IPAC2011 - List of Keywords (kicker)

Paper	Title	Other Keywords	Page
MOPC077	Commissioning of Multibunch Feedback Systems at the Fast Ramping Stretcher Ring ELSA	synchrotron, cavity, feedback, booster	250
	A. Roth, F. Frommberger, N. Heurich, W. Hillert, M. Schedler, R. Zimmermann ELSA, Bonn, Germany
	Funding: Supported by German Research Foundation through SFB/TR 16 and by Helmholtz Alliance through HA-10¹. At the Electron Stretcher Facility ELSA of Bonn University, an external beam of either unpolarized or polarized electrons is supplied to hadron physics experiments. The ELSA stretcherring operates in the energy range of 1.2 to 3.5 GeV and achieves a duty cycle of up to 80% using a fast energy ramp of 4 GeV/s. Under these conditions, an increase of the internal beam current from an actual value of 20 mA up to 200 mA is planned. Such an upgrade is mainly limited by the excitation of multibunch instabilities. As one active counteraction, we have installed state-of-the-art bunch-by-bunch feedback systems for the longitudinal, as well as for both transverse planes. The detailed setup with all main components and first results of the commissioning of the systems will be presented. In particular, the performance of the longitudinal feedback with a stabilized synchrotron frequency during the fast energy ramp will be discussed.

MOPO003	A Broadband RF Stripline Kicker for Damping Transversal Multibunch Instabilities	impedance, feedback, single-bunch, damping	481
	M. Schedler, D. Heiliger, W. Hillert, A. Roth ELSA, Bonn, Germany
	When operating an RF feedback system, being able to reliably act upon every single bunch is a necessity. By employing a broadband RF stripline kicker, any bunch displacement can be corrected for. In a 500 MHz accelerator, the decay time of the electromagnetic field inside the kicker has to be less than 2 ns in order to avoid the following bunch to be affected. By designing the kicker as an RF coax device matched to the line impedance of the power cables, perturbing reflected signals are avoided. Additionally, the kicking strength and thus the shunt impedance should be maximized over the full spectrum from DC to 250 MHz. The kicker design has been optimized to meet the above requirements by relying on CST Microwave Studio simulations. Their results and first measurements are presented.

MOPO004	A Longitudinal Kicker Cavity for a Bunch-by-bunch Feedback System at ELSA	cavity, simulation, feedback, impedance	484
	N. Heurich, W. Hillert, A. Roth, R. Zimmermann ELSA, Bonn, Germany
	At the Electron Stretcher Facility ELSA of Bonn University, a longitudinal bunch-by-bunch feedback system is currently being installed in order to damp multibunch instabilities and to enable a future intensity upgrade of up to 200 mA. As a main component, a longitudinal kicker cavity was developed and manufactured. The kicker requires a bandwidth of 250~MHz taking into account the bunch spacing of 2 ns at ELSA. Existing designs used at other facilities were optimized in view of the considerably larger bunch lenght at ELSA. The choice of 1.125 GHz as a center frequency is a result of these considerations. With the resulting low quality factor, the design had to be optimized in order to maximize the shunt impedance. The longitudinal feedback is succesfully working with the prototype installed in the stretcher ring. The design and detailed simulations of the geometry are discussed and laboratory measurements are presented.

MOPO005	A Transverse Feedback System using Multiple Pickups for Noise Minimization	pick-up, synchrotron, feedback, betatron	487
	M. Alhumaidi, A.M. Zoubir TU Darmstadt, Darmstadt, Germany
	A new concept for using multiple pickups for estimating beam angle at the kicker is addressed. The estimated signal should be the driving feedback signal. The signals from the different pickups are delayed, such that they correspond to the same bunch. Consequently a weighted sum of the delayed signals is suggested as an estimator of the beam angle at the kicker. The weighting coefficients are calculated such that the estimator is unbiased, i.e. the output corresponds to the actual beam angle at the kicker for non-noisy pickup signals. Furthermore, the estimator must give the minimal noise power at the output among all linear unbiased estimators. Finally results for the heavy ions synchrotron SIS 18 at the GSI are shown.

MOPO007	Resonant Strip-line Type Longitudinal Kicker	simulation, impedance, feedback, wakefield	493
	T. Nakamura JASRI/SPring-8, Hyogo-ken, Japan
	The longitudinal feedback for the SPring-8 storage ring is under consideration as the device for suppression of the longitudinal instabilities driven by higher order modes of cavities, observed at test operation with 4 to 6 GeV low energy beam. As the beam energy and the ring circumference are rather high, and the length of the space for the longitudinal kickers is limited, high efficiency kicker per length is required in the our case. As a candidate of such kicker, we propose a resonant strip-line type longitudinal kicker with drive frequency of 13/4 of RF frequency. The shut impedance per length is higher than over-loaded cavities and the drive circuits can be simplified because of higher drive frequency. The design consideration, the result of the simulation and measurement of the prototype model, and the detail of the drive circuit will be reported in the presentation.

MOPO008	Design and Simulation of the Transverse Feedback Kicker for the HLSⅡ	impedance, feedback, simulation, vacuum	496
	W.B. Li, P. Lu, B.G. Sun, F.F. Wu, Y.L. Yang, Z.R. Zhou USTC/NSRL, Hefei, Anhui, People's Republic of China
	In order to suppress the coupled bunch instabilities in the HLSⅡ storage ring, a transverse feedback system is required. The vital component of the system is the kicker that is the feedback actuator. We design a stripline kicker for the HLSⅡ. The horizontal and vertical electrodes are combined in a structure on account of the space limit. In addition to the design issues, this paper focuses on the simulation results for the kicker using the computer codes. By the 2D code POSSION, we calculate and optimize the characteristic impedance of the stripline kicker to match the 50Ω external transmission lines so as to reduce the reflected power. The reflection coefficient and the shunt impedance in the working frequency range are obtained by the 3D code HFSS. The simulation results provide many important supports for the structure design.

MOPO012	LHC Damper Beam Commissioning in 2010	damping, feedback, injection, ion	505
	W. Höfle, G. Kotzian, M. Schokker, D. Valuch CERN, Geneva, Switzerland
	The LHC transverse dampers were commissioned in 2010 with beam and their use at injection energy of 450 GeV, during the ramp and in collisions at 3.5 TeV for Physics have become part of the standard operations procedure. The system proved important to limit emittance blow-up at injection and maintain smaller than nominal emittances throughout the accelerating cycle. We describe the commissioning of the system step-by-step as done in 2010 and summarize its performance as achieved for proton as well as ion beams in 2010. Although its principle function is to keep transverse oscillations under control, the system has also been used as an exciter for abort gap cleaning and tune measurement. The dedicated beam position measurement system with its low noise properties provides additional possibilities for diagnostics.

MOPO015	Operation Status of Bunch-by-bunch Feedback System in the TLS	feedback, controls, injection, diagnostics	514
	C.H. Kuo, Y.-S. Cheng, P.C. Chiu, K.T. Hsu, K.H. Hu, C.-Y. Liao NSRRC, Hsinchu, Taiwan
	There are several FPGA based bunch-by-bunch feedback systems that were deployed in the Taiwan Light Source now. They play various roles to suppress beam instability. By using SPring-8 designed feedback processors is pioneer to apply in the storage ring of TLS successfully and help Dimtel system to be quick commission. The Dimtel feedback system provide a life spare unit and explore to control system integration especially to the EPICS toolkit system. Rich functionality includes of excitation of individual bunch or specifies bunches, averaged spectrum, tune measurement by the feedback dip in the averaged spectrum. Operation status of the system will be summary in this report.

MOPO017	Latest Performance Results from the FONT5 Intra-train Position and Angle Feedback System at ATF2	feedback, linear-collider, collider, positron	520
	G.B. Christian, D.R. Bett, M.R. Davis, C. Perry JAI, Oxford, United Kingdom R. Apsimon, P. Burrows Oxford University, Physics Department, Oxford, Oxon, United Kingdom B. Constance, A. Gerbershagen CERN, Geneva, Switzerland J. Resta-López IFIC, Valencia, Spain
	A prototype Interaction Point beam-based feedback system for future electron-positron colliders, such as the International Linear Collider, has been designed and tested on the extraction line of the KEK Accelerator Test Facility (ATF). The FONT5 intra-train feedback system aims to stabilize the beam orbit by correcting both the position and angle jitter in the vertical plane on bunch-to-bunch timescales, providing micron-level stability at the entrance to the ATF2 final-focus system. The system comprises three stripline beam position monitors (BPMs) and two stripline kickers, custom low-latency analogue front-end BPM processors, a custom FPGA-based digital processing board with fast ADCs, and custom kicker-drive amplifiers. An overview of the hardware, and the latest results from beam tests at ATF2, will be presented. A total system latency as low as approximately 140 ns has been demonstrated.

MOPS004	Mitigation of Beam Instability due to Space Charge Effects at 3 GeV RCS in J-PARC	impedance, space-charge, bunching, injection	595
	Y. Shobuda, M. Yamamoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan Y.H. Chin KEK, Ibaraki, Japan F. Tamura KEK/JAEA, Ibaraki-Ken, Japan
	In order to accomplish high intensity proton beams, it is important to identify the impedance source in accelerators. At 3 GeV rapid cycling synchrotron (RCS) in Japan Proton Research Complex (J-PARC), the kicker impedance is the most dominant among such impedance sources. Beam instability can be observed by correcting chromaticity during the acceleration. Growth rate due to the beam instability can be reduced by making peak current larger (bunching factor smaller). In other words, it is experimentally found that space charge effects mitigate the beam instability.

MOPS054	Impedance of the Pulse Power Converter for the SIS100 Bipolar Extraction Kicker System	impedance, coupling, simulation, extraction	727
	K. Samuelsson, V. Hinrichsen TU Darmstadt, Darmstadt, Germany U. Blell, P.J. Spiller GSI, Darmstadt, Germany
	SIS100 will be operated with high intensity heavy-ion and proton beams. The reduction of ring impedances is therefore of great importance in order to avoid coherent beam instabilities. The kicker system is one of the main contributors to the overall ring impedance in SIS100. This paper will focus on the contribution of the external network to the kicker impedance. Calculations as well as experimental impedance measurements of the network contribution have already been carried out for the SIS18 and ESR kickers. The SIS100 will be equipped with a bipolar kicker system, which uses a Pulse Forming Network (PFN) as energy storage. For potential detachment purposes an insulation transformer will be installed. Since this setup is new in several ways it is important to know its contribution to the coupling impedance of the kicker system. In this contribution the corresponding numerical calculation is presented.

MOPS057	Beam-beam Interaction under External Force Oscillation	luminosity, positron, simulation, electron	736
	K. Ohmi KEK, Ibaraki, Japan
	Beam-ion interaction is strongly nonlinear. Response for external oscillation applied to beam shows characteristic feature. Simulations for external frequency scan becomes feasible for the recent computer power. We show the frequency response for beam-ion system in KEK-PF and recent low emittance rings.

MOPS059	Transverse Impedance Calculation for Simplified Model of Ferrite Kicker Magnet with Beta < 1	impedance, coupling, extraction, proton	742
	N. Wang, Q. Qin IHEP Beijing, Beijing, People's Republic of China
	In high intensity rings, kicker magnet is usually considered as a main source to the total impedance. Transverse coupling impedance of a simplified kicker model has been derived analytically in the ultrarelativistic limit. We extend the result to the general case of v < c, and present the analytical formulae of both horizontal and vertical transverse impedances. Numerical results are given for the CSNS extraction kicker magnets.

MOPS064	Longitudinal Beam Stability and Related Effects at the ALBA Storage Ring	impedance, resonance, vacuum, injection	748
	T.F. Günzel CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain
	The risk of longitudinal instabilities excited by narrowband and broadband resonator impedance was studied. A campaign for the search of modes trapped in vacuum chamber elements of the ALBA storage ring via electromagnetic simulation was initiated. Several critical vacuum elements in the ring like the vertical scraper, the injection and feedback kickers were identified. The outlets of the injection kicker had to be protected with RF-fingers whereas the scraper only produces dangerous modes in the withdrawn state, both do not pose a real problem. However, the calculated power distribution generated in the feedback kickers could be an obstacle for reaching the nominal current of 400mA. Furthermore, the budget of Z(n)/n of the storage ring was computed and checked on the risk of microwave instability using the Boussard criterion.

MOPS065	Transverse Instability Studies at the ALBA Storage Ring	impedance, vacuum, single-bunch, storage-ring	751
	T.F. Günzel CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain
	In the first phase of the ALBA storage ring operation 3 NEG-coated aluminum chambers, 2 in-vacuum undulators and one wiggler chamber will be installed. Under particular consideration of the multilayer character of these chambers and the injection kickers the thresholds of the transverse mode coupled instability(TMCI) were calculated using MOSES. The thresholds 17.5mA/40.5mA vertical/horizontal leave a rather large operative margin. The detrimental effect of the NEG-coating on the TMCI is relatively limited and on the resistive wall instability is even negligible. As well the thresholds of the head-tail instability were computed as function of chromaticity. Also the incoherent tune shifts generated by the quadrupolar resistive wall wake fields due to the flatness of the vacuum chambers were calculated. The computed results have been compared to first measurements of the storage ring commissioning. Y.H.Chin, MOSES 2.0, CERN/LEP-TH/88-05

MOPS070	Electromagnetic Modeling of C Shape Ferrite Loaded Kickers	impedance, simulation, vacuum, ion	763
	C. Zannini EPFL, Lausanne, Switzerland E. Métral, G. Rumolo, B. Salvant, V.G. Vaccaro, C. Zannini CERN, Geneva, Switzerland
	The kickers are major contributors to the CERN SPS beam coupling impedance. As such, they may represent a limitation to increasing the SPS bunch current in the frame of an intensity upgrade of the LHC. In this paper, analytical approach and CST Particle Studio time domain electromagnetic simulations are performed to obtain the longitudinal and transverse impedances/wake potentials of models of ferrite loaded kickers. It turns out that the existing models are not sufficient to characterize correctly these components from the coupling impedance point of view. In particular the results show that below few hundred MHz the real C-structure of the magnet cannot be neglected. Therefore an analytical model was developed and benchmarked with EM simulations to take into account the C-shape of the magnet.

MOPS072	Broadband Electromagnetic Characterization of Materials for Accelerator Components	impedance, simulation, damping, RF-structure	769
	C. Zannini, A. Grudiev, E. Métral, T. Pieloni, G. Rumolo CERN, Geneva, Switzerland G. De Michele PSI, Villigen, Switzerland C. Zannini EPFL, Lausanne, Switzerland
	Electromagnetic (EM) characterization of materials up to high frequencies is a major requirement for the correct modeling of many accelerator components: collimators, kickers, high order modes damping devices for accelerating cavities. In this scenario, the coaxial line method has gained much importance compared to other methods because of its applicability in a wide range of frequencies. In this paper we describe a new coaxial line method that allows using only one measurement setup to characterize the material in a range of frequency from few MHz up to several GHz. A coaxial cable fed at one side is filled with the material under test and closed on a known load on the other side. The properties of the material are obtained from the measured reflection coefficient by using it as input for a transmission line (TL) model or for 3D EM simulations, which describe the measurements setup. We have applied this method to characterize samples of SiC (Silicon Carbide) which could be used for LHC collimators and for CLIC accelerating structures and NiZn ferrite used for kicker magnets.

MOPS073	Impedance Calculation for Simple Models of Kickers in the Non-ultrarelativistic Regime	impedance, vacuum, coupling, neutron	772
	N. Biancacci, N. Mounet, E. Métral, B. Salvant, C. Zannini CERN, Geneva, Switzerland N. Biancacci, M. Migliorati, A. Mostacci, L. Palumbo Rome University La Sapienza, Roma, Italy Q. Qin, N. Wang IHEP Beijing, Beijing, People's Republic of China
	Kicker magnets are usually significant contributors to the beam coupling impedance of particle accelerators. An accurate understanding of their impedance is required in order to correctly assess the machine intensity limitations. The field matching method derived by H. Tsutsui for the longitudinal and transverse dipolar (driving) impedance of simple models of kickers in the ultrarelativistic regime was already extended to the non-ultrarelativistic case, and to the quadrupolar (detuning) impedance in the ultrarelativistic case. This contribution presents the extension to the quadrupolar impedance in the non-ultrarelativistic case, as well as benchmarks with other available methods to compute the impedance. In particular, all the components of the impedances are benchmarked with Tsutsui's model, i.e. in the ultrarelativistic limit, with the model for a flat chamber impedance recently computed by N. Mounet and E. Métral, in the case of finite relativistic gamma, and with CST Particle Studio simulations.

MOPS078	Coaxial Wire Measurements of Ferrite Kicker Magnets	impedance, simulation, injection, extraction	784
	H.A. Day, R.M. Jones UMAN, Manchester, United Kingdom M.J. Barnes, F. Caspers, H.A. Day, E. Métral, B. Salvant, C. Zannini CERN, Geneva, Switzerland
	Fast kicker magnets are used to inject beam into and eject beam out of the CERN accelerator rings. These kickers are generally transmission line type magnets with a rectangular shaped aperture through which the beam passes. Unless special precautions are taken the impedance of the yoke can provoke significant beam induced heating, especially for high intensities. In addition the impedance may contribute to beam instabilities. The results of longitudinal and transverse impedance measurements, for various kicker magnets, are presented and compared with analytical calculations: in addition predictions from a numerical analysis are discussed.

MOPS079	Simulations of Coaxial Wire Measurements of the Impedance of Asymmetric Structures	impedance, simulation, coupling, synchrotron	787
	H.A. Day, R.M. Jones UMAN, Manchester, United Kingdom F. Caspers, H.A. Day, E. Métral CERN, Geneva, Switzerland
	Coaxial wire measurements have provided a simple and effective way to measure the beam coupling impedance of accelerator structures for a number of years. It has been known how to measure the longitudinal and dipolar transverse impedance using one and two wires for some time. Recently the ability to measure the quadrupolar impedance of structures exhibiting top/bottom and left/right symmetry has been demonstrated. A method for measuring the beam coupling impedance of asymmetric structures using displaced single wires and two wire measurements is proposed. Simulations of the measurement system are presented with further work proposed.

MOPS089	Identification of Bunch Dynamics in the Presence of E-cloud and TMCI for the CERN SPS Ring	simulation, controls, feedback, coupling	811
	O. Turgut, J.D. Fox, C.H. Rivetta, S. Uemura SLAC, Menlo Park, California, USA W. Höfle CERN, Geneva, Switzerland
	Funding: Work is supported by the U.S. Department of Energy under contract DE-AC02-76SF00515 and the US LHC Accelerator Research Program (LARP). Measurements and multi-particle simulation codes (i.e. HEAD-TAIL, WARP, CMAD) indicate that bunched particle beams show unstable motions induced by electron-clouds and strong head-tail interactions. The bunch dynamics exhibits highly non-linear, complex and unstable behavior under certain operating conditions. Feedback control systems have been proposed to mitigate these instabilities in the CERN SPS ring. The design of feedback systems requires the knowledge of a reduced dynamic model of the bunch. It allows to include and quantify the effect of noise and signal perturbations, as well as system robustness to parameter variation. Identification techniques are used to estimate those models based on bunch motion measurements. In this work we present reduced mathematical models representing the transverse bunch dynamics and identification techniques to extract the model parameters based on measurements. These techniques are validated using time domain simulations of the bunch motion conducted using multi-particle simulation codes. For that, different sections of the bunch are driven by random signals, and the vertical motion of those areas is used to estimate the reduced model.

MOPZ004	Studies for the PRISM FFAG Ring for the Next Generation Muon to Electron Conversion Experiment	injection, electron, extraction, septum	826
	J. Pasternak STFC/RAL, Chilton, Didcot, Oxon, United Kingdom M. Aslaninejad, L.J. Jenner, A. Kurup, J. Pasternak, Y. Shi, Y. Uchida Imperial College of Science and Technology, Department of Physics, London, United Kingdom R.J. Barlow UMAN, Manchester, United Kingdom K.M. Hock, B.D. Muratori Cockcroft Institute, Warrington, Cheshire, United Kingdom D.J. Kelliher, S. Machida, C.R. Prior STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom Y. Kuno, A. Sato Osaka University, Osaka, Japan J.-B. Lagrange, Y. Mori KURRI, Osaka, Japan M. Lancaster UCL, London, United Kingdom C. Ohmori KEK, Tokai, Ibaraki, Japan T. Planche TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada S.L. Smith STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom H. Witte, T. Yokoi JAI, Oxford, United Kingdom
	High intensity and high quality muon beams are needed for the next generation lepton flavour violation experiments. Such beams can be produced by sending a short proton pulse to a pion production target, capturing the pions and performing RF phase rotation on the resulting muon beam in an FFAG ring. Such a solution was proposed for the PRISM project and this paper summarizes its current status. In particular the PRISM task force was created to address the accelerator and detector issues that need to be solved in order to realise the PRISM experiment. Alternative designs for the PRISM FFAG ring are discussed and their performance compared. The injection/extraction systems and matching to the solenoid channels upstream and downstream of the FFAG ring are presented. The future direction for the study will be outlined.

MOPZ007	A Non-scaling Fixed Field Alternating Gradient Accelerator for the Final Acceleration Stage of the International Design Study of the Neutrino Factory	extraction, injection, cavity, lattice	832
	J.S. Berg BNL, Upton, Long Island, New York, USA M. Aslaninejad, J. Pasternak Imperial College of Science and Technology, Department of Physics, London, United Kingdom N. Bliss, M.A. Cordwell, T.J. Jones STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom D.J. Kelliher, S. Machida STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom A.A. Muir STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom H. Witte JAI, Oxford, United Kingdom
	Funding: This manuscript has been authored by employees of Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The International Design Study of the Neutrino Factory (IDS-NF) has recently completed its Interim Design Report (IDR), which presents our current baseline design of the neutrino factory. To increase the efficiency and reduce the cost of acceleration, the IDR design uses a linear non-scaling fixed field alternating gradient accelerator (FFAG) for its final acceleration stage. We present the current lattice design of that FFAG, including the main ring plus its injection and extraction systems. We describe parameters for the main ring magnets, kickers, and septa, as well as the power supplies for the kickers. We present a first pass at an engineering layout for the ring and its subsystems.

MOPZ030	Status of Studies of Achromat-based 6D Ionization Cooling Rings for Muons	injection, lattice, solenoid, extraction	865
	X.P. Ding, D.B. Cline UCLA, Los Angeles, California, USA J.S. Berg, H.G. Kirk BNL, Upton, Long Island, New York, USA A.A. Garren Particle Beam Lasers, Inc., Northridge, California, USA
	Funding: This work was supported by the U.S. Department of Energy in part under award numbers DE-FG02-92ER40695 (UCLA), DE-AC02-98CH10886 (BNL) and DE-FG02-07ER84855 (Particle Beam Lasers, Inc.)” Six dimensional ionization cooling of muons is needed to achieve the necessary luminosity for a muon collider. If that cooling could occur over multiple turns in a closed ring, there would be significant cost savings over a single-pass cooling channel. We report on the status of a cooling ring with achromatic arcs. The achromatic design permits the design to easily switch between a closed ring and a snaking geometry on injection or extraction from the ring. The ring is designed with sufficient space in each superperiod for injection and extraction magnets. We describe the ring's lattice design, performance, and injection/extraction requirements.

MOPZ038	EMMA Injection and Extraction	injection, extraction, dipole, septum	883
	B.D. Muratori, J.K. Jones STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom Y. Giboudot Brunel University, Middlesex, United Kingdom D.J. Holder The University of Liverpool, Liverpool, United Kingdom
	EMMA (Electron Machine with Many Applications) is a prototype non-scaling electron FFAG hosted at Daresbury Laboratory. NS-FFAGs related to EMMA have an unprecedented potential for medical accelerators for carbon and proton hadron therapy. They could also be used as the accelerator for a sub-critical reactor. We summarize the design and commissioning of both the injection and extraction lines for this machine. In particular, we look at the commissioning challenges of injection and extraction.

TUYA03	Stochastic Cooling of a High Energy Collider	simulation, pick-up, cavity, luminosity	913
	M. Blaskiewicz, J.M. Brennan, R.C. Lee, K. Mernick BNL, Upton, Long Island, New York, USA
	Three dimensional stochastic cooling was successfully implemented at the Relativistic Heavy Ion Collider to overcome emittance growth from intra-beam scattering. The talk reports on the experience of operating a collider with continuous cooling. The application of such techniques to other hadron machine (e.g. LHC) will be discussed.
	Slides TUYA03 [1.350 MB]

TUPC007	Kicker and Monitor for CTF3 Phase Feed Forward	impedance, pick-up, coupling, collider	1000
	F. Marcellini, D. Alesini, A. Ghigo INFN/LNF, Frascati (Roma), Italy
	Funding: Work partially supported by the EuCARD research programme, Grant Agreement 227579, within the 'Assessment of Novel Accelerator Concepts'. In the Compact LInear Collider (CLIC) the synchronization of the Drive Beam and the Main Beam has to be assured in the femtosecond range to avoid luminosity reduction of the collider. The Drive and Main Beams arrival time is measured with longitudinal monitors and the correction is applied changing the path length of one beam respect to the other in a magnetic chicane by means of two transverse fast stripline kicker. The performance of the feed forward system will be tested in the CLIC Test Facility (CTF3) measuring the phase at the linac exit, correcting in the chicane after the combination rings and comparing the longitudinal position change before the power RF production system. The developed phase monitors and kicker magnets for the test in CTF3 are described.

TUPC011	Striplines for CLIC Pre-Damping and Damping Rings*	impedance, vacuum, damping, extraction	1012
	C. Belver-Aguilar, A. Faus-Golfe IFIC, Valencia, Spain M.J. Barnes, G. Rumolo CERN, Geneva, Switzerland F. Toral CIEMAT, Madrid, Spain C. Zannini EPFL, Lausanne, Switzerland
	The Compact Linear Collider (CLIC) study explores the scheme for an electron-positron collider with high luminosity and a nominal center-of-mass energy of 3 TeV: CLIC would complement LHC physics in the multi-TeV range. The CLIC design relies on the presence of Pre-Damping Rings (PDR) and Damping Rings (DR) to achieve, through synchrotron radiation, the very low emittance needed to fulfil the luminosity requirements. The specifications for the kicker systems are very challenging and include very low beam coupling impedance and excellent field homogeneity: striplines have been chosen for the kicker elements. Analytical calculations have been carried out to determine the effect of tapering upon the high frequency beam coupling impedance. In addition detailed numerical modeling of the field homogeneity has been performed and the sensitivity of the homogeneity to various parameters, including stripline cross-section, has been studied. This paper presents the main conclusions of the beam impedance calculations and field homogeneity predictions.

TUPC013	Simulation of Phase Stability at the Flat Top of the CLIC Drive Beam	linac, simulation, luminosity, collider	1018
	A. Gerbershagen, D. Schulte CERN, Geneva, Switzerland P. Burrows Oxford University, Physics Department, Oxford, Oxon, United Kingdom
	Funding: University of Oxford The drive beam phase stability is one of the critical issues of the Compact Linear Collider (CLIC). In this paper the generation and propagation of drive beam phase errors is studied for effects that vary during the drive beam pulse. This includes the influence of drive beam current and phase errors as well as of drive beam accelerator RF phase and amplitude errors on the drive beam phase after the compressor chicanes and the analysis of the propagation of these errors through the drive beam combination scheme. The impact of the imperfections on the main beam is studied including the possible correction with help of a feedforward system.

TUPC080	Pickup Design with Beta Matching	pick-up, impedance, simulation, resonance	1189
	J.A. Tsemo Kamga, W.F.O. Müller, K.K. Stavrakakis, T. Weiland TEMF, TU Darmstadt, Darmstadt, Germany
	Funding: Work supported by GSI The main goal of this project is to investigate the Schottky noise of an ion beam in the frequency range from 3 to 5 GHz. In order to accomplish this task, a pickup design is required. For an efficient study of this Schottky noise the pickup sensitivity for low beta must be increased. A design for such a problem has been developed by McGinnis for a fixed beam velocity but can also be used for variable beta by using a tunable material (ferroelectric) inside the waveguide. Since such tunable materials like for instance BST (Barium Strontium Titanate) are lossy, the impact of dielectric losses on the pickup sensitivity will also be investigated in this work. Additionally to the classical parameter studies where multiple simulation runs based on the original numerical model are initiated to characterize the various design parameters it is also possible to utilize a reduced model instead. In particular one is interested in a fast evaluation of the frequency response while taking also material variations into account. In this work, a multivariate parameterized dynamical system is set up and used complementary to the full model for the required beam characterization.

TUPC095	Bucket-by-bucket On/Off-axis Injection with Variable Field Fast Kicker	injection, dipole, quadrupole, emittance	1230
	T. Nakamura JASRI/SPring-8, Hyogo-ken, Japan
	Dynamic aperture of ultra-low emittance storage rings is expected to be as small as a few mm; one order smaller than that of current rings, because of their high nonlinearity. The conventional injection scheme with bump formation may not be applied for such small aperture. On-axis injection with fast magnet is one of the solutions, however, it requires the injection beam of long trains of bunches, which impose serious limitation on the injector and the filling pattern. We propose a bucket-by-bucket on-axis/off-axis injection scheme, which manipulates the injection and stored beams bucket-by-bucket with a variable field fast kicker. For on-axis injection, this scheme eliminates the limitation on injectors and filling pattern, and also it can reject the contaminated electrons from the injector to keep the bunch purity. Those advantages allow the SPring-8 XFEL low emittance linac to be an injector matched with ultra-low emittance rings like the SPring-8 II: upgrade plan of SPring-8. By changing the drive power to the kicker, it can also produce position dependent kick required for the off-axis injection, with minimal perturbation on the stored beam achieved by bucket-by-bucket scheme.

TUPC103	Monitoring of the Betatron Tune and Amplitude at Multi-batch Injection of J-PARC MR	injection, betatron, feedback, quadrupole	1254
	S. Hatakeyama JAEA/J-PARC, Tokai-mura, Japan M. Takagi Kanto Information Service (KIS), Accelerator Group, Ibaraki, Japan M. Tejima, T. Toyama KEK, Ibaraki, Japan
	The beam power of J-PARC Main Ring Synchrotron (MR) increased gradually from 2008, and came to be able regularly to supply the beam of 145kW February, 2011. Many of current beam losses are localized to the collimator located on the injection section. One of the problems of the beam injection is that the orbit of the beam transportation line is unstable. It causes sometimes large transverse injection error. Because the transverse injection error is essentially proportional to the amplitude of the betatron oscillation, it is possible to observe by measuring the turn-by-turn position for every bunch of injected beam by using BPMs located on the injection section. In this report, it is described the method how to measure injection error from beam position. It is also discussed about the effect of reflection wave of injection kicker magnets.

TUPC107	Some Preliminary Experiments using LIBERA BPMs in BEPCII*	coupling, resonance, injection, feedback	1266
	Y. Zhang, H.Z. Ma, J. Yue IHEP Beijing, Beijing, People's Republic of China
	Funding: Supported by the National Natural Science Foundation of China (10805051) There are total 16 LIBERA BPMs in BEPCII, which is a double ring e⁺e⁻ collider. The turn-by-turn BPMs serve as only tune measurement system in most cases during normal operation. We tried to do some more machine study using them: the local coupling parameter at the BPM, the resonance driving term, the decoherence parameter which could be used to calibrate the strength of octupole in the ring. We also compare the difference from the different exciting method: single time kick with injection kicker or sinusoidal kick with feedback system.

TUPC128	Transverse Beam Jitter Propagation in Multi-bunch Operation at ATF2	extraction, simulation, feedback, lattice	1320
	J. Resta-López, J. Alabau-Gonzalvo IFIC, Valencia, Spain P. Burrows, G.B. Christian JAI, Oxford, United Kingdom B. Constance CERN, Geneva, Switzerland
	Pulse-to-pulse orbit jitter, if not controlled, can drastically degrade the luminosity in future linear colliders. The second goal of the ATF2 project at the KEK accelerator test facility is to stabilize the vertical beam position down to approximately 5% of the nominal rms vertical beam size at the virtual interaction point (IP). This will require control of the orbit to better than 1 micrometer at the entrance of the ATF2 final focus system. In this paper, by means of computer simulations, we study the vertical jitter propagation along the ATF2 from the start of the extraction line to the IP. For this study pulse-to-pulse vertical jitter measurements using three stripline beam position monitors are used as initial inputs. This study is performed for the case of a bunch-train with three bunches, but could easily be extended for a larger number of bunches. The cases with and without intra-train orbit feedback correction in the extraction line of ATF2 are compared.

TUPC137	UFOs in the LHC	beam-losses, injection, simulation, acceleration	1347
	T. Baer, M.J. Barnes, B. Goddard, E.B. Holzer, J.M. Jimenez, A. Lechner, V. Mertens, E. Nebot Del Busto, A. Nordt, J.A. Uythoven, B. Velghe, J. Wenninger, F. Zimmermann CERN, Geneva, Switzerland
	One of the major known limitations for the performance of the Large Hadron Collider are so called UFOs (”Unidentified Falling Objects”). UFOs were first observed in July 2010 and have since caused numerous protection beam dumps. UFOs are thought to be micrometer sized dust particles which lead to fast beam losses with a duration of about 10 turns when they interact with the beam. In 2011, the diagnostics for such events was significantly improved which allows estimates of the properties, dynamics and production mechanisms of the dust particles. The state of knowledge and mitigation strategies are presented.

TUPO018	Self-stimulated Undulator Klystron	undulator, FEL, electron, storage-ring	1482
	E.G. Bessonov, A.L. Osipov LPI, Moscow, Russia A.A. Mikhailichenko CLASSE, Ithaca, New York, USA
	The Self Stimulated Undulator Klystron (SSUK) and its possible applications in the Particle Accelerator Physics, incoherent Self-Stimulated Undulator Radiation Sources (SSUR) and Free-Electron Lasers are discussed. E.G.Bessonov et al., Self-Stimulated Undulator Radiation and its Possible Applications: http://arxiv.org/ftp/arxiv/papers/10⁰⁹/1009.3724.pdf

TUPS101	A Fast 650V Chopper Driver	controls, linac, impedance, status	1777
	M.M. Paoluzzi CERN, Geneva, Switzerland
	In the framework of Linac4 and the Superconducting Proton Linac (SPL) studies at CERN, the design for a beam chopper has been carried out. The chopper is basically a kicker that deviates part of the beam towards a dump. It is made of two 50 Ω, slow wave lines facing each other, matching the beam velocity and driven with a minimum of 500 V. Due to the bunch spacing of 2.84 ns, a system rise and fall time (3 %-90 %) below 2.5 ns is required with pulse lengths ranging from 8 ns to hundreds of μs. Although different solutions for the driver amplifier where devised in the past, none of the achievements was entirely satisfactory. This paper describes a new design and prototype that meets all the required specifications.

TUPZ023	Observation of Bunch to Bunch Differences due to Beam-beam Effects	luminosity, injection, emittance, dynamic-aperture	1855
	G. Papotti, R. Alemany-Fernandez, R. Giachino, W. Herr, T. Pieloni, M. Schaumann, G. Trad CERN, Geneva, Switzerland
	Due to the bunch filling schemes in the LHC the bunches experience a very different collision schedule and therefore different beam-beam effects. These differences and the effect on the performance have been observed and compared with the expectations. Possible limitations due to these effects are discussed.

WEOBA02	KEK Digital Accelerator and its Beam Commissioning	injection, ion, acceleration, induction	1920
	K. Takayama, T. Arai, Y. Arakida, M. Hasimoto, T. Iwashita, E. Kadokura, T. Kawakubo, T. Kubo, H. Nakanishi, K. Okamura, H. Someya, A. Takagi, M. Wake KEK, Ibaraki, Japan T. Adachi, K.W. Leo Sokendai, Ibaraki, Japan K. Okazaki Nippon Advanced Technology Co. Ltd., Ibaraki-prefecture, Japan
	The digital accelerator (DA), which is a small-scale induction synchrotron no requiring a high-energy injector accelerator and capable of providing a wide variety of ions, has been constructed at KEK. Since the last winter beam commissioning has been carried out. Preliminary results of the beam commissioning experiment as well as the accelerator itself will be presented at the conference. The KEK-DA consists of a 200 kV high voltage terminal, in which an ECRIS is embedded, 15 m long LEBT, electro-static injection kicker, and a 10 Hz rapid cycle synchrotron, which is the recycle use of the former 500 MeV Booster synchrotron. An ion pulse, which is chopped in 5 μs by the newly developed Marx generator driven chopper, is guided through the LEBT and injected by the electrostatic kicker, which is turned off before the injected ion pulse completes the first turn. Then the ion pulse is captured with a pair of barrier voltages and accelerated with the induction acceleration voltage through a full acceleration period. Beam commissioning has been started with a He¹⁺ ion beam of 50 micro-ampere. Beam commissioning of other ions such as C, N, O, Ne, and Ar will be expected. T. Iwashita et al., “KEK Digital Accelerator”, Phys. Rev. ST-AB, published in 2011. ** T.Adachi et al., “A Solid-State Marx Generator Driven Einzel Lens Chopper”, these proceedings.
	Slides WEOBA02 [4.268 MB]

WEPC008	Optics for the Beam Switchyard at the European XFEL	septum, undulator, quadrupole, extraction	2016
	N. Golubeva, V. Balandin, W. Decking DESY, Hamburg, Germany
	The European XFEL is planed as a multi-user facility with the possibility to distribute electron bunches of one beam pulse to different beamlines. The initial stage foresees two electron beamlines each serving its own set of undulators. The later addition of a third beamline is also considered in the design of the distribution system. In addition, the integration of the transport line to the beam abortion dump allows a flexible selection of the bunch repetition pattern for each beamline. The beam extraction, both in undulator beamlines and in the beamline to the dump, will be realized with fast kickers and a Lambertson septum. In this paper we describe the magnet lattice of the deflection arcs with simultaneous horizontal and vertical dispersions and the beam optics of the beam switchyard.

WEPC030	Measurement of Coupling Resonance Driving Terms in the LHC with AC Dipoles	dipole, optics, quadrupole, resonance	2067
	R. Miyamoto, R. Calaga BNL, Upton, Long Island, New York, USA M. Aiba PSI, Villigen, Switzerland R. Tomás, G. Vanbavinckhove CERN, Geneva, Switzerland
	Funding: This work partially supported by the US Department of Energy through the US LHC Accelerator Research Program (LARP). Transverse betatron coupling in the LHC is measured from Fourier analysis of turn-by-turn beam oscillations excited by AC dipoles. The use of the AC dipole for optics measurements induces a small systematic error which can be corrected with an appropriate data interpretation. An algorithm to apply this correction to the measurement of the coupling resonance driving terms is developed for the first time. This paper will review this new algorithm and present results of its application to the LHC.

WEPC032	First Measurements of Higher Order Optics Parameters in the LHC	simulation, optics, resonance, injection	2073
	G. Vanbavinckhove NIKHEF, Amsterdam, The Netherlands M. Aiba PSI, Villigen, Switzerland R. Bartolini Diamond, Oxfordshire, United Kingdom R. Calaga, R. Miyamoto BNL, Upton, Long Island, New York, USA M. Giovannozzi, F. Schmidt, R. Tomás CERN, Geneva, Switzerland E.H. Maclean JAI, Oxford, United Kingdom
	Higher order effects can play an important role in the performance of the LHC. Lack of knowledge of these parameters can increase the tune footprint and compromise the beam lifetime. First measurements of these parameters at injection and flattop have been conducted. Detailed simulations are compared to the measurements together with discussions on the measurement limitations.

WEPC044	Minimizing Beam Motion in a Long-pulse Linear Induction Accelerator	induction, target, injection, focusing	2109
	C. Ekdahl, E.O. Abeyta, J.B. Johnson, K. Nielsen, M.E. Schulze LANL, Los Alamos, New Mexico, USA T.P. Hughes, C.H. Thoma Voss Scientific, Albuquerque, New Mexico, USA C.-Y. Tom NSTec, Los Alamos, New Mexico, USA
	Funding: This work was supported by the US National Nuclear Security Agency and the US Department of Energy under contract DE-AC52-06NA25396. The Dual Axis Radiography for Hydrodynamic Testing (DARHT) Facility at Los Alamos uses two linear induction accelerators (LIAs) for flash radiography of explosively driven experiments from orthogonal viewpoints. The DARHT Axis-II long-pulse 1.8-kA, 16.5-MeV LIA is unique. It has a beam pulse with a 1600-ns flattop during which the kinetic energy varies < 2%. During this flattop, a kicker cleaves out four short micro-pulses, which are focused onto a high-Z target and converted to bremsstrahlung for multi-pulse flash radiography of the experiments. Asymmetric injection of the beam into the solenoidal focusing field, small temporal variations in accelerating potentials, and slight cell misalignments cause the beam position to wander during the flattop. This is undesirable for radiography, because it causes a displacement of the four radiographic source spots. Since the specific energy deposition from each micro-pulse can vaporize target material, succeeding pulses impact an asymmetric object causing a distortion of the source spot. This presentation will review the physics of the beam motion and the tuning procedures we have optimized to minimize the number of shots required.

WEPC104	Vicky : A Computer Code for Use in the Design and Simulation of Particle Accelerators	dynamic-aperture, sextupole, quadrupole, closed-orbit	2256
	F. Iazzourene ELETTRA, Basovizza, Italy
	Vicky is a computer code under development for designing and simulating particle accelerators. Like other existing codes, the features include machine imperfections, closed orbit correction, Twiss functions matching, chromaticity evaluation and correction, particle tracking and so on. The goal is to give the users a friendly graphical interface with widgets to perform the wished tasks, for example to plot the orbit, the Twiss functions, the tune diagram, the dynamic aperture and so on, to select and read an input file describing the considered lattice, to perform the Twiss functions matching, a closed orbit correction and so on. The code provides a description of the particle motion by 10 parameters: four beta-functions, four alpha-functions and two phase advances, that is a 4*4 generalized transverse coupling, together with an emphasis on the treatment of the complex 3D magnetic fields of the undulators used in today’s modern synchrotron radiation facilities. The code is written in C++. It uses the free packages QT for the online plots and the graphical user interface and IT++ for the mathematics. The present status and some results of its application will be presented.

WEPC123	Numerical Algorithm based on the PDE Method for the Solution of the Fokker-Planck Equation	simulation, pick-up, storage-ring, impedance	2298
	M. Dolinska NASU/INR, Kiev, Ukraine C. Dimopoulou, A. Dolinskii, F. Nolden, M. Steck GSI, Darmstadt, Germany
	Funding: Work supported by HIC for FAIR This paper discus a fast and accurate algorithm for numerical solution of Fokker-Planck equation based on the solution of the parabolic Partial Differential Equations (PDE), where the Crank–Nicholson scheme is used. The stability, convergence and round-off errors of the algorithm are studied. The numerical results on Fokker–Planck equation solution with PDE method are compared with other numerical methods. Using the PDE solver, we will be able to predict the stochastic cooling process of notch filter in storage rings.

WEPO013	Septum and Kicker Magnets for the ALBA Booster and Storage Ring	injection, booster, vacuum, storage-ring	2421
	M. Pont, R. Nunez CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain E. Huttel KIT, Karlsruhe, Germany
	At the ALBA Synchrotron light source 6 kicker and 3 septa magnets are installed for beam injection and extraction. A 100 MeV beam coming from the linac is injected on axis into the Booster. The full energy (3 GeV) beam is extracted from the booster and injected into the Storage Ring, where 4 kicker magnets bring the stored beam close to the septa. All septa are direct driven out-of-vacuum magnets with C shape iron laminated yoke. The magnets are excited by a full sine approx. 300 μs pulse length; the nominal field is 0.15/0.84/0.9 T (booster injection/extraction/storage-ring-injection). The stray field seen by the stored beam is less than 1 μT. The booster kicker magnets are in-vacuum magnets with C-ferrite yoke. The magnets are excited by a 0.4 μs flat top pulse; the nominal field is 0.03/0.04 T (booster injection/extraction). The storage ring kickers have a C-ferrite yoke and a 0.4 μm Ti coated ceramic vacuum chamber. The excitation is done by 6 μs half sine; the nominal field is 0.13 T. The paper will present the design of the elements and their magnetic characteristics. First results of their behaviour during commissioning will also be discussed.

WEPS008	Operation Status and Future Plan of J-PARC Main Ring	extraction, beam-losses, linac, betatron	2499
	T. Koseki KEK, Ibaraki, Japan
	The J-PARC Main Ring (MR) has started users operation since 2009. The MR has two beam extraction systems. One is a fast extraction (FX) system for beam delivery to the neutrino beam line of the Tokai-to-Kamioka (T2K) experiment, and the other is a slow extraction (SX) system for beam delivery to the hadron experimental hall. For the T2K experiment, the maximum beam power of 145 kW is delivered continuously. For users of the hadron experimental hall, the beam power of 3 kW is delivered with extraction efficiency of 99.5%. In this paper, status of the high power beam operation of the MR is presented. Future prospect for increasing beam intensity is also discussed.

WEPS099	Physics Design of CSNS RCS Injection and Extraction System	extraction, injection, septum, emittance	2739
	J. Qiu, N. Huang, J. Tang, S. Wang IHEP Beijing, Beijing, People's Republic of China
	In this paper, the injection and extraction system design for CSNS RCS are discussed. The injection system is designed to place all the injection devices in one uninterrupted long drift in one of the four dispersion free straight sections. Painting bumper magnets are used for both horizontal and vertical phase space painting. The beam extraction process from the CSNS RCS is a single turn two step process, requiring a group of kickers and a Lambertson septum magnet.

WEPZ015	Staging in Two Beam Dielectric Wakefield Accelerators	cavity, acceleration, wakefield, septum	2802
	J.G. Power, M.E. Conde, W. Gai, C.-J. Jing ANL, Argonne, USA
	Funding: The work is supported by the U.S. Department of Energy under Contract No. DE-AC02-06CH11357 with Argonne National Laboratory. A new experimental program to demonstrate staging in a two beam dielectric wakefield accelerator (DWA) is being planned at the Argonne Wakefield Accelerator facility. DWA uses a drive beam to generate acceleration fields to accelerate a main beam and is one of the most promising advanced acceleration methods being pursued for a future high-energy physics linear collider. Staging is the ability to use two accelerating modules back to back to accelerate a charged particle bunch and it is one of basic requirements of any acceleration method. In this paper, a new beamline design consisting of a fast kicker to pick pulses from the drive bunch train and deliver them to the individual acceleration modules will be presented.

WEPZ017	ESTB: A New Beam Test Facility at SLAC	electron, hadron, linac, emittance	2808
	M.T.F. Pivi, H. Fieguth, C. Hast, R.H. Iverson, J. Jaros, R.K. Jobe, L. Keller, T.V.M. Maruyama, D.R. Walz, M. Woods SLAC, Menlo Park, California, USA
	Funding: Work supported by the Director, Office of Science, High Energy Physics, U.S. DOE under Contract No. DE-AC02-76SF00515. End Station A Test Beam (ESTB) is a beam line at SLAC using a small fraction of the bunches of the 13.6 GeV electron beam from the Linac Coherent Light Source (LCLS), restoring test beam capabilities in the large End Station A (ESA) experimental hall. ESTB will provide one of a kind test beam essential for developing accelerator instrumentation and accelerator R&D, performing particle and particle astrophysics detector research, linear collider machine and detector interface (MDI) R&D studies, development of radiation-hard detectors, and material damage studies with several distinctive features. In the past, 18 institutions participated in the ESA program at SLAC. In stage I, 4 new kicker magnets will be added to divert 5 Hz of the LCLS beam to ESA. A new beam dump is installed and a new Personnel Protection System (PPS) is built in ESA. In stage II, we plan to install a secondary hadron target, able to produce pions up to about 12 GeV/c at 1 particle/pulse. We report about the ESTB commissioning, status and plan for tests.

THOBA03	Dual AC Dipole Excitation for the Measurement of Magnetic Multipole Strength from Beam Position Monitor Data*	dipole, sextupole, simulation, lattice	2865
	M. Spata, G.A. Krafft JLAB, Newport News, Virginia, USA
	Funding: Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. An experiment was conducted at Jefferson Lab's Continuous Electron Beam Accelerator Facility to develop a technique for characterizing the nonlinear fields of the beam transport system. Two air-core dipole magnets were simultaneously driven at two different frequencies to provide a time-dependent transverse modulation of the electron beam. Fourier decomposition of beam position monitor data was then used to measure the amplitude of these frequencies at different positions along the beamline. For a purely linear transport system one expects to find solely the frequencies that were applied to the dipoles with amplitudes that depend on the phase advance of the lattice. In the presence of nonlinear fields one expects to also find harmonics of the driving frequencies that depend on the order of the nonlinearity. The technique was calibrated using one of the sextupole magnets in a CEBAF beamline and then applied to a dipole to measure the sextupole and octupole strength of the magnet. A comparison is made between the beam-based measurements, results from TOSCA and data from our Magnet Measurement Facility.
	Slides THOBA03 [6.193 MB]

THPC003	Installation of the ASTRID2 Synchrotron Light Source	extraction, dipole, cavity, vacuum	2909
	J.S. Nielsen, N. Hertel, S.P. Møller ISA, Aarhus, Denmark
	ASTRID2 is the new 10 nm UV and soft x-ray light source being built at Aarhus University, to replace the aging source ASTRID. ASTRID2 is now in the middle of its installation. An update of the design will be presented. Almost all components have now been acquired and received. Several choices and solutions of hardware will be described, and future commissioning plans outlined. Commissioning is expected to take place in the winter 2011/2012.

THPC005	First Measurements with a Kicked Off Axis Bunch for Pseudo Single Bunch Mode Studies at SOLEIL	single-bunch, closed-orbit, storage-ring, synchrotron	2912
	L.S. Nadolski, J.-P. Lavieville, P. Lebasque, A. Nadji, J.P. Ricaud, M.G. Silly, F. Sirotti SOLEIL, Gif-sur-Yvette, France
	At SOLEIL, the time resolved French community benefits of single bunch operation few weeks a year. Meanwhile most of the multi-bunch filling pattern based experiments are not possible due to the low photon flux. Following the pioneer work performed at ALS, a new operation mode is under study at SOLEIL where the storage ring is filled up with a special hybrid mode: ¾ multibunch filling pattern and a single bunch with higher current in the last ¼. The so-called pseudo single bunch-filling pattern is obtained if the closed orbit of the single bunch is not the same as the one of the other bunches. Preliminary results are presented where the pinger magnet time impulse response has been significantly reduced while its frequency was increased from 3 Hz up to 1 kHz. This magnet is used as an additional corrector magnet to change only the single bunch closed orbit. First experimental results observed at one interested beamline are also discussed. S. Kwiatkowski et al., “'CAMSHAFT' Bunch Kicker Design for the ALS Storage Ring", Proc. of EPAC2006, THPLS114, p. 3547, (2006).

THPC045	Design of a Compact Storage Ring for the TTX	cavity, injection, scattering, emittance	3005
	H.S. Xu, W.-H. Huang, C.-X. Tang TUB, Beijing, People's Republic of China S.-Y. Lee IUCEEM, Bloomington, Indiana, USA
	We study a compact storage ring with circumference 3-m, 4 dipoles, and two quadrupoles for the Tsinghua Thomson scattering X-ray (TTX) source. The effects of Touschek lifetime, rf system requirement, the Intra-beam scattering (IBS) and coherent synchrotron radiation (CSR) will be addressed. A top-up injection system will be designed to maximize the Photon flux. Conceptual laser cavity to enhance photon flux will be discussed. Expected performance of the compact X-ray source will be presented.

THPC139	Study of a Pulsed Sextupole Magnet Injection System for LNLS	injection, sextupole, power-supply, pulsed-power	3212
	X.R. Resende, F.C. Arroyo, R.H.A. Farias, L. Liu, A.R.D. Rodrigues, P.P. Sanchez, G. Tosin LNLS, Campinas, Brazil
	An injection system consisting of a pulsed sextupole magnet (PSM) is being considered for Sirius, the project of a new 3rd generation 3 GeV synchrotron source in development in Brazil. This novel injection scheme will be implemented and tested in the existing UVX ring. This will also serve as an opportunity to get acquainted with the new technology and become ready for Sirius. On this paper we report on the ongoing PSM study at LNLS. In particular, details of injection dynamics calculations, magnet and pulsed power supply designs are described, as well as machine preparations for experimental tests in the UVX storage ring.

THPC140	Design, Tuning and Results of the Pulsed Magnetic Systems for the Beam Injection in the SOLEIL Storage Ring Operated in ‘Transparent’ Top Up Mode	septum, injection, vacuum, storage-ring	3215
	P. Lebasque, R. Ben El Fekih, M. Bol, J. Da Silva Castro, A. Hardy, C. Herbeaux, J.-P. Lavieville, A. Loulergue, J.L. Marlats, D. Muller, G. Renaud, J.P. Ricaud SOLEIL, Gif-sur-Yvette, France
	From the beginning, the SOLEIL Storage Ring was designed to operate in Top Up injection mode. So all equipments involved have been specified to generate as small as possible beam perturbations of the stored beam during the electron beam injection. This concerns many aspects of the design and realization of the injection pulsed magnets (kickers and septa), their vacuum chambers, pulsed power supplies and timing electronics. Despite quite satisfactory results of pulsed magnetic measurements in labs, a still too large perturbation was observed on the e^- beam orbit during the Storage Ring commissioning. Therefore a strong work of systematic measurements, analysis of each phenomena, tuning or modification of each device was led until reaching rather good and acceptable performances. This paper will present the results obtained. At this stage, the Storage Ring beam orbit is sufficiently stable in Top Up injection mode so that it is almost transparent to the 24 beam lines, even for the most sensitive ones. After a summary of the main significant topics, we present the developments foreseen to further improve the performances and make a new step towards a “perfect” Top Up injection.

THPC146	The Radiated EMI Isolation for TPS Kicker Magnet*	shielding, radiation, electromagnetic-fields, controls	3227
	C.S. Chen, C.K. Chan, C.L. Chen, Y.L. Chu, K.H. Hsu, C.Y. Kuo, Y.-H. Liu, C.-S. Yang NSRRC, Hsinchu, Taiwan
	Electromagnetic interference is a critical problem for electronic equipment, especially for those sophisticated measuring sensors using in TLS. Therefore, lots of efforts have been made to isolate the EM noise from the kicker magnets. In this article, different thicknesses of aluminum chambers are applied to block the radiated EM noise. Furthermore, the different widths of slits simulate the necessary openings on kicker assembly. According to the results of small-scale experiment, some parameters are obtained to design the enclosure of kicker magnet. Compared the results with the data from the original scale kicker, these parameters provide a believable guideline in the beginning of design status.

THPC147	TPS SR Kicker Prototype Installation Status*	injection, storage-ring, high-voltage, vacuum	3230
	Y.-H. Liu, C.K. Chan, C.-S. Chen, Y.L. Chu, K.H. Hsu, H.P. Hsueh, C.K. Kuan, C.Y. Kuo, C.-S. Yang NSRRC, Hsinchu, Taiwan
	The purpose of this paper is to illustrate the installation sequence of TPS SR kicker. Because of adding the rotation function in row direction, the position of every component of kicker must be very precise. The kicker magnet and EMI enclosure were fastened on the rotation motor plate which could rotate ±3.0 mrad. The ceramic chamber remain fixed on the bottom plate in order to let the bellow stress free during rotation. After installation, the inductance measurement and the high voltage breakdown test were also tested. The experimental results showed the good uniformity and reached the expected request. The field mapping and EMI prevention schemes will be tested in the future.

THPC177	Field Correction Results from NSRRC Elliptically Polarized Undulator 46	undulator, electron, multipole, synchrotron	3317
	J.C. Huang, C.-H. Chang, C.-S. Hwang, C. JunTune, F.-Y. Lin NSRRC, Hsinchu, Taiwan
	Elliptically polarized undulator (EPU) is a common insertion device to use in storage ring in order to provide circular polarization. The field correction is an essential step for EPU construction, and it can prevent the photon flux reduction from idea case and electron beam trajectory and exit angle from EPU. The conventional field correction method is tedious works and strongly based on experiences. An initial state of NSRRC EPU46 has phase error over 40 degrees, and many difficulties on field correction to reduce the phase error under 5 degrees. This paper will describe the detailed magnetic field correction process and practical results from in NSRRC EPU.

THPO022	Risk Assessment of the Chopper Dipole Kicker Magnets for the MedAustron Facility	dipole, controls, power-supply, radiation	3388
	T. Kramer, T. Stadlbauer EBG MedAustron, Wr. Neustadt, Austria M.J. Barnes, M. Benedikt, T. Fowler CERN, Geneva, Switzerland
	The MedAustron facility, to be built in Wiener Neustadt (Austria), will provide protons and ions for both cancer therapy and research. Different types of kicker magnets will be used in the facility, including fast beam chopper dipoles: these allow the beam to be switched on and off for routine operational reasons or in case of emergency. One of the main requirements for the beam chopper system is reliability. A criticality analysis, to chart the probability of failure modes against the severity of their consequences of the fault, has been carried out for the chopper dipole system. This “Failure Mode, Effects, and Criticality Analysis” (FMECA), has been used to highlight failure modes with relatively high probability and severity of consequences: conservative ratings of critical components and appropriate redundancy, together with measurements and interlocks, have been used to reduce the probability and criticality of faults. This paper presents the results of the FMECA.

THPO024	Development of a Non-Linear Kicker System to Facilitate a New Injection Scheme for the BESSY II Storage Ring	injection, vacuum, storage-ring, impedance	3394
	O. Dressler, T. Atkinson, M. Dirsat, P. Kuske HZB, Berlin, Germany H. Rast DELTA, Dortmund, Germany
	Top-Up injections without noticeable motion of the stored beam is a challenge. The common method of beam accumulation with a local bump formed by four independent pulsed dipole kicker magnets usually causes beam oscillations. The matching of the four independent kicker systems regarding pulse jitters and shapes is technologically limited. Afterward the beam excitation was reduced more when two kicker magnets on each side of the septum were powered in series by one pulser unit. An even more promising approach is to adopt an alternative injection method deploying a single non-linear kicker magnet with zero Bx,y-field in the center and an off-axis maximum, By, which is horizontally displaced by 10^-12 mm. There the injected beam gets kicked and looses half of its transverse momentum. Such a magnet was designed and built as a short in-vacuum magnet with a small vertical gap height. For first beam tests the kicker was placed in the second straight section after the injection point, and the 1.5 μs pulse was designed to deflect the 1.72 GeV beam by 1 mrad. In this paper, the calculations of the magnetic fields, the mechanical design as well as the electrical pulser circuit are described. *New injection scheme using a pulsed quadrupole magnet in electron storage rings, Kentaro Harada, PHYSICAL REVIEW SPECIAL TOPICS - AB 10, 123501 (2007)

THPO032	Preliminary Design of an Inductive Adder for CLIC Damping Rings	damping, emittance, collider, impedance	3409
	J. Holma, M.J. Barnes CERN, Geneva, Switzerland
	The Compact Linear Collider (CLIC) study is exploring the scheme for an electron-positron collider with high luminosity and a nominal centre-of-mass energy of 3 TeV. The CLIC damping rings will produce ultra-low emittance, with high bunch charge, necessary for the luminosity performance of the collider. To limit the beam emittance blow-up due to oscillations, the pulse power modulators for the damping rings kickers must provide extremely flat, high-voltage pulses: specifications call for a 160 ns duration flattop of 12.5 kV, 250 A, with a combined ripple and droop of not more than ±0.02 %. A solid-state modulator, the inductive adder, is a very promising approach to meeting the demanding specifications; this topology allows the use of both digital and analogue modulation. To effectively use modulation techniques to achieve such low ripple and droop requires an in-depth knowledge of the behaviour of the solid-state switching components and their gate drivers, as well as a good understanding of the overall circuit behaviour. This paper describes the initial design of the inductive adder.

THPO033	Calculation of Metallization Resistivity and Thickness for MedAustron Kicker Systems	simulation, vacuum, status, proton	3412
	M.J. Barnes CERN, Geneva, Switzerland T. Kramer, T. Stadlbauer EBG MedAustron, Wr. Neustadt, Austria
	The MedAustron facility, to be built in Wiener Neustadt (Austria), will provide protons and ions for both cancer therapy and research. Different types of kicker magnets will be used in the facility. The kicker magnets are outside machine vacuum: each kicker magnet has a ceramic beam chamber whose inner surface is metallized. The resistivity and thickness of the metallization are chosen such that the induced eddy currents, resulting from the pulsed kicker magnetic field, do not unduly affect the rise/fall times or homogeneity of the magnetic field. A comparison of an analytical calculation and measurement is reported for the effect of metallization of the ceramic beam chamber of an existing kicker system at CERN. For a MedAustron kicker the result of an analytical calculation is compared with predictions from electromagnetic simulations: conclusions concerning the metallization of the ceramic beam chambers, for the MedAustron kicker magnets, are presented.

THPO034	Optimization of a Dual One-turn Coils Kicker Magnet System	extraction, synchrotron, monitoring, vacuum	3415
	K.L. Tsai, C.-T. Chen, C.-S. Fann, S.Y. Hsu, Y.D. Li, K.-K. Lin, K.-B. Liu, H.M. Shih, Y.S. Wong NSRRC, Hsinchu, Taiwan
	Optimization of a dual one-turn coils configuration for fast kicker magnet system is presented in this report. Emphasis has been made on the: 1) optimization of various possible coils arrangement restricted by the existing available hardware; and 2) synchronization between pulsed currents delivering on the respective upper and lower coils. In the consideration of coils arrangement, good field region is utilized as the guiding parameter while adjusting fixture gap between the coils. As for coil currents timing optimization, fast rise-time and pulse shape preservation are used for practical implementation purpose. Both numerical analysis and experimental data will be presented and discussed.

THPS003	Status of Stochastic Cooling Predictions at the HESR	antiproton, accumulation, pick-up, injection	3430
	H. Stockhorst, R. Maier, D. Prasuhn, R. Stassen FZJ, Jülich, Germany T. Katayama GSI, Darmstadt, Germany
	Detailed theoretical studies of stochastic cooling have been performed in order to fulfil the requirements for internal target experiments at the High-Energy Storage Ring (HESR) of the future Facility for Antiproton and Ion Research (FAIR) at the GSI in Darmstadt. A Fokker-Planck model and a particle tracking code utilizing the Filter and time-of-flight momentum cooling method have been developed for the 2 to 4 GHz cooling system. A barrier bucket cavity is included to compensate the mean energy loss due to the beam-target interaction. The code has been experimentally verified at the cooler synchrotron COSY. Since the RESR accumulator ring is postponed in the modularized start version of FAIR it is proposed to include the anti-proton accumulation function in the HESR downstream of the Collector Ring. Applying the radial stacking scheme well established at CERN and FNAL would result in a completely new and additional cooling system in the HESR. Instead a different way of beam accumulation has been selected that uses the already designed stochastic cooling system and the barrier bucket cavity of the HESR. Simulation results of the anti-proton accumulation in the HESR are presented.

THPS041	Design of Beam Transport Line from RCS to Target for CSNS	target, proton, simulation, octupole	3514
	W.B. Liu, N. Huang, J. Qiu, J. Tang, S. Wang, G. Xu IHEP Beijing, Beijing, People's Republic of China
	China Spallation Neutron Source (CSNS) uses the high energy proton beam to strike the Tungsten target to generate neutrons through spallation reaction. The proton beam is extracted from the Rapid Cycling Synchrotron (RCS), whose beam power reaches 100 kW. For the sake of target lifetime, beam distribution at the target surface is required as uniform as possible. Nonlinear beam density redistribution method with two octupole magnets has been studied. Also some simulation and theoretical calculation have been done. According to the simulation result, the beam density at the target is optimized and the beam loss is under control.

THPS047	New Injection and Extraction at CRYRING for FLAIR	extraction, injection, septum, ion	3529
	A. Simonsson, L. Brännholm, S. Das, A. Källberg, P. Löfgren, A. Paal, J. Sjöholm MSL, Stockholm, Sweden H. Danared ESS, Lund, Sweden D. Reistad Intégro Utbildnings AB, Sigtuna, Sweden
	As a preparation for a future transfer of CRYRING to FLAIR at FAIR in Darmstadt, Germany, we have installed and tested a slow extraction system. At FLAIR CRYRING will be used for deceleration of antiprotons from 30 MeV to 0.3 MeV. The tests of the slow extraction show that the beam can be extracted during 2 s with 30-60% efficiency and with rather constant amplitude, apart from noise from 50 Hz harmonics. A new injection system has also been designed. It will be able to inject 30 MeV antiprotons from NESR as well as 0.3 MeV/u ions created in a separate ion source and accelerated in an RFQ.

THPS049	Feasibility Study of a CERN PS Injection at 2 GeV	injection, optics, septum, vacuum	3535
	J. Borburgh, S. Aumon, W. Bartmann, S.S. Gilardoni, B. Goddard, L. Sermeus, R.R. Steerenberg CERN, Geneva, Switzerland
	In the framework of the potential CERN PS Booster (PSB) energy upgrade, a study was initiated to look into the possibilities and constraints to inject protons into the PS at kinetic energies up to 2 GeV, for LHC type beams and other (high intensity) beams. This paper highlights the identified bottlenecks and potential solutions and addresses the resulting requirements for the hardware in the transfer line and injection region of the PS. In conjunction with the proposed upgrade of the PSB-PS transfer line hardware the optics can be changed for different cycles. Optics solutions optimized for the different requirements of LHC type and other beams are presented.

THPS052	Studies on Transverse Painting for H⁻ Injection into the PSB	injection, emittance, linac, space-charge	3544
	C. Bracco, C. Carli, T. Fowler, B. Goddard, G. Gräwer, J.-B. Lallement, M. Martini, M. Scholz, W.J.M. Weterings CERN, Geneva, Switzerland
	Linac4 will inject 160 MeV H− ions in to the CERN PS Booster (PSB). This will allow to reduce space charge effects and increase beam intensity but will require a substantial upgrade of the injection region, with the implementation of a charge-exchange multi-turn injection scheme. The PSB has to provide beam to several users with different requirements in terms of beam intensity and emittance. Four kicker magnets (KSW), which are already installed in the PSB lattice, will be used to accomplish painting in the horizontal phase space to match the injected beams to the required emittances. Double linear functions, with varying slopes for each user, have been defined for the KSW generators waveforms according to detailed beam dynamic studies for all target intensities and emittances. Effect of space charge, injection offsets, dispersion and betatron mismatch have been taken into account. Preliminary studies have been carried out to evaluate how to obtain the required vertical emittance and the option of a transverse painting, also in the vertical plane, is explored.

THPS054	Injection and Extraction Considerations for a 2 GeV RCS at CERN	extraction, injection, quadrupole, septum	3550
	W. Bartmann, B. Balhan, J. Borburgh, L. Ducimetière, M. Fitterer, B. Goddard, L. Sermeus CERN, Geneva, Switzerland
	Conceptual studies have been made for a 2 GeV RCS at CERN as a possible replacement of the four-ring PS Booster. The lattice design has to accommodate suitable straight sections for a 160 MeV H⁻ charge exchange injection system, and for a 2 GeV fast extraction system. The design constraints for the injection and extraction systems are described, together with the proposed concepts and potential equipment limitations. In particular, the features of different possible H⁻ injection configurations are compared.

THPS055	Controlling Beamloss at Injection into the LHC	injection, beam-losses, emittance, shielding	3553
	B. Goddard, F. Alessio, W. Bartmann, P. Baudrenghien, V. Boccone, C. Bracco, M. Brugger, K. Cornelis, B. Dehning, A. Di Mauro, L.N. Drosdal, E.B. Holzer, W. Höfle, R. Jacobsson, V. Kain, M. Meddahi, V. Mertens, A. Nordt, J.A. Uythoven, D. Valuch, S. Weisz, E.N. del Busto CERN, Geneva, Switzerland R. Appleby UMAN, Manchester, United Kingdom
	Losses at injection into the superconducting LHC can adversely affect the machine performance in several important ways. The high injected beam intensity and energy mean that precautions must be taken against damage and quenches, including collimators placed close to the beam in the injection regions. Clean injection is essential, to avoid spurious signals on the sensitive beam loss monitoring system which will trigger beam dumps. In addition, the use of the two injection insertions to house downstream high energy physics experiments brings constraints on permitted beam loss levels. In this paper the sources of injection beam loss are discussed together with the contributing factors and various issues experienced in the first full year of LHC operation. Simulations are compared with measurement, and the implemented and planned mitigation measures and diagnostic improvements are described. An outlook for future LHC operation is given.

THPS087	Engineering Prototype for a Compact Medical Dielectric Wall Accelerator	rfq, proton, laser, acceleration	3636
	A. Zografos, T. Brown, A. Hening, V. Joshkin, K. Leung, Y.K. Parker, H.T. Pearce-Percy, D. Pearson, M. Rougieri, J. Weir CPAC, Livermore, CA, USA R. Becker SSS, Gelnhausen, Germany D.T. Blackfield, G.J. Caporaso, Y.-J. Chen, S. Falabella, G. Guethlein, S.A. Hawkins, S.D. Nelson, B. R. Poole, J.A. Watson LLNL, Livermore, California, USA R.W. Hamm R&M Technical Enterprises, Pleasanton, California, USA
	Funding: Prepared by LLNL under Contract DE-AC52-07NA27344. The Compact Particle Accelerator Corporation has developed an architecture to produce pulsed proton bunches that will be suitable for proton treatment of cancers. Subsystems include a RFQ injection system with a pulsed kicker to select the desired proton bunches and a linear accelerator incorporating a High Gradient Insulator with stacked Blumleins to produce the required voltage. The Blumleins are switched with solid state laser driven optical switches that are an integral part of the Blumlein assemblies. Other subsystems include a laser, a fiber optic distribution system, an electrical charging system and beam diagnostics. An engineering prototype has been constructed and it has been fully characterized. Results obtained from the engineering prototype support the development of an extremely compact 150 MeV system capable of modulating energy, beam current and spot size on a shot to shot basis within the next two years. The paper will detail the construction of the engineering prototype and discuss experimental results. In addition, future development milestones and commercialization plans will also be discussed.

THPS088	LHC Beam Impact on Materials Considering the Time Structure of the Beam	target, proton, simulation, extraction	3639
	N.A. Tahir GSI, Darmstadt, Germany J. Blanco, R. Schmidt CERN, Geneva, Switzerland R. Piriz Universidad de Castilla-La Mancha, Ciudad Real, Spain A. Shutov IPCP, Chernogolovka, Moscow region, Russia
	The LHC is the world's largest and highest energy accelerator. Two counter-rotating beams can be accelerated up to 7 TeV and kept colliding for several hours. The energy stored in each beam is up to 362MJ, enough to melt 500 kg of copper. A fast loss of a small fraction of the beam can cause damage to a superconducting coil in a magnet. Primary beam collimators, one of the most robust parts of the machine protection, can be damaged with about 5% of the beam. An accident involving the entire beam is very unlikely but cannot be fully excluded. Understanding the consequences of such accidents is fundamental for the machine protection. Detailed numerical simulations have been carried out to assess the damage caused by full LHC beam impact on solid Cu and C cylinders. The energy loss of the protons is calculated with the FLUKA code and this data is used as input to a 2D hydrodynamic code BIG2, to study the thermodynamic and hydrodynamic response of the material. Since the target parameters change substantially during the time of impact, a new approach of running the two codes iteratively, has been developed. In this paper the results are presented and compared with the previous studies.

THPZ025	Stability of the LHC Transfer lines	injection, extraction, ion, controls	3741
	V. Kain, W. Bartmann, C. Bracco, L.N. Drosdal, B. Goddard, M. Meddahi, J.A. Uythoven, J. Wenninger CERN, Geneva, Switzerland
	The LHC is filled from the SPS through two 3 km transfer lines. The injected beam parameters need to be well under control for luminosity performance, machine protection and operational efficiency. Small fractions of beam loss on the transfer line collimation system create showers which can trigger the sensitive LHC beam loss monitor system nearby and cause a beam abort during filling. The stability of the transfer line trajectory through the collimators is particularly critical in this respect. This paper will report on the transfer line trajectory stability during the proton run in 2011, correlations with injection losses, correction frequency and the most likely sources for the observed oscillations.

Paper

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Other Keywords

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MOPC077

Commissioning of Multibunch Feedback Systems at the Fast Ramping Stretcher Ring ELSA

synchrotron, cavity, feedback, booster

250

A. Roth, F. Frommberger, N. Heurich, W. Hillert, M. Schedler, R. Zimmermann
ELSA, Bonn, Germany

Funding: Supported by German Research Foundation through SFB/TR 16 and by Helmholtz Alliance through HA-10¹.
At the Electron Stretcher Facility ELSA of Bonn University, an external beam of either unpolarized or polarized electrons is supplied to hadron physics experiments. The ELSA stretcherring operates in the energy range of 1.2 to 3.5 GeV and achieves a duty cycle of up to 80% using a fast energy ramp of 4 GeV/s. Under these conditions, an increase of the internal beam current from an actual value of 20 mA up to 200 mA is planned. Such an upgrade is mainly limited by the excitation of multibunch instabilities. As one active counteraction, we have installed state-of-the-art bunch-by-bunch feedback systems for the longitudinal, as well as for both transverse planes. The detailed setup with all main components and first results of the commissioning of the systems will be presented. In particular, the performance of the longitudinal feedback with a stabilized synchrotron frequency during the fast energy ramp will be discussed.

MOPO003

A Broadband RF Stripline Kicker for Damping Transversal Multibunch Instabilities

impedance, feedback, single-bunch, damping

481

M. Schedler, D. Heiliger, W. Hillert, A. Roth
ELSA, Bonn, Germany

When operating an RF feedback system, being able to reliably act upon every single bunch is a necessity. By employing a broadband RF stripline kicker, any bunch displacement can be corrected for. In a 500 MHz accelerator, the decay time of the electromagnetic field inside the kicker has to be less than 2 ns in order to avoid the following bunch to be affected. By designing the kicker as an RF coax device matched to the line impedance of the power cables, perturbing reflected signals are avoided. Additionally, the kicking strength and thus the shunt impedance should be maximized over the full spectrum from DC to 250 MHz. The kicker design has been optimized to meet the above requirements by relying on CST Microwave Studio simulations. Their results and first measurements are presented.

MOPO004

A Longitudinal Kicker Cavity for a Bunch-by-bunch Feedback System at ELSA

cavity, simulation, feedback, impedance

484

N. Heurich, W. Hillert, A. Roth, R. Zimmermann
ELSA, Bonn, Germany

At the Electron Stretcher Facility ELSA of Bonn University, a longitudinal bunch-by-bunch feedback system is currently being installed in order to damp multibunch instabilities and to enable a future intensity upgrade of up to 200 mA. As a main component, a longitudinal kicker cavity was developed and manufactured. The kicker requires a bandwidth of 250~MHz taking into account the bunch spacing of 2 ns at ELSA. Existing designs used at other facilities were optimized in view of the considerably larger bunch lenght at ELSA. The choice of 1.125 GHz as a center frequency is a result of these considerations. With the resulting low quality factor, the design had to be optimized in order to maximize the shunt impedance. The longitudinal feedback is succesfully working with the prototype installed in the stretcher ring. The design and detailed simulations of the geometry are discussed and laboratory measurements are presented.

MOPO005

A Transverse Feedback System using Multiple Pickups for Noise Minimization

pick-up, synchrotron, feedback, betatron

487

M. Alhumaidi, A.M. Zoubir
TU Darmstadt, Darmstadt, Germany

A new concept for using multiple pickups for estimating beam angle at the kicker is addressed. The estimated signal should be the driving feedback signal. The signals from the different pickups are delayed, such that they correspond to the same bunch. Consequently a weighted sum of the delayed signals is suggested as an estimator of the beam angle at the kicker. The weighting coefficients are calculated such that the estimator is unbiased, i.e. the output corresponds to the actual beam angle at the kicker for non-noisy pickup signals. Furthermore, the estimator must give the minimal noise power at the output among all linear unbiased estimators. Finally results for the heavy ions synchrotron SIS 18 at the GSI are shown.

MOPO007

Resonant Strip-line Type Longitudinal Kicker

simulation, impedance, feedback, wakefield

493

T. Nakamura
JASRI/SPring-8, Hyogo-ken, Japan

The longitudinal feedback for the SPring-8 storage ring is under consideration as the device for suppression of the longitudinal instabilities driven by higher order modes of cavities, observed at test operation with 4 to 6 GeV low energy beam. As the beam energy and the ring circumference are rather high, and the length of the space for the longitudinal kickers is limited, high efficiency kicker per length is required in the our case. As a candidate of such kicker, we propose a resonant strip-line type longitudinal kicker with drive frequency of 13/4 of RF frequency. The shut impedance per length is higher than over-loaded cavities and the drive circuits can be simplified because of higher drive frequency. The design consideration, the result of the simulation and measurement of the prototype model, and the detail of the drive circuit will be reported in the presentation.

MOPO008

Design and Simulation of the Transverse Feedback Kicker for the HLSⅡ

impedance, feedback, simulation, vacuum

496

W.B. Li, P. Lu, B.G. Sun, F.F. Wu, Y.L. Yang, Z.R. Zhou
USTC/NSRL, Hefei, Anhui, People's Republic of China

In order to suppress the coupled bunch instabilities in the HLSⅡ storage ring, a transverse feedback system is required. The vital component of the system is the kicker that is the feedback actuator. We design a stripline kicker for the HLSⅡ. The horizontal and vertical electrodes are combined in a structure on account of the space limit. In addition to the design issues, this paper focuses on the simulation results for the kicker using the computer codes. By the 2D code POSSION, we calculate and optimize the characteristic impedance of the stripline kicker to match the 50Ω external transmission lines so as to reduce the reflected power. The reflection coefficient and the shunt impedance in the working frequency range are obtained by the 3D code HFSS. The simulation results provide many important supports for the structure design.

MOPO012

LHC Damper Beam Commissioning in 2010

damping, feedback, injection, ion

505

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

The LHC transverse dampers were commissioned in 2010 with beam and their use at injection energy of 450 GeV, during the ramp and in collisions at 3.5 TeV for Physics have become part of the standard operations procedure. The system proved important to limit emittance blow-up at injection and maintain smaller than nominal emittances throughout the accelerating cycle. We describe the commissioning of the system step-by-step as done in 2010 and summarize its performance as achieved for proton as well as ion beams in 2010. Although its principle function is to keep transverse oscillations under control, the system has also been used as an exciter for abort gap cleaning and tune measurement. The dedicated beam position measurement system with its low noise properties provides additional possibilities for diagnostics.

MOPO015

Operation Status of Bunch-by-bunch Feedback System in the TLS

feedback, controls, injection, diagnostics

514

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

There are several FPGA based bunch-by-bunch feedback systems that were deployed in the Taiwan Light Source now. They play various roles to suppress beam instability. By using SPring-8 designed feedback processors is pioneer to apply in the storage ring of TLS successfully and help Dimtel system to be quick commission. The Dimtel feedback system provide a life spare unit and explore to control system integration especially to the EPICS toolkit system. Rich functionality includes of excitation of individual bunch or specifies bunches, averaged spectrum, tune measurement by the feedback dip in the averaged spectrum. Operation status of the system will be summary in this report.

MOPO017

Latest Performance Results from the FONT5 Intra-train Position and Angle Feedback System at ATF2

feedback, linear-collider, collider, positron

520

G.B. Christian, D.R. Bett, M.R. Davis, C. Perry
JAI, Oxford, United Kingdom
R. Apsimon, P. Burrows
Oxford University, Physics Department, Oxford, Oxon, United Kingdom
B. Constance, A. Gerbershagen
CERN, Geneva, Switzerland
J. Resta-López
IFIC, Valencia, Spain

A prototype Interaction Point beam-based feedback system for future electron-positron colliders, such as the International Linear Collider, has been designed and tested on the extraction line of the KEK Accelerator Test Facility (ATF). The FONT5 intra-train feedback system aims to stabilize the beam orbit by correcting both the position and angle jitter in the vertical plane on bunch-to-bunch timescales, providing micron-level stability at the entrance to the ATF2 final-focus system. The system comprises three stripline beam position monitors (BPMs) and two stripline kickers, custom low-latency analogue front-end BPM processors, a custom FPGA-based digital processing board with fast ADCs, and custom kicker-drive amplifiers. An overview of the hardware, and the latest results from beam tests at ATF2, will be presented. A total system latency as low as approximately 140 ns has been demonstrated.

MOPS004

Mitigation of Beam Instability due to Space Charge Effects at 3 GeV RCS in J-PARC

impedance, space-charge, bunching, injection

595

Y. Shobuda, M. Yamamoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
Y.H. Chin
KEK, Ibaraki, Japan
F. Tamura
KEK/JAEA, Ibaraki-Ken, Japan

In order to accomplish high intensity proton beams, it is important to identify the impedance source in accelerators. At 3 GeV rapid cycling synchrotron (RCS) in Japan Proton Research Complex (J-PARC), the kicker impedance is the most dominant among such impedance sources. Beam instability can be observed by correcting chromaticity during the acceleration. Growth rate due to the beam instability can be reduced by making peak current larger (bunching factor smaller). In other words, it is experimentally found that space charge effects mitigate the beam instability.

MOPS054

Impedance of the Pulse Power Converter for the SIS100 Bipolar Extraction Kicker System

impedance, coupling, simulation, extraction

727

K. Samuelsson, V. Hinrichsen
TU Darmstadt, Darmstadt, Germany
U. Blell, P.J. Spiller
GSI, Darmstadt, Germany

SIS100 will be operated with high intensity heavy-ion and proton beams. The reduction of ring impedances is therefore of great importance in order to avoid coherent beam instabilities. The kicker system is one of the main contributors to the overall ring impedance in SIS100. This paper will focus on the contribution of the external network to the kicker impedance. Calculations as well as experimental impedance measurements of the network contribution have already been carried out for the SIS18 and ESR kickers. The SIS100 will be equipped with a bipolar kicker system, which uses a Pulse Forming Network (PFN) as energy storage. For potential detachment purposes an insulation transformer will be installed. Since this setup is new in several ways it is important to know its contribution to the coupling impedance of the kicker system. In this contribution the corresponding numerical calculation is presented.

MOPS057

Beam-beam Interaction under External Force Oscillation

luminosity, positron, simulation, electron

736

K. Ohmi
KEK, Ibaraki, Japan

Beam-ion interaction is strongly nonlinear. Response for external oscillation applied to beam shows characteristic feature. Simulations for external frequency scan becomes feasible for the recent computer power. We show the frequency response for beam-ion system in KEK-PF and recent low emittance rings.

MOPS059

Transverse Impedance Calculation for Simplified Model of Ferrite Kicker Magnet with Beta < 1

impedance, coupling, extraction, proton

742

N. Wang, Q. Qin
IHEP Beijing, Beijing, People's Republic of China

In high intensity rings, kicker magnet is usually considered as a main source to the total impedance. Transverse coupling impedance of a simplified kicker model has been derived analytically in the ultrarelativistic limit. We extend the result to the general case of v < c, and present the analytical formulae of both horizontal and vertical transverse impedances. Numerical results are given for the CSNS extraction kicker magnets.

MOPS064

Longitudinal Beam Stability and Related Effects at the ALBA Storage Ring

impedance, resonance, vacuum, injection

748

T.F. Günzel
CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain

The risk of longitudinal instabilities excited by narrowband and broadband resonator impedance was studied. A campaign for the search of modes trapped in vacuum chamber elements of the ALBA storage ring via electromagnetic simulation was initiated. Several critical vacuum elements in the ring like the vertical scraper, the injection and feedback kickers were identified. The outlets of the injection kicker had to be protected with RF-fingers whereas the scraper only produces dangerous modes in the withdrawn state, both do not pose a real problem. However, the calculated power distribution generated in the feedback kickers could be an obstacle for reaching the nominal current of 400mA. Furthermore, the budget of Z(n)/n of the storage ring was computed and checked on the risk of microwave instability using the Boussard criterion.

MOPS065

Transverse Instability Studies at the ALBA Storage Ring

impedance, vacuum, single-bunch, storage-ring

751

T.F. Günzel
CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain

In the first phase of the ALBA storage ring operation 3 NEG-coated aluminum chambers, 2 in-vacuum undulators and one wiggler chamber will be installed. Under particular consideration of the multilayer character of these chambers and the injection kickers the thresholds of the transverse mode coupled instability(TMCI) were calculated using MOSES*. The thresholds 17.5mA/40.5mA vertical/horizontal leave a rather large operative margin. The detrimental effect of the NEG-coating on the TMCI is relatively limited and on the resistive wall instability is even negligible. As well the thresholds of the head-tail instability were computed as function of chromaticity. Also the incoherent tune shifts generated by the quadrupolar resistive wall wake fields due to the flatness of the vacuum chambers were calculated. The computed results have been compared to first measurements of the storage ring commissioning.
* Y.H.Chin, MOSES 2.0, CERN/LEP-TH/88-05

MOPS070

Electromagnetic Modeling of C Shape Ferrite Loaded Kickers

impedance, simulation, vacuum, ion

763

C. Zannini
EPFL, Lausanne, Switzerland
E. Métral, G. Rumolo, B. Salvant, V.G. Vaccaro, C. Zannini
CERN, Geneva, Switzerland

The kickers are major contributors to the CERN SPS beam coupling impedance. As such, they may represent a limitation to increasing the SPS bunch current in the frame of an intensity upgrade of the LHC. In this paper, analytical approach and CST Particle Studio time domain electromagnetic simulations are performed to obtain the longitudinal and transverse impedances/wake potentials of models of ferrite loaded kickers. It turns out that the existing models are not sufficient to characterize correctly these components from the coupling impedance point of view. In particular the results show that below few hundred MHz the real C-structure of the magnet cannot be neglected. Therefore an analytical model was developed and benchmarked with EM simulations to take into account the C-shape of the magnet.

MOPS072

Broadband Electromagnetic Characterization of Materials for Accelerator Components

impedance, simulation, damping, RF-structure

769

C. Zannini, A. Grudiev, E. Métral, T. Pieloni, G. Rumolo
CERN, Geneva, Switzerland
G. De Michele
PSI, Villigen, Switzerland
C. Zannini
EPFL, Lausanne, Switzerland

Electromagnetic (EM) characterization of materials up to high frequencies is a major requirement for the correct modeling of many accelerator components: collimators, kickers, high order modes damping devices for accelerating cavities. In this scenario, the coaxial line method has gained much importance compared to other methods because of its applicability in a wide range of frequencies. In this paper we describe a new coaxial line method that allows using only one measurement setup to characterize the material in a range of frequency from few MHz up to several GHz. A coaxial cable fed at one side is filled with the material under test and closed on a known load on the other side. The properties of the material are obtained from the measured reflection coefficient by using it as input for a transmission line (TL) model or for 3D EM simulations, which describe the measurements setup. We have applied this method to characterize samples of SiC (Silicon Carbide) which could be used for LHC collimators and for CLIC accelerating structures and NiZn ferrite used for kicker magnets.

MOPS073

Impedance Calculation for Simple Models of Kickers in the Non-ultrarelativistic Regime

impedance, vacuum, coupling, neutron

772

N. Biancacci, N. Mounet, E. Métral, B. Salvant, C. Zannini
CERN, Geneva, Switzerland
N. Biancacci, M. Migliorati, A. Mostacci, L. Palumbo
Rome University La Sapienza, Roma, Italy
Q. Qin, N. Wang
IHEP Beijing, Beijing, People's Republic of China

Kicker magnets are usually significant contributors to the beam coupling impedance of particle accelerators. An accurate understanding of their impedance is required in order to correctly assess the machine intensity limitations. The field matching method derived by H. Tsutsui for the longitudinal and transverse dipolar (driving) impedance of simple models of kickers in the ultrarelativistic regime was already extended to the non-ultrarelativistic case, and to the quadrupolar (detuning) impedance in the ultrarelativistic case. This contribution presents the extension to the quadrupolar impedance in the non-ultrarelativistic case, as well as benchmarks with other available methods to compute the impedance. In particular, all the components of the impedances are benchmarked with Tsutsui's model, i.e. in the ultrarelativistic limit, with the model for a flat chamber impedance recently computed by N. Mounet and E. Métral, in the case of finite relativistic gamma, and with CST Particle Studio simulations.

MOPS078

Coaxial Wire Measurements of Ferrite Kicker Magnets

impedance, simulation, injection, extraction

784

H.A. Day, R.M. Jones
UMAN, Manchester, United Kingdom
M.J. Barnes, F. Caspers, H.A. Day, E. Métral, B. Salvant, C. Zannini
CERN, Geneva, Switzerland

Fast kicker magnets are used to inject beam into and eject beam out of the CERN accelerator rings. These kickers are generally transmission line type magnets with a rectangular shaped aperture through which the beam passes. Unless special precautions are taken the impedance of the yoke can provoke significant beam induced heating, especially for high intensities. In addition the impedance may contribute to beam instabilities. The results of longitudinal and transverse impedance measurements, for various kicker magnets, are presented and compared with analytical calculations: in addition predictions from a numerical analysis are discussed.

MOPS079

Simulations of Coaxial Wire Measurements of the Impedance of Asymmetric Structures

impedance, simulation, coupling, synchrotron

787

H.A. Day, R.M. Jones
UMAN, Manchester, United Kingdom
F. Caspers, H.A. Day, E. Métral
CERN, Geneva, Switzerland

Coaxial wire measurements have provided a simple and effective way to measure the beam coupling impedance of accelerator structures for a number of years. It has been known how to measure the longitudinal and dipolar transverse impedance using one and two wires for some time. Recently the ability to measure the quadrupolar impedance of structures exhibiting top/bottom and left/right symmetry has been demonstrated. A method for measuring the beam coupling impedance of asymmetric structures using displaced single wires and two wire measurements is proposed. Simulations of the measurement system are presented with further work proposed.

MOPS089

Identification of Bunch Dynamics in the Presence of E-cloud and TMCI for the CERN SPS Ring

simulation, controls, feedback, coupling

811

O. Turgut, J.D. Fox, C.H. Rivetta, S. Uemura
SLAC, Menlo Park, California, USA
W. Höfle
CERN, Geneva, Switzerland

Funding: Work is supported by the U.S. Department of Energy under contract DE-AC02-76SF00515 and the US LHC Accelerator Research Program (LARP).
Measurements and multi-particle simulation codes (i.e. HEAD-TAIL, WARP, CMAD) indicate that bunched particle beams show unstable motions induced by electron-clouds and strong head-tail interactions. The bunch dynamics exhibits highly non-linear, complex and unstable behavior under certain operating conditions. Feedback control systems have been proposed to mitigate these instabilities in the CERN SPS ring. The design of feedback systems requires the knowledge of a reduced dynamic model of the bunch. It allows to include and quantify the effect of noise and signal perturbations, as well as system robustness to parameter variation. Identification techniques are used to estimate those models based on bunch motion measurements. In this work we present reduced mathematical models representing the transverse bunch dynamics and identification techniques to extract the model parameters based on measurements. These techniques are validated using time domain simulations of the bunch motion conducted using multi-particle simulation codes. For that, different sections of the bunch are driven by random signals, and the vertical motion of those areas is used to estimate the reduced model.

MOPZ004

Studies for the PRISM FFAG Ring for the Next Generation Muon to Electron Conversion Experiment

injection, electron, extraction, septum

826

J. Pasternak
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
M. Aslaninejad, L.J. Jenner, A. Kurup, J. Pasternak, Y. Shi, Y. Uchida
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
R.J. Barlow
UMAN, Manchester, United Kingdom
K.M. Hock, B.D. Muratori
Cockcroft Institute, Warrington, Cheshire, United Kingdom
D.J. Kelliher, S. Machida, C.R. Prior
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
Y. Kuno, A. Sato
Osaka University, Osaka, Japan
J.-B. Lagrange, Y. Mori
KURRI, Osaka, Japan
M. Lancaster
UCL, London, United Kingdom
C. Ohmori
KEK, Tokai, Ibaraki, Japan
T. Planche
TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
S.L. Smith
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
H. Witte, T. Yokoi
JAI, Oxford, United Kingdom

High intensity and high quality muon beams are needed for the next generation lepton flavour violation experiments. Such beams can be produced by sending a short proton pulse to a pion production target, capturing the pions and performing RF phase rotation on the resulting muon beam in an FFAG ring. Such a solution was proposed for the PRISM project and this paper summarizes its current status. In particular the PRISM task force was created to address the accelerator and detector issues that need to be solved in order to realise the PRISM experiment. Alternative designs for the PRISM FFAG ring are discussed and their performance compared. The injection/extraction systems and matching to the solenoid channels upstream and downstream of the FFAG ring are presented. The future direction for the study will be outlined.

MOPZ007

A Non-scaling Fixed Field Alternating Gradient Accelerator for the Final Acceleration Stage of the International Design Study of the Neutrino Factory

extraction, injection, cavity, lattice

832

J.S. Berg
BNL, Upton, Long Island, New York, USA
M. Aslaninejad, J. Pasternak
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
N. Bliss, M.A. Cordwell, T.J. Jones
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
D.J. Kelliher, S. Machida
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
A.A. Muir
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
H. Witte
JAI, Oxford, United Kingdom

Funding: This manuscript has been authored by employees of Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The International Design Study of the Neutrino Factory (IDS-NF) has recently completed its Interim Design Report (IDR), which presents our current baseline design of the neutrino factory. To increase the efficiency and reduce the cost of acceleration, the IDR design uses a linear non-scaling fixed field alternating gradient accelerator (FFAG) for its final acceleration stage. We present the current lattice design of that FFAG, including the main ring plus its injection and extraction systems. We describe parameters for the main ring magnets, kickers, and septa, as well as the power supplies for the kickers. We present a first pass at an engineering layout for the ring and its subsystems.

MOPZ030

Status of Studies of Achromat-based 6D Ionization Cooling Rings for Muons

injection, lattice, solenoid, extraction

865

X.P. Ding, D.B. Cline
UCLA, Los Angeles, California, USA
J.S. Berg, H.G. Kirk
BNL, Upton, Long Island, New York, USA
A.A. Garren
Particle Beam Lasers, Inc., Northridge, California, USA

Funding: This work was supported by the U.S. Department of Energy in part under award numbers DE-FG02-92ER40695 (UCLA), DE-AC02-98CH10886 (BNL) and DE-FG02-07ER84855 (Particle Beam Lasers, Inc.)”
Six dimensional ionization cooling of muons is needed to achieve the necessary luminosity for a muon collider. If that cooling could occur over multiple turns in a closed ring, there would be significant cost savings over a single-pass cooling channel. We report on the status of a cooling ring with achromatic arcs. The achromatic design permits the design to easily switch between a closed ring and a snaking geometry on injection or extraction from the ring. The ring is designed with sufficient space in each superperiod for injection and extraction magnets. We describe the ring's lattice design, performance, and injection/extraction requirements.

MOPZ038

EMMA Injection and Extraction

injection, extraction, dipole, septum

883

B.D. Muratori, J.K. Jones
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
Y. Giboudot
Brunel University, Middlesex, United Kingdom
D.J. Holder
The University of Liverpool, Liverpool, United Kingdom

EMMA (Electron Machine with Many Applications) is a prototype non-scaling electron FFAG hosted at Daresbury Laboratory. NS-FFAGs related to EMMA have an unprecedented potential for medical accelerators for carbon and proton hadron therapy. They could also be used as the accelerator for a sub-critical reactor. We summarize the design and commissioning of both the injection and extraction lines for this machine. In particular, we look at the commissioning challenges of injection and extraction.

TUYA03

Stochastic Cooling of a High Energy Collider

simulation, pick-up, cavity, luminosity

913

M. Blaskiewicz, J.M. Brennan, R.C. Lee, K. Mernick
BNL, Upton, Long Island, New York, USA

Three dimensional stochastic cooling was successfully implemented at the Relativistic Heavy Ion Collider to overcome emittance growth from intra-beam scattering. The talk reports on the experience of operating a collider with continuous cooling. The application of such techniques to other hadron machine (e.g. LHC) will be discussed.

Slides TUYA03 [1.350 MB]

TUPC007

Kicker and Monitor for CTF3 Phase Feed Forward

impedance, pick-up, coupling, collider

1000

F. Marcellini, D. Alesini, A. Ghigo
INFN/LNF, Frascati (Roma), Italy

Funding: Work partially supported by the EuCARD research programme, Grant Agreement 227579, within the 'Assessment of Novel Accelerator Concepts'.
In the Compact LInear Collider (CLIC) the synchronization of the Drive Beam and the Main Beam has to be assured in the femtosecond range to avoid luminosity reduction of the collider. The Drive and Main Beams arrival time is measured with longitudinal monitors and the correction is applied changing the path length of one beam respect to the other in a magnetic chicane by means of two transverse fast stripline kicker. The performance of the feed forward system will be tested in the CLIC Test Facility (CTF3) measuring the phase at the linac exit, correcting in the chicane after the combination rings and comparing the longitudinal position change before the power RF production system. The developed phase monitors and kicker magnets for the test in CTF3 are described.

TUPC011

Striplines for CLIC Pre-Damping and Damping Rings*

impedance, vacuum, damping, extraction

1012

C. Belver-Aguilar, A. Faus-Golfe
IFIC, Valencia, Spain
M.J. Barnes, G. Rumolo
CERN, Geneva, Switzerland
F. Toral
CIEMAT, Madrid, Spain
C. Zannini
EPFL, Lausanne, Switzerland

The Compact Linear Collider (CLIC) study explores the scheme for an electron-positron collider with high luminosity and a nominal center-of-mass energy of 3 TeV: CLIC would complement LHC physics in the multi-TeV range. The CLIC design relies on the presence of Pre-Damping Rings (PDR) and Damping Rings (DR) to achieve, through synchrotron radiation, the very low emittance needed to fulfil the luminosity requirements. The specifications for the kicker systems are very challenging and include very low beam coupling impedance and excellent field homogeneity: striplines have been chosen for the kicker elements. Analytical calculations have been carried out to determine the effect of tapering upon the high frequency beam coupling impedance. In addition detailed numerical modeling of the field homogeneity has been performed and the sensitivity of the homogeneity to various parameters, including stripline cross-section, has been studied. This paper presents the main conclusions of the beam impedance calculations and field homogeneity predictions.

TUPC013

Simulation of Phase Stability at the Flat Top of the CLIC Drive Beam

linac, simulation, luminosity, collider

1018

A. Gerbershagen, D. Schulte
CERN, Geneva, Switzerland
P. Burrows
Oxford University, Physics Department, Oxford, Oxon, United Kingdom

Funding: University of Oxford
The drive beam phase stability is one of the critical issues of the Compact Linear Collider (CLIC). In this paper the generation and propagation of drive beam phase errors is studied for effects that vary during the drive beam pulse. This includes the influence of drive beam current and phase errors as well as of drive beam accelerator RF phase and amplitude errors on the drive beam phase after the compressor chicanes and the analysis of the propagation of these errors through the drive beam combination scheme. The impact of the imperfections on the main beam is studied including the possible correction with help of a feedforward system.

TUPC080

Pickup Design with Beta Matching

pick-up, impedance, simulation, resonance

1189

J.A. Tsemo Kamga, W.F.O. Müller, K.K. Stavrakakis, T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany

Funding: Work supported by GSI
The main goal of this project is to investigate the Schottky noise of an ion beam in the frequency range from 3 to 5 GHz. In order to accomplish this task, a pickup design is required. For an efficient study of this Schottky noise the pickup sensitivity for low beta must be increased. A design for such a problem has been developed by McGinnis for a fixed beam velocity but can also be used for variable beta by using a tunable material (ferroelectric) inside the waveguide. Since such tunable materials like for instance BST (Barium Strontium Titanate) are lossy, the impact of dielectric losses on the pickup sensitivity will also be investigated in this work. Additionally to the classical parameter studies where multiple simulation runs based on the original numerical model are initiated to characterize the various design parameters it is also possible to utilize a reduced model instead. In particular one is interested in a fast evaluation of the frequency response while taking also material variations into account. In this work, a multivariate parameterized dynamical system is set up and used complementary to the full model for the required beam characterization.

TUPC095

Bucket-by-bucket On/Off-axis Injection with Variable Field Fast Kicker

injection, dipole, quadrupole, emittance

1230

T. Nakamura
JASRI/SPring-8, Hyogo-ken, Japan

Dynamic aperture of ultra-low emittance storage rings is expected to be as small as a few mm; one order smaller than that of current rings, because of their high nonlinearity. The conventional injection scheme with bump formation may not be applied for such small aperture. On-axis injection with fast magnet is one of the solutions, however, it requires the injection beam of long trains of bunches, which impose serious limitation on the injector and the filling pattern. We propose a bucket-by-bucket on-axis/off-axis injection scheme, which manipulates the injection and stored beams bucket-by-bucket with a variable field fast kicker. For on-axis injection, this scheme eliminates the limitation on injectors and filling pattern, and also it can reject the contaminated electrons from the injector to keep the bunch purity. Those advantages allow the SPring-8 XFEL low emittance linac to be an injector matched with ultra-low emittance rings like the SPring-8 II: upgrade plan of SPring-8. By changing the drive power to the kicker, it can also produce position dependent kick required for the off-axis injection, with minimal perturbation on the stored beam achieved by bucket-by-bucket scheme.

TUPC103

Monitoring of the Betatron Tune and Amplitude at Multi-batch Injection of J-PARC MR

injection, betatron, feedback, quadrupole

1254

S. Hatakeyama
JAEA/J-PARC, Tokai-mura, Japan
M. Takagi
Kanto Information Service (KIS), Accelerator Group, Ibaraki, Japan
M. Tejima, T. Toyama
KEK, Ibaraki, Japan

The beam power of J-PARC Main Ring Synchrotron (MR) increased gradually from 2008, and came to be able regularly to supply the beam of 145kW February, 2011. Many of current beam losses are localized to the collimator located on the injection section. One of the problems of the beam injection is that the orbit of the beam transportation line is unstable. It causes sometimes large transverse injection error. Because the transverse injection error is essentially proportional to the amplitude of the betatron oscillation, it is possible to observe by measuring the turn-by-turn position for every bunch of injected beam by using BPMs located on the injection section. In this report, it is described the method how to measure injection error from beam position. It is also discussed about the effect of reflection wave of injection kicker magnets.

TUPC107

Some Preliminary Experiments using LIBERA BPMs in BEPCII*

coupling, resonance, injection, feedback

1266

Y. Zhang, H.Z. Ma, J. Yue
IHEP Beijing, Beijing, People's Republic of China

Funding: Supported by the National Natural Science Foundation of China (10805051)
There are total 16 LIBERA BPMs in BEPCII, which is a double ring e⁺e⁻ collider. The turn-by-turn BPMs serve as only tune measurement system in most cases during normal operation. We tried to do some more machine study using them: the local coupling parameter at the BPM, the resonance driving term, the decoherence parameter which could be used to calibrate the strength of octupole in the ring. We also compare the difference from the different exciting method: single time kick with injection kicker or sinusoidal kick with feedback system.

TUPC128

Transverse Beam Jitter Propagation in Multi-bunch Operation at ATF2

extraction, simulation, feedback, lattice

1320

J. Resta-López, J. Alabau-Gonzalvo
IFIC, Valencia, Spain
P. Burrows, G.B. Christian
JAI, Oxford, United Kingdom
B. Constance
CERN, Geneva, Switzerland

Pulse-to-pulse orbit jitter, if not controlled, can drastically degrade the luminosity in future linear colliders. The second goal of the ATF2 project at the KEK accelerator test facility is to stabilize the vertical beam position down to approximately 5% of the nominal rms vertical beam size at the virtual interaction point (IP). This will require control of the orbit to better than 1 micrometer at the entrance of the ATF2 final focus system. In this paper, by means of computer simulations, we study the vertical jitter propagation along the ATF2 from the start of the extraction line to the IP. For this study pulse-to-pulse vertical jitter measurements using three stripline beam position monitors are used as initial inputs. This study is performed for the case of a bunch-train with three bunches, but could easily be extended for a larger number of bunches. The cases with and without intra-train orbit feedback correction in the extraction line of ATF2 are compared.

TUPC137

UFOs in the LHC

beam-losses, injection, simulation, acceleration

1347

T. Baer, M.J. Barnes, B. Goddard, E.B. Holzer, J.M. Jimenez, A. Lechner, V. Mertens, E. Nebot Del Busto, A. Nordt, J.A. Uythoven, B. Velghe, J. Wenninger, F. Zimmermann
CERN, Geneva, Switzerland

One of the major known limitations for the performance of the Large Hadron Collider are so called UFOs (”Unidentified Falling Objects”). UFOs were first observed in July 2010 and have since caused numerous protection beam dumps. UFOs are thought to be micrometer sized dust particles which lead to fast beam losses with a duration of about 10 turns when they interact with the beam. In 2011, the diagnostics for such events was significantly improved which allows estimates of the properties, dynamics and production mechanisms of the dust particles. The state of knowledge and mitigation strategies are presented.

TUPO018

Self-stimulated Undulator Klystron

undulator, FEL, electron, storage-ring

1482

E.G. Bessonov, A.L. Osipov
LPI, Moscow, Russia
A.A. Mikhailichenko
CLASSE, Ithaca, New York, USA

The Self Stimulated Undulator Klystron (SSUK) and its possible applications in the Particle Accelerator Physics, incoherent Self-Stimulated Undulator Radiation Sources (SSUR) and Free-Electron Lasers are discussed*.
* E.G.Bessonov et al., Self-Stimulated Undulator Radiation and its Possible Applications: http://arxiv.org/ftp/arxiv/papers/10⁰⁹/1009.3724.pdf

TUPS101

A Fast 650V Chopper Driver

controls, linac, impedance, status

1777

M.M. Paoluzzi
CERN, Geneva, Switzerland

In the framework of Linac4 and the Superconducting Proton Linac (SPL) studies at CERN, the design for a beam chopper has been carried out. The chopper is basically a kicker that deviates part of the beam towards a dump. It is made of two 50 Ω, slow wave lines facing each other, matching the beam velocity and driven with a minimum of 500 V. Due to the bunch spacing of 2.84 ns, a system rise and fall time (3 %-90 %) below 2.5 ns is required with pulse lengths ranging from 8 ns to hundreds of μs. Although different solutions for the driver amplifier where devised in the past, none of the achievements was entirely satisfactory. This paper describes a new design and prototype that meets all the required specifications.

TUPZ023

Observation of Bunch to Bunch Differences due to Beam-beam Effects

luminosity, injection, emittance, dynamic-aperture

1855

G. Papotti, R. Alemany-Fernandez, R. Giachino, W. Herr, T. Pieloni, M. Schaumann, G. Trad
CERN, Geneva, Switzerland

Due to the bunch filling schemes in the LHC the bunches experience a very different collision schedule and therefore different beam-beam effects. These differences and the effect on the performance have been observed and compared with the expectations. Possible limitations due to these effects are discussed.

WEOBA02

KEK Digital Accelerator and its Beam Commissioning

injection, ion, acceleration, induction

1920

K. Takayama, T. Arai, Y. Arakida, M. Hasimoto, T. Iwashita, E. Kadokura, T. Kawakubo, T. Kubo, H. Nakanishi, K. Okamura, H. Someya, A. Takagi, M. Wake
KEK, Ibaraki, Japan
T. Adachi, K.W. Leo
Sokendai, Ibaraki, Japan
K. Okazaki
Nippon Advanced Technology Co. Ltd., Ibaraki-prefecture, Japan

The digital accelerator (DA), which is a small-scale induction synchrotron no requiring a high-energy injector accelerator and capable of providing a wide variety of ions, has been constructed at KEK*. Since the last winter beam commissioning has been carried out. Preliminary results of the beam commissioning experiment as well as the accelerator itself will be presented at the conference. The KEK-DA consists of a 200 kV high voltage terminal, in which an ECRIS is embedded, 15 m long LEBT, electro-static injection kicker, and a 10 Hz rapid cycle synchrotron, which is the recycle use of the former 500 MeV Booster synchrotron. An ion pulse, which is chopped in 5 μs by the newly developed Marx generator driven chopper**, is guided through the LEBT and injected by the electrostatic kicker, which is turned off before the injected ion pulse completes the first turn. Then the ion pulse is captured with a pair of barrier voltages and accelerated with the induction acceleration voltage through a full acceleration period. Beam commissioning has been started with a He¹⁺ ion beam of 50 micro-ampere. Beam commissioning of other ions such as C, N, O, Ne, and Ar will be expected.
* T. Iwashita et al., “KEK Digital Accelerator”, Phys. Rev. ST-AB, published in 2011.
** T.Adachi et al., “A Solid-State Marx Generator Driven Einzel Lens Chopper”, these proceedings.

Slides WEOBA02 [4.268 MB]

WEPC008

Optics for the Beam Switchyard at the European XFEL

septum, undulator, quadrupole, extraction

2016

N. Golubeva, V. Balandin, W. Decking
DESY, Hamburg, Germany

The European XFEL is planed as a multi-user facility with the possibility to distribute electron bunches of one beam pulse to different beamlines. The initial stage foresees two electron beamlines each serving its own set of undulators. The later addition of a third beamline is also considered in the design of the distribution system. In addition, the integration of the transport line to the beam abortion dump allows a flexible selection of the bunch repetition pattern for each beamline. The beam extraction, both in undulator beamlines and in the beamline to the dump, will be realized with fast kickers and a Lambertson septum. In this paper we describe the magnet lattice of the deflection arcs with simultaneous horizontal and vertical dispersions and the beam optics of the beam switchyard.

WEPC030

Measurement of Coupling Resonance Driving Terms in the LHC with AC Dipoles

dipole, optics, quadrupole, resonance

2067

R. Miyamoto, R. Calaga
BNL, Upton, Long Island, New York, USA
M. Aiba
PSI, Villigen, Switzerland
R. Tomás, G. Vanbavinckhove
CERN, Geneva, Switzerland

Funding: This work partially supported by the US Department of Energy through the US LHC Accelerator Research Program (LARP).
Transverse betatron coupling in the LHC is measured from Fourier analysis of turn-by-turn beam oscillations excited by AC dipoles. The use of the AC dipole for optics measurements induces a small systematic error which can be corrected with an appropriate data interpretation. An algorithm to apply this correction to the measurement of the coupling resonance driving terms is developed for the first time. This paper will review this new algorithm and present results of its application to the LHC.

WEPC032

First Measurements of Higher Order Optics Parameters in the LHC

simulation, optics, resonance, injection

2073

G. Vanbavinckhove
NIKHEF, Amsterdam, The Netherlands
M. Aiba
PSI, Villigen, Switzerland
R. Bartolini
Diamond, Oxfordshire, United Kingdom
R. Calaga, R. Miyamoto
BNL, Upton, Long Island, New York, USA
M. Giovannozzi, F. Schmidt, R. Tomás
CERN, Geneva, Switzerland
E.H. Maclean
JAI, Oxford, United Kingdom

Higher order effects can play an important role in the performance of the LHC. Lack of knowledge of these parameters can increase the tune footprint and compromise the beam lifetime. First measurements of these parameters at injection and flattop have been conducted. Detailed simulations are compared to the measurements together with discussions on the measurement limitations.

WEPC044

Minimizing Beam Motion in a Long-pulse Linear Induction Accelerator

induction, target, injection, focusing

2109

C. Ekdahl, E.O. Abeyta, J.B. Johnson, K. Nielsen, M.E. Schulze
LANL, Los Alamos, New Mexico, USA
T.P. Hughes, C.H. Thoma
Voss Scientific, Albuquerque, New Mexico, USA
C.-Y. Tom
NSTec, Los Alamos, New Mexico, USA

Funding: This work was supported by the US National Nuclear Security Agency and the US Department of Energy under contract DE-AC52-06NA25396.
The Dual Axis Radiography for Hydrodynamic Testing (DARHT) Facility at Los Alamos uses two linear induction accelerators (LIAs) for flash radiography of explosively driven experiments from orthogonal viewpoints. The DARHT Axis-II long-pulse 1.8-kA, 16.5-MeV LIA is unique. It has a beam pulse with a 1600-ns flattop during which the kinetic energy varies < 2%. During this flattop, a kicker cleaves out four short micro-pulses, which are focused onto a high-Z target and converted to bremsstrahlung for multi-pulse flash radiography of the experiments. Asymmetric injection of the beam into the solenoidal focusing field, small temporal variations in accelerating potentials, and slight cell misalignments cause the beam position to wander during the flattop. This is undesirable for radiography, because it causes a displacement of the four radiographic source spots. Since the specific energy deposition from each micro-pulse can vaporize target material, succeeding pulses impact an asymmetric object causing a distortion of the source spot. This presentation will review the physics of the beam motion and the tuning procedures we have optimized to minimize the number of shots required.

WEPC104

Vicky : A Computer Code for Use in the Design and Simulation of Particle Accelerators

dynamic-aperture, sextupole, quadrupole, closed-orbit

2256

F. Iazzourene
ELETTRA, Basovizza, Italy

Vicky is a computer code under development for designing and simulating particle accelerators. Like other existing codes, the features include machine imperfections, closed orbit correction, Twiss functions matching, chromaticity evaluation and correction, particle tracking and so on. The goal is to give the users a friendly graphical interface with widgets to perform the wished tasks, for example to plot the orbit, the Twiss functions, the tune diagram, the dynamic aperture and so on, to select and read an input file describing the considered lattice, to perform the Twiss functions matching, a closed orbit correction and so on. The code provides a description of the particle motion by 10 parameters: four beta-functions, four alpha-functions and two phase advances, that is a 4*4 generalized transverse coupling, together with an emphasis on the treatment of the complex 3D magnetic fields of the undulators used in today’s modern synchrotron radiation facilities. The code is written in C++. It uses the free packages QT for the online plots and the graphical user interface and IT++ for the mathematics. The present status and some results of its application will be presented.

WEPC123

Numerical Algorithm based on the PDE Method for the Solution of the Fokker-Planck Equation

simulation, pick-up, storage-ring, impedance

2298

M. Dolinska
NASU/INR, Kiev, Ukraine
C. Dimopoulou, A. Dolinskii, F. Nolden, M. Steck
GSI, Darmstadt, Germany

Funding: Work supported by HIC for FAIR
This paper discus a fast and accurate algorithm for numerical solution of Fokker-Planck equation based on the solution of the parabolic Partial Differential Equations (PDE), where the Crank–Nicholson scheme is used. The stability, convergence and round-off errors of the algorithm are studied. The numerical results on Fokker–Planck equation solution with PDE method are compared with other numerical methods. Using the PDE solver, we will be able to predict the stochastic cooling process of notch filter in storage rings.

WEPO013

Septum and Kicker Magnets for the ALBA Booster and Storage Ring

injection, booster, vacuum, storage-ring

2421

M. Pont, R. Nunez
CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain
E. Huttel
KIT, Karlsruhe, Germany

At the ALBA Synchrotron light source 6 kicker and 3 septa magnets are installed for beam injection and extraction. A 100 MeV beam coming from the linac is injected on axis into the Booster. The full energy (3 GeV) beam is extracted from the booster and injected into the Storage Ring, where 4 kicker magnets bring the stored beam close to the septa. All septa are direct driven out-of-vacuum magnets with C shape iron laminated yoke. The magnets are excited by a full sine approx. 300 μs pulse length; the nominal field is 0.15/0.84/0.9 T (booster injection/extraction/storage-ring-injection). The stray field seen by the stored beam is less than 1 μT. The booster kicker magnets are in-vacuum magnets with C-ferrite yoke. The magnets are excited by a 0.4 μs flat top pulse; the nominal field is 0.03/0.04 T (booster injection/extraction). The storage ring kickers have a C-ferrite yoke and a 0.4 μm Ti coated ceramic vacuum chamber. The excitation is done by 6 μs half sine; the nominal field is 0.13 T. The paper will present the design of the elements and their magnetic characteristics. First results of their behaviour during commissioning will also be discussed.

WEPS008

Operation Status and Future Plan of J-PARC Main Ring

extraction, beam-losses, linac, betatron

2499

T. Koseki
KEK, Ibaraki, Japan

The J-PARC Main Ring (MR) has started users operation since 2009. The MR has two beam extraction systems. One is a fast extraction (FX) system for beam delivery to the neutrino beam line of the Tokai-to-Kamioka (T2K) experiment, and the other is a slow extraction (SX) system for beam delivery to the hadron experimental hall. For the T2K experiment, the maximum beam power of 145 kW is delivered continuously. For users of the hadron experimental hall, the beam power of 3 kW is delivered with extraction efficiency of 99.5%. In this paper, status of the high power beam operation of the MR is presented. Future prospect for increasing beam intensity is also discussed.

WEPS099

Physics Design of CSNS RCS Injection and Extraction System

extraction, injection, septum, emittance

2739

J. Qiu, N. Huang, J. Tang, S. Wang
IHEP Beijing, Beijing, People's Republic of China

In this paper, the injection and extraction system design for CSNS RCS are discussed. The injection system is designed to place all the injection devices in one uninterrupted long drift in one of the four dispersion free straight sections. Painting bumper magnets are used for both horizontal and vertical phase space painting. The beam extraction process from the CSNS RCS is a single turn two step process, requiring a group of kickers and a Lambertson septum magnet.

WEPZ015

Staging in Two Beam Dielectric Wakefield Accelerators

cavity, acceleration, wakefield, septum

2802

J.G. Power, M.E. Conde, W. Gai, C.-J. Jing
ANL, Argonne, USA

Funding: The work is supported by the U.S. Department of Energy under Contract No. DE-AC02-06CH11357 with Argonne National Laboratory.
A new experimental program to demonstrate staging in a two beam dielectric wakefield accelerator (DWA) is being planned at the Argonne Wakefield Accelerator facility. DWA uses a drive beam to generate acceleration fields to accelerate a main beam and is one of the most promising advanced acceleration methods being pursued for a future high-energy physics linear collider. Staging is the ability to use two accelerating modules back to back to accelerate a charged particle bunch and it is one of basic requirements of any acceleration method. In this paper, a new beamline design consisting of a fast kicker to pick pulses from the drive bunch train and deliver them to the individual acceleration modules will be presented.

WEPZ017

ESTB: A New Beam Test Facility at SLAC

electron, hadron, linac, emittance

2808

M.T.F. Pivi, H. Fieguth, C. Hast, R.H. Iverson, J. Jaros, R.K. Jobe, L. Keller, T.V.M. Maruyama, D.R. Walz, M. Woods
SLAC, Menlo Park, California, USA

Funding: Work supported by the Director, Office of Science, High Energy Physics, U.S. DOE under Contract No. DE-AC02-76SF00515.
End Station A Test Beam (ESTB) is a beam line at SLAC using a small fraction of the bunches of the 13.6 GeV electron beam from the Linac Coherent Light Source (LCLS), restoring test beam capabilities in the large End Station A (ESA) experimental hall. ESTB will provide one of a kind test beam essential for developing accelerator instrumentation and accelerator R&D, performing particle and particle astrophysics detector research, linear collider machine and detector interface (MDI) R&D studies, development of radiation-hard detectors, and material damage studies with several distinctive features. In the past, 18 institutions participated in the ESA program at SLAC. In stage I, 4 new kicker magnets will be added to divert 5 Hz of the LCLS beam to ESA. A new beam dump is installed and a new Personnel Protection System (PPS) is built in ESA. In stage II, we plan to install a secondary hadron target, able to produce pions up to about 12 GeV/c at 1 particle/pulse. We report about the ESTB commissioning, status and plan for tests.

THOBA03

Dual AC Dipole Excitation for the Measurement of Magnetic Multipole Strength from Beam Position Monitor Data*

dipole, sextupole, simulation, lattice

2865

M. Spata, G.A. Krafft
JLAB, Newport News, Virginia, USA

Funding: Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
An experiment was conducted at Jefferson Lab's Continuous Electron Beam Accelerator Facility to develop a technique for characterizing the nonlinear fields of the beam transport system. Two air-core dipole magnets were simultaneously driven at two different frequencies to provide a time-dependent transverse modulation of the electron beam. Fourier decomposition of beam position monitor data was then used to measure the amplitude of these frequencies at different positions along the beamline. For a purely linear transport system one expects to find solely the frequencies that were applied to the dipoles with amplitudes that depend on the phase advance of the lattice. In the presence of nonlinear fields one expects to also find harmonics of the driving frequencies that depend on the order of the nonlinearity. The technique was calibrated using one of the sextupole magnets in a CEBAF beamline and then applied to a dipole to measure the sextupole and octupole strength of the magnet. A comparison is made between the beam-based measurements, results from TOSCA and data from our Magnet Measurement Facility.

Slides THOBA03 [6.193 MB]

THPC003

Installation of the ASTRID2 Synchrotron Light Source

extraction, dipole, cavity, vacuum

2909

J.S. Nielsen, N. Hertel, S.P. Møller
ISA, Aarhus, Denmark

ASTRID2 is the new 10 nm UV and soft x-ray light source being built at Aarhus University, to replace the aging source ASTRID. ASTRID2 is now in the middle of its installation. An update of the design will be presented. Almost all components have now been acquired and received. Several choices and solutions of hardware will be described, and future commissioning plans outlined. Commissioning is expected to take place in the winter 2011/2012.

THPC005

First Measurements with a Kicked Off Axis Bunch for Pseudo Single Bunch Mode Studies at SOLEIL

single-bunch, closed-orbit, storage-ring, synchrotron

2912

L.S. Nadolski, J.-P. Lavieville, P. Lebasque, A. Nadji, J.P. Ricaud, M.G. Silly, F. Sirotti
SOLEIL, Gif-sur-Yvette, France

At SOLEIL, the time resolved French community benefits of single bunch operation few weeks a year. Meanwhile most of the multi-bunch filling pattern based experiments are not possible due to the low photon flux. Following the pioneer work performed at ALS*, a new operation mode is under study at SOLEIL where the storage ring is filled up with a special hybrid mode: ¾ multibunch filling pattern and a single bunch with higher current in the last ¼. The so-called pseudo single bunch-filling pattern is obtained if the closed orbit of the single bunch is not the same as the one of the other bunches. Preliminary results are presented where the pinger magnet time impulse response has been significantly reduced while its frequency was increased from 3 Hz up to 1 kHz. This magnet is used as an additional corrector magnet to change only the single bunch closed orbit. First experimental results observed at one interested beamline are also discussed.
* S. Kwiatkowski et al., “'CAMSHAFT' Bunch Kicker Design for the ALS Storage Ring", Proc. of EPAC2006, THPLS114, p. 3547, (2006).

THPC045

Design of a Compact Storage Ring for the TTX

cavity, injection, scattering, emittance

3005

H.S. Xu, W.-H. Huang, C.-X. Tang
TUB, Beijing, People's Republic of China
S.-Y. Lee
IUCEEM, Bloomington, Indiana, USA

We study a compact storage ring with circumference 3-m, 4 dipoles, and two quadrupoles for the Tsinghua Thomson scattering X-ray (TTX) source. The effects of Touschek lifetime, rf system requirement, the Intra-beam scattering (IBS) and coherent synchrotron radiation (CSR) will be addressed. A top-up injection system will be designed to maximize the Photon flux. Conceptual laser cavity to enhance photon flux will be discussed. Expected performance of the compact X-ray source will be presented.

THPC139

Study of a Pulsed Sextupole Magnet Injection System for LNLS

injection, sextupole, power-supply, pulsed-power

3212

X.R. Resende, F.C. Arroyo, R.H.A. Farias, L. Liu, A.R.D. Rodrigues, P.P. Sanchez, G. Tosin
LNLS, Campinas, Brazil

An injection system consisting of a pulsed sextupole magnet (PSM) is being considered for Sirius, the project of a new 3rd generation 3 GeV synchrotron source in development in Brazil. This novel injection scheme will be implemented and tested in the existing UVX ring. This will also serve as an opportunity to get acquainted with the new technology and become ready for Sirius. On this paper we report on the ongoing PSM study at LNLS. In particular, details of injection dynamics calculations, magnet and pulsed power supply designs are described, as well as machine preparations for experimental tests in the UVX storage ring.

THPC140

Design, Tuning and Results of the Pulsed Magnetic Systems for the Beam Injection in the SOLEIL Storage Ring Operated in ‘Transparent’ Top Up Mode

septum, injection, vacuum, storage-ring

3215

P. Lebasque, R. Ben El Fekih, M. Bol, J. Da Silva Castro, A. Hardy, C. Herbeaux, J.-P. Lavieville, A. Loulergue, J.L. Marlats, D. Muller, G. Renaud, J.P. Ricaud
SOLEIL, Gif-sur-Yvette, France

From the beginning, the SOLEIL Storage Ring was designed to operate in Top Up injection mode. So all equipments involved have been specified to generate as small as possible beam perturbations of the stored beam during the electron beam injection. This concerns many aspects of the design and realization of the injection pulsed magnets (kickers and septa), their vacuum chambers, pulsed power supplies and timing electronics. Despite quite satisfactory results of pulsed magnetic measurements in labs, a still too large perturbation was observed on the e^- beam orbit during the Storage Ring commissioning. Therefore a strong work of systematic measurements, analysis of each phenomena, tuning or modification of each device was led until reaching rather good and acceptable performances. This paper will present the results obtained. At this stage, the Storage Ring beam orbit is sufficiently stable in Top Up injection mode so that it is almost transparent to the 24 beam lines, even for the most sensitive ones. After a summary of the main significant topics, we present the developments foreseen to further improve the performances and make a new step towards a “perfect” Top Up injection.

THPC146

The Radiated EMI Isolation for TPS Kicker Magnet*

shielding, radiation, electromagnetic-fields, controls

3227

C.S. Chen, C.K. Chan, C.L. Chen, Y.L. Chu, K.H. Hsu, C.Y. Kuo, Y.-H. Liu, C.-S. Yang
NSRRC, Hsinchu, Taiwan

Electromagnetic interference is a critical problem for electronic equipment, especially for those sophisticated measuring sensors using in TLS. Therefore, lots of efforts have been made to isolate the EM noise from the kicker magnets. In this article, different thicknesses of aluminum chambers are applied to block the radiated EM noise. Furthermore, the different widths of slits simulate the necessary openings on kicker assembly. According to the results of small-scale experiment, some parameters are obtained to design the enclosure of kicker magnet. Compared the results with the data from the original scale kicker, these parameters provide a believable guideline in the beginning of design status.

THPC147

TPS SR Kicker Prototype Installation Status*

injection, storage-ring, high-voltage, vacuum

3230

Y.-H. Liu, C.K. Chan, C.-S. Chen, Y.L. Chu, K.H. Hsu, H.P. Hsueh, C.K. Kuan, C.Y. Kuo, C.-S. Yang
NSRRC, Hsinchu, Taiwan

The purpose of this paper is to illustrate the installation sequence of TPS SR kicker. Because of adding the rotation function in row direction, the position of every component of kicker must be very precise. The kicker magnet and EMI enclosure were fastened on the rotation motor plate which could rotate ±3.0 mrad. The ceramic chamber remain fixed on the bottom plate in order to let the bellow stress free during rotation. After installation, the inductance measurement and the high voltage breakdown test were also tested. The experimental results showed the good uniformity and reached the expected request. The field mapping and EMI prevention schemes will be tested in the future.

THPC177

Field Correction Results from NSRRC Elliptically Polarized Undulator 46

undulator, electron, multipole, synchrotron

3317

J.C. Huang, C.-H. Chang, C.-S. Hwang, C. JunTune, F.-Y. Lin
NSRRC, Hsinchu, Taiwan

Elliptically polarized undulator (EPU) is a common insertion device to use in storage ring in order to provide circular polarization. The field correction is an essential step for EPU construction, and it can prevent the photon flux reduction from idea case and electron beam trajectory and exit angle from EPU. The conventional field correction method is tedious works and strongly based on experiences. An initial state of NSRRC EPU46 has phase error over 40 degrees, and many difficulties on field correction to reduce the phase error under 5 degrees. This paper will describe the detailed magnetic field correction process and practical results from in NSRRC EPU.

THPO022

Risk Assessment of the Chopper Dipole Kicker Magnets for the MedAustron Facility

dipole, controls, power-supply, radiation

3388

T. Kramer, T. Stadlbauer
EBG MedAustron, Wr. Neustadt, Austria
M.J. Barnes, M. Benedikt, T. Fowler
CERN, Geneva, Switzerland

The MedAustron facility, to be built in Wiener Neustadt (Austria), will provide protons and ions for both cancer therapy and research. Different types of kicker magnets will be used in the facility, including fast beam chopper dipoles: these allow the beam to be switched on and off for routine operational reasons or in case of emergency. One of the main requirements for the beam chopper system is reliability. A criticality analysis, to chart the probability of failure modes against the severity of their consequences of the fault, has been carried out for the chopper dipole system. This “Failure Mode, Effects, and Criticality Analysis” (FMECA), has been used to highlight failure modes with relatively high probability and severity of consequences: conservative ratings of critical components and appropriate redundancy, together with measurements and interlocks, have been used to reduce the probability and criticality of faults. This paper presents the results of the FMECA.

THPO024

Development of a Non-Linear Kicker System to Facilitate a New Injection Scheme for the BESSY II Storage Ring

injection, vacuum, storage-ring, impedance

3394

O. Dressler, T. Atkinson, M. Dirsat, P. Kuske
HZB, Berlin, Germany
H. Rast
DELTA, Dortmund, Germany

Top-Up injections without noticeable motion of the stored beam is a challenge. The common method of beam accumulation with a local bump formed by four independent pulsed dipole kicker magnets usually causes beam oscillations. The matching of the four independent kicker systems regarding pulse jitters and shapes is technologically limited. Afterward the beam excitation was reduced more when two kicker magnets on each side of the septum were powered in series by one pulser unit. An even more promising approach is to adopt an alternative injection method deploying a single non-linear kicker magnet with zero Bx,y-field in the center and an off-axis maximum, By, which is horizontally displaced by 10^-12 mm. There the injected beam gets kicked and looses half of its transverse momentum. Such a magnet was designed and built as a short in-vacuum magnet with a small vertical gap height. For first beam tests the kicker was placed in the second straight section after the injection point, and the 1.5 μs pulse was designed to deflect the 1.72 GeV beam by 1 mrad. In this paper, the calculations of the magnetic fields, the mechanical design as well as the electrical pulser circuit are described.
*New injection scheme using a pulsed quadrupole magnet in electron storage rings, Kentaro Harada, PHYSICAL REVIEW SPECIAL TOPICS - AB 10, 123501 (2007)

THPO032

Preliminary Design of an Inductive Adder for CLIC Damping Rings

damping, emittance, collider, impedance

3409

J. Holma, M.J. Barnes
CERN, Geneva, Switzerland

The Compact Linear Collider (CLIC) study is exploring the scheme for an electron-positron collider with high luminosity and a nominal centre-of-mass energy of 3 TeV. The CLIC damping rings will produce ultra-low emittance, with high bunch charge, necessary for the luminosity performance of the collider. To limit the beam emittance blow-up due to oscillations, the pulse power modulators for the damping rings kickers must provide extremely flat, high-voltage pulses: specifications call for a 160 ns duration flattop of 12.5 kV, 250 A, with a combined ripple and droop of not more than ±0.02 %. A solid-state modulator, the inductive adder, is a very promising approach to meeting the demanding specifications; this topology allows the use of both digital and analogue modulation. To effectively use modulation techniques to achieve such low ripple and droop requires an in-depth knowledge of the behaviour of the solid-state switching components and their gate drivers, as well as a good understanding of the overall circuit behaviour. This paper describes the initial design of the inductive adder.

THPO033

Calculation of Metallization Resistivity and Thickness for MedAustron Kicker Systems

simulation, vacuum, status, proton

3412

M.J. Barnes
CERN, Geneva, Switzerland
T. Kramer, T. Stadlbauer
EBG MedAustron, Wr. Neustadt, Austria

The MedAustron facility, to be built in Wiener Neustadt (Austria), will provide protons and ions for both cancer therapy and research. Different types of kicker magnets will be used in the facility. The kicker magnets are outside machine vacuum: each kicker magnet has a ceramic beam chamber whose inner surface is metallized. The resistivity and thickness of the metallization are chosen such that the induced eddy currents, resulting from the pulsed kicker magnetic field, do not unduly affect the rise/fall times or homogeneity of the magnetic field. A comparison of an analytical calculation and measurement is reported for the effect of metallization of the ceramic beam chamber of an existing kicker system at CERN. For a MedAustron kicker the result of an analytical calculation is compared with predictions from electromagnetic simulations: conclusions concerning the metallization of the ceramic beam chambers, for the MedAustron kicker magnets, are presented.

THPO034

Optimization of a Dual One-turn Coils Kicker Magnet System

extraction, synchrotron, monitoring, vacuum

3415

K.L. Tsai, C.-T. Chen, C.-S. Fann, S.Y. Hsu, Y.D. Li, K.-K. Lin, K.-B. Liu, H.M. Shih, Y.S. Wong
NSRRC, Hsinchu, Taiwan

Optimization of a dual one-turn coils configuration for fast kicker magnet system is presented in this report. Emphasis has been made on the: 1) optimization of various possible coils arrangement restricted by the existing available hardware; and 2) synchronization between pulsed currents delivering on the respective upper and lower coils. In the consideration of coils arrangement, good field region is utilized as the guiding parameter while adjusting fixture gap between the coils. As for coil currents timing optimization, fast rise-time and pulse shape preservation are used for practical implementation purpose. Both numerical analysis and experimental data will be presented and discussed.

THPS003

Status of Stochastic Cooling Predictions at the HESR

antiproton, accumulation, pick-up, injection

3430

H. Stockhorst, R. Maier, D. Prasuhn, R. Stassen
FZJ, Jülich, Germany
T. Katayama
GSI, Darmstadt, Germany

Detailed theoretical studies of stochastic cooling have been performed in order to fulfil the requirements for internal target experiments at the High-Energy Storage Ring (HESR) of the future Facility for Antiproton and Ion Research (FAIR) at the GSI in Darmstadt. A Fokker-Planck model and a particle tracking code utilizing the Filter and time-of-flight momentum cooling method have been developed for the 2 to 4 GHz cooling system. A barrier bucket cavity is included to compensate the mean energy loss due to the beam-target interaction. The code has been experimentally verified at the cooler synchrotron COSY. Since the RESR accumulator ring is postponed in the modularized start version of FAIR it is proposed to include the anti-proton accumulation function in the HESR downstream of the Collector Ring. Applying the radial stacking scheme well established at CERN and FNAL would result in a completely new and additional cooling system in the HESR. Instead a different way of beam accumulation has been selected that uses the already designed stochastic cooling system and the barrier bucket cavity of the HESR. Simulation results of the anti-proton accumulation in the HESR are presented.

THPS041

Design of Beam Transport Line from RCS to Target for CSNS

target, proton, simulation, octupole

3514

W.B. Liu, N. Huang, J. Qiu, J. Tang, S. Wang, G. Xu
IHEP Beijing, Beijing, People's Republic of China

China Spallation Neutron Source (CSNS) uses the high energy proton beam to strike the Tungsten target to generate neutrons through spallation reaction. The proton beam is extracted from the Rapid Cycling Synchrotron (RCS), whose beam power reaches 100 kW. For the sake of target lifetime, beam distribution at the target surface is required as uniform as possible. Nonlinear beam density redistribution method with two octupole magnets has been studied. Also some simulation and theoretical calculation have been done. According to the simulation result, the beam density at the target is optimized and the beam loss is under control.

THPS047

New Injection and Extraction at CRYRING for FLAIR

extraction, injection, septum, ion

3529

A. Simonsson, L. Brännholm, S. Das, A. Källberg, P. Löfgren, A. Paal, J. Sjöholm
MSL, Stockholm, Sweden
H. Danared
ESS, Lund, Sweden
D. Reistad
Intégro Utbildnings AB, Sigtuna, Sweden

As a preparation for a future transfer of CRYRING to FLAIR at FAIR in Darmstadt, Germany, we have installed and tested a slow extraction system. At FLAIR CRYRING will be used for deceleration of antiprotons from 30 MeV to 0.3 MeV. The tests of the slow extraction show that the beam can be extracted during 2 s with 30-60% efficiency and with rather constant amplitude, apart from noise from 50 Hz harmonics. A new injection system has also been designed. It will be able to inject 30 MeV antiprotons from NESR as well as 0.3 MeV/u ions created in a separate ion source and accelerated in an RFQ.

THPS049

Feasibility Study of a CERN PS Injection at 2 GeV

injection, optics, septum, vacuum

3535

J. Borburgh, S. Aumon, W. Bartmann, S.S. Gilardoni, B. Goddard, L. Sermeus, R.R. Steerenberg
CERN, Geneva, Switzerland

In the framework of the potential CERN PS Booster (PSB) energy upgrade, a study was initiated to look into the possibilities and constraints to inject protons into the PS at kinetic energies up to 2 GeV, for LHC type beams and other (high intensity) beams. This paper highlights the identified bottlenecks and potential solutions and addresses the resulting requirements for the hardware in the transfer line and injection region of the PS. In conjunction with the proposed upgrade of the PSB-PS transfer line hardware the optics can be changed for different cycles. Optics solutions optimized for the different requirements of LHC type and other beams are presented.

THPS052

Studies on Transverse Painting for H⁻ Injection into the PSB

injection, emittance, linac, space-charge

3544

C. Bracco, C. Carli, T. Fowler, B. Goddard, G. Gräwer, J.-B. Lallement, M. Martini, M. Scholz, W.J.M. Weterings
CERN, Geneva, Switzerland

Linac4 will inject 160 MeV H− ions in to the CERN PS Booster (PSB). This will allow to reduce space charge effects and increase beam intensity but will require a substantial upgrade of the injection region, with the implementation of a charge-exchange multi-turn injection scheme. The PSB has to provide beam to several users with different requirements in terms of beam intensity and emittance. Four kicker magnets (KSW), which are already installed in the PSB lattice, will be used to accomplish painting in the horizontal phase space to match the injected beams to the required emittances. Double linear functions, with varying slopes for each user, have been defined for the KSW generators waveforms according to detailed beam dynamic studies for all target intensities and emittances. Effect of space charge, injection offsets, dispersion and betatron mismatch have been taken into account. Preliminary studies have been carried out to evaluate how to obtain the required vertical emittance and the option of a transverse painting, also in the vertical plane, is explored.

THPS054

Injection and Extraction Considerations for a 2 GeV RCS at CERN

extraction, injection, quadrupole, septum

3550

W. Bartmann, B. Balhan, J. Borburgh, L. Ducimetière, M. Fitterer, B. Goddard, L. Sermeus
CERN, Geneva, Switzerland

Conceptual studies have been made for a 2 GeV RCS at CERN as a possible replacement of the four-ring PS Booster. The lattice design has to accommodate suitable straight sections for a 160 MeV H⁻ charge exchange injection system, and for a 2 GeV fast extraction system. The design constraints for the injection and extraction systems are described, together with the proposed concepts and potential equipment limitations. In particular, the features of different possible H⁻ injection configurations are compared.

THPS055

Controlling Beamloss at Injection into the LHC

injection, beam-losses, emittance, shielding

3553

B. Goddard, F. Alessio, W. Bartmann, P. Baudrenghien, V. Boccone, C. Bracco, M. Brugger, K. Cornelis, B. Dehning, A. Di Mauro, L.N. Drosdal, E.B. Holzer, W. Höfle, R. Jacobsson, V. Kain, M. Meddahi, V. Mertens, A. Nordt, J.A. Uythoven, D. Valuch, S. Weisz, E.N. del Busto
CERN, Geneva, Switzerland
R. Appleby
UMAN, Manchester, United Kingdom

Losses at injection into the superconducting LHC can adversely affect the machine performance in several important ways. The high injected beam intensity and energy mean that precautions must be taken against damage and quenches, including collimators placed close to the beam in the injection regions. Clean injection is essential, to avoid spurious signals on the sensitive beam loss monitoring system which will trigger beam dumps. In addition, the use of the two injection insertions to house downstream high energy physics experiments brings constraints on permitted beam loss levels. In this paper the sources of injection beam loss are discussed together with the contributing factors and various issues experienced in the first full year of LHC operation. Simulations are compared with measurement, and the implemented and planned mitigation measures and diagnostic improvements are described. An outlook for future LHC operation is given.

THPS087

Engineering Prototype for a Compact Medical Dielectric Wall Accelerator

rfq, proton, laser, acceleration

3636

A. Zografos, T. Brown, A. Hening, V. Joshkin, K. Leung, Y.K. Parker, H.T. Pearce-Percy, D. Pearson, M. Rougieri, J. Weir
CPAC, Livermore, CA, USA
R. Becker
SSS, Gelnhausen, Germany
D.T. Blackfield, G.J. Caporaso, Y.-J. Chen, S. Falabella, G. Guethlein, S.A. Hawkins, S.D. Nelson, B. R. Poole, J.A. Watson
LLNL, Livermore, California, USA
R.W. Hamm
R&M Technical Enterprises, Pleasanton, California, USA

Funding: Prepared by LLNL under Contract DE-AC52-07NA27344.
The Compact Particle Accelerator Corporation has developed an architecture to produce pulsed proton bunches that will be suitable for proton treatment of cancers. Subsystems include a RFQ injection system with a pulsed kicker to select the desired proton bunches and a linear accelerator incorporating a High Gradient Insulator with stacked Blumleins to produce the required voltage. The Blumleins are switched with solid state laser driven optical switches that are an integral part of the Blumlein assemblies. Other subsystems include a laser, a fiber optic distribution system, an electrical charging system and beam diagnostics. An engineering prototype has been constructed and it has been fully characterized. Results obtained from the engineering prototype support the development of an extremely compact 150 MeV system capable of modulating energy, beam current and spot size on a shot to shot basis within the next two years. The paper will detail the construction of the engineering prototype and discuss experimental results. In addition, future development milestones and commercialization plans will also be discussed.

THPS088

LHC Beam Impact on Materials Considering the Time Structure of the Beam

target, proton, simulation, extraction

3639

N.A. Tahir
GSI, Darmstadt, Germany
J. Blanco, R. Schmidt
CERN, Geneva, Switzerland
R. Piriz
Universidad de Castilla-La Mancha, Ciudad Real, Spain
A. Shutov
IPCP, Chernogolovka, Moscow region, Russia

The LHC is the world's largest and highest energy accelerator. Two counter-rotating beams can be accelerated up to 7 TeV and kept colliding for several hours. The energy stored in each beam is up to 362MJ, enough to melt 500 kg of copper. A fast loss of a small fraction of the beam can cause damage to a superconducting coil in a magnet. Primary beam collimators, one of the most robust parts of the machine protection, can be damaged with about 5% of the beam. An accident involving the entire beam is very unlikely but cannot be fully excluded. Understanding the consequences of such accidents is fundamental for the machine protection. Detailed numerical simulations have been carried out to assess the damage caused by full LHC beam impact on solid Cu and C cylinders. The energy loss of the protons is calculated with the FLUKA code and this data is used as input to a 2D hydrodynamic code BIG2, to study the thermodynamic and hydrodynamic response of the material. Since the target parameters change substantially during the time of impact, a new approach of running the two codes iteratively, has been developed. In this paper the results are presented and compared with the previous studies.

THPZ025

Stability of the LHC Transfer lines

injection, extraction, ion, controls

3741

V. Kain, W. Bartmann, C. Bracco, L.N. Drosdal, B. Goddard, M. Meddahi, J.A. Uythoven, J. Wenninger
CERN, Geneva, Switzerland

The LHC is filled from the SPS through two 3 km transfer lines. The injected beam parameters need to be well under control for luminosity performance, machine protection and operational efficiency. Small fractions of beam loss on the transfer line collimation system create showers which can trigger the sensitive LHC beam loss monitor system nearby and cause a beam abort during filling. The stability of the transfer line trajectory through the collimators is particularly critical in this respect. This paper will report on the transfer line trajectory stability during the proton run in 2011, correlations with injection losses, correction frequency and the most likely sources for the observed oscillations.