. Funakoshi, H. Fukuma, T. Kawamoto, M. Masuzawa, S. Nakamura, K. Ohmi, T. Oki, S. Uehara KEK, Ibaraki, Japan P. Bambade, D. El Khechen, D. Jehanno, V. Kubytskyi, C. Rimbault LAL, Orsay, France A.S. Fisher SLAC, Menlo Park, California, USA U. Wienands ANL, Argonne, Illinois, USA
	Recent progress of the dithering system at SuperKEKB is described. Some details of the system layout are shown. Beam orbit and optics related issues are discussed. Preliminary tests of the some components in the Phase 1 beam commissioning or in the bench are described.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK059
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK091	Simulation Tools for the Design and Performance Evaluation of Transverse Feedback Systems	1912
	J. Komppula, W. Höfle, K.S.B. Li CERN, Geneva, Switzerland
	Transverse feedback systems are used in synchrotrons and storage rings to damp injection oscillations and suppress transverse instabilities. Especially instabilities driven by high intensity beams in future circular colliders such as the FCC set challenging requirements for transverse feedback systems. In order to develop a transverse feedback system able to meet those requirements, sophisticated simulation tools are required. For this purpose, a new modular framework for modeling a transverse feedback system has been developed in Python. The framework can be used as a transverse feedback module in the macro-particle beam dynamics simulation code PyHEADTAIL or as a separate tool for studying a feedback model from a control theory point of view by using a simple signal models for the beam. The main principle of the code is presented and simulation methods used for the conceptual design of the FCC are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK091
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK093	Sensitivity of the LHC Transverse Feedback System to Intra-Bunch Motion	1916
	G. Kotzian, W. Höfle, D. Valuch CERN, Geneva, Switzerland
	The LHC Transverse Feedback System is designed to damp and counteract all possible coupled bunch modes between the lowest betatron frequency and 20 MHz. The present study reveals that the analogue frontend processing scheme based on down converting the pick-up signal at the LHC RF frequency to baseband considerably extends the detected bunch movements visible to the feedback system to beyond 1 GHz. We develop an analytical model of the signal processing chain to explore the impact of even-symmetric and odd-symmetric intra-bunch movements on the detected beam position as a function of the longitudinal bunch shape. A set of equations is derived suitable for numerical simulations, or as a complement in particle tracking codes to further refine the behaviour of the LHC transverse feedback system.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK093
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK094	Transverse Feedback Parameter Extraction from Excitation Data	1920
	G. Kotzian CERN, Geneva, Switzerland
	In this paper we present a simple and fast approach to extract essential parameters of a transverse feedback system such as phase advances between pick-ups and kickers, fractional tune, kicker delay, or per-bunch transverse activity from discrete-time samples of position signals. In this approach the beam is excited and subsequent beam oscillations are recorded. Given that any number of pick-ups can be evaluated at once with only a marginal increase of transverse beam size this method is suitable for regular health checks of a transverse feedback system, e.g., for every injection. The fundamental idea relies on the reconstruction of the transverse phase space by means of digital filters. We sketch a simple mathematical model to illustrate the underlying method. Examples are given together with a set of filter kernels for the fractional tunes of the LHC transverse feedback system.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK094
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK095	Possibilities for Transverse Feedback Phase Adjustment by Means of Digital Filters	1924
	G. Kotzian CERN, Geneva, Switzerland
	In transverse feedback systems a phase adjustment is generally required to convert a beam position signal from a pick-up into a momentum correction signal used by a transverse kicker. In this paper we outline several possibilities for phase adjustments using only single pick-ups or the vector combination of two pick-ups. Analytical expressions are given as a function of the fractional tune and the betatron phase advance between the pick-up location and the kicker. The shortest possible digital filter is formulated, including a notch for closed orbit suppression and a free parameter to adjust for betatron phase. We introduce a novel, fully parametrized digital filter with the feature to be insensitive to variations in fractional tune. Examples are given for the SPS transverse feedback system and compared with measurements.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK095
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK096	Data-Driven Controller Design for High Precision Pulsed Power Converters for Bumper Magnets of the PS Booster	1928
	A. Nicoletti, M. Martino CERN, Geneva, Switzerland
	A new data-driven approach using the frequency response function of a system is proposed for designing robust digital controllers for the injection bumper magnet (BSW) power supplies of the PS Booster. The powering of the BSW requires high precision 3.4 kA to 6.7 kA trapezoidal current pulses with 2 ms flat-top and 5 ms ramp-up and ramp-down time. The tracking error must remain within ± 50 parts-per-million (ppm) during the flat-top of the trapezoidal reference, and ± 500 ppm during the ramp-down. The BSW is powered with a four quadrant switch-mode power converter and the current through the magnet is controlled in closed-loop form with a 2-degree-of-freedom controller at a sampling rate of 10 kHz. A convex optimization algorithm is performed for obtaining the controller parameters. The effectiveness of the method is illustrated by designing the controller for a full-scale prototype of the BSW system at CERN, which is in the framework of the LHC Injector Upgrade (LIU) project.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK096
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK097	Improving the Performance of an Orbit Feed-forward Based on Quadrupole Motion at the KEK ATF	1931
	D.R. Bett, C. Charrondière, M. Patecki, J. Pfingstner, D. Schulte, R. Tomás CERN, Geneva, Switzerland P. Burrows, G.B. Christian, C. Perry JAI, Oxford, United Kingdom A. Jeremie IN2P3-LAPP, Annecy-le-Vieux, France K. Kubo, S. Kuroda, T. Naito, T. Okugi, T.T. Tauchi, N. Terunuma KEK, Ibaraki, Japan
	The high luminosity requirement for a future linear collider sets a demanding limit on the beam quality at the Interation Point (IP). Even the natural motion of the ground could misalign the quadrupole magnets to such an extent that the resulting dipole kicks would require compensation. The novel technique described in this paper uses seismometers to measure the positions of the quadrupole magnets in real time and a kicker to counteract the effect of their misalignment. The prototype system deployed at the Accelerator Test Facility (ATF) at KEK in Japan has already demonstrated a reduction in the pulse-to-pulse vertical position jitter of the beam by about 10%. Based on the observed correlation of the beam position to the quadrupole positions the maximum possible jitter reduction from such a system is estimated to be about 25%. This paper details the latest improvements made to the system with the aim of achieving this limit.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK097
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK105	The Design Improvement of Horizontal Stripline Kicker in TPS Storage Ring	1961
	P.J. Chou, C.K. Chan, C.-C. Chang, K.T. Hsu, K.H. Hu, C.K. Kuan, I.C. Sheng NSRRC, Hsinchu, Taiwan
	We plan to replace the existing horizontal stripline kicker of the transverse feedback system with an improved design. Large reflected power was observed at the downstream port of stripline kicker driven by the feedback amplifier. A rapid surge of vacuum pressure was observed when we tested the high current operation in TPS storage ring in April 2016. A burned feedthrough of the horizontal stripline kicker was discovered during a maintenance shutdown. The improved design is targeted to reduce the reflection of driving power from feedback system and to reduce beam induced RF heating. This major modification of the design is described. The results of RF simulation performed with the electromagnetic code GdfidL are reported as well.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK105
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK110	Optimisation of a High-Resolution, Low-Latency Stripline Beam Position Monitor System for Use in Intra-Train Feedback	1979
	N. Blaskovic Kraljevic, R.M. Bodenstein, T. Bromwich, P. Burrows, G.B. Christian, C. Perry, R.L. Ramjiawan JAI, Oxford, United Kingdom D.R. Bett CERN, Geneva, Switzerland
	A high-resolution, low-latency beam position monitor (BPM) system has been developed for use in feedback systems at particle accelerators and beamlines that operate with trains of particle bunches with bunch separations as low as several tens of nanoseconds, such as future linear electron-positron colliders and free-electron lasers. The system was tested with electron beams in the extraction line of the Accelerator Test Facility at the High Energy Accelerator Research Organization (KEK) in Japan. The fast analogue front-end signal processor is based on a single-stage RF down-mixer, with a measured latency of 15.6 ± 0.1 ns. The processor has been optimised, doubling the maximum operating beam intensity up to 1.6 nC, and the signal processing in the custom digital acquisition board has been upgraded in order to improve the resolution beyond the 300 nm level measured previously. The latest results, demonstrating a position resolution of order 150 nm with single-pass beam, will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK110
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK111	IP Feedback Ground Motion Simulation Studies for the ILC	1983
	R.M. Bodenstein, N. Blaskovic Kraljevic, T. Bromwich, P. Burrows, G.B. Christian, C. Perry, R.L. Ramjiawan JAI, Oxford, United Kingdom J. Pfingstner CERN, Geneva, Switzerland
	The International Linear Collider (ILC), as described in its Technical Design Report (TDR), must maintain strict control of its electron and positron beams in order to achieve the desired luminosity at each of its proposed center-of-mass energies. Controlling the beam parameters requires a dynamic system, capable of adjusting to a myriad of perturbations and errors. One of the components used to control the beam is the Interaction Point (IP) feedback system, which is used to dynamically steer the beams back into collision within nanoseconds. This work will show the simulation of the IP Feedback system's compensation for ground motion model K at the ILC.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK111
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK112	Progress Towards Nanometre-Level Beam Stabilisation Using a Cavity BPM System at ATF2	1986
	T. Bromwich, N. Blaskovic Kraljevic, R.M. Bodenstein, P. Burrows, G.B. Christian, C. Perry, R.L. Ramjiawan JAI, Oxford, United Kingdom
	A low-latency feedback system has been designed and tested to achieve inter-bunch position stabilisation at the final focus of the Accelerator Test Facility (ATF2) at KEK. This system has now been enhanced through the use of position information from two cavity beam position monitors (BPMs) to enable beam stabilisation at a third, intermediate location where a witness BPM measures the correction. Low-Q cavity BPMs were used, along with custom signal processing electronics designed for low latency and optimal position resolution. A custom stripline kicker, power amplifier and digital feedback board were used to provide beam correction and feedback control. The system was tested in single-pass, multi-bunch mode with the aim of providing inter-bunch beam stabilisation on electron bunches of charge ~1 nC separated in time by 280 ns. In 2015 a single BPM feedback system demonstrated beam stabilisation to below 75 nm. To date the two BPM input feedback system has demonstrated beam stabilisation to 83 ± 6 nm. This performance is limited by the current understanding of the cavity BPM resolution. Work will be described with the aim of improving this result.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK112
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK113	Performance of the Fast Orbit Feedback System with the Double-Double Bend Achromat Installed in Diamond Light Source	1989
	S. Gayadeen, G. Rehm DLS, Oxfordshire, United Kingdom
	At Diamond Light Source, the Double-Double Bend Achromat (DDBA) lattice upgrade involved the conversion of one cell of the storage ring from a double bend achromat (DBA) structure to a double-DBA (DDBA). The new cell includes corrector magnets that are different in design to the DBA corrector magnets. The DDBA vacuum chamber cross section is also different from the DBA cells and includes both stainless steel and copper sections over which corrector magnets are fitted. The performance of the Fast Orbit Feedback (FOFB) used for electron beam stabilisation with the DDBA cell installed is presented in this paper. Firstly the different corrector magnet dynamic responses are characterised and secondly the closed loop performance of the FOFB is measured and analysed for the upgraded lattice.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK113
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK114	First Experiences with the Longitudinal Feedback System at Diamond Light Source	1992
	A.F.D. Morgan, M.G. Abbott, G. Rehm DLS, Oxfordshire, United Kingdom
	In order to avoid longitudinal multibunch instabilities potentially caused by the addition of normal conducting RF cavities into the Diamond storage ring, a longitudinal feedback was installed. The main components are newly developed feedback electronics, in-house built modulator and amplifier, and a low Q kicker cavity. This paper describes the performance of the cavity as well as the full longitudinal feedback system as it is installed on the machine and tested before the installation of the normal conducting RF cavities.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK114
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK116	Injection Bucket Jitter Compensation Using Phase Lock System at Fermilab Booster	1999
	K. Seiya, S. Chaurize, C.C. Drennan, W. Pellico Fermilab, Batavia, Illinois, USA
	Phase synchronization between Booster extraction and Recycler injection has been done with the phase lock loop at Booster extraction. The phase Lock Loop control rf phase by changing radial position at extraction and it causes ± one bucket error, not phase error at Recycler injection. By switching a mode of operation for the phase lock loop by measuring the extraction gap position, the jitter was eliminated. The beam loss at the Recycler injection was reduced by 20%. Beam studies and the phase lock system will be discussed in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK116
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK119	Control of Intra-Bunch Vertical Instabilities at the SPS - Measurements and Technology Demonstration	2005
	J.D. Fox, J.E. Dusatko, C.H. Rivetta, O. Turgut SLAC, Menlo Park, California, USA H. Bartosik, W. Höfle, K.S.B. Li, E. Métral, B. Salvant, U. Wehrle CERN, Geneva, Switzerland S. De Santis LBNL, Berkeley, California, USA
	Funding: Work supported by the U.S. Department of Energy under contract # DOE-AC02-76SF00515, the US LHC Accelerator Research Program ( LARP), the FP7 High Luminosity LHC Project and the US-Japan Cooperative Program in High Energy Physics We present recent measurements demonstrating control of unstable beam motion in single bunch and bunch train configurations at the SPS. The work is motivated by anticipated intensity increases from the LIU and HL-LHC upgrade programs, and has included the development of a GHz bandwidth reconfigurable 4 GS/S signal processor with wideband kickers and associated amplifiers. The system was operated at 3.2GS/s with 16 samples across a 5 ns RF bucket (4.2 ns bunch at injection). The experimental results confirm damping of intra-bunch instabilities in both Q20 and Q26 optics configurations for intensities of 2x10¹¹ P/bunch. Instabilities with growth times of 200 turns are well-controlled from injection, consistent with the achievable gains for the 2 installed stripline kickers with 1 kW broadband power. Measurements from multiple studies in single-bunch and bunch train configurations show achieved damping rates, control of multiple intra-bunch modes, behavior of the system at injection and final damped noise floor. We present an analysis method to study the relative phase of slice motion during a transient to discriminate between TMCI and other types of Head-Tail instabilities.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK119
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK122	Bunch-by-Bunch Feedback Kickers for SPEAR3	2012
	K. Tian, W.J. Corbett, J.D. Fox, S.M. Gierman, R.O. Hettel, X. Huang, A.K. Krasnykh, N. Kurita, D.J. Martin, J.A. Safranek, J.J. Sebek SLAC, Menlo Park, California, USA Q. Lin DongHua University, Songjiang, People's Republic of China D. Teytelman Dimtel, San Jose, USA
	SPEAR3 operates with a large cross-section copper vacuum chamber, mode-damped RF cavities and low-impedance insertion devices. As a result, the beam is passively stable for 280-bunch circulating beam current up to 500ma when the background gas pressure is low. In the future, more small-gap insertion devices will be installed and plans are underway to implement resonant bunch-crabbing for the ultrafast x-ray research program. These requirements drive the need for a fast, bunch-by-bunch feedback system to control beam instabilities, remove unwanted satellite bunches and resonantly crab select bunches on demand. In this paper we present a conceptual design for the transverse bunch-by-bunch stripline kickers.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK122
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Orbit Correction With Path Length Compensation Based on Rf Frequency Adjusments in TPS

1553

P.C. Chiu, K.T. Hsu, K.H. Hu, C.H. Huang, C.-C. Kuo, C.C. Liang, Y.-C. Liu, H.-J. Tsai, F.H. Tseng
NSRRC, Hsinchu, Taiwan

The 3 GeV Taiwan Photon Source has been routinely operated for public users since September 2016. Orbit reproducibility and stability are critical for the quality of user experiments. Ambient temperature variations and earth tides can cause a change in circumference, changing in turn the beam energy, and orbit drift. Therefore both, orbit correction and rf frequency adjustments are necessary to keep the ring circumference constant. A Fast Orbit Feedback (FOFB) system combined with rf frequency correction deduced from the fast corrector strengths is applied to the FOFB routine. The correlation between the measured frequency variation with ambient temperature and earth tides is also reported in this article.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB103

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK040

Commissioning of the Fast Orbit Feedback System at the Australian Synchrotron

1770

Y.E. Tan, S. Chen, T.D. Cornall, A. Michalczyk, A. C. Starritt, E.J. Vettoor
SLSA, Clayton, Australia
B. Dickson
Arrayware Pty Ltd, Scoresby, Australia
D.J. Peake
DETECT Australia, Bundoora, Australia
D.O. Tavares
LNLS, Campinas, Brazil

An FPGA based fast orbit feedback system developed at the Australian Synchrotron aims to improve the stability of the electron beam by reducing the impact of moving insertion devices and targeting orbit perturbations at the mains frequency (50 Hz, 100 Hz and 300 Hz). The feedback system uses a PI controller with harmonic suppressors in parallel to specifically target perturbations at the mains frequency and its harmonics. This report will present the results of the commissioning of the FOFB system demonstrating a reduction in the integrated RMS motion up to 300 Hz by 75% to 90%.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK040

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK041

Cleaning of Parasitic Bunches for Time Structured Filling of the ESRF Storage Ring During Top Up Operation

1774

E. Plouviez, L. Farvacque, J.M. Koch, T.P. Perron, B. Roche, K.B. Scheidt, R. Versteegen, S.M. White
ESRF, Grenoble, France

In order to generate time structured synchrotron radiation the 6GeV ESRF storage ring can be operated with 16 buckets filled with 15nC separated by 16 gaps of 61 nearly perfectly empty buckets. The contrast required by some users between the population of the main and empty buckets is 10¹¹. In order to obtain these empty buckets some RF knock out (cleaning) of the parasitic bunches is needed. Until now this cleaning was performed on the beam stored in the storage ring. Recently we have started to deliver this 16 bunches filling in a so called top up mode, drastically increasing the rate of the storage ring refills. In this top up mode it is very penalizing to perform the cleaning in the storage ring so we are now performing it in the booster synchrotron which accelerates the 200MeV beam coming from the linac up to 6GeV. We describe the set up used to perform the cleaning in the booster and all the measurement and experiments performed in order to correctly understand the origin of the unwanted electrons populating buckets of the gaps separating the 16 main bunches.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK041

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK045

Closed Orbit Feedback for FAIR - Prototype Tests at SIS18

1784

B.R. Schlei, H. Liebermann, D. Ondreka, P.J. Spiller, R.J. Steinhagen
GSI, Darmstadt, Germany

A new steering software for cycle-to-cycle closed orbit as well as trajectory control is currently under development for FAIR's planned control system. It has been successfully tested with beam at the SIS18 in 2016. COAT (i.e., Controlling Orbits And Trajectories) has been realized as a distributed, Java-based application. It consists of a background daemon process that handles the actual beam-based feedback logic, and independent clients that provide visualization and various user-interaction capabilities. Built on top of the LSA settings management system, code-shared and also used at CERN, the system is kept generic. Furthermore, it is designed to support multiple accelerators, transfer lines and users in parallel. In particular, it can handle continuously changing optics and other in advance known changing beam parameters. The COAT computer program is part of a set of newly developed beam-based feedback tools* for FAIR. Preliminary results of our proof-of-concept prototype studies indicate, e.g., in view of the observed SIS18 machine reproducibility, that such a cycle-to-cycle feedback control scheme may be adequate also for the other FAIR accelerators and transfer lines.
*see separate contribution by R. J. Steinhagen et al.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK045

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK046

Beam-Based Feedbacks for FAIR - Prototyping at the SIS18

1787

R.J. Steinhagen, J. Fitzek, H.C. Hüther, H. Liebermann, R. Müller, D. Ondreka, H. Reeg, B.R. Schlei, P.J. Spiller
GSI, Darmstadt, Germany

The 'Facility for Anti-Proton and Ion Research' (FAIR) presently under construction, extends and supersedes GSI's existing infrastructure. Its core challenges include the precise control of highest proton and uranium ion beam intensities, the required extreme high vacuum conditions, machine protection and activation issues while providing a high degree of multi-user mode of operation with facility reconfiguration on time-scales of a few times per week. To optimise turn-around times and to establish a safe and reliable machine operation, a comprehensive suite of semi-automated measurement applications, as well as fully-automated beam-based feedbacks will be deployed, covering the control of orbit, Q/Q', spill structure, optics, and other machine parameters. These systems are based on the LSA settings management framework, code-shared with and also used at CERN. The concepts, software architecture and first prototype beam tests at the SIS18 in 2016 are presented. As an initial proof-of-concept, a cycle-to-cycle orbit* and macro-spill feedback, as well as a semi-automated magnetic quadrupole- and sextupole-centre measurement tool have been selected.
*results presented in separate contribution

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK046

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK048

Longitudinal Beam Stabilization at FAIR by Means of a Derivative Estimation

1795

B.R. Reichardt, D. Domont-Yankulova
Technische Universität Darmstadt (TU Darmstadt, RMR), Darmstadt, Germany
D. Domont-Yankulova, H. Klingbeil
TEMF, TU Darmstadt, Darmstadt, Germany
H. Klingbeil, D.E.M. Lens
GSI, Darmstadt, Germany

Funding: Supported by the GSI
During acceleration in SIS18/SIS100 at GSI/FAIR longitudinal beam-oscillations are expected to occur. To reduce emittance blow-up, dedicated LLRF beam feedback systems are planned. To date longitudinal beam oscillations have been damped in machine experiments with a finite-impulse-response (FIR) filter controller with 3 filter taps[1]. An alternative approach implementing the FIR filter as a derivative estimator controller is simulated and tested. This approach shares the same controller topology and can therefore be easily integrated in the system. It exploits the fact that the sampling rate of the feedback hardware is considerably higher than the frequency of the beam oscillations. It is therefore capable of damping oscillations without overshoot within one oscillation period.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK048

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK050

COSY Slow Orbit Feedback System

1802

M. Simon, M. Bai, C. Böhme, F. Hinder, B. Lorentz, C. Weidemann
FZJ, Jülich, Germany
J. Bobnar, J. Malec, R. Modic, K. Žagar
Cosylab, Ljubljana, Slovenia
A. Marusic
BNL, Upton, Long Island, New York, USA

The Cooler Synchrotron (COSY) at Forschungszentrum Jülich is currently carrying out the preparation for a direct measurement of the electric Dipole Moment (EDM) of the deuteron using an RF Wien filter*,**. In a magnetic storage ring with the spin vector aligned along the direction of motion, the EDM manifests in a buildup of the vertical spin component. Besides this signal, radial magnetic fields due to a distortion of the vertical closed orbit can produce a similar signal. This signal is a systematic limit of the proposed measurement procedure. Based on simulation studies***, a vertical closed orbit distortion with a RMS smaller than 0.1 mm is required to achieve a sensitivity of 10^-19 e.cm or better. In order to accomplish this challenging goal, a slow orbit feedback system was proposed and recently commissioned at COSY. The design and commissioning results will be presented, and the future plan will also be discussed.
* A. Lehrach et. al, arXiv:1201.5773 [hep-ex].
** W. M. Morse, Y. F. Orlov and Y. K. Semertzidis, PRSTAB 16, no.11, 114001 (2013).
*** M. Rosenthal, Ph.D. thesis, RWTH Aachen University, 2016, available from http://collaborations.fz-juelich.de/ikp/jedi/public_files/theses/Thesis_MRosenthal.pdf

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK050

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK053

A Broadband Transverse Kicker Prototype for Intra-Bunch Feedback in the CERN SPS

1812

M. Wendt, I.A. Alonso Romero, S.J. Calvo, W. Höfle, O.R. Jones, E. Montesinos
CERN, Geneva, Switzerland

A transverse intra-bunch feedback system is currently under study at CERN for the SPS, to mitigate beam instabilities caused by electron clouds and coupled transverse modes (TMCI). This feedback system is designed for a bandwidth of 1 GHz, and based on a digital feedback controller and broadband power amplifiers. For the kicker, a periodic, quasi-TEM slotted transmission-line structure is foreseen which promises to meet the bandwidth requirements. This paper discusses the electromagnetic design and the mechanical implementation of a prototype kicker, demonstrating its performance and limitations based on numerical simulations.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK053

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK059

Recent Progress of Dithering System at SuperKEKB

1827

Y. Funakoshi, H. Fukuma, T. Kawamoto, M. Masuzawa, S. Nakamura, K. Ohmi, T. Oki, S. Uehara
KEK, Ibaraki, Japan
P. Bambade, D. El Khechen, D. Jehanno, V. Kubytskyi, C. Rimbault
LAL, Orsay, France
A.S. Fisher
SLAC, Menlo Park, California, USA
U. Wienands
ANL, Argonne, Illinois, USA

Recent progress of the dithering system at SuperKEKB is described. Some details of the system layout are shown. Beam orbit and optics related issues are discussed. Preliminary tests of the some components in the Phase 1 beam commissioning or in the bench are described.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK059

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK091

Simulation Tools for the Design and Performance Evaluation of Transverse Feedback Systems

1912

J. Komppula, W. Höfle, K.S.B. Li
CERN, Geneva, Switzerland

Transverse feedback systems are used in synchrotrons and storage rings to damp injection oscillations and suppress transverse instabilities. Especially instabilities driven by high intensity beams in future circular colliders such as the FCC set challenging requirements for transverse feedback systems. In order to develop a transverse feedback system able to meet those requirements, sophisticated simulation tools are required. For this purpose, a new modular framework for modeling a transverse feedback system has been developed in Python. The framework can be used as a transverse feedback module in the macro-particle beam dynamics simulation code PyHEADTAIL or as a separate tool for studying a feedback model from a control theory point of view by using a simple signal models for the beam. The main principle of the code is presented and simulation methods used for the conceptual design of the FCC are discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK091

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK093

Sensitivity of the LHC Transverse Feedback System to Intra-Bunch Motion

1916

G. Kotzian, W. Höfle, D. Valuch
CERN, Geneva, Switzerland

The LHC Transverse Feedback System is designed to damp and counteract all possible coupled bunch modes between the lowest betatron frequency and 20 MHz. The present study reveals that the analogue frontend processing scheme based on down converting the pick-up signal at the LHC RF frequency to baseband considerably extends the detected bunch movements visible to the feedback system to beyond 1 GHz. We develop an analytical model of the signal processing chain to explore the impact of even-symmetric and odd-symmetric intra-bunch movements on the detected beam position as a function of the longitudinal bunch shape. A set of equations is derived suitable for numerical simulations, or as a complement in particle tracking codes to further refine the behaviour of the LHC transverse feedback system.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK093

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK094

Transverse Feedback Parameter Extraction from Excitation Data

1920

G. Kotzian
CERN, Geneva, Switzerland

In this paper we present a simple and fast approach to extract essential parameters of a transverse feedback system such as phase advances between pick-ups and kickers, fractional tune, kicker delay, or per-bunch transverse activity from discrete-time samples of position signals. In this approach the beam is excited and subsequent beam oscillations are recorded. Given that any number of pick-ups can be evaluated at once with only a marginal increase of transverse beam size this method is suitable for regular health checks of a transverse feedback system, e.g., for every injection. The fundamental idea relies on the reconstruction of the transverse phase space by means of digital filters. We sketch a simple mathematical model to illustrate the underlying method. Examples are given together with a set of filter kernels for the fractional tunes of the LHC transverse feedback system.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK094

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK095

Possibilities for Transverse Feedback Phase Adjustment by Means of Digital Filters

1924

G. Kotzian
CERN, Geneva, Switzerland

In transverse feedback systems a phase adjustment is generally required to convert a beam position signal from a pick-up into a momentum correction signal used by a transverse kicker. In this paper we outline several possibilities for phase adjustments using only single pick-ups or the vector combination of two pick-ups. Analytical expressions are given as a function of the fractional tune and the betatron phase advance between the pick-up location and the kicker. The shortest possible digital filter is formulated, including a notch for closed orbit suppression and a free parameter to adjust for betatron phase. We introduce a novel, fully parametrized digital filter with the feature to be insensitive to variations in fractional tune. Examples are given for the SPS transverse feedback system and compared with measurements.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK095

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK096

Data-Driven Controller Design for High Precision Pulsed Power Converters for Bumper Magnets of the PS Booster

1928

A. Nicoletti, M. Martino
CERN, Geneva, Switzerland

A new data-driven approach using the frequency response function of a system is proposed for designing robust digital controllers for the injection bumper magnet (BSW) power supplies of the PS Booster. The powering of the BSW requires high precision 3.4 kA to 6.7 kA trapezoidal current pulses with 2 ms flat-top and 5 ms ramp-up and ramp-down time. The tracking error must remain within ± 50 parts-per-million (ppm) during the flat-top of the trapezoidal reference, and ± 500 ppm during the ramp-down. The BSW is powered with a four quadrant switch-mode power converter and the current through the magnet is controlled in closed-loop form with a 2-degree-of-freedom controller at a sampling rate of 10 kHz. A convex optimization algorithm is performed for obtaining the controller parameters. The effectiveness of the method is illustrated by designing the controller for a full-scale prototype of the BSW system at CERN, which is in the framework of the LHC Injector Upgrade (LIU) project.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK096

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK097

Improving the Performance of an Orbit Feed-forward Based on Quadrupole Motion at the KEK ATF

1931

D.R. Bett, C. Charrondière, M. Patecki, J. Pfingstner, D. Schulte, R. Tomás
CERN, Geneva, Switzerland
P. Burrows, G.B. Christian, C. Perry
JAI, Oxford, United Kingdom
A. Jeremie
IN2P3-LAPP, Annecy-le-Vieux, France
K. Kubo, S. Kuroda, T. Naito, T. Okugi, T.T. Tauchi, N. Terunuma
KEK, Ibaraki, Japan

The high luminosity requirement for a future linear collider sets a demanding limit on the beam quality at the Interation Point (IP). Even the natural motion of the ground could misalign the quadrupole magnets to such an extent that the resulting dipole kicks would require compensation. The novel technique described in this paper uses seismometers to measure the positions of the quadrupole magnets in real time and a kicker to counteract the effect of their misalignment. The prototype system deployed at the Accelerator Test Facility (ATF) at KEK in Japan has already demonstrated a reduction in the pulse-to-pulse vertical position jitter of the beam by about 10%. Based on the observed correlation of the beam position to the quadrupole positions the maximum possible jitter reduction from such a system is estimated to be about 25%. This paper details the latest improvements made to the system with the aim of achieving this limit.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK097

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK105

The Design Improvement of Horizontal Stripline Kicker in TPS Storage Ring

1961

P.J. Chou, C.K. Chan, C.-C. Chang, K.T. Hsu, K.H. Hu, C.K. Kuan, I.C. Sheng
NSRRC, Hsinchu, Taiwan

We plan to replace the existing horizontal stripline kicker of the transverse feedback system with an improved design. Large reflected power was observed at the downstream port of stripline kicker driven by the feedback amplifier. A rapid surge of vacuum pressure was observed when we tested the high current operation in TPS storage ring in April 2016. A burned feedthrough of the horizontal stripline kicker was discovered during a maintenance shutdown. The improved design is targeted to reduce the reflection of driving power from feedback system and to reduce beam induced RF heating. This major modification of the design is described. The results of RF simulation performed with the electromagnetic code GdfidL are reported as well.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK105

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK110

Optimisation of a High-Resolution, Low-Latency Stripline Beam Position Monitor System for Use in Intra-Train Feedback

1979

N. Blaskovic Kraljevic, R.M. Bodenstein, T. Bromwich, P. Burrows, G.B. Christian, C. Perry, R.L. Ramjiawan
JAI, Oxford, United Kingdom
D.R. Bett
CERN, Geneva, Switzerland

A high-resolution, low-latency beam position monitor (BPM) system has been developed for use in feedback systems at particle accelerators and beamlines that operate with trains of particle bunches with bunch separations as low as several tens of nanoseconds, such as future linear electron-positron colliders and free-electron lasers. The system was tested with electron beams in the extraction line of the Accelerator Test Facility at the High Energy Accelerator Research Organization (KEK) in Japan. The fast analogue front-end signal processor is based on a single-stage RF down-mixer, with a measured latency of 15.6 ± 0.1 ns. The processor has been optimised, doubling the maximum operating beam intensity up to 1.6 nC, and the signal processing in the custom digital acquisition board has been upgraded in order to improve the resolution beyond the 300 nm level measured previously. The latest results, demonstrating a position resolution of order 150 nm with single-pass beam, will be presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK110

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK111

IP Feedback Ground Motion Simulation Studies for the ILC

1983

R.M. Bodenstein, N. Blaskovic Kraljevic, T. Bromwich, P. Burrows, G.B. Christian, C. Perry, R.L. Ramjiawan
JAI, Oxford, United Kingdom
J. Pfingstner
CERN, Geneva, Switzerland

The International Linear Collider (ILC), as described in its Technical Design Report (TDR), must maintain strict control of its electron and positron beams in order to achieve the desired luminosity at each of its proposed center-of-mass energies. Controlling the beam parameters requires a dynamic system, capable of adjusting to a myriad of perturbations and errors. One of the components used to control the beam is the Interaction Point (IP) feedback system, which is used to dynamically steer the beams back into collision within nanoseconds. This work will show the simulation of the IP Feedback system's compensation for ground motion model K at the ILC.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK111

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK112

Progress Towards Nanometre-Level Beam Stabilisation Using a Cavity BPM System at ATF2

1986

T. Bromwich, N. Blaskovic Kraljevic, R.M. Bodenstein, P. Burrows, G.B. Christian, C. Perry, R.L. Ramjiawan
JAI, Oxford, United Kingdom

A low-latency feedback system has been designed and tested to achieve inter-bunch position stabilisation at the final focus of the Accelerator Test Facility (ATF2) at KEK. This system has now been enhanced through the use of position information from two cavity beam position monitors (BPMs) to enable beam stabilisation at a third, intermediate location where a witness BPM measures the correction. Low-Q cavity BPMs were used, along with custom signal processing electronics designed for low latency and optimal position resolution. A custom stripline kicker, power amplifier and digital feedback board were used to provide beam correction and feedback control. The system was tested in single-pass, multi-bunch mode with the aim of providing inter-bunch beam stabilisation on electron bunches of charge ~1 nC separated in time by 280 ns. In 2015 a single BPM feedback system demonstrated beam stabilisation to below 75 nm. To date the two BPM input feedback system has demonstrated beam stabilisation to 83 ± 6 nm. This performance is limited by the current understanding of the cavity BPM resolution. Work will be described with the aim of improving this result.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK112

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK113

Performance of the Fast Orbit Feedback System with the Double-Double Bend Achromat Installed in Diamond Light Source

1989

S. Gayadeen, G. Rehm
DLS, Oxfordshire, United Kingdom

At Diamond Light Source, the Double-Double Bend Achromat (DDBA) lattice upgrade involved the conversion of one cell of the storage ring from a double bend achromat (DBA) structure to a double-DBA (DDBA). The new cell includes corrector magnets that are different in design to the DBA corrector magnets. The DDBA vacuum chamber cross section is also different from the DBA cells and includes both stainless steel and copper sections over which corrector magnets are fitted. The performance of the Fast Orbit Feedback (FOFB) used for electron beam stabilisation with the DDBA cell installed is presented in this paper. Firstly the different corrector magnet dynamic responses are characterised and secondly the closed loop performance of the FOFB is measured and analysed for the upgraded lattice.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK113

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK114

First Experiences with the Longitudinal Feedback System at Diamond Light Source

1992

A.F.D. Morgan, M.G. Abbott, G. Rehm
DLS, Oxfordshire, United Kingdom

In order to avoid longitudinal multibunch instabilities potentially caused by the addition of normal conducting RF cavities into the Diamond storage ring, a longitudinal feedback was installed. The main components are newly developed feedback electronics, in-house built modulator and amplifier, and a low Q kicker cavity. This paper describes the performance of the cavity as well as the full longitudinal feedback system as it is installed on the machine and tested before the installation of the normal conducting RF cavities.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK114

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK116

Injection Bucket Jitter Compensation Using Phase Lock System at Fermilab Booster

1999

K. Seiya, S. Chaurize, C.C. Drennan, W. Pellico
Fermilab, Batavia, Illinois, USA

Phase synchronization between Booster extraction and Recycler injection has been done with the phase lock loop at Booster extraction. The phase Lock Loop control rf phase by changing radial position at extraction and it causes ± one bucket error, not phase error at Recycler injection. By switching a mode of operation for the phase lock loop by measuring the extraction gap position, the jitter was eliminated. The beam loss at the Recycler injection was reduced by 20%. Beam studies and the phase lock system will be discussed in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK116

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK119

Control of Intra-Bunch Vertical Instabilities at the SPS - Measurements and Technology Demonstration

2005

J.D. Fox, J.E. Dusatko, C.H. Rivetta, O. Turgut
SLAC, Menlo Park, California, USA
H. Bartosik, W. Höfle, K.S.B. Li, E. Métral, B. Salvant, U. Wehrle
CERN, Geneva, Switzerland
S. De Santis
LBNL, Berkeley, California, USA

Funding: Work supported by the U.S. Department of Energy under contract # DOE-AC02-76SF00515, the US LHC Accelerator Research Program ( LARP), the FP7 High Luminosity LHC Project and the US-Japan Cooperative Program in High Energy Physics
We present recent measurements demonstrating control of unstable beam motion in single bunch and bunch train configurations at the SPS. The work is motivated by anticipated intensity increases from the LIU and HL-LHC upgrade programs, and has included the development of a GHz bandwidth reconfigurable 4 GS/S signal processor with wideband kickers and associated amplifiers. The system was operated at 3.2GS/s with 16 samples across a 5 ns RF bucket (4.2 ns bunch at injection). The experimental results confirm damping of intra-bunch instabilities in both Q20 and Q26 optics configurations for intensities of 2x10¹¹ P/bunch. Instabilities with growth times of 200 turns are well-controlled from injection, consistent with the achievable gains for the 2 installed stripline kickers with 1 kW broadband power. Measurements from multiple studies in single-bunch and bunch train configurations show achieved damping rates, control of multiple intra-bunch modes, behavior of the system at injection and final damped noise floor. We present an analysis method to study the relative phase of slice motion during a transient to discriminate between TMCI and other types of Head-Tail instabilities.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK119

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPIK122

Bunch-by-Bunch Feedback Kickers for SPEAR3

2012

K. Tian, W.J. Corbett, J.D. Fox, S.M. Gierman, R.O. Hettel, X. Huang, A.K. Krasnykh, N. Kurita, D.J. Martin, J.A. Safranek, J.J. Sebek
SLAC, Menlo Park, California, USA
Q. Lin
DongHua University, Songjiang, People's Republic of China
D. Teytelman
Dimtel, San Jose, USA

SPEAR3 operates with a large cross-section copper vacuum chamber, mode-damped RF cavities and low-impedance insertion devices. As a result, the beam is passively stable for 280-bunch circulating beam current up to 500ma when the background gas pressure is low. In the future, more small-gap insertion devices will be installed and plans are underway to implement resonant bunch-crabbing for the ultrafast x-ray research program. These requirements drive the need for a fast, bunch-by-bunch feedback system to control beam instabilities, remove unwanted satellite bunches and resonantly crab select bunches on demand. In this paper we present a conceptual design for the transverse bunch-by-bunch stripline kickers.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK122

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)