| Paper | Title | Other Keywords | Page |
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| MOPAB040 | Linear and Nonlinear Optics Measurements With Multiturn Data at PETRA III | optics, operation, diagnostics, injection | 170 |
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| At Petra III measuring multiturn beam response to pulsed and continuous excitations allows linear and nonlinear (e.g. frequency maps) optics parameter determination. We describe the measurement setup, approaches to optics parameter determination, and the measurement results for Petra III. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB040 | ||
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| MOPAB125 | Post-Mortem System for the Taiwan Photon Source | timing, operation, photon, data-acquisition | 422 |
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| The Taiwan Photon Source (TPS), a 3-GeV third-generation synchrotron light source located in Hsinchu, is available to users since 2016. During operation, it will inevitably encounter system trips caused by beam losses. Thus, a post-mortem (PM) system is an important tool to analyze the cause of such events. Main functions of the PM system are: (i) PM trigger will be generated when the stored beam is suddenly lost abnormally; (ii) storage of relevant signals when the server receives such a trigger; (iii) PM Viewer to analyze each event and understand the cause and effect of a beam trip event. The post-mortem system architecture, plans and implementation will be discussed in this report. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB125 | ||
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| MOPIK036 | Study of the Magnetizing Relationship of the Kickers for CSNS | extraction, neutron, software, target | 582 |
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Funding: Work supported by National Natural Science Foundation of China (11205185) The extraction system of CSNS mainly consists of two kinds of magnets: eight kickers and one lambertson magnet. In this paper, firstly, the magnetic test results of the eight kickers were introduced and then the filed uniformity and magnetizing relationship of the kickers were given. Secondly, during the beam commissioning in the future, in order to obtain more accurate magnetizing relationship, a new method to measure the magnetizing coefficients of the kickers by the real extraction beam was given and the data analysis would also be processed. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK036 | ||
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| MOPIK042 | Beam-Based Kicker Waveform Measurements Using Long Bunches | flattop, emittance, injection, proton | 599 |
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| The increased bunch length demanded by the LHC Injectors Upgrade (LIU) project to mitigate emittance growth from space-charge on the PS injection plateau puts strong constraints on the rise-times of the recombination kickers in the transfer lines between the CERN Proton Synchrotron Booster (PSB) and the Proton Synchrotron (PS). A beam-based technique has been developed to validate the waveforms of the recombination kickers. In this paper high-resolution measurements are presented by extracting the intra-bunch deflection along bunches with lengths comparable to or longer than the rise-time of the kicker being probed. The methodology has been successfully applied to the three vertical recombination kickers named BT1. KFA10, BT4. KFA10 and BT2. KFA20, and benchmarked with direct measurements of the kicker field made using a magnetic field probe. This paper describes the beam-based technique, summarises the main characteristics of the measured waveforms, such as rise-time and flat-top ripple, and estimates their impact on beam brightness. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK042 | ||
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| MOPIK043 | Beam-Based Waveform Measurements of the CERN PS Injection Kicker | flattop, injection, impedance, timing | 603 |
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| In the framework of the LHC Injectors Upgrade (LIU) project, a beam-based technique has been developed for measuring the waveform the CERN Proton Synchrotron (PS) horizontal injection kicker, named KFA45. The technique avoids the need for tedious magnetic measurements, especially when a spare magnet is presently unavailable and measuring the operational magnet with a magnetic field probe is complicated by integration reasons. In this paper, the technique and results of the waveform measurements are summarised. The results already provide additional information in terms of waveform characterisation for the validation of numerical simulations and are of great interest for the future LIU performance upgrade. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK043 | ||
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| MOPIK063 | Non-Linear Kickers Using Eddy Current Screens and Application to the ESRF | injection, sextupole, storage-ring, flattop | 670 |
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| The ESRF storage ring injection and accumulation is performed using standard 4-kickers bump and septum magnet. Sextupoles are located within the injection bump leading to significant bump non-closure during the ramp-up and ramp-down and optics distorsion for both stored and injected beam. Introducing non-linearities in the kickers allows for compensation of the perturbation from these sextupoles. We report on the feasibility of adding eddy current screens to a standard kicker magnet design to generate a non-linear field and its recent application to mitigate the injection perturbations at the ESRF. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK063 | ||
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| MOPIK104 | Top-Up Injection With Anti-Septum | septum, injection, simulation, storage-ring | 774 |
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| We present a novel improvement for injection into the very restricted machine aperture of future light source synchrotrons. A conventional injection scheme is based on a septum to deflect the injected bunch plus a fast pulsed three or four kicker bump to bring the stored beam close to the septum wall. With the novel improvement, the bump kickers are fitted with a thin wall longitudinal metal plate which screens the injected bunch from deflection without changing the stored beam bump behaviour. This metal screen then forms the final septum, but inverted in function of the conventional approach, hence the name anti-septum. The approach does not remove the need for the main septum magnet, but for modest cost it permits the injected bunch to be brought closer to the stored beam. Application of the anti-septum to the SLS-2 project and simulation results on a prototype are presented. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK104 | ||
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| MOPIK105 | Preliminary Study of Injection Transients in TPS Storage Ring | septum, injection, vacuum, storage-ring | 777 |
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| An optimized injection efficiency is related to a perfect match between the pulsed magnetic fields in the storage ring and transfer line extraction in the TPS. However, misalignment errors, hardware output errors and leakage fields are unavoidable. We study the influence of injection transients on the stored TPS beam and discuss solutions to compensate these. Related simulations and measurements will be presented. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK105 | ||
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| MOPVA147 | High Energy Transport Line Orbit Correction at CNAO | dipole, proton, synchrotron, ion | 1200 |
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| CNAO is the only Italian facility for the cancer treatment with protons and carbon ions. Each treatment needs hundreds of energies in the range of the tumor and needs a great precision in terms of beam position and divergence at the target. Goal of the article is to show the layout of the CNAO high energy lines and the strategy that has been used to optimize the transport and set the beam trajectory. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA147 | ||
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| TUPAB033 | Design of a Stripline Kicker for the ELBE Accelerator | emittance, electron, neutron, laser | 1393 |
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| ELBE is a linac based cw electron accelerator serving different secondary beams one at a time. Depending on the user demand the bunch repetition rate may vary from single pulse up to 13 MHz. For the future different end stations should be served simultaneously, hence specific bunch patterns have to be kicked to other beam-lines. To use e.g. one bunch out of the bunch train very short kicking durations have to be realized. The variability of the bunch pattern and the frequency resp. switching time are one of the main arguments for a stripline-kicker combined with HV-switches as basic concept. A nearly homogenous field in the kicker has to be realized for uniform deflection of the electron bunch and emittance grow of the bunch has to be kept as low as possible. Furthermore the fast switching ability of the kicker demands for a fast decay of the HV-pulse resp. its reflections in the structure implying a specific design of the kicker elements. For this reason a design with two tapered active electrodes and two ground fenders was optimized in time and frequency domain with the software package CST. Additionally a first prototype was manufactured for laboratory and first beam-line tests. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB033 | ||
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| TUPAB062 | Single Dipole Kicker Injection Into the Sesame Storage Ring | injection, dipole, septum, storage-ring | 1463 |
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| SESAME (Synchrotron Radiation Light Source in Allan, Jordan) consists of an 800 MeV injector (original from BESSY I, Berlin, Germany) and a 2.5 GeV storage ring. Extraction out of the Booster is done by means of a bumper, a delay-line kicker, and a direct driven in-vacuum septum. This paper will present the injection procedure into the storage ring. Simulations of the injection process are compared to the results obtained during commissioning | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB062 | ||
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| TUPAB080 | Considerations of the HALS Injection System and a New Non-linear Kicker Design | injection, accumulation, multipole, lattice | 1503 |
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Funding: Work supported by The National Key Research and Development Program of China No. 2016YFA0402000(2016YFA0402002) Hefei Advanced Light Source (HALS) is a newly designed diffraction-limited synchrotron radiation source with an energy of 2GeV and a natural emittance of 18.4 pm. A project to build test facility of this new light source has been approved and funded in 2017. Among many key subsystems, the injection system of HALS is a very important one. Both on-axis swap out, on-axis longitudinal accumulation and off-axis single multipole kicker injection are considered. For on-axis fast kicker injection, basic parameters of the system are given. Layout of kickers and septums are presented. For off-axis multipole injection, non-linear kickers (NLK) draw much attention in recent years, various studies have been carried out in many laboratories. But it suffered from low injection efficiency and has not been used in routine operation. In this paper, we propose a new ferrite-loaded non-linear kicker (FNLK) and a prototype FNLK has been developed and tested. Compared to the air bus design of NLK, the FNLK not only improves the flat region of magnetic field but also reduce the error sensitivity of bars' position. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB080 | ||
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| TUPAB109 | Study on Injection with Pulsed Multipole Magnet for SPS Storage Ring | injection, multipole, operation, storage-ring | 1573 |
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| Pulsed multipole magnet (PM) has zero magnetic field at the centre, therefore it introduces no perturbation to the stored beam. It has been demonstrated that this injection scheme is able to minimise the oscillation of the stored beam, and thus make it suitable for top-up operation. To investigate the suitability of employing this injection method at Siam Photon Source, PM was modelled and optimised for best performance using particle tracking based method. This work presents injection optimisation process with PM considering various constraints such as position of injected beam, injection conditions, and effects of installed IDs. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB109 | ||
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| TUPAB121 | Bench Measurements and Beam Tests of a Prototype Stripline Kicker for Swap-Out Injection in the ALS-U | impedance, vacuum, injection, alignment | 1599 |
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Funding: Work supported by the the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. The ALS upgrade to a diffraction-limited light source (ALS-U Project) relies on a swap-out injection scheme, where the circulating current is maintained constant by injecting on-axis fresh bunch trains, replacing old trains, which are simultaneously extracted. The realization of a stripline kicker to perform such an operation presents several challenges in terms of optimal matching to the pulser, contributions to the beam coupling impedance, and dissipation of the power deposited by the stored beam. To test our design choices for the ALS-U kicker, we have built and installed on the ALS a kicker with characteristics similar to the design for the ALS-U, as the more challenging aspects of the project are concerned. In particular, while the small distance between stripline electrodes reduces the required pulser voltage, the extreme proximity of the circulating beam requires a careful evaluation of the interaction between beam and kicker. In this paper we present the first measurements with beam, after the test kicker installation, together with the results of bench measurements performed on a cold model and computer simulations. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB121 | ||
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| TUPIK041 | Cleaning of Parasitic Bunches for Time Structured Filling of the ESRF Storage Ring During Top Up Operation | extraction, booster, electron, storage-ring | 1774 |
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| In order to generate time structured synchrotron radiation the 6GeV ESRF storage ring can be operated with 16 buckets filled with 15nC separated by 16 gaps of 61 nearly perfectly empty buckets. The contrast required by some users between the population of the main and empty buckets is 1011. In order to obtain these empty buckets some RF knock out (cleaning) of the parasitic bunches is needed. Until now this cleaning was performed on the beam stored in the storage ring. Recently we have started to deliver this 16 bunches filling in a so called top up mode, drastically increasing the rate of the storage ring refills. In this top up mode it is very penalizing to perform the cleaning in the storage ring so we are now performing it in the booster synchrotron which accelerates the 200MeV beam coming from the linac up to 6GeV. We describe the set up used to perform the cleaning in the booster and all the measurement and experiments performed in order to correctly understand the origin of the unwanted electrons populating buckets of the gaps separating the 16 main bunches. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK041 | ||
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| TUPIK053 | A Broadband Transverse Kicker Prototype for Intra-Bunch Feedback in the CERN SPS | impedance, simulation, feedback, coupling | 1812 |
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| A transverse intra-bunch feedback system is currently under study at CERN for the SPS, to mitigate beam instabilities caused by electron clouds and coupled transverse modes (TMCI). This feedback system is designed for a bandwidth of 1 GHz, and based on a digital feedback controller and broadband power amplifiers. For the kicker, a periodic, quasi-TEM slotted transmission-line structure is foreseen which promises to meet the bandwidth requirements. This paper discusses the electromagnetic design and the mechanical implementation of a prototype kicker, demonstrating its performance and limitations based on numerical simulations. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK053 | ||
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| TUPIK087 | Phase Advance Interlocking Throughout the Whole LHC Cycle | quadrupole, optics, software, operation | 1901 |
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| Each beam of CERN's Large Hadron Collider (LHC) stores 360 MJ at design energy and design intensity. In the unlikely event of an asynchronous beam dump, not all particles would be extracted immediately. They would still take one turn around the ring, oscillating with potentially high amplitudes. In case the beam would hit one of the experimental detectors or the collimators close to the interaction points, severe damage could occur. In order to minimize the risk during such a scenario, a new interlock system was put in place in 2016. This system guarantees a phase advance of zero degrees (within tolerances) between the extraction kicker and the interaction point. This contribution describes the motivation for this new system as well as the technical implementation and the strategies used to derive appropriate tolerances to allow sufficient protection without risking false beam dump triggers. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK087 | ||
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| TUPIK094 | Transverse Feedback Parameter Extraction from Excitation Data | feedback, pick-up, damping, operation | 1920 |
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| In this paper we present a simple and fast approach to extract essential parameters of a transverse feedback system such as phase advances between pick-ups and kickers, fractional tune, kicker delay, or per-bunch transverse activity from discrete-time samples of position signals. In this approach the beam is excited and subsequent beam oscillations are recorded. Given that any number of pick-ups can be evaluated at once with only a marginal increase of transverse beam size this method is suitable for regular health checks of a transverse feedback system, e.g., for every injection. The fundamental idea relies on the reconstruction of the transverse phase space by means of digital filters. We sketch a simple mathematical model to illustrate the underlying method. Examples are given together with a set of filter kernels for the fractional tunes of the LHC transverse feedback system. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK094 | ||
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| TUPIK095 | Possibilities for Transverse Feedback Phase Adjustment by Means of Digital Filters | pick-up, feedback, betatron, damping | 1924 |
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| In transverse feedback systems a phase adjustment is generally required to convert a beam position signal from a pick-up into a momentum correction signal used by a transverse kicker. In this paper we outline several possibilities for phase adjustments using only single pick-ups or the vector combination of two pick-ups. Analytical expressions are given as a function of the fractional tune and the betatron phase advance between the pick-up location and the kicker. The shortest possible digital filter is formulated, including a notch for closed orbit suppression and a free parameter to adjust for betatron phase. We introduce a novel, fully parametrized digital filter with the feature to be insensitive to variations in fractional tune. Examples are given for the SPS transverse feedback system and compared with measurements. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK095 | ||
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| TUPIK097 | Improving the Performance of an Orbit Feed-forward Based on Quadrupole Motion at the KEK ATF | quadrupole, feedback, ground-motion, collider | 1931 |
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| The high luminosity requirement for a future linear collider sets a demanding limit on the beam quality at the Interation Point (IP). Even the natural motion of the ground could misalign the quadrupole magnets to such an extent that the resulting dipole kicks would require compensation. The novel technique described in this paper uses seismometers to measure the positions of the quadrupole magnets in real time and a kicker to counteract the effect of their misalignment. The prototype system deployed at the Accelerator Test Facility (ATF) at KEK in Japan has already demonstrated a reduction in the pulse-to-pulse vertical position jitter of the beam by about 10%. Based on the observed correlation of the beam position to the quadrupole positions the maximum possible jitter reduction from such a system is estimated to be about 25%. This paper details the latest improvements made to the system with the aim of achieving this limit. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK097 | ||
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| TUPIK105 | The Design Improvement of Horizontal Stripline Kicker in TPS Storage Ring | impedance, storage-ring, vacuum, operation | 1961 |
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| We plan to replace the existing horizontal stripline kicker of the transverse feedback system with an improved design. Large reflected power was observed at the downstream port of stripline kicker driven by the feedback amplifier. A rapid surge of vacuum pressure was observed when we tested the high current operation in TPS storage ring in April 2016. A burned feedthrough of the horizontal stripline kicker was discovered during a maintenance shutdown. The improved design is targeted to reduce the reflection of driving power from feedback system and to reduce beam induced RF heating. This major modification of the design is described. The results of RF simulation performed with the electromagnetic code GdfidL are reported as well. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK105 | ||
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| TUPIK112 | Progress Towards Nanometre-Level Beam Stabilisation Using a Cavity BPM System at ATF2 | feedback, cavity, dipole, electronics | 1986 |
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| A low-latency feedback system has been designed and tested to achieve inter-bunch position stabilisation at the final focus of the Accelerator Test Facility (ATF2) at KEK. This system has now been enhanced through the use of position information from two cavity beam position monitors (BPMs) to enable beam stabilisation at a third, intermediate location where a witness BPM measures the correction. Low-Q cavity BPMs were used, along with custom signal processing electronics designed for low latency and optimal position resolution. A custom stripline kicker, power amplifier and digital feedback board were used to provide beam correction and feedback control. The system was tested in single-pass, multi-bunch mode with the aim of providing inter-bunch beam stabilisation on electron bunches of charge ~1 nC separated in time by 280 ns. In 2015 a single BPM feedback system demonstrated beam stabilisation to below 75 nm. To date the two BPM input feedback system has demonstrated beam stabilisation to 83 ± 6 nm. This performance is limited by the current understanding of the cavity BPM resolution. Work will be described with the aim of improving this result. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK112 | ||
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| TUPIK114 | First Experiences with the Longitudinal Feedback System at Diamond Light Source | cavity, feedback, simulation, hardware | 1992 |
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| In order to avoid longitudinal multibunch instabilities potentially caused by the addition of normal conducting RF cavities into the Diamond storage ring, a longitudinal feedback was installed. The main components are newly developed feedback electronics, in-house built modulator and amplifier, and a low Q kicker cavity. This paper describes the performance of the cavity as well as the full longitudinal feedback system as it is installed on the machine and tested before the installation of the normal conducting RF cavities. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK114 | ||
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| TUPIK117 | Optimization of the Booster Notch System at Fermilab | booster, proton, extraction, power-supply | 2002 |
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| The Booster Beam Notch is a beam gap needed to allow extraction kickers to reach full field strength for a single turn extraction scheme. The Notch is created at injection energy by kicking 3 out of the 84 bunches to a dedicated absorber. The kicker voltage, pulse length and geometry of the absorber must be optimized to minimize the beam loss due to the notch creation. Beam studies, simulation and implementation as well as the optimization and improvement of the notch system will be discussed in this paper. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK117 | ||
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| TUPIK119 | Control of Intra-Bunch Vertical Instabilities at the SPS - Measurements and Technology Demonstration | feedback, controls, injection, optics | 2005 |
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Funding: Work supported by the U.S. Department of Energy under contract # DOE-AC02-76SF00515, the US LHC Accelerator Research Program ( LARP), the FP7 High Luminosity LHC Project and the US-Japan Cooperative Program in High Energy Physics We present recent measurements demonstrating control of unstable beam motion in single bunch and bunch train configurations at the SPS. The work is motivated by anticipated intensity increases from the LIU and HL-LHC upgrade programs, and has included the development of a GHz bandwidth reconfigurable 4 GS/S signal processor with wideband kickers and associated amplifiers. The system was operated at 3.2GS/s with 16 samples across a 5 ns RF bucket (4.2 ns bunch at injection). The experimental results confirm damping of intra-bunch instabilities in both Q20 and Q26 optics configurations for intensities of 2x1011 P/bunch. Instabilities with growth times of 200 turns are well-controlled from injection, consistent with the achievable gains for the 2 installed stripline kickers with 1 kW broadband power. Measurements from multiple studies in single-bunch and bunch train configurations show achieved damping rates, control of multiple intra-bunch modes, behavior of the system at injection and final damped noise floor. We present an analysis method to study the relative phase of slice motion during a transient to discriminate between TMCI and other types of Head-Tail instabilities. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK119 | ||
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| TUPIK121 | Dark Sector Experiments at LCLS-II (DASEL) Accelerator Design | FEL, experiment, laser, septum | 2008 |
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Funding: Work supported by the US DOE Contract DE-AC02-76SF00515. DASEL (Dark Sector Experiments at LCLS-II) is a new accelerator and detector facility proposed to be built at SLAC. Its primary target is a direct observation of dark matter produced in electron-nuclear fixed-target collisions. DASEL takes advantage of the LCLS-II free electron laser (FEL) under construction at SLAC which will deliver a continuous electron beam from a 4-GeV superconducting linac. DASEL will operate parasitically to the LCLS-II FEL by extracting low intensity unused dark current bunches downstream of the FEL kickers. The DASEL key accelerator components include a 46-MHz gun laser system providing controlled intensity and timing of the dark current, a fast (MHz) kicker with 600-ns flat-top, a new transport line connecting the LCLS-II to the existing A-line and to End Station-A where the experiments will take place, and a spoiler and collimator system in the A-line for final shaping of the DASEL beam. An overview of the DASEL accelerator system is presented. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK121 | ||
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| TUPIK122 | Bunch-by-Bunch Feedback Kickers for SPEAR3 | impedance, feedback, ion, vacuum | 2012 |
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| SPEAR3 operates with a large cross-section copper vacuum chamber, mode-damped RF cavities and low-impedance insertion devices. As a result, the beam is passively stable for 280-bunch circulating beam current up to 500ma when the background gas pressure is low. In the future, more small-gap insertion devices will be installed and plans are underway to implement resonant bunch-crabbing for the ultrafast x-ray research program. These requirements drive the need for a fast, bunch-by-bunch feedback system to control beam instabilities, remove unwanted satellite bunches and resonantly crab select bunches on demand. In this paper we present a conceptual design for the transverse bunch-by-bunch stripline kickers. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK122 | ||
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| TUPVA007 | Impact of LHC and SPS Injection Kicker Rise Times on Lhc Filling Schemes and Luminosity Reach | injection, emittance, luminosity, timing | 2043 |
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| The 2016 LHC proton filling schemes generally used a spacing between injections of batches of bunches into SPS and LHC corresponding to the design report specification for the SPS and LHC injection kicker rise times, respectively. A reduction of the batch spacing can be directly used to increase luminosity without detrimental effects on beam stability, and with no increase in the number of events per crossing seen by the experiments. Measurements and simulations were performed in SPS and LHC to understand if a shorter injection kicker rise time and associated tighter batch spacing would lead to increased injection oscillations of the first and last bunches of a bunch train and eventually also a systematic growth of the transverse emittance. The results were used to define the minimum possible batch spacing for an acceptable emittance growth in LHC, with gains of reductions of about 10% possible in both machines. The results are discussed, including the potential improvement of the LHC luminosity for different filling schemes. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA007 | ||
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| TUPVA020 | The LHC Injectors Upgrade (LIU) Project at CERN: Ion Injector Chain | ion, injection, extraction, luminosity | 2089 |
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| The LHC injector chain for Pb-ion beams at CERN consists of Linac3, the accumulator ring LEIR, the PS and the SPS. In the context of the LHC injectors upgrade (LIU) project an intense program of machine development studies has been performed in the last two years to maximise the intensity of Pb-ion beams at LHC injection. In this paper we present an analysis of the operational performance achieved so far, with the goal of 1) identifying the remaining performance bottlenecks along the chain and possible areas for improvement, and 2) to optimize the Pb-ion beam production scheme for the High Luminosity (HL-) LHC era. A consistent set of beam parameters for the HL-LHC era has been established taking into account the already achieved improvements as well as foreseen upgrades still to be implemented, such as slip stacking in the SPS. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA020 | ||
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| TUPVA046 | Beam Energy Scan With Asymmetric Collision at RHIC | cavity, operation, emittance, booster | 2175 |
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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. A beam energy scan of deuteron-gold collision, with center-of-mass energy at 19.6, 39, 62.4 and 200.7 GeV/n, was performed at the Relativistic Heavy Ion Collider in 2016 to study the threshold for quark-gluon plasma (QGP) production. The lattice, RF, stochastic cooling and other subsystems were in different configurations for the various energies. The operational challenges changed with every new energy. The operational experience at each energy, the operation performance, highlights and lessons of the beam energy scan are reviewed in this report. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA046 | ||
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| TUPVA048 | Calculation of Particle Loss Maps for 2016 RHIC Gold-Gold Run | simulation, detector, operation, radiation | 2181 |
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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. In the 2016 RHIC 100~GeV gold-gold (Au-Au) run, 20~mm orbit bumps were installed in the arcs to protect the experimental detectors from abort kicker prefiring. Chronic particle losses were observed in the arcs with these orbit bumps. Those particle losses are mainly from the 78+Au197 and 79+Au196 particles generated from bound-free pair production (BFPP) and electromagnetic dissociation (EMD) associated with the Au-Au collision at the IPs. In this article, we present simulated particle losses of 78+Au197 and 79+Au196 and calculate the particle loss distribution in the ring. The calculated particle loss maps are compared with operational observations. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA048 | ||
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| TUPVA080 | Stochastic Cooling Hardware for Low Energy Deuterons at COSY | pick-up, impedance, experiment, electron | 2261 |
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| One of the central utilizations of the COSY facility nowadays is to host experiments for the JEDI (Jülich Electric Dipole moment Investigations) collaboration. These experiments use polarized deuteron beams at momenta below 1 GeV/c, that are stored for several minutes. In order to increase the spin coherence time, beam cooling is necessary. Electron cooling is applied to pre-cool the beam, but the solenoids of the electron cooler may not be perfectly compensated. Thus, stochastic cooling would be desirable instead. Unfortunately, the existing stochastic cooling system is not sensitive at low beam velocities. This paper presents newly developed stochastic cooling pickups and kickers for a system dedicated to low beam velocities of approximately 0.5c. The design is based on the slot-ring type pickups that have been developed for the High Energy Storage Ring (HESR), but optimized for low particle velocities and a low frequency band of 350-700 MHz. Since the structures get much bigger in comparison to the HESR version, mechanical properties must be reconsidered and a trade-off between electrical properties, cooling performance and constructability must be found. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA080 | ||
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| TUPVA085 | First Experiences with HESR Stochastic Cooling System | pick-up, hardware, impedance, ion | 2278 |
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| The stochastic cooling system of the HESR (High Energy Storage Ring) is based on completely new structures especially designed for the HESR. Each beam surrounding slot of these so called slot-ring couplers covers the whole image current without a reduction of the HESR aperture and without any plunging system. One pickup and one kicker have been already fabricated and installed into the COSY ring to demonstrate stochastic cooling in all three dimensions with only one structure. First results of commissioning with proton beams will be presented. The longitudinal cooling system at HESR is based on filter cooling with an optical notch-filter and ToF cooling. The demanding accuracy concerning phase stability requires dedicated control of the notch-frequency. The optical COSY filter has been modified and can be proven in long term runs together with the new stochastic cooling system. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA085 | ||
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| TUPVA138 | Status of the Warm Front End of PIP-II Injector Test | rfq, ion, ion-source, linac | 2421 |
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Funding: Fermilab is operated by Fermi Research Alliance, LLC under Contract No. DEAC02-07CH11359 with the United States Department of Energy The Proton Improvement Plan II (PIP-II) at Fermilab is a program of upgrades to the injection complex. At its core is the design and construction of a CW-compatible, pulsed H− SRF linac. To validate the concept of the front-end of such machine, a test accelerator known as PIP-II Injector Test is under construction. It includes a 10 mA DC, 30 keV H− ion source, a 2 m-long Low Energy Beam Transport (LEBT), a 2.1 MeV CW RFQ, followed by a Medium Energy Beam Transport (MEBT) that feeds the first of 2 cryomodules increasing the beam energy to about 25 MeV, and a High Energy Beam Transport section (HEBT) that takes the beam to a dump. The ion source, LEBT, RFQ, and initial version of the MEBT have been built, installed, and commissioned. This report presents the overall status of the warm front end. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA138 | ||
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| WEPAB001 | Parallel Operation of SASE1 and SASE3 Undulator Sections of European XFEL | radiation, undulator, simulation, operation | 2554 |
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| In the current paper the numerical simulation results for parallel (decoupled) operation of SASE1 and SASE3 undulator sections of European XFEL are presented. The study was based on the idea of betatron switcher imple-mentation. It was shown that it is possible to avoid energy spread growth in SASE1 and to reach the saturation in SASE3 in desirable range of radiation wavelengths by a trajectory kick before SASE1 and its correction before SASE3. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB001 | ||
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| WEPAB050 | Commissioning of SESAME Storage Ring | storage-ring, injection, optics, sextupole | 2694 |
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| SESAME light source uses a 2.5GeV storage ring, designed to produce synchrotron light in the hard X-ray region. The 133.2 m circumference ring composed of 16 Double Bend Achromat cells with 16 dispersive straight sections, offers a maximum capacity of 25 beamlines. The storage ring is filled with electrons using an 800MeV injector of 1 Hz repetition rate. This article reports on the main results and first experience of storage ring commissioning and operation. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB050 | ||
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| WEPAB103 | On-Axis Swap-Out Injection R+D for ALS-U | injection, emittance, alignment, storage-ring | 2821 |
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Funding: This work is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. The ALS-U upgrade promises to deliver diffraction limited performance throughout the soft x-ray range by lowering the horizontal emittance by a factor of 40 compared to the current ALS. One of the consequences of producing a small emittance is a small dynamic aperture, although the momentum acceptance will remain large enough for acceptable beam lifetime. To overcome this challenge, ALS-U will use on-axis swap-out injection to exchange bunch trains between the storage ring and an accumulator ring. On-axis swapout injection requires special fast pulsers and state-of-the-art stripline kicker magnets. This paper reports on the results of the on-axis swap-out injection R&D program, including beam tests of a complete stripline kicker/pulser system on the current ALS and the development of methods to speed up beam based commissioning after the upgrade shutdown. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB103 | ||
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| WEPAB104 | Status of the Conceptual Design of ALS-U | emittance, lattice, storage-ring, vacuum | 2824 |
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Funding: This work is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. The ALS-U upgrade promises to deliver diffraction limited performance throughout the soft x-ray range by lowering the horizontal emittance to about 50~pm resulting in 2-3 orders of brightness increase for soft x-rays compared to the current ALS. The design utilizes a multi bend achromat lattice with on-axis swap-out injection and an accumulator ring. One central design goal is to install and commission ALS-U within a short dark period. This paper summarizes the status of the conceptual design of the accelerator, as well as some results of the R&D program that has been ongoing for the last 3 years. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB104 | ||
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| WEPIK007 | Optics Design and Observation for the Beam Abort System in SuperKEKB HER | sextupole, optics, injection, quadrupole | 2922 |
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| In the first commissioning of SuperKEKB, which is 'Phase 1', the new abort system is tested in the High Energy Ring (HER). There is a risk that aborted beams with low emittance and high current may destroy the window for extraction from beam pipe. In order to enlarge the aborted beam at the window, quadrupole field is applied only for the aborted beam. In the Low Energy Ring (LER), quadrupole pulsed magnets will be installed to enlarge the aborted beam, and in the HER, a pair of identical sextupole magnets is installed between the abort kickers and the extraction window. These sextrupole magnets are connected by I or 'I transformation to cancel the geometrical nonlinearity for the stored beam in the ring. This paper will report the optics design for the abort system of the HER as well as the observation of the aborted beam. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK007 | ||
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| WEPIK011 | Ceramic Chamber Used in SuperKEKB High Energy Ring Beam Abort System | operation, vacuum, target, injection | 2936 |
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| The water-cooled type ceramic chambers were used for Super-KEKB high energy ring beam abort system. Since the horizontal abort kicker magnets are required to have very fast rise time and large current, the gap of kicker magnet must be as small as possible. The thin and compact ceramic chamber were developed. The chamber has racetrack type chamber whose inner diameter is 60mm in horizontal and 40 mm in vertical. And the gap of horizontal kicker magnet is 70mm. The thickness of the ceramic chamber is 30 % reduced from that of KEKB. The 500mm long hollow type ceramic, which includes cooling water path inside, is fabricated. It makes the structure of ceramic chamber simple and compact. The new copper electroforming is applied to deposit the 100μmeter thickness Cu conducting layer on the inner wall of Kovar. The Cu conducting layer reduces the heat generated by image beam current on the Kovar brazering. They are installed in the Super-KEKB electron ring beam abort system, and used in the phase 1 operation. The paper describes the performance of the water-cooled ceramic chamber under phase 1 operation. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK011 | ||
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| WEPIK012 | Performance of SuperKEKB High Energy Ring Beam Abort System | extraction, operation, sextupole, power-supply | 2939 |
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| New Beam abort system was installed at the Super-KEKB High Energy Ring. It was designed to enlarge the horizontal beam size at the beam extraction window to protect the extraction window, and it also makes the beam abort gap shorter. It consists of four horizontal kicker magnets, one vertical kicker to sweep the beam position in vertical direction, sextupole magnet to enlarge the horizontal beam size, one lambertson magnet, Ti extraction window and beam dump. Four horizontal kicker magnets and one vertical kicker magnet connects to the one power supply. The ceramic chambers cooled by the water are inserted in each kicker coils. The Abort system had been used during SuperKEKB phase 1 operation. This paper describes the performance of the abort system. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK012 | ||
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| WEPIK014 | Coupled Bunch Instability and Its Cure at J-PARC RCS | impedance, space-charge, emittance, injection | 2946 |
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| The RCS at J-PARC is a kicker-impedance dominant machine, which violates the impedance budget from a classical viewpoint. Nevertheless, we have recently succeeded to accelerate a 1-MW equivalent beam by making maximum use of the space charge effect on the beam instabilities. In this report, we explain the manipulation to suppress the beam instability, at first. Then, we discuss some issues to suppress the beam instabilities for beams with much smaller transverse emittance, as well as the present status of our efforts to reduce the kicker impedance toward the realization of the higher beam power at the RCS. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK014 | ||
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| WEPIK033 | LHC Beam Dump Performance in View of the High Luminosity Upgrade | extraction, operation, proton, hardware | 2999 |
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| The High Luminosity Large Hadron Collider (HL-LHC) project will increase the total beam intensity in the LHC by nearly a factor of two. Analysis and follow-up of recent operational issues as well as dedicated studies of the LHC Beam Dump System (LBDS) have been carried out to ensure the safe operation with HL-LHC parameters and to decide on possible hardware upgrades to meet the HL-LHC requirements. The fail-safe design must ensure the LBDS performance also for abnormal operation such as asynchronous beam dumps or failing dilution kickers. In this paper, we report on newly observed failure scenarios as the erratic firing of more than one dilution kicker, and discuss their consequences as well as possible mitigation measures in view of the high luminosity upgrade. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK033 | ||
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| WEPIK078 | Development of the Impedance Model in HEPS | impedance, vacuum, injection, feedback | 3110 |
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| The High Energy Photon Source (HEPS) is a new designed photon source at beam energy of 6 GeV. Due to the small beam pipe aperture and a large number of insertion devices in the machine, the impedance can drive collective instabilities and limit the machine performance. Therefore, a thorough estimation of the coupling impedance is necessary in controlling the total impedance of the whole machine. A primary impedance model is obtained for the storage ring. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK078 | ||
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| WEPIK087 | Measurement and Characterization of Cable Losses for High Voltage Coaxial Cables Used in Kicker Systems | impedance, simulation, network, injection | 3131 |
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| In the framework of CERN's LHC Injector Upgrade, simulation models for kicker pulse generators have been improved. A key element in the conventional pulse generators, among many others, are the high voltage coaxial cables. Since they can have significant impact on the waveform characteristics, an accurate cable model for simulation is crucial for reliable results during development. For this purpose, precise measurements of scatter parameters have been carried out in order to improve existing simulation models. Specialized high voltage cables, sometimes SF6 gas filled, used in various CERN kicker systems are usually large, heavy, not very flexible and often only one end is easy accessible. In addition, the impedance of these cables is rarely of 50 Ohms, which presents an extra difficulty. This paper describes the methods that have been defined and used to measure any kind of coaxial structures relying on S11 parameters exclusively. Measurements for various specialized cable types are presented and compared with their improved models. The implications for overall kicker system performance are briefly discussed. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK087 | ||
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| WEPIK097 | An Optimization Tool to Design a Coreless Non-Linear Injection Kicker Magnet | injection, emittance, target, sextupole | 3170 |
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| Top-up injection into low emittance light sources is challenging due to their inherent small dynamic apertures (DA). The use of a multipole-magnet injection kicker prevents disturbing the circulating beam. However, the injected bunch will be mismatched due to unwanted focusing (linear field profile) or even filamented (nonlinear field profile). Coreless nonlinear kicker magnets, using different configurations of straight conductors, can produce transverse step-like magnetic field distribution which prevent the mismatch. We explored an 8-conductor configuration and a multi-conductor approach like unipolar massless septum design. Maximizing the spatial derivative of the transverse field step function is crucial in order to kick the injected bunch inside the DA. Comparing the results of different designs a particular dependence between the smallest clear aperture and the maximum transverse field spatial derivative was observed. We have developed an optimization tool to generate arbitrary 2D magnetic fields and determine the associated current distribution. With it we obtained new design solutions for possible injection magnets that go beyond the limitations of the standard designs. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK097 | ||
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| WEPIK098 | Resonant Kicker System With Sub-part-per-million Amplitude Stability | electron, resonance, operation, dipole | 3174 |
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| High stability resonant kicker magnet systems have been developed as part of the fast electron beam switching system of Swiss Free Electron Laser (SwissFEL). They are designed to separate two closely spaced electron bunches (28 ns apart) accelerated in one RF macro-pulse and to send them to two separate undulator lines. High shot-to-shot amplitude stability is required to minimize the disturbance of the electron beam trajectories and to ensure stable X-ray lasing. The stability and speed was unlikely to be achieved by standard pulsed systems and a novel 18 MHz, lumped-element resonator deflector with high Q was developed. It is driven into resonance by a specialized pulsed RF driver. At resonance, the circulating currents can approach 300 A and the resulting magnetic field gives the required deflection to the electron bunches. The advanced DC offset measurement system is also described in this paper. The measured stability reached less than 1 ppm (10e-6) rms, well within the project requirements. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK098 | ||
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| WEPVA023 | Performance of the PS Injection Kicker System Short Circuit Mode Upgrade for Operation with 2 GeV LIU Beams | flattop, injection, simulation, operation | 3308 |
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| In the framework of the LHC Injector Upgrade (LIU) project an upgrade of the existing PS proton injection kicker system for 2 GeV operation is in progress. The upgrade is based on the operation of the existing kicker system in short circuit mode. This paper briefly reviews the deployed modifications to the system to obtain the specified reduction of pulse reflections unavoidably induced by such a configuration. The implementation of improvements to the magnet entry box, transmission cables and the short circuit plug with integrated LC-filter are described as well as tests and measurements during the 2016/17 annual shutdown. The impact of the residual pulse shape structure on the beam performance for the reference LIU beam is quantified. The paper concludes with a performance analysis, a comparison of measurements vs. simulations and an outlook to the remaining modifications during the next long shut down. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA023 | ||
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| WEPVA024 | Design of an Inductive Adder for the FCC Injection Kicker Pulse Generator | injection, impedance, high-voltage, collider | 3312 |
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| The injection system for a 100 TeV centre-of-mass collider is an important part of the Future Circular Collider (FCC) study. Due to issues with conventional kicker systems, such as self-triggering and long term availability of thyratrons and limitations of HV-cables, innovative design changes are planned for the FCC injection kicker pulse generator. An inductive adder (IA) based on semiconductor (SC) switches is a promising technology for kicker systems. Its modular design, and the possibility of an active ripple suppression are significant advantages. Since the IA is a complex device, with multiple components whose characteristics are important, a detailed design study and construction of a prototype is necessary. This paper summarizes the system requirements and constraints, and describes the main components and design challenges of the prototype IA. It outlines the results from simulations and measurements on different magnetic core materials as well as on SC switches. The paper concludes on the design choices and progress for the prototype to be built at CERN. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA024 | ||
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| WEPVA038 | Tail Repopulation Measurements in the PSB | emittance, simulation, injection, experiment | 3343 |
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| The PS Booster (PSB) is the first circular accelerator in the LHC injector chain providing protons for the full CERN complex. Each of its four rings provides beams in a range of intensities varying from 40 e11 p/cycle to 0.8 e13 p/cycle. Low intensity beams are produced by transverse shaving, that is by scraping the tails, in order to tailor the intensity and transverse emittances. Eventually, tails repopulate and the beam profile reshapes, under the effect of space charge, which is dominant at low energy in the PS Booster. This paper describes the results of the measurements after the shaving process, where the tails are scraped but finally re-appear in the transverse profile, and it provides a first benchmark with space-charge simulations. It highlights the challenges encountered and the lessons learned, to guide the future experiments. The final outcome of these studies is the characterisation of the halo creation mechanism and the determination of the diffusion speed, important for the design of the future PS Booster scraping system. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA038 | ||
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| WEPVA050 | Developments for the Injection Kicker Vacuum System of the HESR at FAIR | vacuum, injection, controls, ion | 3369 |
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| The Research Center Jülich has taken the leadership of a consortium being responsible for the design and manufacturing of the High-Energy Storage Ring (HESR) going to be part of FAIR. The HESR is designed both for antiprotons and for heavy ion experiments. The injection kicker system of the HESR is located directly behind the septum and consists of two pumping crosses for pumps and measurement devices as well as two vacuum tanks housing the four ferrite magnets which will be operated with 40 kV, 4kA. As well as the magnets, the adjustments frames and the electrical feedthroughs will be installed inside the tanks. Due to the large surface of the magnets the injection kicker system will be very sensitive with regard to the achievable vacuum quality that is expected to be in the order of 10-11 mbar or better. Thus the vacuum system is designed to heat up to 250°C. In order to investigate the achievable end pressure and to develop the heating system a test facility was constructed. The actual vacuum layout of the injection kicker system as well as the experimental test results will be presented and in similar the layout of the control system of the test facility will be described. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA050 | ||
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| WEPVA060 | Construction of the New Kicker Magnet Systems for PF-Advanced Ring | injection, timing, impedance, power-supply | 3401 |
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| From July 2016 we are constructing a new beam transport (BT) line for the Photon Factory Advanced Ring (PF-AR). The new BT line was designed to transport the full energy 6.5-GeV beam directly from the LINAC, and the top up injection will be possible for the PF-AR. We designed and produced new kicker systems for this project. Three kicker magnets are used for the injection of the 6.5-GeV beam. The kicker magnets were designed as a window frame type ferrite core magnet. The magnetic fields of these magnets have been measured by the search coil method. We paid attention to evaluating eddy current losses of the metal coated ceramic duct in the magnetic field measurement. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA060 | ||
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| WEPVA061 | High-Precision Pattern Power Supply of Kicker Magnet for Multi-Beamline Operation at SACLA | operation, power-supply, optics, electron | 3404 |
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| At the Japanese XFEL facility SACLA, two XFEL beamlines (BL2 and BL3) and an injection line to the SPring-8 storage ring are switched by a kicker magnet. This multi-beamline operation has been tested since February 2015, however, CSR effects at a dogleg beam transport to BL2 with a deflecting angle of 3 degree currently limit the peak current of the electron beam. In order to suppress and cancel out the CSR effects, new beam optics is introduced for the dogleg in January 2017. In the new optics, a deflecting angle of the first kicker magnet is increased to 1.5 degree, which is three times larger than that of the old optics. To drive the kicker magnet, a high-power pattern power supply has been developed. To achieve the maximum output of 300 A and 1 kV, SiC MOSFETs are used as switching modules. The newly developed power supply can generate bipolar trapezoidal current waveforms at 60 Hz, and the amplitude and polarity of each waveform are controlled from pulse to pulse according to the beam energy and destination. The target stability is 10 ppm (peak to peak). In this presentation, we report the design and operation results of the newly developed pattern power supply. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA061 | ||
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| WEPVA062 | Improvements of Vacuum System in J-PARC 3 GeV Synchrotron | vacuum, injection, operation, cavity | 3408 |
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| The RCS vacuum system has been upgraded since the completion of its construction towards the objectives of both better vacuum quality and higher reliability of the components. For the better vacuum quality, (1) pressure of the injection beam line was improved to prevent the H− beam from converting to H0; (2) leakage in the beam injection area due to the thermal expansion was eliminated by applying the adequate torque amount for the clamps; (3) new in-situ degassing method of the kicker magnet was developed. For the reliability increase of the components, (1) A considerable number of fluoroelastmer seal was exchanged to metal seal with the low spring constant bellows and the light clamps; (2) TMP controller for the long cable was developed to prevent the controller failure by the severe electrical noise; (3) A number of TMP were installed instead of ion pumps in the RF cavity section as an insurance for the case of pump trouble. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA062 | ||
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| WEPVA063 | Development of a New Pulsed Power Supply with the SiC-MOSFET | power-supply, flattop, pulsed-power, operation | 3412 |
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| A new power supply has been developed using linear transformer driver (LTD) technology that adopts SiC-MOSFETs and capacitors without a thyratron switch or a pulse forming network (PFN) device. A new power supply was also designed by connecting the SiC-MOSFETs and the LTD modules in parallel-series. The output voltage and current were 40 kV and 4 kA, respectively with a pulse width of 1500 nsec at a repetition rate of 25 Hz. Furthermore, by adjusting the correction module, to an output voltage per stage of 1/1000, a resolution of the voltage correction of ±0.1 % could be achieved. It was possible to output the current with arbitrary timing by using a trigger input for each LTD module. As a result, fine adjustment of the output voltage waveform was possible within the order of nanoseconds. This new power supply with high voltage output, cur-rent output, and very fast pulse operation is one of the most important key technologies for a kicker system using SiC-MOSFETs. The design and preliminary test results of this prototype power supply are presented here. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA063 | ||
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| WEPVA064 | The Pulsed Power Supplies of the SESAME Booster and Storage Ring | septum, injection, booster, extraction | 3415 |
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| SESAME the Synchrotron Radiation Light Source in Allan (Jordan) consists of an 800 MeV injector (original from BESSY I, Berlin, Germany) and a 2.5 GeV Storagering. Injection into the Booster is done by an electrostatic Septum and one stripline kicker. Extraction out of the Booster is done by means of a bumper magnet, a strip-line-line kicker and a direct driven in-vacuum septum. Injection into the Storagering is done by a direct driven out-off vacuum septum and one kicker. The pulses of all septa are full sine, the ones of the kicker half sine with exception of the extraction kicker (flat-top). Extraction Kicker and Storage ring injection kicker are switched by Thyratron, all others via transistors. This report describes the injection and extraction optics and the results of the commissioning. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA064 | ||
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| WEPVA094 | Study of an Improved Beam Screen Design for the LHC Injection Kicker Magnet for HL-LHC | impedance, injection, simulation, coupling | 3471 |
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| During Run 1 of the LHC, one of the injection kicker magnets (MKIs) occasionally exhibited an excessively high ferrite temperature, caused by coupling of the high intensity beam to the real impedance of the magnet. Beam-screen upgrades have been very effective in reducing beam coupling impedance during Run 2. However, temperature measurements during LHC operation have shown that one end of the MKIs ferrite yoke is consistently hotter than the other: this effect is due to highly non-uniform beam induced power deposition along the kicker. Electromagnetic and thermal simulations show that part of the ferrite yoke will be above its Curie temperature when the LHC is operated with HL-LHC beam parameters, which could increase the turn-around time between fills of the LHC. An impedance mitigation study is presented in this paper with emphasis on the effect of the beam screen layout upon both total beam induced power deposition and its longitudinal distribution. Results of complex thermal simulations, to benchmark the effectiveness of the proposed schemes, are reported. To validate the proposed modification a test bench measurement was performed and preliminary results are discussed | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA094 | ||
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| WEPVA095 | Preliminary Estimate of Beam Induced Power Deposition in a FCC-hh Injection Kicker Magnet | impedance, injection, coupling, collider | 3475 |
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| The Future Circular Collider for hadrons (FCC-hh) will require a fast injection kicker system that is highly reliable and that does not limit accelerator performance. Important considerations in the design of such a system are machine protection constraints, collider filling factor and hence rise and fall times of the kicker magnet field. Fast rise time kicker magnets are generally ferrite loaded transmission line type magnets with a rectangular shaped aperture. The beam coupling impedance of the kicker magnets is crucial, as this can be a dominant contribution to beam instabilities. In addition, beam-induced heating of the ferrite yoke due to the real component of the longitudinal beam coupling impedance needs to be controlled: if the ferrite temperature exceeds the Curie point this impacts the ability to inject beam and hence the availability of the machine. This paper presents estimates for the beam induced power deposition in the ferrite yoke, based on a calculated FCC beam spectrum and an analytical model of longitudinal impedance for unshielded kicker magnets. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA095 | ||
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| WEPVA096 | Thermal Analysis of the LHC Injection Kicker Magnets | injection, vacuum, operation, simulation | 3479 |
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Funding: Research supported by the HL-LHC project. The CERN Large Hadron Collider LHC is equipped with two fast pulsed magnet systems (MKIs) that inject particle beams coming from the injector chain. Operation with high intensity beams for many hours can lead to significant beam induced heating of the ferrite yokes of the MKIs. When the ferrite exceeds the Curie temperature of 125°C it loses its magnetic properties, preventing further injection until the ferrite cools down, potentially causing a delay of several hours. Hence important upgrades of the beam-screen were implemented after Run 1 of LHC. However, the High-Luminosity (HL) LHC will be operated with significantly higher intensity beams and hence additional measures are required to limit the ferrite temperature. These magnets operate under ultra-high vacuum conditions: convection is negligible and, as a result of low emissivity of the inside of the vacuum tanks, thermal radiation is limited. A detailed study of the thermal behaviour of these magnets is reported and compared with measurements. In addition several options to improve cooling of the ferrites are presented and analysed. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA096 | ||
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| WEPVA097 | Upgrading the SPS Fast Extraction Kicker Systems for HL-LHC | impedance, electron, extraction, resonance | 3483 |
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| The CERN SPS has two fast extraction systems, each consisting of travelling wave kicker magnets (MKEs). The beam induced heating in the ferrite yoke of these magnets was historically kept to an acceptable level by implementing water cooling of the kicker magnets: in addition serigraphy was applied on the surfaces of the ferrite yoke facing the beam. Nevertheless, high intensity beams needed in the future for HL-LHC will significantly increase the beam induced heating, potentially raising the MKE ferrite yoke temperature to its Curie point. Hence detailed studies of longitudinal beam coupling impedance were carried out to identify simple but effective methods of further reducing beam induced power deposition. Based on the results of these studies, and in the framework of the LHC Injectors Upgrade (LIU) project, an upgraded MKE kicker magnet was installed during the 2015-2016 shutdown. This paper reports and compares results of predictions, laboratory measurements, temperature measurements during SPS operation, and machine development studies. Measurements of both dynamic pressure rise in the upgraded magnet and Secondary Electron Yield, on samples, are also reported. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA097 | ||
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| WEPVA098 | Measurements on a 12.5 kV Prototype Inductive Adder for the CLIC DR Extraction Kickers | flattop, extraction, damping, collider | 3487 |
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| The CLIC study is investigating the technical feasibility of an electron-positron collider with high luminosity and a nominal centre-of-mass energy of 3 TeV. The pre-damping rings and damping rings (DRs) will produce ultra-low emittance beam with high bunch charge. To avoid beam emittance increase, the DR kicker systems must provide extremely stable field pulses during injection and extraction of bunches. The DR extraction kicker system consists of a stripline kicker and two pulse modulators. The current specifications for the modulators call for pulses with 160 ns or 900 ns flattop duration of ±12.5 kV and 305 A, with ripple of not more than ±0.02 % (±2.5 V). An inductive adder is a very promising approach to meeting the specifications because analogue modulation methods can be applied to adjust the output waveform. Recently, the first full-scale, 20-layer, 12.5 kV prototype inductive adder has been assembled at CERN and testing has commenced. The goal is to tailor the output waveform of the prototype to the waveform required for the DR extraction stripline kicker. The results of the initial tests and measurements are presented. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA098 | ||
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| WEPVA099 | Influence of Conducting Serigraphy Upon Field Pulse Shape of the SPS Extraction Kicker Systems | flattop, extraction, impedance, high-voltage | 3491 |
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| Fast pulsed magnets with ferrite yokes are used for beam extraction from the CERN SPS accelerator. These kickers are transmission line type magnets with a rectangular shaped aperture through which the beam circulates. Unless special precautions are taken, the beam impedance of the yoke can provoke significant induced heating, especially for high intensity beams. Previous upgrades of the SPS extraction kicker magnets have included silver fingers serigraphed on the surface of the ferrite facing the beam, to help shield the ferrite yoke from circulating beam. Beam based measurements of the extracted beam indicated that the serigraphy may influence the shape of the field pulse, causing it to increase slightly in magnitude during the flat-top. Hence theoretical studies have been carried out to determine whether the serigraphy influences the field pulse: these studies are reported in this paper. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA099 | ||
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| WEPVA100 | Operational Experience of the Upgraded LHC Injection Kicker Magnets During Run 2 and Future Plans | injection, electron, impedance, vacuum | 3495 |
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| During Run 1 of the LHC, one of the injection kicker magnets caused occasional operational delays due to beam induced heating with high bunch intensity and short bunch lengths. In addition, there were also sporadic issues with vacuum activity and electrical flashover of the injection kickers. An extensive program of studies was launched and significant upgrades were carried out during Long Shutdown 1 (LS 1). These upgrades included a new design of beam screen to reduce both beam coupling impedance of the kicker magnet and the electric field associated with the screen conductors, hence decreasing the probability of electrical breakdown in this region. This paper presents operational experience of the injection kicker magnets during the first years of Run 2 of the LHC, including a discussion of faults and kicker magnet issues that limited LHC operation. In addition, in light of these issues, plans for further upgrades are briefly discussed. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA100 | ||
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| WEPVA101 | Review of Stripline Beam Impedance: Application to the Extraction Kicker for the CLIC Damping Rings | impedance, coupling, simulation, extraction | 3499 |
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| The beam coupling impedance of the stripline kicker for beam extraction from the CLIC Damping Rings (DRs) has been studied analytically, numerically with CST Particle Studio (PS) and measured in the laboratory, although not all the results were understood. In order to have a better knowledge about the beam coupling impedance of a stripline kicker, a simple model has been first studied, with flat electrodes and a cylindrical beam pipe. From this preliminary study, a new approach for the dipolar component of the horizontal impedance has been derived, when considering both odd and even operating modes of the striplines. This new approach has been used to understand the differences found between the predicted transverse impedance and the two wire measurements carried out in the laboratory for the prototype CLIC DR striplines. Future tests of beam coupling impedance with beam in the ALBA Synchrotron Ligth Source will complete this study. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA101 | ||
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| THPAB027 | Symplectic Multi-Particle Tracking Using Cuda | GPU, space-charge, simulation, emittance | 3756 |
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Funding: Work supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 and the Ministry of Science and Technology of China under Grant No.2014CB845501. The symplectic tracking model can preserve phase space structure and reduce non-physical effects in long term simulation. Though this model is computationally expensive, it is very suitable for parallelization and can be accelerated significantly by using Graphic Processing Units (GPUs). Using a single GPU, the code achieves a speedup of more than 400 compared with the time on a single CPU core. It also shows good scalability on a GPU cluster at Oak Ridge Leadership Computing Facility. In this paper, we report on the GPU code implement, the performance test on both single-GPU and multi-GPU cluster, and an application of beam dynamics simulation. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB027 | ||
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| THPAB153 | An Online Multi-Objective Optimisation Package | injection, controls, storage-ring, timing | 4092 |
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| The overall performance of an electron storage ring is critically dependant on a large number of variables. It can be characterised in many ways, such as by lifetime, injection efficiency, beam stability and so on. It is frequently the case however that improving one parameter comes at the cost of harming another. Equally, given the large number of variables involved in optimising the ring performance, the true, global optimum solution may be difficult to identify using simple parameter scans. In order to address this problem, a flexible optimisation tool has been developed. This tool is capable of optimising several parameters at once and can cope with an arbitrary number of variables (individually or in families). The tool is designed to be robust to measurement noise, and has been applied to a number of different optimisation problems. This paper presents an overview of the package, as well as the results of the first tests. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB153 | ||
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| THPIK086 | Design and Implementation of Stripline Feedback Kickers in the MAX IV 3 GeV Ring | feedback, impedance, storage-ring, cavity | 4285 |
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| The commissioning of a bunch-by-bunch feedback system for the MAX IV 3 GeV storage ring was started in early 2016. At date, the actuators are two stripline kickers oriented in the horizontal and in the vertical plane, respectively. Apart from providing feedback in the transverse plane, the horizontal stripline is simultaneously operating as a longitudinal kicker. This is done by upconverting the longitudinal 0 - 50 MHz baseband signal to the 150 MHz - 250 MHz range where the longitudinal shunt impedance of the stripline is higher. This signal is then fed to the stripline electrodes in common-mode. The design of the stripline kickers and the layout of the bunch-by bunch feedback system in the 3 GeV ring are presented in this report. Results from instability studies in this ring are also discussed. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK086 | ||
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| THPIK087 | A Waveguide Overloaded Cavity Kicker for the MAX IV Bunch-by-Bunch Feedback System | cavity, feedback, impedance, storage-ring | 4289 |
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| The higher-order modes (HOMs) in the main and the 3:rd harmonic cavities are driving longitudinal coupled-bunch mode instabilities (CBMIs) in the MAX IV 3 GeV storage ring. This far, negative feedback has been applied in the longitudinal plane by a stripline kicker at lower ring currents. However, the maximum longitudinal feedback voltage provided by the stripline is rather weak, and a waveguide overload cavity was therefore designed in order to suppress CBMIs at higher ring currents as well. Due to the long bunch length in the MAX IV storage rings, a relatively low center frequency of 625 MHz is selected. The new cavity kicker has been manufactured, and will be installed in the 3 GeV ring during the summer shut-down of 2017. In this paper, the RF and mechanical design of the cavity is presented. Simulation results are also compared with measurements of the manufactured cavity. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK087 | ||
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| THPIK096 | Jitter Measurement to 10ppm Level for Pulsed RF Power Amplifiers 3 - 12GHz | operation, timing, hardware, pulsed-power | 4314 |
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| Linacs for FEL applications require a low jitter RF path from RF source through pulsed amplifiers, klystron / modulators and cavities. For the SwissFEL project, pulsed solid state power amplifiers of the 500W / 3us class for driving the klystrons were required. For these amplifiers, a stable and reliable interferometer system was developed to measure the residual RF jitter levels to <10 ppm (parts per million) and <10 urad (0.6mdeg) rms. This paper describes the system and gives some measurement results for 3GHz, 5.7GHz and 12GHz amplifiers. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK096 | ||
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| THPVA073 | Latest Results on Fast Kicker for g-2 E-989 Experiment at Fermilab | impedance, experiment, storage-ring, injection | 4616 |
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| We are describing the latest results on fabrication and measurements of kicker and pulser and beam dynamics in E-989 experiment at FERMILAB on precise measurement of anomalous magnetic moment of muon. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA073 | ||
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| THPVA095 | Storage Ring Injection Kickers Alignment Optimization in NSLS-II | injection, timing, storage-ring, operation | 4683 |
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| The National Synchrotron Light Source II (NSLS-II) is a state of the art 3 GeV third generation light source at Brookhaven National Laboratory. The SR is designed to work in top-off injection mode. The injection straight includes a septum and four fast kicker magnets with independent amplitude and timing control. Ideally, fast kickers formed a local bump, which is transparent to stored beam during top off injection. Due to mismatch of kicker voltage, timing or waveform, there is residual betatron oscillation and impact normal operation. This paper will present the injection kicker waveform measurement with beam, local and global alignment optimization to in improve top off injection transition. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA095 | ||
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| THPVA100 | Future Plans of ADS Proton Drivers at Kyoto University Research Reactor Institute | proton, extraction, synchrotron, neutron | 4695 |
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| The accelerator complex using FFAG synchrotrons at Kyoto University Research Reactor Institute has been operated for the ADS experiments connecting the 100 MeV proton beam line with the research reactor facility KUCA (Kyoto University Critical Assembly) since 2009. Number of neutrons produced through the nuclear spallation process strongly depends on the beam energy of the pri- mary protons. If the beam energy is increased from 100 MeV to 400 MeV, the number of neutrons corresponding to single primary proton is increased by a factor of 20. Therefore, the energy upgrade of the accelerator facility is desired by the reactor physicists. A new 400 MeV FFAG synchrotron has been designed. The results of the feasibility study of the 400 MeV ring will be presented. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA100 | ||
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