| Paper | Title | Other Keywords | Page |
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| MOPPC004 | Experiments on the Margin of Beam Induced Quenches for LHC Superconducting Quadrupole Magnet in the LHC | injection, proton, quadrupole, monitoring | 124 |
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| Protection of LHC equipment relies on a complex system of collimators to capture injected or circulating beam in case of LHC injection kicker magnet failures. However, for specific failures of the injection kicker, the beam can graze the injection protection collimators and induce quenches of downstream superconducting magnets. This occurred twice during 2011 operation and can also not be excluded during further operation. Tests were performed during Machine Development periods of the LHC to assess the quench margin of the quadrupole located just downstream of the last injection protection collimator in point 8. In addition to the existing Quench Protection System, a special monitoring instrumentation was installed at this magnet to detect any resistance increase below the quench limit. The correlation between the magnet and Beam Loss Monitor signals was analysed for different beam intensities and magnet current. The results of the experiments are presented in this paper. | |||
| MOPPC030 | Status of the Decay Ring Design for the IDS Neutrino Factory | injection, lattice, insertion, optics | 199 |
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In the International Design Study for the Neutrino Factory (IDS-NF) a racetrack design has been adopted for the decay ring*. The injection system into the decay ring is described. The feasibility of injecting both positive and negative muons into the ring is explored from the point of view of injection timing. Considerations for the design of a decay ring for a 10 GeV neutrino factory are included.
* ”International Design Study for the Neutrino Factory – interim design report”, RAL-TR-2011-018 (2011) |
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| MOPPC043 | Injection/Extraction of Achromat-based 6D Ionization Cooling Rings for Muons | injection, solenoid, dipole, extraction | 229 |
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Funding: This work was supported in part by the US Department of Energy in part under award numbers DE-FG02-92ER40695 (UCLA), DE-AC02-98CH10886 (BNL) and DE-FG02-07ER84855 (Particle Beam Lasers, Inc.). An achromat-based cooing ring using dipoles and solenoids is introduced and it can cool muons by large factors in six dimensions to achieve the necessary luminosity for a muon collider. The ring is designed with sufficient space in each superperiod for injection and extraction magnets. We estimate the parameters for the injection system into the solenoid-dipole ring cooler. We also present some simulations for injection/extraction system and discuss the injection/extraction requirements*. * Al Garren, J.S. Berg, D. Cline, X. Ding, H.G. Kirk, “Robust 6D μ± cooling using a solenoid-dipole ring cooler for a muon collider”, NIM A 654 (2011) 40-44. |
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| MOPPD005 | Stochastic Cooling of Antiprotons in the Collector Ring at FAIR | pick-up, antiproton, simulation, ion | 376 |
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| In order to reach the required luminosities for the experiments at FAIR, the hot secondary beams (antiprotons or rare isotopes) emerging from the production targets will be efficiently collected and phase-space cooled in the large-acceptance Collector Ring (CR), which is equipped with pertinent stochastic cooling systems. Simulations of the system performance are underway in parallel with the finalization of the system design. After an overview of the CR stochastic cooling systems, simulation results for antiproton cooling in the bandwidth 1-2 GHz are presented. The CERN Fokker-Planck code is used for momentum cooling and an analytical model based on "rms" theory for the simultaneous betatron cooling. In the focus is the comparison between the time of flight and the notch filter momentum cooling methods. The results are essential for system optimization as well as input for the users of the CR-precooled beams i.e. the HESR. | |||
| MOPPD008 | RF and Stochastic Cooling System of the HESR | pick-up, accumulation, controls, coupling | 385 |
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| The High Energy Storage Ring HESR (1.5-15 GeV/c) for antiprotons at the FAIR complex (Facility for Antiprotons and Ion Research) in Darmstadt (GSI) will have a dedicated stochastic cooling system not only during the experiments to fulfill the beam requirements, but also during the accumulation due to the postponed RESR. Here the cooperation of stochastic cooling with different Barrier-Bucket configurations is necessary for an high accumulation efficiency. The latest hardware configurations and recent tests results of both the RF-system with air-cooled cavities and the stochastic cooling based on slot-ring couplers will be presented. | |||
| MOPPD053 | Reduction of Outgassing from the Ferrite Cores in the Kicker Magnet of J-PARC RCS | vacuum, high-voltage, beam-transport, proton | 487 |
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| Kicker magnets are used to kick out the accelerated beam to the beam transport lines in the RCS of the J-PARC. A high voltage is applied to kickers for a short period, so they must be installed in a vacuum to prevent discharge. Therefore, it is important to reduce the outgassing of water vapor from the ferrite cores. After bake-out at 200°C for 300 hours, the outgassing rate decreased to less than 1×10-7 Pam/s. However, the small amount of water vapor and carbon monoxide were emitted from the ferrite cores at charging voltage of 80 kV. This time, we have decided to construct the reserve magnets with very low outgassing at high-voltage discharge. First of all, the thermal desorption behavior of the ferrite was investigated. Water vapor has two peaks: at ~ 100°C and 350°C. Carbon monoxide is rather largely emitted until 300°C. From these results, the ferrite cores were vacuum-fired at 450°C for 10 h. Then the good properties for the magnetic cores were confirmed. And now the assembling of the kicker magnet is undertaken. The performance of the kicker magnet made of the vacuum-fired ferrite will be shown in this meeting. | |||
| MOPPD058 | LHC Abort Gap Cleaning Studies during Luminosity Operation | luminosity, injection, emittance, beam-losses | 496 |
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| The presence of significant intensities of un-bunched beam is a potentially serious issue in the LHC. Procedures using damper kickers for cleaning both Abort Gap (AG) and buckets targeted for injection, are currently in operation at flat bottom. Recent observations of relatively high population of the AG during physics runs brought up the need for AG cleaning during luminosity operation as well. In this paper the results of experimental studies performed in October 2011 are presented. | |||
| MOPPD060 | Modified Extraction Scheme for the CERN PS Multi-Turn Extraction | extraction, septum, beam-losses, quadrupole | 502 |
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| High-activation of the extraction magnetic septum of the CERN PS machine was observed due to the losses of the continuous beam extracted via the Multi-Turn Extraction (MTE) method. A possible mitigation measure consists of using an existing electrostatic septum, located upstream of the extraction magnetic septum, to deflect the beam. This would highly decrease the beam losses, and hence the induced activation, during the rise time of the MTE kickers due to the reduced thickness of the electrostatic septum with respect to the magnetic one. The layout of this new extraction will be described in detail and the results of beam measurements presented. | |||
| MOPPD069 | Challenges for the SNS Ring Energy Upgrade | injection, electron, septum, extraction | 520 |
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Funding: ORNL/SNS is managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725. The Oak Ridge Spallation Neutron Source accumulator ring presently operates at a beam power of about 1 MW and a beam energy of 925 MeV. A power upgrade is planned to increase the beam energy to 1.3 GeV. For the accumulator ring this mostly involves modifications to the injection and extraction sections. A variety of modifications to the existing injection section were necessary to achieve 1 MW, and the tools developed and the lessons learned from this work are now being applied to the design of the new injection section. This paper will discuss the tools and the lessons learned, and also present the design and status of the upgrades to the accumulator ring. |
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| MOPPD078 | Accelerator Physics Study on the Effects from an Asynchronous Beam Dump in the LHC Experimental Region Collimators | proton, simulation, betatron, optics | 547 |
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Funding: This work has been carried out through of the European Coordination for Accelerator Research and Development (EuCARD), co-sponsored by EU 7th Framework Program. Asynchronous beam aborts at the LHC are to be expected once per year. Accelerator physics studies of asynchronous dumps have been performed at different beam energies and beta-stars. The loss patterns are analyzed in order to identify the losses in particular on the Phase 1 Tertiary Collimators (TCT), since their Tungsten jaw insert has a low damage threshold with respect to the loss load expected. Settings for the tilt angle of the TCTs are discussed with the aim of reducing the thermal loads on the TCT themselves. |
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| MOPPD079 | Preliminary Thermo-Mechanical Analysis of Angular Beam Impact on LHC Collimators | simulation, collimation, superconducting-magnet, controls | 550 |
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Funding: This work is supported by EuCARD. The correct functioning of the LHC collimation system is crucial to attain the desired LHC luminosity performance. However, the requirements to handle high intensity beams can be demanding. In this respect, accident scenarios must be well studied in order to assess if the collimator design is robust against likely error scenarios. One of the catastrophic - though not very probable - accident scenarios identified is an asynchronous beam dump coupled with slight angular misalignment errors of the collimator jaw. Previous work presented a preliminary thermal evaluation of the extent of beam-induced damage for such scenarios, where it was shown that in some cases, a tilt of the jaw could actually serve to mitigate the effect of an asynchronous dump on the collimators. This paper will further analyze the response of tertiary collimators in presence of such angular jaw alignments, with the aim to identify optimal operational conditions. |
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| MOPPD081 | Upgrade of the LHC Beam Dumping Protection Elements | simulation, extraction, dumping, vacuum | 556 |
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| The Beam Dumping System for the Large Hadron Collider comprises for each ring a set of horizontally deflecting extraction kicker magnets, vertically deflecting steel septa, dilution kickers and finally, a couple of hundred meters further downstream, an absorber block. A mobile diluter (TCDQ) protects the superconducting quadrupole immediately downstream of the extraction as well as the arc at injection energy and the triplet aperture at top energy from bunches with small impact parameters, in case of a beam dump that is not synchronized with the particle free gap or a spontaneous firing of the extraction kickers. Simulations have shown that an asynchronous dump of a 7 TeV nominal beam into the TCDQ absorber blocks could damage it. This paper describes the proposed changes to this device in order to maintain the protection for the downstream elements while reducing the risk of damaging the TCDQ in case of such a beam loss. | |||
| MOPPD083 | Improving the Fermilab Booster Notching Efficiency, Beam Losses and Radiation Levels | booster, radiation, injection, beam-losses | 562 |
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Funding: Work supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy. Currently a fast vertical 1.08-m long kicker (notcher) located in the Fermilab Booster Long-5 straight section is used to remove 3 out of 84 circulating bunches after injection to generate an abort gap. With magnetic field of 72.5 Gauss it removes only 87% of the 3-bunch intensity at 400 MeV, with 75% loss on pole tips of the focusing Booster magnets, 11% on the Long-6 collimators, and 1% in the rest of the ring. We propose to improve the notching efficiency and reduce beam loss in the Booster by using two horizontal kickers in the Long-12 section. The STRUCT calculations show that using such horizontal notchers, one can remove up to 99% of the 3-bunch intensity at 400-700 MeV, directing 96% of it to a new beam dump at the Long-13 section. This fully decouples notching and collimation. The beam dump absorbs most of the impinging proton energy in its jaws. The latter are encapsulated into an appropriate radiation shielding that reduces impact on the machine components, personnel and environment to the tolerable levels. The MARS simulations show that corresponding prompt and residual radiation levels can be reduced ten times compared to the current ones. |
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| MOPPP053 | Failure Mode Analysis in Preparation for Top-up Injection at the Canadian Light Source (CLS) | injection, storage-ring, dipole, simulation | 682 |
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| Top-up injection involves injecting beam with beamline safety shutters open. Consequently it is extremely important that no electrons enter the beamlines where they could be a potential safety hazard to beamline personnel. To investigate the likelihood that electrons could exit the storage ring various failure mode simulations have been done. The approach is to account for all possible injection trajectories and show that these particles will be intercepted by various storage ring apertures before they reach an amplitude that is deemed unsafe. This amplitude was chosen to be 50 mm and the field roll-off of all storage ring magnets were defined to this amplitude. Failure modes invested included injection kicker failures, uncorrected misalignment errors, off-energy injection and shorted storage ring magnet coils. Errors that would render it impossible to store beam were not investigated. As some particles reached amplitudes beyond the safe limit measures have been devised to eliminate these unsafe scenarios. | |||
| MOPPP054 | Study of a New Injection Scheme for the SSRF Storage Ring | injection, storage-ring, emittance, dynamic-aperture | 685 |
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| A low emittance configuration of the SSRF storage ring had been designed and commissioned. Along with reducing the emittance, the dynamic aperture decreases quickly. It doesn’t meet aperture require of the normal injection scheme anymore and the injection efficiency is lower. The pulsed multi-pole magnets give the opportunity to overcome the smaller dynamic aperture. Pulsed quadrupole and sextupole both are study for the injection scheme. With and without the orbit bump kickers are also considered in this study. The injection scheme suggestions are presented in this paper. | |||
| MOPPP056 | Injection Transient Motion at PLS-II | injection, septum, electron, linac | 688 |
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| PLS-II is an upgraded third generation synchrotron which includes many insertion devices with improved beam properties. Top-up operation is short time-interval injection to make roughly constant current and is essential to provide high intensity beam. When the electrons are injected to synchrotron, the stored beam is disturbed by small error of the injection system and the beam quality at the beamline can be decreased. We present this injection transient motion at PLS-II. | |||
| MOPPR015 | Bunch-by-bunch Feedback Systems at the DELTA Storage Ring | feedback, electron, synchrotron, injection | 807 |
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Funding: Work supported by BMBF (05K10PEB) At the DELTA 1.5-GeV electron storage ring operated as a synchrotron radiation source by the TU Dortmund University, bunch-by-bunch feedback systems have been recently installed and commissioned to detect and suppress longitudinal as well as transverse multibunch instabilities. Besides that, the feedback systems are used as a diagnostics tool. Growth rates of multibunch instabilities and their dependence on the beam current have been measured. Additionally, the oscillation amplitudes of electron bunches have been studied during the injection process. |
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| TUPPC081 | First Experimental Observations from the LHC Dynamic Aperture Experiment | dynamic-aperture, beam-losses, synchrotron, injection | 1362 |
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| Following intensive numerical simulations to compute the dynamic aperture for the LHC in the design phase, the successful beam commissioning and the ensuing beam operations opened the possibility of performing beam measurements of the dynamics aperture. In this paper the experimental set-up and the first observations based on the few experimental sessions performed will be presented and discussed in detail. | |||
| TUPPC091 | Simulation of Colliding Beams with Feedback in LHC | simulation, emittance, feedback, luminosity | 1374 |
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Funding: This work supported partially by the US LHC Accelerator Research Program (LARP) of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Beam-beam effects impose restrictions on beam and beam optical parameters as they may degrade the luminosity and the emittance or cause coherent instabilities and particle loss. In the planned High Luminosity Large Hadron Collider (HL-LHC), beam-beam effects will significantly affect the beams because of unprecedented beam parameters and new features like crab cavities or elliptical beam cross sections at the interaction points. Noise from various sources can further worsen the situation. Therefore investigations are required to identify limitations of possible HL-LHC layouts. The impact of beam-beam effects on the beam dynamics is investigated by virtue of particle tracking simulations. Using the code BeamBeam3D and the strong-strong collision model, simulations including perturbations by noise and LHC's feedback system, an important means to mitigate transverse emittance growth due to coherent beam excitation, were carried out. The impact of numerical noise on the emittance in simulations and the state of the feedback modeling are presented. |
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| TUPPD015 | Optimization of Muon Capturing in g-2 Ring | betatron, vacuum, impedance, closed-orbit | 1440 |
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| We describe optimization procedure for muons capturing in g-2 ring under reconstruction at FERMILAB. This procedure includes both the beam dynamics consideration and HV inflector geometry and technique. Some engineering aspects of HV inflector and pulser are presented in detail. | |||
| TUPPP023 | Operation Status of ALBA Synchrotron Light Source | storage-ring, feedback, vacuum, emittance | 1659 |
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| ALBA is a 3.0 GeV third generation synchrotron light source which has been commissioned during 2011. From October 2011 up to 7 beamlines are delivering beam for beamline commissioning, 6 from insertion devices and 1 from a bending magnet. Since April 2012 the facility is open to external users. Beam current has been continuously increased and the present stored beam current for users is 200 mA in a multi-bunch filling pattern. Orbit stability is kept at ±1 micron with a slow orbit feedback. The paper will review the operation and performance status of the different subsystems and review also the main objectives for 2012: target current of 400 mA, delivery of 3000 hours of beam to beamlines, testing of a fast orbit feedback system as well as preparations for top-up operation. | |||
| TUPPP025 | Resurrection of RESOLVE at NSRRC Prepared for the First Turn Beam Steering of the TPS Commissioning | injection, storage-ring, controls, quadrupole | 1665 |
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| MATLAB based high level application software prepared for the 3GeV Taiwan Photon Source has been built and tested on the 1.5GeV Taiwan Light Source continuously. The RESOLVE program is surveyed and resurrected at NSRRC to support and help the first turn beam steering in the coming commissioning of the TPS accelerator complex. Due to the RESOLVE’s history, it contributed a lot in the past commissioning of SLC at SLAC National Accelerator Laboratory, we believe it may give help although most of the first turn beam steering of current light source machines may pass smoothly with well machine construction. In order to make the revised RESOLVE working, not only the compiling problem but also some memory bugs have been fixed, the updated RESOLVE now can be run on PC/Linux and Mac/OSX computer systems. We are trying to apply and test it on the TLS SR with the turn-by-turn digital BPM system. Some exercises of the error finding in beam steering of the off-axis injection beam are performed for presentation. | |||
| TUPPP071 | Design Concepts of a Beam Spreader for a Next Generation Free Electron Laser | electron, FEL, septum, linac | 1765 |
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| LBNL is developing design concepts for a multi-beamline soft x-ray FEL array powered by a superconducting linear accelerator, operating with a high bunch repetition rate of approximately one MHz. Electron bunches are distributed from the linac to the array (up to 10) independently configurable FEL beamlines with nominal bunch rates up to 100 kHz in each FEL, and with even pulse spacing. This distribution to the different FELs is made by the beam spreader for which the design has to relative compact while not significantly perturbing the quality of the electron beam and subsequent performance of the FELs. We report on our conceptual design for the spreader. The spreader lattice has two distinct parts, namely the beam take-off section and the FEL fan-out distributions section. Each section is achromatic and isochronous. The effect of coherent synchrotron radiation and micro-bunching has been studied when passing through the spreader and simulations show no significant deterioration in the beam quality. | |||
| TUPPR011 | Six-dimensional Bunch Merging for Muon Collider Cooling | emittance, simulation, collider, solenoid | 1831 |
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Funding: Work supported by US Department of Energy under contracts DE-AC02-98CH10886 and DE-AC02-07CH11359. Muons for a Muon Collider are diffusely produced from pion decay. They are first phase rotated into a trains of bunches. The trains are ionization cooled in all six dimensions until they can be merged into single bunches, one of each sign. They are then further cooled in six dimensions before acceleration and injection into the collider. This merging matches more efficiently into the second phase of cooling if the merging is also in six dimensions. A scheme to do this is proposed. Groups of 3, of the initial 12, bunches are merged longitudinally into 4 longer bunches, using rf with multiple harmonics. These 4 are then kicked into 4 separate (trombone) channels of different lengths to bring them to closely packed transverse locations at the same time. Here they are captured into a single bunch with now increased transverse emittance. |
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| TUPPR016 | Final Cross Section Design of the Stripline Kicker for the CLIC Damping Rings | impedance, damping, extraction, wakefield | 1843 |
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Funding: IDC-20101074 and FPA2010-21456-C02-01 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 fulfill the luminosity requirements. Kicker systems are required to inject and extract the beam from the Pre-Damping and Damping Rings. In order to achieve low beam coupling impedance and reasonable broadband impedance matching to the electrical circuit, striplines have been chosen for the kicker elements. In this paper the final design for the DR kicker is presented, including an optimization of the geometric parameters to achieve the requirements for both characteristic impedance and field homogeneity. In addition, a sensitivity analysis of characteristic impedance and field homogeneity to geometric parameters is reported. |
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| TUPPR018 | Beam Impedance Study of the Stripline Kicker for the CLIC Damping Ring | impedance, coupling, damping, simulation | 1849 |
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Funding: FPA2010-21456-C02-01 CLIC Pre-Damping (PDR) and Damping Rings (DR) are required for reducing the emittance of the electron and positron beams before being accelerated in the main linac. Several stripline kicker systems are used to inject and extract the beam from the PDR and DR. Wakefields produced by the charged particles when passing through the aperture of the stripline kickers may become an important source of emittance growth; for this reason, simulations of longitudinal and transverse beam impedance in the frequency domain, and their equivalent in the time domain are needed. First analytical approaches, future simulations and tests planned are presented in this paper. |
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| TUPPR072 | Status of ESTB: A Novel Beam Test Facility at SLAC | electron, wakefield, linac, emittance | 1990 |
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Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515 End Station A Test Beam (ESTB) is a test beam line at SLAC in the large End Station A (ESA) experimental hall. It uses a fraction of the bunches of the 14.7 GeV electron beam from the Linac Coherent Light Source (LCLS). ESTB provides a unique test beam for particle and particle astrophysics detector research, accelerator instrumentation and accelerator R&D, development of radiation-hard detectors, and material damage studies. It has exceptionally clean and well-defined secondary electron beams, a huge experimental area and good existing conventional facilities. Recently, a new kicker magnet has been installed to divert 5 Hz of the LCLS low energy beam into the A-line. The full installation will include 4 kicker magnets to allow diversion of high energy beams. A new beam dump and a new Personnel Protection System (PPS) have been built in ESA. In stage II, a secondary hadron target will be able to produce pions up to about 12 GeV/c at 1 particle/pulse. This paper reports the progress on ESTB construction and commissioning. |
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| TUPPR083 | Kink Instability Suppression with Stochastic Cooling Pickup and Kicker | ion, electron, feedback, pick-up | 2017 |
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Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The kink instability is one of the major beam dynamics issues of the linac-ring based electron ion collider. This head-tail type instability arises from the oscillation of the electron beam inside the opposing ion beam. It must be suppressed to achieve the desired luminosity. There are various ways to suppress the instability, such as tuning the chromaticity in the ion ring or by a dedicated feedback system of the electron beam position at IP, etc. However, each method has its own limitation. In this paper, we will discuss an alternative opportunity of suppressing the kink instability of the proposed eRHIC at BNL using the existing pickup-kicker system of the stochastic cooling system in RHIC. |
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| TUPPR086 | Transport from the Recycler Ring to the Antiproton Source Beamlines | proton, antiproton, booster, extraction | 2026 |
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| In the post-Nova era, the protons are directly transported from the Booster ring to the Recycler ring rather than the Main Injector. For Mu2e and g-2 project, the Debuncher ring will be modified into a Delivery ring to deliver the protons to both Mu2e and g-2 experiemnts. Therefore, It requires the transport of protons from the Recycler Ring to the Delivery ring. A new transfer line from the Recycler ring to the P1 beamline will be constructed to transport proton beam from the Recycler Ring to existing Antiproton Source beamlines. This new beamline provides a way to deliver 8 GeV kinetic energy protons from the Booster to the Delivery ring, via the Recycler, using existing beam transport lines, and without the need for new civil construction. This paper presents the Conceptual Design of this new beamline. | |||
| TUPPR090 | Analysis of Ferrite Heating of the LHC Injection Kickers and Proposals for Future Reduction of Temperature | injection, vacuum, impedance, coupling | 2038 |
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| The two LHC injection kicker magnet (MKI) systems produce a kick of 1.3 T-m with a flattop duration variable up to 7860 ns, and rise and fall times of less than 900 ns and 3000 ns, respectively. A beam screen, consisting of a ceramic tube with conductors on the inner wall, is placed in the aperture of the magnets. The conductors provide a path for the image current of the, high intensity, LHC beam and screen the ferrite against wake fields. The conductors initially used gave adequately low beam coupling impedance however inter-conductor discharges occurred during pulsing of the magnet; hence an alternative design was implemented to meet the often conflicting requirements for low beam coupling impedance, fast magnetic field rise-time and good high voltage behaviour. During 2011 the LHC has been operated with high intensity beam, coasting for many hours at a time, resulting in heating of both the ferrite yoke and beam impedance reduction ferrites, of the MKIs. This paper presents an analysis of thermal measurement data and an extrapolation of the heating for future operation; in addition means are discussed for reducing ferrite heating and improving cooling. | |||
| TUPPR092 | Transient Beam Losses in the LHC Injection Kickers from Micron Scale Dust Particles | beam-losses, vacuum, electron, injection | 2044 |
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| Transient beam losses on a time scale of a few ms have been observed in the LHC injection kickers, occurring mainly shortly after beam injection with a strong correlation in time to the kicker pulsing. The beam losses, which have at times affected LHC availability, are attributed to micron scale ceramic dust particles detached from the alumina beam pipe and accelerated into the beam. The beam related observations are described, together with laboratory measurements of beam pipe contamination and kicker vibration, simulations of electric field in the beam pipe and the basic dynamic model. Energy deposition simulations modelling the beam losses are presented and compared to measurement. Extrapolations to future LHC operation at higher intensities and energies are made, and prospects for mitigation are discussed. | |||
| TUPPR093 | Sources and Solutions for LHC Transfer Line Stability Issues | extraction, injection, septum, controls | 2047 |
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| The LHC is filled through two 3km transfer lines from the last pre-injector, the SPS. Safe injection into the LHC requires stable trajectories in the transfer lines. During the LHC proton operations 2011 instabilities were observed. In particular shot-by-shot and bunch-by-bunch variations cause difficulties for steering of the beam and can potentially cause high beam losses at injection. The causes of these instabilities have been studied and will be presented in this paper. Based on the studies solutions will be proposed and finally the effects of the solutions will be studied. | |||
| TUPPR095 | Update on Kicker Development for the NGLS | controls, status, impedance, electron | 2053 |
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| The latest requirements for the Next Generation Light Source (NGLS) beam spreader call for a kicker to deflect a 2.4 GeV electron beam by an angle of 3 mrad over a length of 2 meters. The rise and fall time requirements for the integrated B field are <50 ns, the pulse frequency is up to 100 kHz, and both the inter-pulse and pulse to pulse ripple requirements are <0.01% of full scale. These requirements, along with the basic design of the beam spreader are still evolving, and several magnet types and modulator topologies have been considered. This paper will discuss this evolution as it pertains to the kickers, what the current status is of the R&D effort, and the plan to build a full power prototype system. | |||
| TUPPR096 | Angular Alignment of the LHC Injection Protection Stopper | injection, alignment, proton, beam-losses | 2056 |
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| Machine safety depends critically on the correct setup of the protection elements. One of the injection protection collimators is constituted by exceptionally long jaws (4 m). For this element, an angular offset of the jaws could affect significantly the measured beam size and, as a consequence, the correct setup with respect to the beam. Dedicated studies and cross-calibrations have been performed to quantify the effect of tilts and offsets on the setup of this collimator and to check the provided passive protection. | |||
| WEPPD016 | Development of Glassy Carbon Blade for LHC Fast Vacuum Valve | vacuum, acceleration, synchrotron, synchrotron-radiation | 2528 |
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| An unexpected gas inrush in a vacuum chamber leads to the development of a fast pressure wave. It carries small particles that can compromise the functioning of sensitive machine systems such as the RF cavities or kickers. In the LHC machine, it has been proposed to protect these equipments by the installation of fast vacuum valves. The main requirements for the fast valves and in particular for the blade are: fast closure in the 20 ms range, high transparency and melting temperature in case of closure with beam in, dust free material to not contaminate sensitive adjacent elements and last but not least vacuum compatibility and adequate leak tightness across the blade. In this paper, a design based on a vitreous carbon blade is proposed. The main reasons for this material choice are given. The mechanical study of the blade behaviour under dynamic forces is shown. Fabrication considerations are addressed as well. Tests on prototypes have been carried out on pendulum type fast valves developed for LEP. Results on glassy carbon blades are presented as well as the motion parameter measurements. Qualification of the material for UHV applications has been carried out. | |||
| WEPPD018 | LHC Beam Vacuum During 2011 Machine Operation | vacuum, electron, injection, proton | 2534 |
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| During the year 2011 the LHC operated for 682 fills, meaning 247 days and 2 hours of stable beam in total. From 368 bunches per beam at 150 ns bunch spacing circulating in the ring in December 2010, the 2011 proton physic ended with 1380 bunches per beam circulating with 50 ns bunch spacing. The machine performances increased in parallel with the vacuum improvement thanks to a well performed scrubbing run in April 2011 and a continuous conditioning of the beam pipes while the machine was running. The 2011 LHC operation ended with one month of ions physic runs. During the machine operation various phenomena of beam - vacuum interaction were detected, analyzed and solved. This paper describes the pressure behavior along the machine layout and mainly in specific components position like TDI and MKI. The “pressure spike” phenomena near the experiment CMS and in some Dipole 1 (D1) regions are discussed. Finally, results obtained during the 25 ns machine developments are presented. | |||
| WEPPD066 | Design of a Stripline Kicker for Tune Measurement in CSNS RCS | impedance, lattice, cyclotron, wakefield | 2675 |
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| For CSNS RCS tune measurement, tune value is measured by exciting the bunch with strip-line kicker fed with white noise and using FFT algorithm to the turn-by-turn position of the bunch in the BPM. This article simulates the strip-line kicker in RCS and the efficiency of the kicker is discussed in the MATLAB environment. The parameters of the kicker with arc electrode structure such as wake impedance, thermal state and VSWR are analyzed based on the advantage of this design. | |||
| WEPPD076 | A Fast Kicker for a Staged Dielectric Two-beam Wakefield Accelerator | wakefield, FEL, cavity, klystron | 2702 |
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Funding: Work supported by DoE, Office of HEP. An experimental program to demonstrate staging in a dielectric two-beam wakefield accelerator (dielectric TBA) is being planned at the Argonne Wakefield Accelerator (AWA) facility. We are planning an experiment that both fits in the AWA tunnel and mimics conditions similar to the recently presented conceptual design of a linear collider based on the dielectric TBA. This conceptual design is based on a new parameter space of the TBA scheme utilizing an ultra-short (~20ns) rf pulse in a dielectric TBA. The decelerating structures are driven by a series of drive microbunch trains that are 20 ns in duration and separated by 100 ns. This means that the fast kicker must have an extremely quick risetime as well as become stable within about 50 ns. In this paper, we consider designs for a fast kicker based on RF deflecting cavities and stripline kickers. |
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| WEPPD078 | Progress with PXIE MEBT Chopper | simulation, vacuum, radio-frequency, coupling | 2708 |
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Funding: Fermilab is operated by Fermi Research Alliance, LLC, under Contract No. DE-AC02-07CH11359 with the United States Department of Energy A capability to provide a large variety of bunch patterns is crucial for the concept of the Project X serving MW-range beam to several experiments simultaneously. This capability will be realized by the Medium Energy Beam Transport’s (MEBT) chopping system that will divert 80% of all bunches of the initially 5mA, 2.1 MeV CW 162.5 MHz beam to an absorber according to a pre-programmed bunch-by-bunch selection. Being considered one of the most challenging components, the chopping system will be tested at the Project X Injector Experiment (PXIE) facility that will be built at Fermilab as a prototype of the Project X front end. The bunch deflection will be made by two identical sets of travelling-wave kickers working in sync. Presently, two versions of the kickers are being investigated: a helical 200 Ω structure with a switching-type 500 V driver and a planar 50 Ω structure with a linear ±250 V amplifier. This paper will describe the chopping system scheme and functional specifications for the kickers, present results of electromagnetic measurements of the models, discuss possible driver schemes, and show a conceptual mechanical design. |
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| WEPPP018 | A New Beam Injection Scheme for a Compact Low-energy Storage Ring | injection, damping, storage-ring, acceleration | 2761 |
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| A very compact storage ring at low energy has an unique application such as Compton X-ray source. Scheme for efficient injection is an issue for such a compact storage ring. Utilizing a phase-shift in the non-relativistic energy region, a new idea for accumulating the incoming bunch on an already circulating bunch without any kicker or orbit bump has been presented. Its applicable parameter range will be presented. | |||
| WEPPP059 | First Measurements with Multibunch Feedback Systems at the Fast Ramping Stretcher Ring ELSA | feedback, damping, cavity, electron | 2840 |
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Funding: Supported by German Research Foundation through SFB/TR 16. At the Electron Stretcher Facility ELSA of Bonn University, an upgrade of the maximum stored beam current from 20 mA to 200 mA is planned. The storage ring operates applying a fast energy ramp of 4 GeV/s from 1.2 GeV to 3.5 GeV. The intended upgrade is mainly limited due to the excitation of multibunch instabilities. As a countermeasure, we succesfully commissioned state-of-the-art bunch by bunch feedback systems in the longitudinal and the two transverse dimensions. First results concerning the commissioning of the systems as well as the operation during the fast energy ramp will be presented. In particular, the performance while controlling the motion of every single bunch, especially in controlled bunch cleaning, will be discussed. |
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| WEPPP060 | A Robust Transverse Feedback System | feedback, status, optics, pick-up | 2843 |
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| Transverse feedback systems use pickups signals to measure the beam instabilities and kickers to correct the beam. The correction signal is calculated according to the transfer matrices between the pickups and the kickers. However, errors due to magnetic field imperfections and magnets misalignments lead to deviations in the transfer matrices from their nominal values, which affects the feedback quality in a negative manner. In this work we address a new concept for robust feedback system against optics errors or uncertainties. A kicker and multiple pickups are used for each transversal direction. We introduce perturbation terms to the transfer matrices between the kicker and the pickups. Consequently, the Extended Kalman Filter is used to estimate the feedback signal and the perturbation terms by means of the measurements from the pickups. Finally results for the heavy ions synchrotron SIS 18 at the GSI are shown. | |||
| WEPPP062 | Characterization and Stabilization of Multi-Bunch Instabilities at the ANKA Storage Ring | feedback, storage-ring, injection, controls | 2849 |
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| ANKA is a 2.5 GeV storage ring for synchrotron radiation. Up to 200 mA are accumulated at 0.5 GeV and then ramped to 2.5 GeV. In the past storage ring operation suffered from vertical multi-bunch instabilities. These could partially be cured by increased chromaticity, a large gap in the filling structure and by keeping the beam longitudinally unstable. A vertical digital bunch-by-bunch system from ITECH has been installed that allows an operation of the storage ring without exciting the longitudinal modes. In addition, the system allows analyzing multi-bunch instabilities both transverse and longitudinal and their dependence from cavity temperature, filling structure and chromaticity. This paper reports on our experience operating this system and presents an investigation of multi-bunch modes in the ANKA storage ring. | |||
| WEPPP064 | Design and Simulation of the Stripline Transverse Quadrupole Kicker for HLS II | quadrupole, impedance, dipole, storage-ring | 2852 |
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| In order to investigate the possibility of excite a transverse quadrupole mode oscillation of the electron bunch in the HLS II storage ring, we design a stripline transverse quadrupole kicker. The characteristic impedance of some modes(dipole modes, sum mode, quadrupole mode) of the optimised stripline kicker must match 50Ω characteristic impedance of the external transmission lines so as to reduce the reflected power. We use nonlinear least square method to optimise the kicker and compare characteristic impedances of calculation using 2D Possion code and fitted function of several variables, then we get optimised size with integrated use of Possion code and fitted function of several variables. Using the 2D Poisson code, we simulate the electric field distribution of dipole modes when the horizontal or the vertical electrodes are at opposite unit potentials, and the electric field distribution of quadrupole mode using quadrupole kick. We verified that the designed stripline kicker can excite a transverse quadrupole mode oscillation of the electron bunch. | |||
| WEPPP066 | Performance Simulations of a Phase Stabilization System Prototype for CTF3 | feedback, simulation, collider, linac | 2858 |
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| The CLIC drive beam provides RF power for acceleration of the main beam, and hence the drive beam’s longitudinal phase tolerances are very tight. A feedforward chicane consisting of four electromagnetic kickers is proposed as a correction system for the phase errors, which should allow loosening of the tolerances. A prototype of such a chicane system, developed by CERN, INFN and the University of Oxford, is planned to be installed at CFT3 in 2012. The present paper summarizes the parameters of the planned phase correction system and presents simulations, which are used to make predictions of the performance of such a feedforward system at CTF3. | |||
| WEPPP068 | Latest Performance Results from the FONT5 Intra-train Beam Position and Angle Feedback System at ATF2 | feedback, extraction, linear-collider, collider | 2864 |
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| 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 time scales, 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. The latest results from beam tests at ATF2 will be presented, including the system latency and correction performance. | |||
| WEPPP074 | Study of a Wideband Feedback Kicker for the SPS | impedance, feedback, cavity, simulation | 2882 |
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Funding: Work supported by the US Department of Energy under Contracts DE-AC02-05CH11231 and DE-AC02-76SF00515, and through the US LHC Accelerator Research Program (LARP). The LHC luminosity upgrade currently being planned at CERN depends in large measure on a successful upgrade of its injectors chain. In particular the storing of higher currents in the SPS presents a significant challenge from the point of view of the beam stability. Electron cloud driven and transverse mode-coupled instabilities can disrupt the stored beam to the point of making injection in the LHC impossible. These types of instabilities are characterized by fast growth times and substantial spectral components at high frequency. Therefore a key aspect of any feedback system capable of effectively controlling the instability growth is the development of a suitable kicker with a high frequency response. In this paper we investigate the technologies available for such a kicker and identify a possible solution to be implemented on the SPS. By combining a lower frequency stripline kicker with a high frequency module, such as a damped cavity or a slotted waveguide, it would be possible to provide shunt impedances around 1000 Ω on a bandwidth from DC to 1 GHz. The basic parameters and limits of such a solution are discussed. |
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| WEPPP076 | Analysis of Numerical Noise in Particle-In-Cell Simulations of Single-Bunch Transverse Instabilities and Feedback in the CERN SPS | simulation, feedback, emittance, pick-up | 2888 |
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Funding: Work supported by the US-DOE and the US-LHC Accelerator Research Program LARP under Contract DE-AC02-05CH11231. Used resources of NERSC and the Lawrencium cluster at LBNL The operation at high current of the SPS at CERN is limited by transverse Single-Bunch instabilities generated by the effect of electron clouds. A model of a high bandwidth feedback control system has been implemented in the macro-particle code WARP to study bunch dynamics and identify system requirements for the efficient damping of single-bunch transverse instability. We analyze the effect of numerical noise and choice of simulation parameters on the modeling of beam dynamics, focusing in particular on the investigation of the feedback system requirements of minimum power to damp the instability and frequency bandwidth given a fixed gain. We report on simulation results and discuss the plans for the future improvements of the feedback model. |
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| WEPPP078 | Status of the Mixed-signal Active Feedback Damper System for Controlling Electron-proton Instabilities for the Spallation Neutron Source | feedback, pick-up, damping, proton | 2894 |
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Funding: Work supported by Oak Ridge National Laboratory, which is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy As the beam intensity at the Spallation Neutron Source (SNS) in Oak Ridge National Laboratory (ORNL) is leveled up, it becomes necessary to have greater control over the electron-proton (e-p) instability. This paper presents an updated design of a mixed-signal transverse feedback system for active damping of the e-p instability. It describes the design, features and results of this feedback damper and reviews several experimental studies to understand the system performance and its limitations. The updated mixed-signal feedback damper system employs power amplifiers (PAs), analog-to-digital converters (ADCs), multiple field programmable gate array (FPGA) chips, and digital-to-analog converters (DACs) to provide feedback damping and system monitoring. Unlike existing analog damping systems, FPGA-based feedback damping systems offer programmability while maintaining high performance. The system gain, delay and digital signal processing components can be programmed during the fly to perform timing adjustments, correct for ring harmonics, and equalize magnitude and phase dispersions. |
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| WEPPP082 | Stochastic Cooling in RHIC | emittance, luminosity, pick-up, simulation | 2900 |
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Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Stochastic cooling is used in the Relativistic Heavy Ion Collider to increase the integrated luminosity of ion collisions by a factor of two. The cooling system has been assembled incrementally over the past several years, starting with longitudinal cooling only, then adding cooling in the vertical planes, and recently completed with cooling systems in all three phase space planes of both rings. The system operates from 6 to 9 GHz in the longitudinal planes and from 4.7 to 7.8 GHz in the transverse planes, yielding a cooling rate that overcomes Intra-Beam Scattering at the beginning of a store and reaches equilibrium with a factor of 2 reduction of emittances. The system’s components and mode of operation will be presented along with measurements of the beam parameters during stores with stochastic cooling in operation. |
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| WEPPR058 | The Vertical Impedance Distribution Measurement Using Response Matrix Method at BEPCII BPR | impedance, feedback, injection, betatron | 3057 |
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Funding: Work supported by the Chinese National Foundation of Natural Sciences, contract 111100512108. In the last run of BEPCII, the single bunch current is limited to about 8mA by the beam-beam effect. To obtain the design luminosity, larger number of bunches are necessary. But higher total current may be limited by the collective effects. A good understanding of the transverse impedance distribution around the BEPCII storage ring is required. Response matrix method has been applied successfully in BEPCII to fit the quadrupole errors and restore the optics. We can also calculate the variation of betatron phase advance around the ring with different single bunch current using the response matrix method and the transverse impedance distribution is thus deduced. In this paper, the first measurement of transverse impedance in BEPCII is presented. |
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| WEPPR071 | Evaluation of the Beam Coupling Impedance of New Beam Screen Designs for the LHC Injection Kicker Magnets | impedance, coupling, simulation, injection | 3093 |
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| During the 2011 run of the LHC there was a measured temperature increase in the LHC Injection Kicker Magnets (LHC-MKI) during operation with 50ns bunch spacing. This was suspected to be due to increased beam-induced heating of the magnet due to beam impedance. Due to concerns about future heating with the increased total intensity to nominal and ultimate luminosities a review of the impedance reduction techniques within the magnet was required. A number of new beam screen designs are proposed and their impedance evaluated. Heating estimates are also given with a particular attention paid to future intensity upgrades to ultimate and HL-LHC parameters. | |||
| WEPPR073 | Effects of an Asymmetric Chamber on the Beam Coupling Impedance | impedance, simulation, wakefield, synchrotron | 3099 |
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| The wake function of an accelerator device appears to have a constant term if the geometry of the device is asymmetric or when the beam passes off axis in a symmetric geometry. Its contribution can be significant and has to be taken into account. In this paper a generalized definition of the impedance/wake is presented to take into account also this constant term. An example of a device where the constant term appears is analyzed. Moreover, the impact of a constant wake on the beam dynamics is discussed and illustrated by a HEADTAIL simulation. | |||
| WEPPR074 | Effect of the TEM Mode on the Kicker Impedance | impedance, coupling, simulation, vacuum | 3102 |
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| 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 a luminosity upgrade of the LHC. The C-Magnet supports a transverse electromagnetic (TEM) mode due to the presence of two conductors. Due to the finite length of the structure this TEM mode affects the impedance below a certain frequency (when the penetration depth in the ferrite becomes comparable to the magnetic circuit length). A theoretical model was developed to take into account also the impedance contribution due to the TEM mode. The model is found to be in good agreement with CST 3D electromagnetic (EM) simulations. It allows for generic terminations in the longitudinal direction. An example of kicker is analyzed taking into account also the external cables. | |||
| WEPPR084 | Measurement of Coherent Damping Rate of the APS Storage Ring | damping, feedback, storage-ring, pick-up | 3126 |
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Funding: Work supported by U.S. Department of Energy, Offices of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. The APS storage ring is a 7-GeV electron storage ring with a single-bunch current of up to 16 mA during normal user operations. To overcome beam instability we employ both chromatic correction and bunch-by- bunch feedback system. Typically we run a chromaticity of 4 for a 24-single fill pattern and 9 for a hybrids fill pattern in both planes with the feedback system loops closed. The APS upgrade (APS-U) calls for a beam current of 150 mA and installation of vertical deflecting cavities for short X-ray (SPX) production. In order to estimate whether the current chromatic correction and feedback system are adequate for the upgrade, we performed coherent damping rate measurements with two methods: kicking the beam with a kicker pulse and exciting the beam with the feedback system. We conclude that with a chromaticity of 4 in both planes, we can achieve a damping rate of 3 kHz in the x- plane and 2 kHz in the y-plane with feedback loops closed. Similar damping rates can also be achieved with chromatic correction alone. A special fitting program was developed to perform the damping rate analysis. This report presents the measurement data and results of the analysis. |
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| WEPPR090 | A 4.2 GS/s Synchronized Vertical Excitation System for SPS Studies - Steps Toward Wideband Feedback | controls, feedback, injection, acceleration | 3144 |
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Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515 and the US LHC Accelerator Research Program (LARP). A 4.2 GS/s beam excitation system with accelerator synchronization and power stages is described. The system is capable of playing unique samples (32 samples/bunch) for 15,000 turns on selected bunch(es) in the SPS in synchronism with the injection and acceleration cycle. The purpose of the system is to excite internal modes of single-bunch vertical motion, and study the bunch dynamics in the presence of developing Electron cloud or TMCI effects. The system includes a synchronized master oscillator, SPS timing functions, an FPGA based arbitrary waveform generator, 4.2 GS/sec. D/A system and four 80W 20 -1000 MHz amplifiers driving a tapered stripline pickup/kicker. A software GUI allows specification of various modulation signals and selection of bunches and turns to excite, while a remote control interface allows simple control/monitoring of the RF power stages located in the tunnel. Excitation signals developed to excite head-tail and other modes of vertical motion are illustrated. The successful use of this system for SPS MD measurements in August and November 2011 is a vital proof-of-principle for wideband feedback using similar functions to correct the beam motion. |
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| THPPD052 | Operation and Current Status of Injection, Extraction, Kicker Magnet and the Power Supply for J-PARC 3 GeV RCS | impedance, extraction, power-supply, injection | 3629 |
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| 3-GeV RCS (Rapid Cycling Synchrotron) at High Intensity Proton Accelerator Facility (J-PARC) have started for 24-hour operation with repetition rate of 25 pps in February, 2009. Kicker power supply system which uses thyratrons switches is used for extraction of the proton beam. There were many troubles for unstable operation of the thyratrons just after beam commissioning started. Recently, however, the operations were improved and the failure rate was reduced to approximately 0.1 % in October 2010. After the earthquake on March 11, 2011, the injection and extraction magnets, power supplies, the cables and the bus-duct have been checked. Insulation resistance test, impedance test were performed. Reflected wave measurements by the low-level and high-power pulse of the kicker magnets were performed. Visual checks by a fiber endoscope were also performed in the kicker magnets. The results of the measurements and the checks were all not in the problem. | |||
| THPPD059 | Conductive EMI Reduction to Kicker Magnet Power Supply in NSRRC | insertion, power-supply, controls, synchrotron | 3647 |
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| The purpose of this paper is to estimate and reduce the conductive Electromagnetic Interference (EMI) from kicker magnet power supply in TLS. A LISN system was conducted to measure the EMI spectrum of kicker power supply. The EMI noise exceeded FCC standards in some frequency range especially during kicker firing. Reducing EMI level by using different EMI filters were applied. Double pi filter was more efficient than single pi filter. After using filter, the conducted EMI could diminish lower than FCC class B. The experimental results will provide useful information to future TPS pulsed magnet design. | |||
| THPPD067 | Performance of Kicker Pulsers for TPS Project | injection, power-supply, storage-ring, booster | 3665 |
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| A set of kicker power suppliers has been designed and fabricated for storage ring beam injection of the Taiwan Photon Source (TPS) project. In order to fulfill the requirements, the performance of the designed units has been bench tested and the results are examined. The matching in four pulsers, the pulse-to-pulse stability and the time jitter are specified according to the beam injection requirements. The engineering evaluation and the measurement results are briefly discussed. | |||
| THPPD069 | Adjustable Pulse Duration Fast Kicker for the CRYRING Storage Ring | extraction, injection, high-voltage, controls | 3671 |
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| The CRYRING storage ring of the Manne Siegbahn Laboratory (MSL, Stockholm) shall be moved to become part of FLAIR accelerators complex in Darmstadt to be used for deceleration of antiprotons and charged ions. That needs an upgrade to adapt it to the full energy range (30MeV – 0.13 MeV) of its future exploitation. SIGMAPHI, in close collaboration with SOLEIL light Source, is in charge of new fast injection and extraction magnets kickers and their pulsed power supplies. The injection will be done at maximum energy (30 MeV) while the extraction need to cover the full energy range (30 MeV – 0.13 MeV) that requires a continuous adjustment capability on the pulse duration and on the deviation amplitude. The development made specifically for the CRYRING kickers is based on a new design involving two different pulsed power supplies, each one managing either the fast rise time or the current flat top. Using solid state switches allows adapting simultaneously the pulse duration and its amplitude. This contribution presents the specific scheme and the development of a kicker system working up to 20 kV with pulse duration from 1.62 μs to 16.3 μs with transient times less than 300 ns. | |||
| THPPD074 | Effect of a Metallized Chamber upon the Field Response of a Kicker Magnet: Simulation Results and Analytical Calculations | simulation, vacuum, ion, booster | 3686 |
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| Metallized racetrack vacuum chambers will be used in the pulsed magnets of the Austrian cancer therapy and research facility, MedAustron. It is important that the metallization does not unduly degrade field rise and fall times or the flattop of the field pulse in the pulsed magnets. This was of particular concern for a tune kicker magnet, which has a specified rise and fall time of 100 ns. The impact of the metallization, upon the transient field response, has been determined by finite element method (FEM) simulations: the dependency of the field response to the metallization thickness and resistivity are presented. Formulae for the field response, which permit the use of a ramped transient excitation current, are presented: thus the coating thickness and resistivity can be determined which result in a maximum permissible field attenuation and delay for a given current rise time. In addition, results of simulations of the effect of a magnetic brazing collar, located between the ceramic vacuum chamber and flange, are reported. | |||
| THPPD076 | Evaluation of Components for the High Precision Inductive Adder for the CLIC Damping Rings | damping, emittance, collider, luminosity | 3692 |
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| The 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, through synchrotron radiation, ultra-low emittance beam with high bunch charge, necessary for the luminosity performance of the collider. To limit the beam emittance blow-up due to oscillations, the pulse generators for the damping ring kickers must provide extremely flat, high-voltage pulses. The specifications for the extraction kickers of the CLIC damping rings are particularly demanding: the flattop of the output pulse must be 160 ns duration, 12.5 kV and 250 A, with a combined ripple and droop of not more than ±0.02 %. An inductive adder allows the use of different modulation techniques and is therefore a very promising approach to meeting the specifications. In addition to semiconductors working in their saturated region, semiconductors working in their linear region are needed for applying analogue modulation techniques. Simulations have been carried out to define component specifications for the inductive adder: this paper reports the results of tests and measurements of various components. | |||
| THPPD078 | Cold Cathode Thyratron Based High-voltage Kicker Generators at the Duke Accelerators: Six Year Experience | power-supply, cathode, extraction, high-voltage | 3698 |
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Funding: This work is supported in part by the US DOE grant #DE-FG02-97ER41033. The performance of the Duke storage ring based light sources, the Duke storage ring FEL and High Intensity Gamma-ray Source (HIGS), has been greatly improved since 2007 as the result of operating a new full-energy, top-off booster injector (0.18 - 1.2 GeV), allowing fixed energy operation of the storage ring (0.25 - 1.2 GeV). The injection/extraction kicker system is one of the key components of the accelerator facility which determines efficiency and reliability of the light source operation. Pseudo-Spark Switches(PSS), also known as cold cathode thyratrons, are the critical components of the high voltage pulse generators for kickers. More than six years of operation has allowed us to study the lifetime issue for the 10 kA class devices. Recently, we have tested the next generation cold cathode thyratron, with one installed in one of our storage ring kicker high voltage generators. In the present paper we will also present preliminary test results of this new thyratron and the required modifications of its triggering driver to improve its performance. |
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| THPPD083 | Analysis of Kicker Noise Induced Beam Emittance Growth | emittance, high-voltage, injection, monitoring | 3710 |
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Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Over the last few years, physicists have suspected the presence of noise acting on the RHIC beams observable as occasional emittance growth at high beam energies. While the noise was sporadic in the past, it became more persistent during the run-11 setup period. An investigation diagnosed the source as originating from the RHIC abort kicker system. Once identified the issue was quickly resolved. We report in this paper the investigation result, circuit analysis, measured and simulated waveforms, solutions, and future plans. |
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| THPPD084 | Analysis of Beam Loss Induced Abort Kicker Instability | radiation, high-voltage, factory, electron | 3713 |
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Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Through more than a decade of operation, we have noticed the phenomena of beam loss induced kicker instability in the RHIC beam abort systems. In this study, we analyze the short term beam loss before abort kicker pre-fire events and operation conditions before capacitor failures. Beam loss has caused capacitor failures and elevated radiation level concentrated at failed end of capacitor has been observed. We are interested in beam loss induced radiation and heat dissipation in large oil filled capacitors and beam triggered thyratron conduction. We hope the analysis result would lead to better protection of the abort systems and improved stability of the RHIC operation. |
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| THPPD085 | Research and Development of RHIC Injection Kicker Upgrade with Nano Second FID Pulse Generator | injection, high-voltage, monitoring, pulsed-power | 3716 |
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Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Our recent effort to test a 50 kV, 1 kA, 50 ns pulse width, 10 ns pulse rise time FID pulse generator with 250 ft transmission cable, resistive load, and existing RHIC injection kicker magnet has produced unparalleled result. This is the very first attempt to drive a high strength fast kicker magnet with a nanosecond high pulsed power (50 MVA) generator for large accelerator and colliders. The technology is impressive. We report here the result and future plan of RHIC Injection kicker upgrade. |
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| THPPP003 | Coupling Impedance Study of the New Injection Kicker Magnets of the JPARC Main Ring | impedance, coupling, simulation, vacuum | 3725 |
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| New lumped inductance kicker magnets have been developed for the J-PARC main ring injection system. For high intensity beam operation, the beam coupling impedance of the new kickers is a critical issue, which not only generates significant heating inside the ferrite impairing the performance of the kickers, but also drives beam instability. Numerical simulations based on CST studio have been studied during the design stage to optimize the kicker structure. Impedance measurements based on wire method have been carried out. The measured results agree well with the simulation results. | |||
| THPPP004 | Design and Test of Injection Kicker Magnets for the JPARC Main Ring | impedance, coupling, injection, proton | 3728 |
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| The present injection kicker magnets of the JPARC main ring consists of three transmission type kickers. To overcome the operational problems, four lumped inductance kicker magnets have been developed for the simplicity and the high reliability. The tight requirements on the rise and fall time create difficulties for the new design. Magnetic field measurements, coupling impedance measurements and have been carried out. The measurement results show that the new kicker magnets can satisfy the requirements of beam injection. | |||
| THPPP079 | Status of J-PARC Main Ring After Recovery from the Great East Japan Earthquake Damage | extraction, injection, proton, status | 3915 |
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| The J-PARC facility was heavily damaged by the Great East Japan Earthquake on March 11, 2011. For the Main Ring synchrotron (MR), a few tens of cracks were found in the tunnel and many of them leaked groundwater. Displacements of magnet positions after the earthquake were larger than ±15 mm in horizontal and ±5 mm in vertical. Re-alignment of all the magnets and monitors in the MR were carried out in the autumn 2011. Accelerator study and users operation are plan to resume in December 2011 and January 2012, respectively. During the long shutdown period from March to December of 2011, we made work not only for the recovery from the earthquake damages but also for improvements to increase beam power as follows; replacement of injection kickers, upgrade of the ring collimator section, installation of a new collimator system in the slow extraction sections, two rf-systems, four skew-quadrupoles and three octupoles. In this paper, the recovery work and the improvements made in the shutdown periods are reported. Status of high power beam operation after the long shutdown is also presented in details. | |||
| THPPP081 | Status of Injection Energy Upgrade for J-PARC RCS | power-supply, injection, impedance, quadrupole | 3921 |
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| The injection energy upgrade for J-PARC RCS is planed in 2013. This includes the power supplies upgrade of injection pulsed magnet system, suppression for leakage field, quadrupole correction magnets, reduction of kicker impedance effect and improvements of beam diagnostic instrumentation. The paper reports the present status. | |||
| THPPR009 | Optimization of the Electron Beam Extraction Efficiency in a Booster for TLS | extraction, electron, booster, factory | 3981 |
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| The Response Surface Methodology (RSM), is used to study the optimization process of the electron beam extraction efficiency for Taiwan Light Source (TLS) in NSRRC. A study model was constructed based on the Artificial Neural Network (ANN) theory by using selected beam extraction tuning knobs as the variables. An optimization procedure is developed by taking extraction efficiency as the objective function and the selected beam tuning knobs as the variables. Furthermore, this theoretical model and optimization procedure have been put into practice in verifying how effectively the model can accomplish. By properly applying the constructed optimization procedure for electron beam extraction study, the efficiency has been improved effectively. The details of the study will be reported in this paper. | |||
| THPPR055 | Compact Gantry with Large Momentum Acceptance | proton, octupole, diagnostics, sextupole | 4100 |
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| Rotatable Ion Beam Cancer Therapy (IBCT) delivery systems or gantries are the largest features in an ion beam therapy facility. They weight 100+ tons and require large (~3 story) heavily shielded rooms to house them. Reducing the size of ion beam gantries using high field One disadvantage of superconducting magnets is the difficulty of changing the fields quickly in order to adjust the beam momentum to scan the depth of penetration. In this paper we present a design of a gantry consisting of many combined function superconducting magnets that have a large enough momentum acceptance (> pm 10%) such that the magnets do not need to be changed while changing the beam energy. | |||