Paper | Title | Other Keywords | Page |
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MOXC01 | Combined Effect of Beam-Beam Interaction and Beam Coupling Impedance in Future Circular Colliders | impedance, collider, synchrotron, luminosity | 25 |
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Funding: This work is supported by National Key Programme for S&T Research and Development, China (Grant No. 2016YFA0400400), National Natural Science Foundation of China (No. 11775238, No. 11775239). The future large scale electron-positron colliders, such as FCC-ee in Europe and CEPC in China, will rely on the crab waist collision scheme with a large Piwinski angle. Differently from the past generation colliders both luminosity and beam-beam tune shifts depend on the bunch length in such a collision scheme. In addition, for the future circular colliders with extreme beam parameters in collision several new effects become important such as beamstrahlung, coherent X-Z instability and 3D flip-flop. For all these effects the longitudinal beam dynamics plays an essential role and should be taken into account for the collider luminosity optimization. In this paper we discuss an impact of the longitudinal beam coupling impedance on the collider performance. |
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Slides MOXC01 [2.269 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOXC01 | ||
About • | paper received ※ 17 May 2021 paper accepted ※ 27 July 2021 issue date ※ 17 August 2021 | ||
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MOPAB001 | Power Deposition in Superconducting Dispersion Suppressor Magnets Downstream of the Betatron Cleaning Insertion for HL-LHC | proton, collimation, dipole, operation | 37 |
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Funding: Research supported by the HL-LHC project The power deposited in dispersion suppressor magnets downstream of the Large Hadron Collider (LHC) betatron cleaning insertion is governed by off-momentum particles scattered out of the primary collimators. In order to mitigate the risk of magnet quenches during periods of short beam lifetime in future High-Luminosity (HL-LHC) operation, new dispersion suppressor (DS) collimators are considered for installation (one per beam). In this paper, we present FLUKA simulations for both protons and Pb ions at 7 TeV, predicting the power deposition in the DS magnets, including the new higher-field dipoles 11T which are needed to integrate the collimator in the cold region next to the cleaning insertion. The simulated power deposition levels for the adopted HL-LHC collimator configuration and settings are used to assess the quench margin by comparison with the present estimated quench levels. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB001 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 07 July 2021 issue date ※ 16 August 2021 | ||
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MOPAB004 | JSPEC - A Simulation Program for IBS and Electron Cooling | electron, experiment, emittance, scattering | 49 |
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Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177. Intrabeam scattering is an important collective effect that can deteriorate the properties of a high-intensity beam, and electron cooling is a method to mitigate the IBS effect. JSPEC (JLab Simulation Package for Electron Cooling) is an open-source program developed at Jefferson Lab, which simulates the evolution of the ion beam under the IBS and/or the electron cooling effect. JSPEC has been benchmarked with BETACOOL and experimental data. In this report, we will introduce the features of JSPEC, including the friction force calculation, the IBS expansion rate and electron cooling rate calculation, and the beam-dynamic simulations for the electron cooling process; explain how to set up the simulations in JSPEC; and demonstrate the benchmarking results. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB004 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 21 May 2021 issue date ※ 27 August 2021 | ||
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MOPAB022 | FailSim: A Numerical Toolbox for the Study of Fast Failures and Their Impact on Machine Protection at the CERN Large Hadron Collider | optics, beam-losses, quadrupole, machine-protect | 111 |
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The High Luminosity LHC (HL-LHC) foresees to reach a nominal, levelled luminosity of 5·1034 cm-2 s−1 through a higher beam brightness and by using new equipment, such as larger aperture final focusing quadrupole magnets. The HL-LHC upgrade has critical impacts on the machine protection strategy, as the stored beam energy reaches 700 MJ for each of the two beams. Some failure modes of the novel active superconducting magnet protection system of the inner triplet magnets, namely the Coupling-Loss Induced Quench (CLIQ) systems, have been identified as critical. This paper reports on FailSim, a Python-language framework developed to study the machine protection impact of failure cases and their proposed mitigation. It provides seamless integration of the successive phases required by the simulation studies, i.e., verifying the optics, preparing and running a MAD-X instance for multiple particle tracking, processing and analysing the simulation results and summarising them with the relevant plots to provide a solid estimate of the beam losses, their location and time evolution. The paper also presents and discusses the result of its application on the spurious discharge of a CLIQ unit. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB022 | ||
About • | paper received ※ 18 May 2021 paper accepted ※ 31 May 2021 issue date ※ 18 August 2021 | ||
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MOPAB024 | Efficient Coupling of Hydrodynamic and Energy-Deposition Codes for Hydrodynamic-Tunnelling Studies on High-Energy Particle Accelerators | target, coupling, proton, experiment | 119 |
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The machine-protection evaluation of high-energy accelerators comprises the study of beyond-design failures, including the direct beam impact onto machine elements. In case of a direct impact, the nominal beam of the Large Hadron Collider (LHC) would penetrate more than 30 meters into a solid copper target. The penetration depth due to the time structure of the particle beam is, thus, significantly longer than predicted from purely static energy-deposition simulations with 7 TeV protons. This effect, known as hydrodynamic tunnelling, is caused by the beam-induced density depletion of the material at the target axis, which allows subsequent bunches to penetrate deeper into the target. Its proper simulation requires, therefore, to sequentially couple an energy-deposition code and a hydrodynamic code for the different target densities. This paper describes a method to efficiently couple the simulations codes Autodyn and FLUKA based on automatic density assignment and input file generation, and presents the results achieved for a sample case. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB024 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 05 July 2021 issue date ※ 28 August 2021 | ||
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MOPAB027 | Improving the Luminosity Burn-Off Estimate by Considering Single-Diffractive Effects | scattering, luminosity, proton, collider | 130 |
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Collisions in a high-luminosity collider result in a continuous burn-off of the circulating beams that is the dominant effect that reduces the instantaneous luminosity over time. In order to obtain a good estimate of the luminosity evolution, it is imperative to have an accurate understanding of the burn-off. Typically, this is calculated based on the inelastic cross-section, as it provides a direct estimate of the number of protons that participate in inelastic collisions, and are hence removed. Likewise, protons that participate in elastic collisions will remain in the machine acceptance, still contributing to luminosity. In between these two regimes lie diffractive collisions, for which the protons have a certain probability to remain in the machine acceptance. Recent developments of the SixTrack code allow it to interface with Pythia, thus allowing for more precise simulations to obtain a better estimate of the diffractive part of the cross-section. In this paper, we will mainly concentrate on slowly-drifting protons that are close to the acceptance limit, resulting from single-diffractive scattering. | |||
Poster MOPAB027 [1.193 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB027 | ||
About • | paper received ※ 18 May 2021 paper accepted ※ 31 May 2021 issue date ※ 11 August 2021 | ||
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MOPAB028 | Using Machine Learning to Improve Dynamic Aperture Estimates | dynamic-aperture, collider, hadron, operation | 134 |
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The dynamic aperture (DA) is an important concept in the study of nonlinear beam dynamics. Several analytical models used to describe the evolution of DA as a function of time, and to extrapolate to realistic time scales that would not be reachable otherwise due to computational limitations, have been successfully developed. Even though these models have been quite successful in the past, the fitting procedure is rather sensitive to several details. Machine Learning (ML) techniques, which have been around for decades and have matured into powerful tools ever since, carry the potential to address some of these challenges. In this paper, two applications of ML approaches are presented and discussed in detail. Firstly, ML has been used to efficiently detect outliers in the DA computations. Secondly, ML techniques have been applied to improve the fitting procedures of the DA models, thus improving their predictive power. | |||
Poster MOPAB028 [1.764 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB028 | ||
About • | paper received ※ 18 May 2021 paper accepted ※ 25 May 2021 issue date ※ 12 August 2021 | ||
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MOPAB029 | Burn-Off with Asymmetric Interaction Points | luminosity, emittance, experiment, controls | 138 |
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LHC can host above 2700 proton bunches per ring providing collisions in the ATLAS, CMS, LHCb and ALICE interaction points. ATLAS and CMS are placed symmetrically so that they feature the same colliding bunch pairs. However this is not the case for LHCb, hence introducing unwanted bunch-by-bunch variations of the bunch intensity as the physics fill evolves. We present first analytical derivations, numerical simulations and experimental data in different bunch train collision configurations. | |||
Poster MOPAB029 [1.502 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB029 | ||
About • | paper received ※ 13 May 2021 paper accepted ※ 25 May 2021 issue date ※ 27 August 2021 | ||
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MOPAB038 | Robustness Studies and First Commissioning Simulations for the SOLEIL Upgrade Lattice | lattice, alignment, sextupole, MMI | 171 |
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Diffraction limited light sources will use very strong focusing elements to achieve their emittance goal. The beam will therefore be more sensitive to magnet field and alignment errors. Impact of errors on the lattice proposed for the SOLEIL upgrade was studied with the Accelerator Toolbox (AT) code. The performance achieved with the imperfect lattice will be presented. In particular the effect of girders misalignment was also accounted for. As the lattice uses a large number of permanent magnets for the beam bending as well as the focusing, challenges arise in terms of beam correction. The correctors and BPMs location and number will be investigated to maximize their efficiency, and corrector magnet strength required to obtain a closed orbit will be studied. The commissioning strategy, and in particular the method used to achieve the first turns and a stored beam in the machine will also be exposed. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB038 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 31 May 2021 issue date ※ 16 August 2021 | ||
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MOPAB039 | Amplitude-Dependent Shift of Betatron Tunes and Its Relation to Long-Term Circumference Variations at NSLS-II | lattice, sextupole, closed-orbit, wiggler | 175 |
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The comparison of amplitude tune dependence measured for NSLSII lattices with models indicated the large change of amplitude tune dependence over time apparently can not be solely explained by magnets variation or beta function changes, but it seems can be explained by energy changes. On the other hand, the energy change required by fitting with the amplitude tune dependence change is too large to be explained by the RF frequency change and the change of the sum of correctors in the period of the measurements. To explain this apparent contradiction, our analysis shows the long term storage ring circumference change can explain the apparent energy change. Our data indeed shows a seasonal change of the amplitude tune dependence over long term observation. This clearly also indicated a relation to long term closed orbit drift. Hence the current work indicates a new strategy to study how to use amplitude tune dependence as a guideline to analyze long term lattice parameter shifts and closed orbit drift, and improve the orbit and machine performance stability. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB039 | ||
About • | paper received ※ 09 May 2021 paper accepted ※ 26 May 2021 issue date ※ 26 August 2021 | ||
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MOPAB043 | Validation of APS-U Beam Dynamics Using 6-GeV APS Beam | HOM, cavity, lattice, impedance | 189 |
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Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. Several beam measurements at the Advanced Photon Sources were done with a lowered-energy beam of 6 GeV in order to verify or validate calculation codes and some predictions for the APS-U. Though the APS lattice is obviously different from that of the APS-U some aspects of the beams at 6 GeV are similar, for example, the synchrotron radiation damping rate. At 6 GeV, one can also store more current and run with a higher rf bucket allowing the characterization of larger momentum aperture lattices. We report measurements (or plans of measurements) on general instabilities thresholds, lifetime, and other subtle effects. The important topic of ion instabilities at 6 GeV is covered in a separate paper by J. Calvey at this conference. |
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Poster MOPAB043 [0.829 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB043 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 23 June 2021 issue date ※ 10 August 2021 | ||
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MOPAB045 | Measurements and Simulations of High Charge Beam in the APS Booster | booster, injection, cavity, extraction | 197 |
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For the APS-Upgrade, swap-out injection will require the booster to support up to 17 nC bunch charge, several times what is used in the present APS. Booster injection efficiency drops sharply at high charge, and is the present bottleneck limiting high charge transport through the injectors. Particle tracking simulations have been used to understand what causes are limiting the injection efficiency, and to guide plans for improving it. In particular, bunch length blowup in the injected beam and beam loading in the RF cavities have been identified as the biggest factors. Simulations and measurements have also been done to characterize beam properties along the booster energy ramp. So far, a bunch charge of 12 nC has been successfully extracted from the booster. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB045 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 26 July 2021 issue date ※ 16 August 2021 | ||
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MOPAB052 | Study of Beam Transmission Efficiency in Injection and Ramping Process of the HEPS Booster | lattice, booster, injection, storage-ring | 225 |
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A high-bunch-charge mode, with a bunch charge of approximately 14.4 nC at 200 mA, has been proposed for the storage ring of High Energy Photon Source (HEPS). In order to reduce the bunch charge requirement to the injector, high-energy accumulation in the HEPS booster is proposed to combine with the on-axis swap-out injection. This allows reducing the requirement of bunch charge accelerated in HEPS booster (500 MeV-6 GeV) from over 14.4 nC to about 5 nC. It is expected that the overall transmission efficiency during the low energy injection and ramping process of the booster should be higher than 80% to fulfill the requirement. In this paper, we present the simulation results of transmission efficiency and potential improvement measures. | |||
Poster MOPAB052 [0.362 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB052 | ||
About • | paper received ※ 13 May 2021 paper accepted ※ 26 May 2021 issue date ※ 15 August 2021 | ||
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MOPAB057 | Evaluation of Pulsed Septum Leakage Fields and Compensation for the Advanced Photon Source Upgrade | septum, emittance, power-supply, injection | 245 |
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Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. The Advanced Photon Source upgrade is considering two options for injection: vertical-plane injection with a DC Lambertson septum and horizontal-plane injection with a pulsed septum. In the latter case, pulsed leakage fields are a concern as they will cause transient beam motion and emittance dilution. In this paper, we describe results of modeling the effect of such leakage fields on the beam. We also evaluate methods of compensating for the leakage fields, including the limited time response of correction elements. Several septum drive-pulse shapes are considered and compared. |
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Poster MOPAB057 [2.066 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB057 | ||
About • | paper received ※ 17 May 2021 paper accepted ※ 26 May 2021 issue date ※ 02 September 2021 | ||
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MOPAB058 | Swap-Out Safety Tracking for the Advanced Photon Source Upgrade | photon, dipole, electron, power-supply | 249 |
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Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. The Advanced Photon Source upgrade will operate in swap-out mode, which is similar to top-up but involves complete replacement of individual depleted bunches in a single shot. As with top-up, safety is a concern given that this process will take place with beamline shutters open. We describe the methods used to model swap-out safety, including creation and validation of a full ring lattice based on 3D field maps. We also describe a new method of implementing complex, intersecting channels for electron beams and photon beams, as well as a method of easily identifying potentially dangerous stray particles. Numerous potential errors (e.g., magnet shorts) were modeled, giving a reliable indication of performance of proposed stored beam and magnet interlocks. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB058 | ||
About • | paper received ※ 14 May 2021 paper accepted ※ 28 May 2021 issue date ※ 29 August 2021 | ||
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MOPAB059 | Tools for Use of Generalized Gradient Expansions in Accelerator Simulations | lattice, dipole, septum, quadrupole | 253 |
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Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. A common assumption in simulation of accelerators is that the magnets can be approximated using a hard-edge model, perhaps with some edge effects implemented in an impulse approximation. This is usually a good assumption but ignores details of the longitudinal variation of the magnetic fields, which makes it straightforward to implement symplectic tracking. Use of generalized gradient expansions* provides an alternative approach that can suppress numerical deficiencies that may be present in computed or measured 3D field maps. However, the computation of the expansions is not particularly straightforward. In this note, we describe several recently-developed tools that make this process fairly painless and allow tracking with such expansions in the program ELEGANT**. We show several examples of using the tools for simulations related to the Advanced Photon Source Upgrade. * M. Venturini et al., NIM A 427, 387 (1999). ** M. Borland, Advanced Photon Source LS-287, September 2000 |
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Poster MOPAB059 [4.311 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB059 | ||
About • | paper received ※ 17 May 2021 paper accepted ※ 26 May 2021 issue date ※ 18 August 2021 | ||
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MOPAB061 | Comparison Simulation Results of the Collimator Aperture in HEPS Storage Ring | lattice, ECR, storage-ring, scattering | 257 |
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The High Energy Photon Source (HEPS) is a 6 GeV diffraction-limited storage ring light source, which is under construction and planned to be in operation in 2025. To protect the sensitive elements from being damaged and reduce the radiation level of the site, collimators will be installed in the storage ring to localize the particle losses. The Touschek scattering is the main cause of particle losses during daily nominal operations. Based on the elegant simulations, we evaluate the physical design of the collimators, especially analysis the collimator performance with different collimator apertures. The simulation results will be introduced in this paper. | |||
Poster MOPAB061 [0.701 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB061 | ||
About • | paper received ※ 13 May 2021 paper accepted ※ 17 August 2021 issue date ※ 21 August 2021 | ||
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MOPAB070 | mbtrack2, a Collective Effect Library in Python | impedance, cavity, collective-effects, synchrotron | 282 |
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This article introduces mbtrack2, a collective effect library written in python3. The idea behind mbtrack2 is to build a coherent object-oriented framework to work on collective effects in synchrotrons. mbtrack2 is composed of different modules allowing to easily write scripts for single bunch or multi-bunch tracking using MPI parallelization in a transparent way. The base of the tracking model of mbtrack2 is inspired by mbtrack, a C multi-bunch tracking code initially developed at SOLEIL*. In addition, many tools to prepare or analyse tracking simulations are included.
* R. Nagaoka, R. Bartolini, and J. Rowland, Studies of Collective Effects in SOLEIL and Diamond Using the Multiparticle Tracking Codes SBTRACK and MBTRACK, in Proc. PAC’09, 2009. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB070 | ||
About • | paper received ※ 17 May 2021 paper accepted ※ 06 July 2021 issue date ※ 16 August 2021 | ||
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MOPAB072 | Single-Bunch Thresholds for the Diamond-II Storage Ring | impedance, cavity, storage-ring, beam-loading | 290 |
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The proposed Diamond Light Source upgrade will see the storage ring replaced with a multibend achromat lattice, increasing the capacity of the facility whilst reducing the emittance and providing higher brightness for the users. As part of the design work, tracking studies have been performed to determine the single-bunch thresholds including both the resistive-wall and geometric contributions to the impedance. As the machine design also foresees a third order harmonic cavity, the paper also provides an initial assessment of the effects of bunch lengthening on the single-bunch thresholds. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB072 | ||
About • | paper received ※ 18 May 2021 paper accepted ※ 01 June 2021 issue date ※ 23 August 2021 | ||
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MOPAB073 | Beam Loss Simulations During Beam Dumping in Heps | kicker, lattice, dumping, photon | 294 |
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The High Energy Photon Source (HEPS) is a 6 GeV storage ring light source under construction in China. Several collimators installed in the vacuum chamber will be used as beam dump in the storage ring operation. Preliminary simulations showed that the temperature rise caused by the beam power deposited on the collimators will far exceed the melting point of the collimator material. In order to cure this problem, special kickers are proposed to be installed in the ring to modulate the beam during beam dumping, thereby increasing the size of the beam hit on the collimators. In this article, some simulation results of the density of particles on the collimators during beam dumping for different HEPS lattice and different kicker parameters are shown. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB073 | ||
About • | paper received ※ 17 May 2021 paper accepted ※ 07 June 2021 issue date ※ 31 August 2021 | ||
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MOPAB087 | Design of a Multi-Bunch Feedback Kicker in SPEAR3 | kicker, impedance, coupling, feedback | 327 |
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The new Multi-bunch feedback kickers have been designed to replace the current device loaned from ALS. In this paper, we first present the specification of the kickers based on the beam physics requirements. Then the mechanical design of the kicker is elaborated. Numerical simulations, both in time domain and in frequency domain, are conducted for evaluating the shunt impedance and beam coupling impedance of the kicker. Surface heating induced from the beam or the external source is estimated from the numerical results as well. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB087 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 11 June 2021 issue date ※ 01 September 2021 | ||
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MOPAB097 | Two Color Grating design for Soft X-Ray Self-Seeding at LCLS-II | FEL, electron, laser, photon | 361 |
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A new grating design is examined for the soft x-ray self-seeding system (SXRSS) at LCLS-II to ultimately produce stable two-color XFEL pulses. The grating performance is analyzed with Fourier optics methods. The final XFEL performance is assessed via full numerical XFEL simulations that substantiate the feasibility of the proposed design. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB097 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 27 July 2021 issue date ※ 21 August 2021 | ||
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MOPAB117 | Single Bunch Collective Effects in the EBS Storage Ring | impedance, SRF, synchrotron, vacuum | 425 |
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The ESRF storage ring (SR) has been dismantled and replaced by the Extremely Brilliant Source (EBS) which has now been commissioned. Beam based measurements have been performed to characterise the impedance of the new machine and to make a first comparison with predictions. The results from instability threshold scans and tune shift measurements will be presented, as well as bunch length and position variation with current and microwave threshold measurements. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB117 | ||
About • | paper received ※ 11 May 2021 paper accepted ※ 31 May 2021 issue date ※ 25 August 2021 | ||
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MOPAB119 | Comparisons Between AT and Elegant Tracking | lattice, closed-orbit, dynamic-aperture, emittance | 432 |
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Funding: This work was supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DEAC02-05CH11231. The simulation codes Elegant* and Accelerator Toolbox (AT)** are both in common use for the study of particle accelerators and light sources. They use different software platforms and have different capabilities, so there is a strong motivation to be able to switch from one version to another to achieve different goals. In addition, it is useful to directly compare results for benchmarking studies. We discuss differences in tracking methods and results for various elements, and explore the impact on simulations performed with lattices designed for the ALS-U. In addition to single-particle tracking, global properties such as chromaticity, dynamics aperture, momentum aperture and beam lifetime are also investigated. We have also developed scripts to translate AT lattices into elegant lattice files to facilitate comparisons. * M. Borland, Advanced Photon Source LS-287, September 2000. ** A. Terebilo, Particle Accelerators Conference 2001, p. 3203. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB119 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 31 May 2021 issue date ※ 30 August 2021 | ||
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MOPAB127 | Construction of an Impedance Model for Diamond-II | impedance, lattice, dipole, cavity | 455 |
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Impedance models for accelerators have traditionally been presented in a static form, usually as tables or spreadsheets which must be read manually. As part of the Diamond-II upgrade work, we have developed an impedance model using a lattice structure. This allows more direct integration with simulation codes while keeping important information easily human readable. We present here a description of this implementation method, along with an overview of the Diamond-II impedance model derived from the latest engineering design. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB127 | ||
About • | paper received ※ 18 May 2021 paper accepted ※ 20 May 2021 issue date ※ 11 August 2021 | ||
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MOPAB134 | Normalized Transverse Emittance Reduction via Ionization Cooling in MICE ’Flip Mode’ | emittance, solenoid, experiment, betatron | 474 |
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Low emittance muon beams are central to the development of a Muon Collider and can significantly enhance the performance of a Neutrino Factory. The international Muon Ionization Cooling Experiment (MICE) has recorded several million individual muon tracks passing through a liquid hydrogen or a lithium hydride absorber and has demonstrated the ionization cooling of muon beams. Previous analysis used a restricted data set, and the beam matching was not perfect. In this analysis, beam sampling routines were employed to account for imperfections in beam matching at the entrance into the cooling channel and enable an improvement of the cooling measurement. A study of the normalized transverse emittance change in the MICE cooling channel set up in a flipped polarity magnetic field configuration is presented. Additionally, the evolution of the canonical angular momentum across the absorber is shown and the characteristics of the cooling effect are discussed. | |||
Poster MOPAB134 [1.821 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB134 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 09 June 2021 issue date ※ 27 August 2021 | ||
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MOPAB138 | Dielectric Wakefield Acceleration with a Laser Injected Witness Beam | wakefield, laser, experiment, cathode | 481 |
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Funding: Work supported by DOE grant DE-SC0017690 The plasma photocathode concept, whereby a two-species gas mixture is used to generate a beam -driven accelerating wakefield and a laser-ionized generation of a witness beam, was recently experimentally demonstrated. In a variation of this concept, a beam-driven dielectric wakefield accelerator is employed, filled with a neutral gas for laser-ionization and creation of a witness beam. The dielectric wakefields, in the terahertz regime, provide comparatively modest timing requirements for the injection phase of the witness beam. In this paper, we provide an update on the progress of the experimental realization of the hybrid dielectric wakefield accelerator with laser injected witness beam at the Argonne Wakefield Accelerator (AWA), including engineering considerations for gas delivery, and preliminary simulations. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB138 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 17 June 2021 issue date ※ 31 August 2021 | ||
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MOPAB142 | A Compact, Low-Field, Broadband Matching Section for Externally-Powered X-Band Dielectric-Loaded Accelerating Structures | vacuum, coupling, GUI, linac | 495 |
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It has been technically challenging to efficiently couple external radiofrequency (RF) power to cylindrical dielectric-loaded accelerating (DLA) structures. This is especially true when the DLA structure has a high dielectric constant. This contribution presents a novel design of a matching section for coupling the RF power from a circular waveguide to an X-band DLA structure with a dielectric constant εr=16.66 and a loss tangent \tanθ = 3.43× 10-5. It consists of a very compact dielectric disk with a width of 2.035 mm and a tilt angle of 60 degrees, resulting in a broadband coupling at a low RF field which has the potential to survive in the high-power environment. To prevent a sharp dielectric corner break, a 45-degree chamfer is added. Moreover, a microscale vacuum gap, caused by metallic clamping between the thin coating and the outer thick copper jacket, is studied in detail. Based on simulation studies, a prototype of the DLA structure with the matching sections was fabricated. Results from preliminary bench measurements and their comparison with design values will also be discussed. | |||
Poster MOPAB142 [2.617 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB142 | ||
About • | paper received ※ 11 May 2021 paper accepted ※ 21 May 2021 issue date ※ 19 August 2021 | ||
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MOPAB143 | Simulations for MeV Energy Gain in Multi-Micron Vacuum Channel Dielectric Structures Driven by a CO2 Laser | laser, electron, vacuum, acceleration | 499 |
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Funding: This work was supported by STFC LIV. DAT under grant agreement ST/P006752/1. This research used the resources of the Supercomputing Laboratory at KAUST in Thuwal, Saudi Arabia. Dielectric Laser Accelerators (DLAs) have been demonstrated as a novel scheme for producing high acceleration gradients (~1 GV/m) within the damage threshold of the dielectric. The compactness of the DLAs and the low emittance of the output electron beam make it an attractive candidate for future endoscopic devices to be used in tumor irradiation. However, due to the small accelerating distances(sub-mm), the total energy gain is limited to sub-MeV which remains an obstacle for its realistic applications. Also, these DLAs operate under solid-state lasers with wavelengths near IR (800 nm to 2 um), where required sub-micron vacuum channel at such wavelengths imposes major aperture restrictions for the amount of charge to be accelerated. Here, we present numerical simulation results for a dielectric structure excited by a CO2 laser with a wavelength of 10.6 um. Upon injecting a 50 MeV electron bunch through a 5.3 um diameter of vacuum channel width, our simulation suggests an energy gain beyond 1 MeV. These results are the initial steps for the realization of an mm-scale DLA capable of producing MeV energy electron beams. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB143 | ||
About • | paper received ※ 18 May 2021 paper accepted ※ 02 June 2021 issue date ※ 11 August 2021 | ||
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MOPAB144 | Investigation of Optimization of Dielectric Terahertz Acceleration Structures | laser, acceleration, radiation, impedance | 502 |
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Funding: This work was supported by the Department of Energy Contract No. DE-AC02-76SF00515 (SLAC) and by NSF Grant No. PHY-1734015. THz-frequency accelerating structures could provide the accelerating gradients needed for next generation particle accelerators with compact, GV/m-scale devices. Current THz accelerators are limited by significant losses during transport of THz radiation from the generating nonlinear crystal to the electron acceleration structure. In addition, the spectral properties of high-field THz sources make it difficult to couple THz radiation into accelerating structures. Dielectric accelerator structures reduce these losses because THz radiation can be coupled laterally into the structure, as opposed to metallic structures where THz radiation must be coupled along the beam path. In order to utilize these advantages, we are investigating the optimization of THz accelerating structures for comparison between metallic and dielectric devices. These results will help to inform future designs of improved dielectric THz acceleration structures. |
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Poster MOPAB144 [6.524 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB144 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 27 May 2021 issue date ※ 22 August 2021 | ||
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MOPAB152 | High Power Tests of Brazeless Accelerating Structures | GUI, experiment, wakefield, target | 532 |
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Funding: DOE SBIR Grant #DE-SC0017749 A typical accelerating structure is a set of copper resonators brazed together. This multi step process is expensive and time consuming. In an effort to optimize production process for rapid prototyping and overall reduction of accelerator cost we developed a split block brazeless accelerating structure. In such structure the vacuum is sealed by the use of knife edges, similar to an industry standard conflat technology. In this paper we present high power tests of several different brazeless structures. First, an inexpensive 1 MeV accelerator powered by radar magnetron. Second, a high gradient power extractor tested at Argonne Wakefield Accelerator Facility. In this experiment a high charge electron beam generated a 180 MW peak power pulse. Finally, we report on high power testing of a brazeless x-band accelerating structure at SLAC. |
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Poster MOPAB152 [0.783 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB152 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 24 June 2021 issue date ※ 31 August 2021 | ||
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MOPAB153 | Laser Microfabrication for Accelerator Applications | laser, FEM, emittance, cathode | 535 |
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Laser microfabrication allows high precision ablation of materials at sub-mm scale. When laser pulse length is shorter than about 10 picoseconds the heat affected zone is minimized and ablation occurs without melting. Work-pieces processed in this fashion exhibit less structural damage and are expected to have a higher damage thresholds. In this paper we will review several case studies of laser-microfabricated components for accelerator and x-ray applications. Ablated materials include diamond, quartz, tungsten, copper, YAG:Ce and silicon. | |||
Poster MOPAB153 [2.781 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB153 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 01 July 2021 issue date ※ 29 August 2021 | ||
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MOPAB155 | Magnetic Breakdowns in Side-Coupled X-Band Accelerating Structures | impedance, coupling, cavity, accelerating-gradient | 540 |
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Funding: DOE SBIR Side coupled accelerating structures are popular in the industrial realizations of linacs due to their high shunt impedance and ease of tuning. We designed and fabricated a side-coupled X-band accelerating structure that achieved 133 MOhm/m shut impedance. This structure was fabricated out of two halves using a novel brazeless approach. The two copper halves are joined together using a stainless steel joining piece with knife edges that bite into copper. This structure had been tested at high power at SLAC National Accelerator Laboratory. The performance of the structure had been limited by magnetic breakdowns on the side-coupling cells. In this paper we will present results of the high gradient tests and after-test analysis. Scanning electron microscopy images show a typical magnetic-field induced breakdown. |
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Poster MOPAB155 [1.069 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB155 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 23 June 2021 issue date ※ 01 September 2021 | ||
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MOPAB159 | Matching of an RFQ and Multicusp Ion Source with Compact LEBT | rfq, LEBT, cyclotron, ion-source | 546 |
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Funding: NSF provided funding for RFQ-DIP project, Draper Laboratory provided fellowship for graduate studnets The IsoDAR project is a neutrino experiment that requires a high current H2+ beam at 60 MeV/amu, which will be produced by a cyclotron. A critical aspect of the design is the injection, which comprises an ion source, a compact low energy beam transport section (LEBT), and a radio-frequency quadrupole (RFQ) buncher embedded in the cyclotron yoke. The LEBT is optimized to match the desired input Twiss parameters of the RFQ. Here we report on the latest results from the ion source commissioning, and on the design and optimization of the LEBT with matching to the RFQ. With this ion source, we have demonstrated a 76% H2+ fraction at a current density of 11 mA/cm2 in DC mode. The design of the LEBT includes a chopper, steering elements, and focusing elements, to achieve the desired matching, which according to our simulations leads to ~95% transmission from the ion source to the exit of the RFQ. |
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Poster MOPAB159 [0.851 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB159 | ||
About • | paper received ※ 15 May 2021 paper accepted ※ 24 June 2021 issue date ※ 13 August 2021 | ||
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MOPAB166 | Wakefield Excitation by a Sequence of Laser Pulses in Plasma | laser, wakefield, plasma, acceleration | 568 |
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Funding: The study is supported by the National Research Fundation of Ukraine under the program "Leading and Young Scientists Research Support" (project # 2020.02/0299). PIC simulation by means of 2.5D UMKA code * of the wakefield excitation by a sequence of three Gaussian laser pulses in plasma was carried out. The dependence of excited wakefield intensity on power and width of laser pulses was investigated. It was shown the coherent addition of wakefield, excited by each laser pulse of the sequence, for linear case, while for the nonlinear case the coherency was destroyed. The profiled sequence of laser pulses was also considered. The possibility to obtain the same total wakefield excited by the profiled sequence of laser pulses with decreasing intensity, as for the uniform sequence was studied. * G. I. Dudnikova et al. Comp. Techn. 10 (2005) 37. |
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Poster MOPAB166 [2.638 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB166 | ||
About • | paper received ※ 17 May 2021 paper accepted ※ 20 May 2021 issue date ※ 15 August 2021 | ||
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MOPAB169 | Generating 510 MW of X-Band Power for Structure-Based Wakefield Acceleration Using a Metamaterial-Based Power Extractor | experiment, wakefield, acceleration, electron | 578 |
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Funding: Research sponsored under Award No. DE-SC0015566 by U.S. Department of Energy, Office of Science, Office of High Energy Physics and Contract No. DE-AC02-06CH11357 by the Office of Science. We present our recent results generating 510 MW of power at 11.7 GHz using a metamaterial-based metallic power-extractor for application in structure-based wakefield acceleration (SWFA). SWFA is a novel acceleration scheme in which high-charge electron bunches are passed through a power extractor structure to produce a high-intensity wakefield. This wakefield can then be used to accelerate a witness bunch in the same beamline or passed to a separate acceleration beamline. MIT’s approach uses a specialized metamaterial for the power extractor design. By using a metamaterial, we can overcome some of the challenges faced by other SWFA techniques. Here, we discuss the Stage 3 experiment. The Stage 1 and Stage 2 experiments successfully demonstrated the functionality of the metamaterial approach by generating high power RF pulses using the 65 MeV electron beam at the Argonne Wakefield Accelerator (AWA) facility. The 510 MW result from Stage 3 experiment is the highest power generated to-date for SWFA at AWA, and was enable by significant design improvements, including an all-copper structure, fully-symmetric coupler design, and breakdown risk-reduction treatment. |
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Poster MOPAB169 [8.882 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB169 | ||
About • | paper received ※ 08 May 2021 paper accepted ※ 16 July 2021 issue date ※ 25 August 2021 | ||
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MOPAB179 | Simulations of AGS Boosters Imperfection Resonances for Protons and Helions | resonance, proton, experiment, quadrupole | 606 |
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Funding: Work supported by Brookhaven Science Associates LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. As part of the effort to increase the polarization of the proton beam for the physics experiments at RHIC, a scan of orbit harmonic corrector strengths is performed in the Booster to ensure polarization transmission through the |G gamma|=3 and 4 imperfection resonances is optimized. These harmonic scans have been simulated using quadrupole alignment data and accurately match experimental data. The method used to simulate polarized protons is extended to polarized helions for crossing the |G gamma|=5 through |G gamma|=10 imperfection resonances and used to determine the corrector strength required to cross each resonance. |
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Poster MOPAB179 [0.437 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB179 | ||
About • | paper received ※ 17 May 2021 paper accepted ※ 31 May 2021 issue date ※ 02 September 2021 | ||
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MOPAB183 | A Framework for Dynamic Aperture Studies for Colliding Beams in the High-Luminosity Large Hadron Collider | luminosity, operation, beam-beam-effects, sextupole | 620 |
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During the last physics run of the Large Hadron Collider (LHC), Dynamic Aperture (DA) studies have been successfully employed to optimize the accelerator’s performance by guiding the selection of the beam and machine parameters. In this paper, we present a framework for single-particle tracking simulations aiming to refine the envisaged operational scenario of the future LHC upgrade, the High-Luminosity LHC (HL-LHC), including strong non-linear fields such as beam-beam interactions. The impact of several parameters and beam processes during the cycle is initially illustrated with frequency maps and then quantified with DA studies. | |||
Poster MOPAB183 [2.789 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB183 | ||
About • | paper received ※ 17 May 2021 paper accepted ※ 06 July 2021 issue date ※ 23 August 2021 | ||
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MOPAB185 | HL-LHC Local Linear Optics Correction at the Interaction Regions | quadrupole, optics, interaction-region, lattice | 628 |
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Magnetic imperfections of the HL-LHC inner triplet are expected to generate a significant \beta-beating. For that reason, improved local optics correction techniques at the low-\beta insertions is essential to ensure a high luminosity performance in the HL-LHC. In this study, we compare different strategies for local optics correction at the Interaction Regions with respect to their final performance in terms of residual \beta-beating. Supervised learning techniques are also explored to predict the inner triplet magnetic error contributions. | |||
Poster MOPAB185 [0.469 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB185 | ||
About • | paper received ※ 14 May 2021 paper accepted ※ 10 June 2021 issue date ※ 31 August 2021 | ||
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MOPAB186 | Comparison of Segment-by-Segment and Action-Phase-Jump Techniques in the Calculation of IR Local Corrections in LHC | optics, quadrupole, interaction-region, MMI | 632 |
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The correction of the local optics at the Interaction Regions of the LHC is crucial to ensure a good performance of the machine. In this paper, we compare two different techniques for local optics correction: Action-Phase Jump and Segment-by-Segment techniques. The comparison is made in view of future machine configurations such as Run 3 LHC optics and HL-LHC optics. | |||
Poster MOPAB186 [0.349 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB186 | ||
About • | paper received ※ 14 May 2021 paper accepted ※ 09 June 2021 issue date ※ 30 August 2021 | ||
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MOPAB187 | Design and Calculation of the RF System of DC140 Cyclotron | cyclotron, coupling, cavity, resonance | 636 |
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Flerov Laboratory of Nuclear Reaction of Joint Institute for Nuclear Research carries out the works under creating of FLNR JINR Irradiation Facility based on the cyclotron DC140. The facility is intended for SEE testing of microchip, for production of track membranes and for solving of applied physics problems. The main systems of DC140 are based on the DC72 cyclotron ones that now are under reconstruction. The DC140 cyclotron is intended for acceleration of heavy ions with mass-to-charge ratio A/Z within interval from 5 to 5.5 up to two fixed energies 2.124 and 4.8 MeV per unit mass. The intensity of the accelerated ions will be about 1 pmcA for light ions (A<86) and about 0.1 pmcA for heavier ions (A>132). The designed RF-system of the DC-72 cyclotron with a half-wave cavity is not suitable due to the big vertical size. For this reason, a new quarter-wave RF-system was developed for the DC140 cyclotron project. The results of calculating the parameters of the new RF-system are given in this work. | |||
Poster MOPAB187 [0.488 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB187 | ||
About • | paper received ※ 17 May 2021 paper accepted ※ 24 May 2021 issue date ※ 15 August 2021 | ||
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MOPAB203 | Benchmark of Superconducting Cavity Models at SNS Linac | cavity, linac, superconducting-cavity, operation | 671 |
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Funding: This manuscript has been authored by UT-Battelle, LLC, under Contract No. DE-AC0500OR22725 with the U.S. Department of Energy. A benchmark of superconducting cavity models against Time-of-Flight measurements at the SNS linac is presented. The superconducting part of SNS linac (SCL) includes 81 RF cavities that accelerates H− beam from 185.6 MeV to the final energy of 1 GeV. During the operation some of cavities can become unstable, and its amplitudes should be reduced, or they should be completely switched off. In this case, the SCL is retuned by using a linac simulation code. This simulation tool relay on an accuracy of the superconducting cavity model. This paper describes the comparison of the measured beam acceleration by one of the SCL cavities and simulations of this process. Different cavity models are used in simulations. The subject of this study is limited to the longitudinal beam dynamics, so no effects on transverse beam characteristics have been considered. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB203 | ||
About • | paper received ※ 14 May 2021 paper accepted ※ 20 May 2021 issue date ※ 24 August 2021 | ||
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MOPAB208 | LLRF Measurements and Cu-plating at the First-of-Series Cavity Section of the Alvarez 2.0 at GSI | cavity, DTL, operation, vacuum | 686 |
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The Alvarez 2.0 will replace the existing post-stripper DTL of the GSI UNILAC. Today’s GSI comprises the UNILAC and the synchrotron SIS18 and is going to serve as the injector chain for the Facility of Antiproton and Ion Research (FAIR). The new Alvarez-type DTL is operated at 108.4 MHz providing acceleration from 1.4 MeV/u to 11.4 MeV/u along a total length of 55 meters. The first-of-series (FoS) cavity section has 12 RF-gaps along a total length of 1.9 m. It is the first cavity section of the new DTL. All main components were delivered in 2019, followed by successful SAT and installation of the 11 drift tubes and copper-plating. Completion of first low level RF-measurements prior to copper plating and the subsequent plating are major project milestones. These proceedings report on the results and compares them to simulation using CST Microwave Studio. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB208 | ||
About • | paper received ※ 18 May 2021 paper accepted ※ 31 May 2021 issue date ※ 22 August 2021 | ||
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MOPAB212 | 3-D Quantum Lifetime | electron, damping, radiation, emittance | 700 |
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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 quantum lifetime of electron beam in storage rings is defined by the particle loss that caused by the aperture limitation. Based on the equilibrium beam distribution produced by radiation damping and quantum excitation, the 1-d quantum lifetime has been well studied by A. Piwinski. In this paper, we give the derivation of the 3-d quantum lifetime, which can be applied to the machines with elliptical aperture and momentum acceptance. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB212 | ||
About • | paper received ※ 04 June 2021 paper accepted ※ 21 June 2021 issue date ※ 16 August 2021 | ||
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MOPAB217 | A Storage Ring for MESA | target, experiment, optics, operation | 719 |
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The Mainz Energy-recovering Superconducting Accelerator (MESA) is an Energy Recovery Linac (ERL) facility under construction at the Johannes Gutenberg-University in Mainz. It provides the opportunity for precision physics experiments with a 1 mA c.w. electron beam in its initial phase. In this phase experiments with unpolarised, high density 1019 atoms cm2 gas jet targets are foreseen at the Mainz Gas Internal Target Experiment (MAGIX). To allow experiments with thin polarised gas targets with sufficiently high interaction rates in a later phase, the beam current has to be increased to up to 100 mA, which would pose significant challenges to the existing ERL machine. Thus, it is proposed here to use MESA in pulsed operation with a repetition rate of several kHz to fill a storage ring, providing a quasi c.w. beam current to a thin gas target. For this purpose, the existing optics need to be extended and adapted, a suitable injection and extraction scheme is necessary and beam target interaction must be investigated. First considerations on these topics are presented here. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB217 | ||
About • | paper received ※ 18 May 2021 paper accepted ※ 08 June 2021 issue date ※ 21 August 2021 | ||
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MOPAB226 | Analytical Description of the Steerer Parameters in the Bilinear-Exponential Model at DELTA | betatron, storage-ring, closed-orbit, coupling | 737 |
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At DELTA, a 1.5 GeV synchrotron radiation source operated by the TU Dortmund University, an analytical description of the steerer parameters in the bilinear-exponential (BE) model has been developed. The BE model describes the coupled orbit response in a storage ring. It is used in the closed-orbit bilinear-exponential analysis (COBEA) algorithm to decompose orbit response matrices into beta function, betatron phase, and a scaled dispersion. After introducing the BE model and the analytical steerer parameters, a simulation-based comparison of the BE model and another coupled orbit response model is presented. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB226 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 08 June 2021 issue date ※ 11 August 2021 | ||
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MOPAB228 | Introducing two Energy-Correction Schemes at DELTA | storage-ring, operation, closed-orbit, injection | 740 |
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At DELTA, a 1.5 GeV synchrotron light source operated by the TU Dortmund University, two methods to correct the beam energy of the storage ring have been tested. The first one is capable of maintaining the current beam energy. The second method is used to find the optimal orbit length. Here, the ideas behind both methods are explained and first test results are presented. Numerical studies are shown together with measurement results. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB228 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 02 June 2021 issue date ※ 29 August 2021 | ||
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MOPAB231 | Tunability Study of the Ultra-Low β* Optics at ATF2 with New Octupole Setup and Tuning Knobs | octupole, optics, alignment, quadrupole | 752 |
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The main goal of the Accelerator Test Facility 2 (ATF2) is to demonstrate the feasibility of future linear colliders’ final focus systems. The Ultra-low β* optics of ATF2 is designed to have the same chromaticity level as CLIC. To ease the tuning procedure, a pair of octupoles was installed in ATF2 in 2017. This paper reports the optimizations performed to the octupoles’ setup for Ultra-low β* optics including the new alignment technique, based on the waist shift and the new tunning knobs constructed for this optics. The full tuning procedure including the static errors is simulated for this setup. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB231 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 28 July 2021 issue date ※ 12 August 2021 | ||
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MOPAB234 | Analysis of the Chromatic Vertical Focusing Effect of Dipole Fringe Fields | dipole, focusing, optics, closed-orbit | 760 |
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Funding: U.S. Department of Energy under Contract No. DE-AC02-05CH11231 There have been questions regarding the impact of the dipole fringe-field models (used by accelerator codes including ELEGANT and MADX) on vertical chromaticity. Here, we analyze the cause of the disagreement among codes and suggest a correction. |
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Poster MOPAB234 [0.486 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB234 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 01 June 2021 issue date ※ 23 August 2021 | ||
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MOPAB239 | Simulation and Optimization of the Spin Coherence Time of Protons in a Prototype EDM Ring | quadrupole, storage-ring, dipole, polarization | 771 |
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The matter-antimatter asymmetry might be understood by investigating the EDM (Electric Dipole Moment) of elementary charged particles. A permanent EDM of a subatomic particle violates time-reversal and parity symmetry at the same time and would be, with the currently achievable experimental accuracy, a strong indication for physics beyond the Standard Model. The JEDI-Collaboration (Jülich Electric Dipole moment Investigations) in Jülich is preparing a direct EDM measurement for protons and deuterons: first at the storage ring COSY (COoler SYnchrotron) and later at a dedicated storage ring. A prototype EDM ring is an intermediate step before building the final storage ring to demonstrate sufficient beam lifetime and SCT (Spin Coherence Time) in a pure electrostatic ring as well as in a storage ring with combined electric and magnetic bending elements. In order to study the effect of E-B-deflectors on the orbit and the spin motion, the software library Bmad is used. The first results of the optics and spin simulations, with a focus on the optimization of the SCT, towards the prototype EDM ring will be discussed. | |||
Poster MOPAB239 [0.560 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB239 | ||
About • | paper received ※ 17 May 2021 paper accepted ※ 09 June 2021 issue date ※ 23 August 2021 | ||
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MOPAB247 | Multipacting Studies for the JAEA-ADS Five-Cell Elliptical Superconducting RF Cavities | multipactoring, cavity, electron, SRF | 793 |
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The Five-cell Elliptical Superconducting Radio-Frequency Cavities (SRFC) provide the final acceleration in the JAEA-ADS linac (from 208 MeV to 1.5 GeV); thus, their performance is essential for the success of the JAEA-ADS project. After their optimization of the cavity geometry to achieve a high acceleration gradient with lower electromagnetic peaks, the next step in the R&D strategy is the accurate estimation of beam-cavity effects which can affect the performance of the cavities. To this end, multipacting studies were developed to investigate its effect in the cavity operation regimen and find countermeasures. The results of this study will help in the development of the SRFC models and in the consolidation of the JAEA-ADS project. | |||
Poster MOPAB247 [0.599 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB247 | ||
About • | paper received ※ 10 May 2021 paper accepted ※ 07 June 2021 issue date ※ 28 August 2021 | ||
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MOPAB255 | Demonstration of a Novel Longitudinal Phase Space Linearization Method without Higher Harmonics | cavity, electron, gun, laser | 805 |
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Nonlinear correlations in the longitudinal phase space of electron bunches can be a decisive limitation to the achievable bunch length compression and attainability of small energy spreads. To overcome the restrictions imposed by nonlinear distortions, the longitudinal phase space distribution must be linearized. Previously, a novel linearization procedure based on the controlled expansion of the bunch between two radio frequency cavities operated at the same fundamental frequency has been presented in *. A demonstration of this linearization method is presented in this work.
*B. Zeitler, K. Floettmann, and F. Grüner, "Linearization of the longitudinal phase space without higher harmonic field," Phys. Rev. ST Accel. Beams, vol. 18, p. 120102, 2015. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB255 | ||
About • | paper received ※ 18 May 2021 paper accepted ※ 02 June 2021 issue date ※ 16 August 2021 | ||
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MOPAB257 | Effects of Mode Launcher on Beam Dynamics in Next Generation High Brightness C-Band Guns | gun, emittance, electron, cathode | 813 |
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High-brightness RF photo-injectors plays nowadays a crucial role in the fields of radiation generation and advanced acceleration schemes. A high gradient C-band photoinjector consisting of a 2.5 cell gun followed by TW sections is here proposed as an electron source for radiation user facilities. The paper reports on beam dynamics studies in the RF injector and illustrates the effects on the beam quality of the mode launcher with a focus on the compensation of the quadrupole RF components. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB257 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 08 June 2021 issue date ※ 16 August 2021 | ||
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MOPAB258 | Corrections of Non-Linear Field Errors with Asymmetric Optics in LHC and HL-LHC Insertion Regions | optics, hadron, collider, insertion | 817 |
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Funding: Research supported by the HL-LHC project, CERN and the german Federal Ministry of Education and Research. Existing correction schemes to locally suppress resonance driving terms in the error-sensitive high-beta regions of the LHC and HL-LHC have operated on the assumption of symmetric beta-functions of the optics in the two rings. As this assumption can fail for a multitude of reasons, such as inherently asymmetric optics and unevenly distributed errors, an extension of this correction scheme has been developed removing the need for symmetry by operating on the two separate optics of the beams at the same time. Presented here is the impact of this novel approach on dynamic aperture as an important measure of particle stability. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB258 | ||
About • | paper received ※ 10 May 2021 paper accepted ※ 23 July 2021 issue date ※ 16 August 2021 | ||
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MOPAB259 | Corrections of Feed-Down of Non-Linear Field Errors in LHC and HL-LHC Insertion Regions | optics, hadron, collider, insertion | 821 |
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Funding: Research supported by the HL-LHC project, CERN and the german Federal Ministry of Education and Research. The optics in the insertion regions of the LHC and its upgrade project the High Luminosity LHC (HL-LHC) are very sensitive to local magnetic errors, due to the extremely high beta-functions present. In collision optics, the non-zero closed orbit in the same region leads to a "feed-down" of high-order errors to lower orders, causing additional effects detrimental to beam lifetime. An extension to the proven method for correcting these errors by locally suppressing resonance driving terms has been undertaken, not only taking this feed-down into account, but also adding the possibility of utilizing it such that the powering of higher-order correctors will compensate for lower order errors. The impact of these corrections on measures of particle stability, namely dynamic aperture and amplitude detuning are presented in this contribution. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB259 | ||
About • | paper received ※ 10 May 2021 paper accepted ※ 23 July 2021 issue date ※ 15 August 2021 | ||
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MOPAB266 | Start-to-End Study on Laser and RF Jitter Effects for MAX-IV SXL | FEL, laser, radiation, linac | 844 |
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A Soft X-ray free electron laser (FEL) for the MAX IV Laboratory is currently in the design phase and it will use the existing 3 GeV linac. Present stability limits in the RF and the photocathode laser will affect the performance of the FEL. One of the critical elements for the design of a FEL is to have an estimation on jitter effects of the accelerator parameters on the X-ray radiation. In this regard, we implemented a start-to-end study using Astra, Elegant and Genesis in order to assess possible variations in pulse energy, photon pulse length and spectral width in the Soft X-ray Laser (SXL) radiation. This investigation provides insights on the final SXL performance variation due to RF and laser related jitter affecting the electron beam. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB266 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 26 July 2021 issue date ※ 24 August 2021 | ||
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MOPAB267 | End to End Simulations of Antiproton Transport and Degradation | proton, antiproton, experiment, electron | 847 |
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The ELENA ring decelerates anti-protons to 100 keV down from 5.3 MeV with transport to experiments handled by electrostatic transfer lines. Even at 100 keV antiprotons are still too high in energy for direct injection into an ion trap, and this is why degrader foils are used to further lower the energy. This contribution presents full end-to-end simulations from the point of extraction until passing through the foil using realistic beam transport simulations coupled with accurate simulations of degrader foils via the use of density functional theory and molecular dynamics. Particles are tracked from the point of extraction until their injection into the trap with full physical modeling at all time steps. The results of this study provide a versatile platform for the optimization of low energy ion experiments towards specific targets. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB267 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 09 June 2021 issue date ※ 24 August 2021 | ||
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MOPAB270 | Beam Dynamics Studies in a Standing Wave Ka-band Linearizer | electron, emittance, bunching, operation | 857 |
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Next-generation FEL user facilities require high-quality electron beams with kA peak current. The combination of a high brightness RF injector and a magnetic compression stage represents a very performant solution in terms of electron beam emittance and peak current. One of the important issues is the design of a proper device that acts as a linearizer for the beam longitudinal phase space. Recently, the design of a SW Ka band RF accelerating structure has been proposed with promising results. The paper reports on electron beam dynamics studies in the described RF structure. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB270 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 29 August 2021 issue date ※ 26 August 2021 | ||
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MOPAB275 | Study on Supports of BPM Displacement Measurement System for HLS | acceleration, factory, storage-ring, feedback | 870 |
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Funding: National Synchrotron Radiation Laboratory HLS is the second-generation light source with energy of 800 MeV and emittance of less than 40 nm-rad. In order to improve the beam orbit stability and correct the errors introduced in the orbital feedback system due to movement of the vacuum chamber and BPM, a system for measuring BPM displacement will be built. It requires a high degree of mechanical and thermal stability for its supports. The support should have a higher eigen-frequency to minimize the amplification of ground vibration. In this paper, a series of simulation, including finite element analysis (FEA), measurement and analysis have been done upon the support to make sure it can meet the requirements of the stability of the BPM displacement measurement system. |
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Poster MOPAB275 [1.025 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB275 | ||
About • | paper received ※ 18 May 2021 paper accepted ※ 21 May 2021 issue date ※ 26 August 2021 | ||
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MOPAB280 | Split Ring Resonator Experiment - Simulation Results | laser, electron, experiment, solenoid | 888 |
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Funding: Supported by "Karlsruhe School of Elementary and Astroparticle Physics: Science and Technology (KSETA)" and European Union’s Horizon 2020 Research and Innovation programme. FLUTE (Ferninfrarot Linac- Und Test-Experiment) is a compact linac-based test facility for accelerator and diagnostics R&D. An example for a new accelerator diagnostics tool currently studied at FLUTE is the split-ring-resonator (SRR) experiment, which aims to measure the longitudinal bunch profile of fs-scale electron bunches. Laser-generated THz radiation is used to excite a high frequency oscillating electromagnetic field in the SRR. Particles passing through the SRR gap are time-dependently deflected in the vertical plane, which allows a vertical streaking of an electron bunch. This principle allows a diagnosis of the longitudinal bunch profile in the femtosecond time domain and will be tested at FLUTE. This contribution presents an overview of the SRR experiment and the results of various tracking simulations for different scenarios as a function of laser pulse length and bunch charge. Based on these results possible working points for the experiments at FLUTE will be proposed. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB280 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 01 September 2021 | ||
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MOPAB283 | Simulations of Space-Charge and Guiding Fields Effects on the Performance of Gas Jet Profile Monitoring | electron, HOM, collimation, GUI | 898 |
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Gas jet based profile monitors inject a usually curtain shaped gas jet across a charged particle beam and exploit the results of the minimally invasive beam-gas interaction to provide information about the beam’s transversal profile. Such monitor will be installed as part of the High Luminosity LHC upgrade at CERN in the Hollow Electron Lens (HEL). The HEL represents a new collimation stage increasing the diffusion rate of halo particles by placing a high intensity hollow electron beam concentrically around the LHC beam. The gas jet monitor will use the fluorescence radiation resulting due to the beam-gas interaction to create an image of the profiles of both hollow electron and LHC beams However, the high beam space-charge and strong guiding magnetic field of the electron beam cause significant displacements of the excited molecules, as they are also ionized, and thus image distortions. This work presents preliminary simulation results showing expected fluorescence images of the hollow electron profile as affected by space-charge and guiding fields using simulation tools such as IPMsim. The influence of the estimated electron beam and gas jet curtain parameters are investigated. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB283 | ||
About • | paper received ※ 18 May 2021 paper accepted ※ 28 July 2021 issue date ※ 19 August 2021 | ||
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MOPAB290 | Machine Learning-Based LLRF and Resonance Control of Superconducting Cavities | cavity, controls, LLRF, SRF | 920 |
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Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics, under award number DE-SC0019468. Superconducting radio frequency (SRF) cavities with high loaded quality factors that operate in continuous wave (CW) and low beam loading are sensitive to microphonics-induced detuning. Cavity detuning can result in an increase of operational power and/or in a cavity quench. Such SRF cavities have bandwidths on the order of 10 Hz and detuning requirements can be as tight as 10 Hz. Passive methods to mitigate vibration sources and their impact in the cryomodule/cavity environment are widely used. Active resonance control techniques that use stepper motors and piezoelectric actuators to tune the cavity resonance frequency by compensating for microphonics detuning have been investigated. These control techniques could be further improved by applying Machine Learning (ML), which has shown promising results in other particle accelerator control systems. In this paper, we describe a Low-level RF (LLRF) and resonance control system based on ML methods that optimally and adaptively tunes the control parameters. We present simulations and test results obtained using a low power test bench with a cavity emulator. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB290 | ||
About • | paper received ※ 03 June 2021 paper accepted ※ 11 June 2021 issue date ※ 29 August 2021 | ||
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MOPAB291 | Design of Cavity BPM Pickup for EuPRAXIA@SPARC_LAB | cavity, coupling, GUI, pick-up | 924 |
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EuPRAXIA@SPARC_LAB will make available at LNF a unique combination offering three different options. A high-brightness electron beam with 1 GeV energy generated in a novel X-band RF linac; A PW-class laser system, and a compact light-source directly driven by a plasma accelerator*. Plasma and conventional RF linac driven FEL provide beam with parameters of 30- 200pC charge range, 10-100Hz repetition rate, and 1 GeV electron energy**. The control of the charge and the trajectory monitoring at a few pC and a few um is mandatory in this machine. Particularly in the plasma interaction region, where the pickup resolution under 1 um is required. As a possible solution, a cavity beam position monitor (cBPM) is proposed. A prototype in the C-band frequency range has been designed. The pickup was optimized for low charge and single-shot bunches. The poster presents the process to achieve the required specifications. The simulations were performed to study RF properties and the electromagnetic response of the device. Finally, the overall performance of the pickup is discussed, and theoretical resolution is approximated.
* https://www.researchgate.net/publication/335459394FromSPARCLABtoEuPRAXIASPARC_LAB **http://www.lnf.infn.it/sis/preprint/detail-new.php?id=5416 |
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Poster MOPAB291 [16.718 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB291 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 09 June 2021 issue date ※ 23 August 2021 | ||
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MOPAB295 | Simulation Study of Emittance Measurement Using a Genetic Algorithm for Space Charge Dominated Beams | emittance, quadrupole, space-charge, lattice | 935 |
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Funding: This work was supported by the HL-LHC-UK phase II project funded by STFC under Grant Ref: ST/T001925/1 under and the STFC Cockcroft core grant No. ST/G008248/1. The quadrupole scan method is one of the traditional ways to measure beam emittance in an accelerator. The required devices are simple: several quadrupole magnets and a beam profile monitor. Beam sizes are measured from the beam profile monitor with different quadrupole settings to bring the beam through its waist and then fitted to a quadratic equation to determine the Twiss parameters. measured data from a quadrupole scan taking the beam through its waist is fitted to a quadratic equation and this allows determining the Twiss parameters. However, with increasing beam intensity, the transfer function becomes non-linear and this causes a deviation of the fitted emittance from its real value, making it no longer useful. In this contribution, a genetic algorithm is applied to find the optimum quadrupole scan fit in space-charge dominated electron beams. Results from simulations using different space charge levels are presented and scenarios identified where this method can be applied. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB295 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 28 May 2021 issue date ※ 02 September 2021 | ||
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MOPAB301 | A Concept for Reconstruction of the Capsulated Microchip Structure Using Its Interaction with High-Energy Ion Beams of the NICA Accelerator Complex | detector, radiation, electron, electronics | 949 |
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Within the framework of the NICA project an applied research station for irradiation by long-range ions (SODIT) is being constructed for testing radiation hardness of semiconductor micro- and nanoelectronics products in the energy range of 150-350 MeV/n. Calculations for the interaction of high-energy gold ions with the microchip and strip detector structures are performed using the GEANT4 simulation toolkit. A concept was developed for reconstruction of the capsulated microchip structure in terms of depth and in terms of cross-section using interaction with high-energy ions at the technical station for irradiation by long-range ions. The possibility of localizing the radiation-vulnerable area of the microchip is evaluated. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB301 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 20 May 2021 issue date ※ 17 August 2021 | ||
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MOPAB302 | Characterization of the Full Transverse Phase Space of Electron Bunches at ARES | experiment, electron, quadrupole, linac | 952 |
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The ARES linear accelerator at the SINBAD facility (DESY) is dedicated to perform accelerator R&D studies with sub-fs short electron bunches to test novel acceleration techniques and diagnostics devices. Currently, the commissioning of the linac is ongoing and first experiments are being performed. For this, the knowledge of the full phase space of the particle beams is of high interest to, for example, optimize the accelerator performance and identify possible errors in the beam line. Tomographic methods can be used to gain insight into the full 4D transverse phase space and its correlations. Here, simulation results and first experimental preparations of a 4D transverse phase-space tomography of electron bunches at ARES are presented and discussed. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB302 | ||
About • | paper received ※ 17 May 2021 paper accepted ※ 16 June 2021 issue date ※ 30 August 2021 | ||
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MOPAB324 | High Voltage Design and Evaluation of Wien Filters for the CEBAF 200 keV Injector Upgrade | electron, vacuum, high-voltage, GUI | 1000 |
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Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177. High-energy nuclear physics experiments at the Jefferson Lab Continuous Electron Beam Accelerator Facility (CEBAF) require highly spin-polarization electron beams, produced from strained super-lattice GaAs photocathodes, activated to negative electron affinity in a photogun operating at 130 kV dc. A pair of Wien filter spin rotators in the injector defines the orientation of the electron beam polarization at the end station target. An upgrade of the CEBAF injector to better support the upcoming MOLLER experiment requires increasing the electron beam energy to 200 keV, to reduce unwanted helicity correlated intensity and position systematics and provide precise control of the polarization orientation. Our contribution describes design, fabrication and testing of the high voltage system to upgrade the Wien spin rotator to be compatible with the 200 keV beam. This required Solidworks modeling, CST and Opera electro- and magnetostatic simulations, upgrading HV vacuum feedthroughs, and assembly techniques for improving electrode alignment. The electric and magnetic fields required by the Wien condition and the successful HV characterization under vacuum conditions are also presented. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB324 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 24 May 2021 issue date ※ 29 August 2021 | ||
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MOPAB327 | Beam Loss Diagnostics System for SKIF Synchrotron Light Source | electron, storage-ring, diagnostics, synchrotron | 1012 |
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The Siberian ring photon source (SKIF) is a new generation synchrotron light source designed and built by the Budker Institute of Nuclear Physics. The beam loss diagnostics system is a tool for monitoring beam loss information. It is widely used in modern large accelerators to provide a basis for diagnosing and locating machine faults, optimizing and debugging working beam parameters, and improving beam lifetime. Two types of beam loss monitor (BLM) will be applied on SKIF: fiber-based Cherenkov beam loss monitor (CBLM) and scintillator-based BLM (SBLM). Multi-mode silica fibers CBLM will be installed on linear accelerator and transfer lines. 128 SBLMs will be placed around the storage ring, dynamic ranges and sophisticated electronic equipment are employed to cover different SKIF operating modes. This article represents the details of design of beam loss diagnostics of SKIF, introduces the simulation and experimental studies of CBLM and SBLM. | |||
Poster MOPAB327 [4.893 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB327 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 26 May 2021 issue date ※ 30 August 2021 | ||
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MOPAB328 | Beam Instrumentation for Linear Accelerator of SKIF Synchrotron Light Source | electron, diagnostics, photon, radiation | 1016 |
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A new synchrotron light source SKIF of the 4th generation is under construction at BINP SB RAS (Novosibirsk, Russia). The linear accelerator is SKIF’s injector to provide 200 MeV electron beam. The set of diagnostics will be applied for tuning of the linear accelerator and measurements of beam parameters from electron RF gun to output of the accelerator. It includes 8 fluorescent screens for the beam transverse dimensions measurement, 2 Cherenkov probes for the beam duration measurement, magnetic spectrometer with range from 0.6 to 200 MeV, and some beam charge and current measurement devices, as Faraday cup, FCT, BPM along linear accelerator. Numerical simulations of diagnostics elements and results of beam dynamics simulations are introduced in paper. Brief description of the design and parameters of each diagnostics system is presented. Possible scenarios of linear accelerator tuning are also discussed. | |||
Poster MOPAB328 [2.324 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB328 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 21 May 2021 issue date ※ 31 August 2021 | ||
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MOPAB335 | SNS Warm Linac Circulator Breakdown Considerations for the PPU Project | operation, linac, DTL, proton | 1041 |
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Funding: * This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under contract number DE-AC05-00OR22725. Multipacting in accelerating structures is a complex phenomenon about which there is much to be understood. While multipacting research efforts have primarily been focused on superconducting radio frequency (SRF) systems, normal conducting accelerating structures which have a higher thermal capacity, and a greater vacuum pressure tolerance could benefit from additional investigation. This research details multipacting simulation methods and the results of 3-D electromagnetic simulations of RF vacuum windows used on normal conducting linac (NCL) cavities. Benchmarking of the peak electric fields in these structures, benefits of material processing and possible techniques for reducing or eliminating multipacting activities are discussed. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB335 | ||
About • | paper received ※ 17 May 2021 paper accepted ※ 28 May 2021 issue date ※ 23 August 2021 | ||
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MOPAB336 | Multipacting Analysis of Warm Linac RF Vacuum Windows | multipactoring, vacuum, GUI, Windows | 1044 |
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Funding: * This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under contract number DE-AC05-00OR22725. Multipacting in accelerating structures is a complex phenomenon with which there is much to be understood. While multipacting research efforts have primarily been focused on superconducting radio frequency (SRF) systems, normal conducting accelerating structures that have a higher thermal capacity and a greater vacuum pressure tolerance could benefit from additional investigation. This research details multipacting simulation methods and the results of 3-D electromagnetic simulations of RF vacuum windows used on normal conducting linac (NCL) cavities. Possible techniques for reducing and eliminating multipacting activities in these structures are discussed. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB336 | ||
About • | paper received ※ 17 May 2021 paper accepted ※ 28 May 2021 issue date ※ 29 August 2021 | ||
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MOPAB340 | Experimental Tests with the First Segment of ESS-Bilbao RFQ Linac | rfq, vacuum, experiment, operation | 1054 |
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The ESS-Bilbao RFQ is an assembly of four segments, each one about 800 mm in length. The first segment has been manufactured before the others, so it could be thoroughly tested in order to validate the chosen technological approach for the RFQ, as it uses polymeric vacuum gaskets and bolts instead of brazing. In this paper we report on the tests run with the segment and their results. Vacuum tests, metrology measurements, low power RF tests as well as extensive tuning tests measuring the cavity resonant quadrupolar frequency as a function of cooling water temperature have been done. Experimental results are compared to the expected values obtained from numerical simulations. We describe the experimental set-ups for the measurements and the simulations. Results are analyzed with the aim of validating the design, and also to provide predictions for tuning and operation of the whole RFQ. As a consequence of the positive results of the tests reported here, the remaining segments have already been tendered. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB340 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 25 May 2021 issue date ※ 20 August 2021 | ||
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MOPAB342 | Design, Fabrication, and Commissioning of the Mode Launchers for High Gradient C-Band Cavity Testing at LANL | GUI, cavity, klystron, MMI | 1060 |
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Funding: Los Alamos National Laboratory LDRD Program. This poster will report on the design, fabrication, and operation status of the new high gradient C-band TM01 mode launchers for the high gradient C-band test stand at LANL. Modern applications require accelerators with optimized cost of construction and operation, naturally calling for high-gradient acceleration. At LANL we commissioned a test stand powered by a 50 MW, 5.712 GHz Canon klystron. The test is capable of conditioning single cell accelerating cavities for operation at surface electric fields up to 300 MV/m. The rf field is coupled into the cavity from a WR187 waveguide through a mode launcher that converts the fundamental mode of the rectangular waveguide into the TM01 mode of the circular waveguide. Several designs for mode launchers were considered and the final design was chosen based on a compromise between the field enhancements, bandwidth, and simplicity and cost of fabrication. Four mode launchers were fabricated and cold-tested. Two mode launchers with the best transmission characteristics were installed and conditioned to high power. The presentation will report achieved gradients, breakdown probabilities, and other characteristics measured during operation. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB342 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 25 May 2021 issue date ※ 19 August 2021 | ||
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MOPAB343 | Optimization of the Parasitic-Mode Damping on the 1.5 GHz TM020-type Harmonic Cavity | cavity, damping, impedance, coupling | 1064 |
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Bunch-lengthening harmonic cavity is one of the essential tools to mitigate the intrabeam scattering in the 4th-generation synchrotron light sources. For this purpose, we proposed a normal-conducting 1.5 GHz harmonic cavity* of TM020-type**. Thanks to its low R/Q (68 ohms) and high unloaded Q (34, 000), bunch gap transient in the harmonic cavity can be reduced to ~20% as compared to that in a typical TM010 cavity. Furthermore, harmful parasitic modes in this cavity can be heavily damped by installing ferrites where no magnetic fields of TM020-mode exist. However, some of the parasitic modes, e.g. TM021 and TM120 modes, are difficult to damp because their field patterns are similar to that of the TM020 mode. To damp such modes effectively, we optimized the cavity inner shape by tailoring the curvature at the cavity equator, the shape of the nose cones, and introducing "bumps" on the inner wall. Our goals of the coupling impedances are fxR < 2.4[kohm GHz] and RT < 23 kohm/m in the longitudinal and the transverse planes, respectively. As a result of optimization, we almost achieved these goals. To confirm our simulation results, fabrication of a low-power test cavity is in progress.
* N . Yamamoto et al., Phys. Rev. Acc. Beams 21, 012001 (2018). ** H. Ego et al., Proc. of the 11th Annual Meeting of Particle Accelerator Society of Japan (PASJ2014), MOOL14 (2014). |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB343 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 26 May 2021 issue date ※ 01 September 2021 | ||
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MOPAB350 | RF Buncher Cavity for Polarized He-3 Beam at BNL | cavity, alignment, insertion, booster | 1090 |
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Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. A 100.625 MHz quarter wave resonator type rf buncher cavity was fabricated for polarized He-3 spin rotator beam line at BNL. This cavity will be installed in the existing EBIS-To-Booster beam line to provide effective voltage of more than 40 kV for 2 MeV/u 3He2+ beam. This cavity has a large drift tube inner diameter of 80 mm and small gap length of 5 mm. The buncher consists of 3 sections, which are a cavity main body including drift tube, stem, and inner wall, a lid with a power coupler, and a lid with an inductive tuner. The main body was machined from a bulk copper only by CNC machining. The result of low power test agreed well with rf simulation without any alignment. The difference between measured and calculated resonant frequency was <0.1 %, and measured Q value was 92 % of that in simulation. The cavity rf design and test results will be shown. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB350 | ||
About • | paper received ※ 26 May 2021 paper accepted ※ 28 May 2021 issue date ※ 12 August 2021 | ||
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MOPAB353 | Design of a compact Ka-Band Mode Launcher for High-gradient Accelerators | cavity, coupling, quadrupole, accelerating-gradient | 1100 |
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In this work, we present the RF design of a table-top Ka-Band mode launcher operating at 35.98 GHz. The structure consists of a symmetrical 4-port WR28 rectangular-TE10-to-circular-TM01 mode converter that is used to couple a peak output RF power of 5 MW (pulse length up to 50 ns and repetition rate up to 100 Hz) in Ka-Band linear accelerator able to achieve very high accelerating gradients (up to 200 MV/m). Numerical simulations have been carried out with the 3D full-wave commercial simulator Ansys HFSS in order to obtain a preliminary tuning of the accelerating field flatness at the operating frequency f0=35.98 GHz. The main RF parameters, such as reflection coefficient, transmission losses, and conversion efficiency are given together with a verification of the field azimuthal symmetry which avoids dipole and quadrupole deflecting modes. To simplify future manufacturing, reduce fabrication costs, and also reduce the probability of RF breakdown, the proposed new geometry has "open" configuration. This geometry eliminates the flow of RF currents through critical joints and allows this device to be milled from metal blocks. | |||
Poster MOPAB353 [3.131 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB353 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 09 June 2021 issue date ※ 27 August 2021 | ||
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MOPAB361 | Threshold in Filling Failure of RF Cavity Caused by Beam Loading in Multipactor | multipactoring, cavity, electron, experiment | 1122 |
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Funding: NSFC A pulsed RF cavity would be heavily detuned caused by beam loading of multipactor current in the RF filling process. Multipactor zone would be expended by several times than that in static states with assumptions of fixed voltage and no beam loading. The dynamic of multipactor in the RF filling process was simulated by coupling with parameters of external circuit with the developed simulation code, and test in experiments with a parallel-plate resonator. Threshold of RF voltage, which means the lower boundary of peak voltage of multipactor zone, had been quantified with different cavity parameters. When we increased the gap length, the measured threshold became larger due to the ionization in background gas. Then the secondary emission factor would be increased in simulation for consistence with the experiment results. Additionally, some multipactor phenomenon could not be predicted precisely because the simulation code did not take account of ionization. The hysteresis of phase and energy of ionization electrons would be a new driving factor for the growth of multipactor in certain conditions. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB361 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 24 May 2021 issue date ※ 10 August 2021 | ||
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MOPAB362 | Atomistic Modeling of the Coupling Between Electric Fields and Bulk Plastic Deformation in Rf Structures | experiment, coupling, feedback, framework | 1125 |
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Funding: LANL-LDRD A notable bottleneck in achieving high-gradient RF technology is dictated by the onset of RF breakdown. While bulk mechanical properties are known to significantly affect breakdown propensity, the underlying mechanisms coupling RF fields to bulk plastic deformation in experimentally relevant thermo-electrical loading conditions remain to be identified at the atomic scale. Here, we present results of large-scale molecular dynamics simulations (MD) to investigate possible modes of coupling. We consider the activation of Frank-Read (FR) sources, which leads to dislocation multiplication, under the action of bi-axial thermal stresses and surface electric-field. With a charge-equilibration formalism incorporated in a classical MD model, we show that a surface electric field acting on an either preexisting or dislocation-induced surface step, can generate a long-range resolved shear stress field inside the bulk of the sample. We investigate the feedback between step growth following dislocation emission and subsequent activations of FR sources and discuss the regimes of critical length-scales and densities of dislocations, where such a mechanism could promote RF breakdown precursors. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB362 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 10 June 2021 issue date ※ 19 August 2021 | ||
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MOPAB364 | Shielded Pair Method for Cylindrical Surface Resistance Measurement at Cryogenic Temperature | factory, cryogenics, dipole, coupling | 1132 |
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The shielded pair resonator method was already used in the past at CERN to measure the surface resistivity of the LHC beam screen both at room temperature and cryogenic temperature. We have refined and adapted the measurement to be able to measure other types of beam screens and also to operate in a strong dipolar magnetic field. This is necessary for testing the properties of HTS coated beam screens or the possible effects of coatings and surface treatments for e-cloud suppression. Several calibration runs were done at cryogenic temperatures (4.2 K) measuring the surface resistivity of a copper pipe to identify the precision, stability and reproducibility achievable using this method. This work describes the challenges of the measurement and ways to mitigate them. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB364 | ||
About • | paper received ※ 17 May 2021 paper accepted ※ 22 June 2021 issue date ※ 12 August 2021 | ||
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MOPAB366 | Improving Magnetic Materials for RCS Cavity Tuners | cavity, solenoid, booster, synchrotron | 1139 |
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Funding: United States Department of Energy, Contract No. DE-AC02-07CH11359 Within the Lab Directed R&D Program at Fermilab, and in partnership with National Magnetics, we have recently begun to study and attempt to improve the loss parameter in garnet material. This could be used for fast tuner applications such as in rapid cycling synchrotrons. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB366 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 25 May 2021 issue date ※ 15 August 2021 | ||
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MOPAB370 | X-Band RF Spiral Load Optimization for Additive Manufacturing Mass Production | GUI, vacuum, ECR, linac | 1143 |
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The CLIC main linac uses X-band traveling-wave normal conducting accelerating structures. The RF power not used for beam acceleration nor dissipated in the resistive wall is absorbed in two high power RF loads that should be as compact as possible to minimize the total footprint of the machine. In recent years, CERN has designed, fabricated and successfully tested several loads produced by additive manufacturing. With the current design, only one load can be produced in the 3D printing machine at a time. The aim of this study is optimizing the internal cross-section of loads in order to create a stackable design to increase the number of produced parts per manufacturing cycle and thus decrease the unit price. This paper presents the new design with an optimization of the internal vacuum part of the so-called RF spiral load. In this case, RF and mechanical designs were carried out in parallel. The new cross section has showed good RF reflection reaching less than -30 dB in simulations. The final load is now ready to be manufactured and high-power tested. This new load will not only provide cost saving but also faster manufacturing for mass production. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB370 | ||
About • | paper received ※ 18 May 2021 paper accepted ※ 26 May 2021 issue date ※ 23 August 2021 | ||
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MOPAB372 | KARVE: A Nanoparticle Accelerator for Space Thruster Applications | acceleration, ECR, radio-frequency, bunching | 1151 |
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We present a concept for using RF-based acceleration of nanoparticles (NPs) as a means of generating thrust for future space missions: the Kinetic Acceleration & Resource Vector Engine (KARVE) thruster. Acceleration of nanoparticles (NPs) via DC accelerators has been shown to be feasible in dust accelerator labs such as the Heidelberg dust accelerator and the 3 MV hypervelocity dust accelerator at the Colorado Center for Lunar Dust and Atmospheric Studies. In contrast, KARVE uses RF-driven acceleration of nanoparticles as the basis of a thruster design lying between chemical and ion engines in performance: more efficient than chemical engines in terms of specific impulse; and higher thrust than ion engines. The properties of multi-gap RF accelerators also allow an on-the-fly tradeoff between specific impulse and thrust. | |||
Poster MOPAB372 [0.694 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB372 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 27 May 2021 issue date ※ 10 August 2021 | ||
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MOPAB374 | Creating Exact Multipolar Fields in Accelerating RF Cavities via an Azimuthally Modulated Design | cavity, quadrupole, dipole, collider | 1154 |
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In this paper, we present a novel method for designing RF structures with specifically tailored multipolar field contributions. This has a range of applications, including the suppression of unwanted multipolar fields or the introduction of wanted terms, such as for quadrupole focusing. In this article, we outline the general design methodology and compare the expected results to 3D CST simulations. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB374 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 08 June 2021 issue date ※ 23 August 2021 | ||
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MOPAB379 | Topological Optimization on SRF Cavities for Nuclear and High Energy Physics | cavity, niobium, superconducting-cavity, radiation | 1162 |
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Topology optimization has been developed for more than twenty years. The progress of additive manufacturing boosts the development in topological optimization since the design can be completely innovated and realized by 3D printing. The potential for cost reductions thanks to weight minimization give an interesting perspective for the small production of niobium superconducting radio-frequency cavities, commonly used in accelerators. The traditional manufacturing technologies of cavities are based on multi-stage processes while additive manufacturing technologies can built fully functional parts in a single operation. For modern accelerators that use superconducting linac, including energy recovery linacs (ERLs), it is particularly important to know the perspectives of additive manufacturing for SRF cavities. In this paper, we try to build a preliminary perception of topological optimization in superconducting cavities manufacturing innovation. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB379 | ||
About • | paper received ※ 11 May 2021 paper accepted ※ 17 August 2021 issue date ※ 15 August 2021 | ||
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MOPAB388 | Status of the High Power Couplers for ESS Elliptical Cavities | cavity, cryomodule, vacuum, SRF | 1186 |
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In the framework of the European Spallation Source (ESS), CEA Paris-Saclay is responsible for the delivery of 30 cryomodules (9 medium beta (β = 0.67) and 21 high beta (β = 0.86) ones). Each cryomodule contains 4 elliptical cavities equipped with a radio frequency power coupler. The ESS nominal pulse is 1.1 MW maximum peak power over a width of 3.6 ms at a repetition rate of 14 Hz. The design of the couplers for medium beta and for high beta cavities is the same, except a small difference of the antenna penetration to adjust the Qext. The mass production of the 120 couplers started and all the medium beta couplers have been conditioned at room temperature. The first cryomodules equipped with the power couplers were successfully tested at high RF power and with cavities at 2K reaching the ESS nominal pulse. The main issue at the start of the series production could be fixed and it was due to bad TiN coatings that caused abnormal dielectric losses in the window. Thus, this paper deals with the TiN coating defect, presents the conditioning procedure and gives a conditioning report of these 36 couplers. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB388 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 24 May 2021 issue date ※ 18 August 2021 | ||
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MOPAB391 | Conduction Cooling Methods for Nb3Sn SRF Cavities and Cryomodules | cavity, SRF, controls, accelerating-gradient | 1192 |
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Rapid progress in the performance of Nb3Sn SRF cavities during the last few years has made Nb3Sn an energy efficient alternative to traditional Nb cavities, thereby initiating a fundamental shift in SRF technology. These Nb3Sn cavities can operate at significantly higher temperatures than Nb cavities while simultaneously requiring less cooling power. This critical property enables the use of new, robust, turn-key style cryogenic cooling schemes based on conduction cooling with commercial cryocoolers. Cornell University has developed and tested a 2.6 GHz Nb3Sn cavity assembly which utilizes such cooling methods. These tests have demonstrated stable RF operation at 10 MV/m and the measured thermal dynamics match what is found in numerical simulations. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB391 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 10 June 2021 issue date ※ 17 August 2021 | ||
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MOPAB392 | Alternative RF Tuning Methods Performed on Spoke Cavities for ESS and MYRRHA Projects | cavity, operation, target, experiment | 1196 |
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In order to obtain the target frequency in operation, the resonant frequency of superconducting radiofrequency cavities is controlled and adjusted from the manufacturing to the end of preparation phase. Reaching this right frequency can be challenging due to the narrow frequency range defined by the tuning sensitivity of the cavity and the capability of the tuner. Mechanical deformation until plasticity is attained is of great interest to tune SRF cavities when large frequency shift is needed. But once a cavity is dressed with its helium tank, the only accessible part is its beam pipe, reducing the mechanical action to a push/pull action. This limited possibility has hence to be skilfully associated with chemical etching. An original mechanical tuning of Spoke dressed cavities consists in increasing the pressure inside the helium tank to induce a permanent deformation of the cavity walls. The frequency shift induced by nonlinear deformation is numerically evaluated in order to determine the pressure increments. Both methods were successfully performed on the cavities of the ESS accelerator and of the Myrrha project. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB392 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 25 June 2021 issue date ※ 17 August 2021 | ||
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MOPAB394 | Preliminary BCP Flow Field Investigation by CFD Simulations and PIV in a Transparent Model of a SRF Elliptical Low Beta Cavity | cavity, experiment, SRF, laser | 1204 |
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Standard vertical Buffered Chemical Polishing (BCP) is one of the main surface treatment for Superconducting Radiofrequency (SRF) cavities. A finite element Computational Fluid Dynamic (CFD) model has been developed. Uncertainties in the solution of fluid simulations are not negligible due to the complex geometry of a SRF cavity; thus without an experimental validation, results from this type of simulations cannot be confidently used to improve the process. To this aim, an experimental study was started to investigate the fluid dynamics of the BCP process by means of Particle Image Velocimetry (PIV) technique. Similitude on Reynolds number and Refractive Index Matching (RIM) technique were also implemented to replace the dangerous BCP mixture with a glycerine-water mixture. The paper describes the preliminary results from simulations and experiment. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB394 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 24 June 2021 issue date ※ 13 August 2021 | ||
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MOPAB416 | BDSIM Developments for Hadron Therapy Centre Applications | proton, radiation, shielding, neutron | 1252 |
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Hadron therapy centres are evolving towards reduced-footprint layouts, often featuring a single treatment room. The evaluation of beam properties, radiation protection quantities, and concrete shielding activation via numerical simulations poses new challenges that can be tackled using the numerical beam transport and Monte-Carlo code Beam Delivery Simulation (BDSIM), allowing a seamless simulation of the dynamics as a whole. Specific developments have been carried out in BDSIM to advance its efficiency toward such applications, and a detailed 4D Monte-Carlo scoring mechanism has been implemented. It produces tallies such as the spatial-energy differential fluence in arbitrary scoring meshes. The feature makes use of the generic boost::histogram library and allows an event-by-event serialisation and storage in the ROOT data format. The pyg4ometry library is extended to improve the visualisation of critical features such as the complex geometries of BDSIM models, the beam tracks, and the scored quantities. Data are converted from Geant4 and ROOT to a 3D visualisation using the VTK framework. These features are applied to a complete IBA Proteus One model. | |||
Poster MOPAB416 [1.575 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB416 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 12 July 2021 issue date ※ 15 August 2021 | ||
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TUXA01 | Advances in Understanding of Ion Effects in Electron Storage Rings | emittance, ion-effects, storage-ring, injection | 1267 |
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Ion instability, in which beam motion couples with trapped ions in an accelerator, is a serious concern for high-brightness electron storage rings. For the APS-Upgrade, we plan to mitigate coherent ion instability using a compensated gap scheme. To study incoherent effects (such as emittance growth), an IONEFFECTS element has been incorporated into the particle tracking code ELEGANT. The simulations include multiple ionization, transverse impedance, and charge variation between bunches. Once these effects are included, the simulations show good agreement with measurements at the present APS. We have also installed a gas injection system, which creates a controlled pressure bump of Nitrogen gas in a short section of the APS ring. The resulting ion instability was studied under a wide variety of beam conditions. For cases with no or insufficient train gaps, large emittance growth was observed. IONEFFECTS simulations of the gas injection experiment and APS-U storage ring show the possibility of runaway emittance blowup, where the blown-up beam traps more ions, driving further instability. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUXA01 | ||
About • | paper received ※ 24 June 2021 paper accepted ※ 27 July 2021 issue date ※ 10 August 2021 | ||
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TUXA03 | Progress in Mastering Electron Clouds at the Large Hadron Collider | electron, operation, luminosity, experiment | 1273 |
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During the second operational run of the Large Hadron Collider (LHC) a bunch spacing of 25 ns was used for the first time for luminosity production. With such a spacing, electron cloud effects are much more severe than with the 50-ns spacing, which had been used in the previous run. Beam-induced conditioning of the beam chambers mitigated the e-cloud formation to an extent that allowed an effective exploitation of 25 ns beams. Nevertheless, even after years of conditioning, e-cloud effects remained very visible, affecting beam stability and beam quality, and generating strong heat loads on the beam screens of the superconducting magnets with puzzling features. In preparation for the High Luminosity LHC upgrade, remarkable progress has been made in the modeling of the e-cloud formation and of its influence on beam stability, slow losses and emittance blow up, as well as in the understanding of the underlying behavior of the beam-chamber surface. In this contribution, we describe the main experimental observations from beam operation, the outcome of laboratory analysis conducted on beam screens extracted after the run, and the main advancements in the modeling of these phenomena. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUXA03 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 12 July 2021 issue date ※ 29 August 2021 | ||
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TUXB07 | High-Current H2+ Beams from a Compact Cyclotron using RFQ Direct Injection | cyclotron, rfq, extraction, ion-source | 1301 |
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Funding: This work was supported by NSF grants PHY-1505858 and PHY-1626069. For the IsoDAR neutrino experiment, we have developed a compact and cost-effective cyclotron-based driver to produce high current beams (cw proton beam currents of >10 mA at 60 MeV). This is a factor of 4 higher than the current state-of-the-art for cyclotrons and a factor of 10 compared to what is commercially available. All areas of physics that call for high cw currents can greatly benefit from this result; e.g. particle physics, medical isotope production, and energy research. This increase in beam current is possible in part because the cyclotron is designed to include and use vortex-motion, allowing clean extraction. Such a design process is only possible with the help of high-fidelity codes, like OPAL. Another novelty is the use of an RFQ embedded in the cyclotron yoke to bunch the beam during axial injection. Finally, using H2+ relieves some of the space charge constraints during injection. In this paper, we will give an overview of the project and then focus on the design and simulations of the cyclotron itself. We will describe the physics, computational tools, and simulation results. At the end, we will describe how we are including machine learning in the simulations. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUXB07 | ||
About • | paper received ※ 27 May 2021 paper accepted ※ 22 July 2021 issue date ※ 31 August 2021 | ||
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TUXC08 | Simulation and Beam Experiments of a Multi-Harmonics Buncher in SSC-Linac | linac, experiment, rfq, heavy-ion | 1319 |
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Funding: This work was supported by the National Natural Science Foundation of China(No. 11375243) and Guangdong Innovative and Entrepreneurial Research Team Program(No.2016ZT06G373). A compact dual-gap Multi-Harmonics Buncher has been successfully used at the SSC-Linac, a linear accelerator dedicates to beam injection into SSC in HIRFL. SSC-Linac operates at 53.667MHz, which is forth time of the RF frequency of the SSC. In order to increase the longitudinal capture efficiency, and enhance the current out of SSC, an independent MHB(Multi-Harmonics Buncher) had been installed into the LEBT of SSC-Linac. The fundamental frequency of the MHB is 13.417MHz. The buncher adopts the mechanical structure of dual-gap and sawtooth waveform is generated by multi-harmonics synthetic technology. Beam performance simulation with MHB have been done with code BEAMPATH. Besides, 84Kr14+ beam has been bunched successfully using the MHB in our experiments, the maximum bunch efficiency of 86.1% has been measured in experiments. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUXC08 | ||
About • | paper received ※ 31 May 2021 paper accepted ※ 12 July 2021 issue date ※ 11 August 2021 | ||
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TUPAB005 | Emittance Estimates for the Future Circular Collider | emittance, quadrupole, alignment, sextupole | 1338 |
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The alignment strategy of the FCC-ee has a large impact on its luminosity. Larger alignment tolerances result in increased coupling and a subsequently higher vertical emittance. At the same time, tighter alignment tolerances around the 100 km ring are a major cost driver. This paper applies analytical emittance estimate methods to the FCC-ee and compares their predictions to data from simulations with different alignment tolerances. These methods can be used to help understand the impact of misalignments of certain magnet groups and to come up with an efficient alignment strategy. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB005 | ||
About • | paper received ※ 16 May 2021 paper accepted ※ 14 June 2021 issue date ※ 26 August 2021 | ||
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TUPAB006 | The Impact of Beam Position Monitor Tilts on Coupling Measurements | coupling, resonance, optics, quadrupole | 1342 |
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The measurement and correction of coupling resonance driving terms is a key tool for improving the performance of synchrotrons. These terms are measured by exciting the beam and observing the subsequent motion in the horizontal and vertical planes through beam position monitors. This paper outlines the impact of tilt errors in these monitors to the distortion of the amount of coupling measured between the planes and how the computation of the resonance driving terms is affected by these tilts. It also attempts to use these results for mimicking tilt errors in simulations and discusses how discrepancies in measured resonance driving terms could be used to estimate the tilt errors that cause them. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB006 | ||
About • | paper received ※ 16 May 2021 paper accepted ※ 14 June 2021 issue date ※ 12 August 2021 | ||
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TUPAB008 | Progress of the First-Turn Commissioning Simulations for HEPS | quadrupole, lattice, MMI, dipole | 1349 |
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The High Energy Photon Source (HEPS) is 6 GeV, kilometer-scale, 4th generation storage ring light source. The lattice has an ultralow emittance and strong focusing such that the beam dynamics is very sensitive to the magnet misalignments and other error sources. Getting the first turn and establishing the closed orbit is essential for accelerator commissioning. This paper describes a simulation algorithm for achieving the first turn commission based on the latest HEPS storage ring lattice. We developed a new accelerator toolbox (AT)-based program for automatic optimizing the first turn commissioning. The algorithm and simulation results will be presented in this paper. | |||
Poster TUPAB008 [0.646 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB008 | ||
About • | paper received ※ 14 May 2021 paper accepted ※ 11 June 2021 issue date ※ 28 August 2021 | ||
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TUPAB026 | Application of Plasma Lenses as Optical Matching Device for Positron Sources at Linear Colliders | plasma, positron, target, optical-matching | 1394 |
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Funding: Quantum Universe In the baseline design of the International Linear Collider (ILC) an undulator-based positron source is foreseen. The proposed luminosity of the recently chosen first energy stage with √{s}=250 GeV requires an improvement by a factor of 2500 to the world’s first linear collider, the past SLC experiment. This ambitious luminosity goal can only be achieved, if all technological boundaries are being pushed. One such area is the captured positron number, which is primarily determined in the capture section within the positron source and specifically by its optical matching device. It is responsible for transforming the phase-space of the outgoing particles produced in the target for the succeeding accelerator sections. The plasma lens is a new candidate for this task. It being an especially adequate method due its magnetic field being azimuthal. Optimizing an idealised tapered active plasma lens for the ILC led us to a design with improved captured positron yield, outperforming ILC’s currently proposed quarter wave transformer by approximately 50%. The captured yield also proved to be stable within ±1.5% for deviations in design parameters of ±10%. |
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Poster TUPAB026 [0.293 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB026 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 24 June 2021 issue date ※ 24 August 2021 | ||
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TUPAB038 | Simulation of the Filling Pattern Dependent Regenerative Beam Breakup Instabilities in Energy Recover Linacs | HOM, cavity, linac, electron | 1431 |
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The interaction of a transversely displaced beam with the higher modes (HOM) of the accelerating cavities causes building up HOM voltages in the cavity, which in turn kicks the beam and increases the offset further. This is known as regenerative beam breakup (BBU) instability and it sets the beam threshold current for the stable beam operation. A study by Setiniyaz et al.~[Setiniyaz2020] showed the filling pattern and recombination schemes of multi-turn energy recovery linacs (ERLs) can create many different beam loading transients, which can have a big impact on the cavity fundamental mode voltage and RF stabilizes. In this work, we extend the study of the filling pattern and recombination schemes to the BBU instabilities and threshold current. In the ERLs, the accelerated and decelerated bunches can be ordered differently while they pass through the cavity and form different filling patterns. Each pattern has a unique bunch energy sequence and bunch arrival times and hence interacts with cavity uniquely and thus drives BBU differently. In this paper, we introduce a simulation tool to investigate the filling pattern dependence of the ERL BBU instability.
* S. Setiniyaz, R. Apsimon, and P. H. Williams, Phys. Rev. Accel. Beams 23, 072002, 2020. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB038 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 09 June 2021 issue date ※ 15 August 2021 | ||
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TUPAB047 | Bunch Compressor Design in the Full Energy Linac Injector for the Southern Advanced Photon Source | linac, electron, bunching, laser | 1458 |
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A mid-energy fourth-generation storage ring light source named the Southern Advanced Photon Source (SAPS), has been considered to be built neighboring the China Spallation Neutron Source (CSNS). A full energy linac has been proposed as an injector to the storage ring, with the capability to generate high brightness electron beams to feed a Free Electron Laser (FEL) at a later stage. To achieve the high peak current in FELs, space charge, RF structure wakefield, coherent synchrotron radiation (CSR), RF curvature, and the second-order momentum compaction factor should be carefully considered and optimized during the bunch compression processes. In this paper, physic design and simulation results of the bunch compressors are described. | |||
Poster TUPAB047 [1.918 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB047 | ||
About • | paper received ※ 15 May 2021 paper accepted ※ 09 June 2021 issue date ※ 28 August 2021 | ||
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TUPAB053 | Design Progress of ALS-U 3rd-Harmonic Cavity | cavity, HOM, damping, impedance | 1481 |
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Funding: Director, Office of Science, Office of Basic Energy Sciences, and LDRD Program of Lawrence Berkeley National Laboratory, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 A higher-harmonic rf cavity (HHC) system is required in the ALS-U storage ring to lengthen the bunches, reduce intrabeam-scattering effects, and improve Touschek beam lifetime. A 3rd harmonic, normal conducting, passive-cavity system has been chosen based on beam-dynamics requirements and cost considerations. We have explored two options for ALS-U 3HC system: a high-R/Q re-entrant cavity with waveguide HOM dampers, and a low-R/Q system with two elliptical cavities and HOM beam line absorbers. In this paper, we present the recent progress on the cavity design and related beam dynamics studies. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB053 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 11 June 2021 issue date ※ 14 August 2021 | ||
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TUPAB059 | Measurement of the Advanced Photon Source Lifetime at Different Level of Beta-Beating | quadrupole, betatron, storage-ring, optics | 1496 |
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Funding: The work is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. Linear optics correction of a particle accelerator may not be perfect due to the existence of different errors sources in response matrix measurements and optics correction process. Previous numerical simulation study has shown that the single particle beam dynamics performance may be highly correlated with the level of residual beta-beating. In this paper, the machine study results on beam lifetime of the APS storage ring is presented. The experiment is performed at different level of predefined beta-beating with negligible betatron tunes variations. As expected, the measured beam lifetime has an inverse correlation with the level of beta-beating. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB059 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 17 June 2021 issue date ※ 16 August 2021 | ||
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TUPAB062 | Expediting APS-U Long-Term Particle Tracking with Arbitrary Order Taylor Map | lattice, damping, collective-effects, resonance | 1505 |
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Funding: The work is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. Truncated power series algebra was integrated within explicit symplectic integration to formulate an arbitrary order multivariate Taylor map for any given particle accelerator lattice. Tracking simulation performed with these Taylor maps shows good long term stability and physics accuracy. There is good agreement in long term particle tracking simulations between Taylor map and element by element tracking of APS-U lattice, when the particle is within 1 to 10 σ of stored beam. It is demonstrated that most of the lower order resonance driving terms, plus chromatic and geometric aberrations are reasonably preserved by the Taylor map approach. Last but maybe most important, the computation time is reduced by a factor of 20 to 50, when compared to symplectic integration based element by element tracking. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB062 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 17 June 2021 issue date ※ 29 August 2021 | ||
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TUPAB066 | Status of the Short-Pulse Source at DELTA | laser, electron, undulator, bunching | 1518 |
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Funding: Work supported by BMBF (05K19PEB). At the synchrotron light source DELTA operated by the TU Dortmund University, the short-pulse source employs the seeding scheme coherent harmonic generation (CHG) and provides ultrashort pulses in the vacuum ultraviolet and terahertz regime. Here, the interaction of laser pulses with the stored electron bunches result in a modulation of the longitudinal electron density which gives rise to coherent emission at harmonics of the laser wavelength. Recently, investigations of the influence of the Gouy phase shift at the focal point of the laser pulses on the laser-electron interaction have been performed. For the planned upgrade towards the more sophisticated seeding scheme echo-enabled harmonic generation (EEHG) featuring a twofold laser-electron interaction, simulations of the ideal parameters of the laser beams have been carried out. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB066 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 22 July 2021 issue date ※ 28 August 2021 | ||
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TUPAB082 | Analysis of the Effect of Energy Chirp in Implementing EEHG at SXL | bunching, electron, FEL, linac | 1566 |
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As a part of the efforts to improve the longitudinal coherence in the design of the Soft X-ray FEL (the SXL) at MAX IV, we present a possible implementation of the EEHG harmonic seeding scheme partly integrated into the second bunch compressor of the existing LINAC. A special focus is given to the effect of CSR on the resulting EEHG bunching and on how this unwanted effect might be controlled. | |||
Poster TUPAB082 [1.825 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB082 | ||
About • | paper received ※ 15 May 2021 paper accepted ※ 28 July 2021 issue date ※ 17 August 2021 | ||
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TUPAB085 | Three-Dimensional Radiative Effects in the Compression of Ultra-Short Electron Micro-Bunches | emittance, FEL, electron, laser | 1577 |
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Funding: DOE Contract DE-SC0009914 DOE Contract DE-SC0020409 National Science Foundation Grant No. PHY-1549132 Micro-bunched current profiles have recently gained traction as an alternative to bulk compression in certain free-electron laser applications. The attraction of the micro-bunched structure is owed in part to its promise to minimize deleterious effects associated with coherent synchrotron radiation during compression. Simultaneously, these profiles push the boundaries of traditional one-dimensional CSR simulation models which assume the bunch length to far exceed the transverse beam size in the bunch rest frame - an assumption which may be violated by the sub-micron length micro-bunches. Here we present simulation studies of the impact of three-dimensional CSR effects on micro-bunching based compression schemes using the General Particle Tracer code. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB085 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 23 June 2021 issue date ※ 13 August 2021 | ||
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TUPAB094 | Multi-Start Foil Wound Solenoids for Multipole Suppression | solenoid, multipole, emittance, quadrupole | 1596 |
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Funding: National Science Foundation Grant No. PHY-1549132 - CBB, DE-SC0020409 Solenoids for beam transport are typically wound helically, with each layer of wire being laid down on top of the previous, or as "pancakes" where the wire is wound radially in before crossing over and winding out. Both of these approaches break rotational symmetry and introduce higher-order multipole moments which can be deleterious to beam emittance. For high brightness beams, this can be particularly problematic. To this end, a solenoid employing multi-start foil windings is simulated and compared to conventional choices. With appropriate design, this approach can forbid certain multipoles by symmetry. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB094 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 20 July 2021 issue date ※ 15 August 2021 | ||
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TUPAB098 | Recent Progress Toward a Conduction-Cooled Superconducting Radiofrequency Electron Gun | cavity, SRF, electron, accelerating-gradient | 1604 |
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Funding: This work was supported by the US Department of Energy (DOE) under contract DE-SC0018367 High-repetition-rate electron sources have widespread applications. This contribution discusses the progress toward a proof-of-principle demonstration for a conduction-cooled electron source. The source consists of a simple modification of an elliptical cavity that enhances the field electric field at the photocathode surface. The source was cooled to cryogenic temperatures and preliminary measurements for the quality factor and accelerating field were performed. Additionally, we present future plans to improve the source along with simulated beam-dynamics performances. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB098 | ||
About • | paper received ※ 29 May 2021 paper accepted ※ 17 June 2021 issue date ※ 17 August 2021 | ||
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TUPAB100 | FEL Design Elements of SABINA: A Free Electron Laser For THz-MIR Polarized Radiation Emission | undulator, radiation, electron, FEL | 1612 |
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Funding: SABINA is a project co-funded by Regione Lazio within POR-FESR 2014-2020 program. SABINA, acronym of "Source of Advanced Beam Imaging for Novel Applications", will be a Self-Amplified Spontaneous Emission Free Electron Laser (SASE FEL) providing a wide spectral range (from THz to MIR) of intense, short and variable polarization pulses for investigation in physics, chemistry, biology, cultural heritage, and material science. In order to reach these goals high brightness electron beams within a 30-100 MeV energy range, produced at SPARC photo-injector, will be transported up to an APPLE-X undulator through a dogleg. Space charge effects and Coherent Synchrotron Radiation (CSR) effects must be held under control to preserve beam quality. Studies on beam transport along the undulator and of the properties of the radiation field have been performed with "Genesis 1.3" simulation code. A downstream THz optics photon delivery system has also been designed to transport radiation on the long path from the undulator exit up to user experimental area. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB100 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 11 June 2021 issue date ※ 02 September 2021 | ||
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TUPAB101 | Monte Carlo Simulations and Neutron and Gamma Fluence Measurements to Investigate Stray Radiation in the European XFEL Undulator System | undulator, electron, radiation, neutron | 1615 |
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The European X-ray Free Electron Laser (XFEL) is an user facility research centre generating extremely bright and ultra-short SASE x-ray pulses. The laser flashes are generated when electrons of GeV energies pass the undulator systems. Even if the dominating contribution of the radiation field in the undulator is from spontaneous undulator radiation, also electron losses can be observed, e.g. during beam steering or due to beam halo, not captured by the upstream collimation system. The interactions of those particles with the vacuum vessel wall result in the emission of stray radiation. The LB 6419 detector allows to measure both the neutron and the gamma component in the pulsed radiation fields nearby the undulators*. Usually, the real-time measurements show the dominance of the gamma signals. However, in case of particle loss occurs, a neutron signal is observed. In addition, Monte Carlo (MC) simulations conducted using the Geant4 code indicate that neutrons are also present within the undulator’s magnets volume. In this work, we present the LB 6419 measurement data and compare these to our MC simulations, to characterize the radiation field nearby the undulator segment.
* KLETT, A., LEUSCHNER, A., TESCH, N., A dose meter for pulsed neutron fields, Radiat Meas 45 (2010) 1242-1244 |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB101 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 02 June 2021 issue date ※ 18 August 2021 | ||
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TUPAB103 | Discussion on CSR instability in EEHG Simulation | electron, bunching, laser, FEL | 1622 |
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Echo-Enabled Harmonic Generation (EEHG) is an external seeding technique for XUV and soft X-ray Free Electron Lasers (FEL). It has recently been experimentally demonstrated and currently many facilities worldwide intend to incorporate it in user operation. The EEHG process relies on very accurate and complex transformations of electron beam phase space by means of a series of undulators coupled to lasers and dispersive chicanes. As a result of the phase space manipulation, electrons are bunched at a high harmonic of the seed laser wavelength allowing coherent emission at few nm wavelength. Dispersion occurring in strong chicanes is imperative for implementation of this scheme and effective electron bunching generation. However, strong chicanes at the same time can be source of beam instability effects, such as Coherent Synchrotron Radiation (CSR), that can significantly grow in these conditions and suppress the bunching process. Therefore, there is a common need to investigate such effects in detail. Here, we discuss their treatment with simulation codes applied to a typical EEHG setup. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB103 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 17 June 2021 issue date ※ 12 August 2021 | ||
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TUPAB105 | Simulation Studies for Dark Current Signature From DLS RF Gun | electron, cavity, solenoid, cathode | 1630 |
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The Delhi Light source (DLS) is an upcoming compact THz facility at IUAC, New Delhi, based on pre-bunched FEL. RF conditioning of the 2.6 cell S-band RF gun is presently carried out with a Cu photo-cathode (PC) plug and dark current is produced when substantial accelerating field is reached inside the cavity. To identify the possible field emission sites contributing to dark current, single electron ASTRA simulations are done with a phase scan of the RF field. The simulation is extended to include multi-particle emission from the PC edge as a ring. The energies present in the dark current is analysed from the the Fowler Nordheim current plot and energy phase scan plot. The distribution of few dark current energies and their respective trajectories upto the YAG screen at a given solenoid setting is traced and shown in the simulations. We also present the dark current images captured during the initial RF conditioning and try to compare it with the simulations. | |||
Poster TUPAB105 [0.742 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB105 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 17 August 2021 issue date ※ 01 September 2021 | ||
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TUPAB106 | Simulation Calculations of Compact THz Facility at IUAC, New Delhi | undulator, radiation, electron, optics | 1633 |
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A compact THz radiation source based on the principle of pre-bunched Free Electron Laser is at the commissioning stage at Inter University Accelerator Centre (IUAC), New Delhi. The facility will generate low emittance train of electron micro-bunches (2, 4, 8 or 16 numbers) from a RF photo-cathode gun in the energy range of 4 to 8 MeV and inject into a compact undulator to generate coherent THz radiation in the frequency range of ~0.18 to 3.0 THz. To optimize the intensity at a given frequency, the beam bunching factor and the betatron oscillation amplitude in the non-wiggling plane of the electronμbunches inside the undulator has been maximized and minimized respectively. The paper presents the optimized beam optics simulation results for two frequencies viz 0.5 and 2 THz. The on-axis radiation spectral intensity computed by in-house developed code using the trajectory data of the beam optics simulation is also presented for the two frequencies. | |||
Poster TUPAB106 [1.208 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB106 | ||
About • | paper received ※ 18 May 2021 paper accepted ※ 31 August 2021 issue date ※ 12 August 2021 | ||
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TUPAB117 | Eigenmode Decomposition for Free-Electron Lasers Using Bayesian Analysis | optics, laser, FEL, distributed | 1666 |
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Funding: This work is supported in part by the US DOE grant no. DE-FG02-97ER41033. Laser beams from an optical cavity, such as free-electron laser (FEL) resonators, are typically a mixture of the cavity’s eigenmodes, such as the Hermite-Gaussian (HG) modes or Laguerre-Gaussian (LG) modes. Robust evaluation of the eigenmode spectrum of a multimode laser beam has various applications in laser development, research, and utilization. In this work, a general eigenmode decomposition method for a multimode laser beam has been developed based on Bayesian analysis. This problem is transformed into a linear system and then solved using a Gaussian probabilistic model. Using Bayesian analysis, prior knowledge about the mode content is further incorporated into the solution to improve the results for laser beams contaminated with complex disturbances. The decomposition of the beam image from the incoherent intensity addition of HG modes is discussed with different types of noise or disturbances. The simulation results have been used to show the robustness of this method. This method can be straightforwardly extended into other cases such as the wavefront decomposition into the coherent superposition of HG and LG modes. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB117 | ||
About • | paper received ※ 18 May 2021 paper accepted ※ 15 June 2021 issue date ※ 01 September 2021 | ||
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TUPAB119 | Beam Loss Study for the Implementation of Dechirper at the European XFEL | FEL, undulator, radiation, electron | 1670 |
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The European XFEL is a free-electron laser facility based on superconducting linac with high repetition rate up to 4.5 MHz. Wakefield structure (also called dechirper module) is planned to be installed in front of the SASE beam line at the European FEL, which can be used as a kicker for two-color scheme or a dechirper to control the bandwidth of SASE radiation. When the beam pass through the dechirper module, strong longitudinal and transverse wakefields can be excited to introduce a correlated energy chirp and a kick along the bunch. However, due to the relatively small gap of dechirper, beam halo particles hitting the dechirper module can lead to energy deposition and generate additional radiation, which can cause serious damage to the downstream undulators. For this reason, simulations have been performed using BDSIM to define the maximum acceptable beam halo, and the results are presented in this paper. | |||
Poster TUPAB119 [1.489 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB119 | ||
About • | paper received ※ 16 May 2021 paper accepted ※ 15 June 2021 issue date ※ 12 August 2021 | ||
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TUPAB125 | Studies of Particle Losses From the Beam in the EU-XFEL Following Scattering by a Slotted Foil | undulator, radiation, FEL, diagnostics | 1681 |
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One technique for producing short radiation pulses in an FEL involves the use of a slotted foil in a bunch compressor. However, the scattering of particles from the foil can lead to increased particle losses and the generation of secondary particles. This is a particular concern for high rep-rate FELs, such as the European XFEL, where there are plans to implement the slotted-foil technique for short pulse generation. The study reported here aims to characterise the impact of a slotted foil in the European XFEL on the radiation dose in the front section of one of the undulators. Simulations were performed using BDSIM: this code tracks primary particles along the beamline, models the interaction between particles and accelerator components and tracks secondary particles produced by these interactions. The results indicate the amount of energy deposited in the front section of one of the FEL undulators, and provide a basis for optimisation of the collimation system to keep the energy deposition and radiation doses within acceptable limits. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB125 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 10 June 2021 issue date ※ 28 August 2021 | ||
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TUPAB127 | Spare Gun Multi-Physics Analysis for LCLS-II | gun, cavity, cathode, electron | 1688 |
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LBNL APEX VHF normal conducting gun was adopted for LCLS-II CW operation to provide ultra-bright high repetition rate X-ray pulses. The initial LCLS-II gun and injector commissioning showed excessive dark current dominated by field emission around the cathode plug outer diameter and the gun cavity nose. There is a concern that the dark current may get worse with time of operation. It is planning to build a spare rf gun largely based on the current LCLS-II gun to replace current LCLS-II gun. The proposed spare gun has a reduced the peak electrical fields around the cathode plug corner and cavity nose by 10% through further optimizing APEX gun cavity shape. In addition, there are some moderate modifications on the engineering design to increase mechanical robustness and vacuum performance. SLAC developed parallel finite-element electromagnetic code suite ACE3P is used to apply for the spare gun modeling including RF, thermal and structural analysis at static and transient states to ensure its successful operation in LCLS-II. In this paper, the spare gun multi-physics analysis is described. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB127 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 25 August 2021 issue date ※ 12 August 2021 | ||
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TUPAB133 | Brazing free RF Pulse Compressor for High Gradient Accelerators | GUI, cavity, coupling, vacuum | 1700 |
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EURPRAXIA@SPARC\LAB, is a proposal to upgrade the SPARC\LAB test facility (at LNF, Frascati) to a soft X-ray user facility based on plasma acceleration and high-gradient X-band (11.9942 GHz) accelerating modules. Each module is made up of a group of 4 TW sections assembled on a single girder and fed by one klystron by means of one rf pulse compressor system and a low attenuation circular waveguide network that transports the rf power to the input hybrids of the sections. The pulse compressor is based on a single Barrel Open Cavity (BOC). The BOC use a ’whispering gallery’ mode which has an intrinsically high quality factor and operates in a resonant rotating wave regime. Compared to the conventional SLED scheme it requires a single cavity instead of two cavities and a 3-dB hybrid. A new brazeless mechanical design has been proposed and is described in the present paper together with the electro-magnetic and thermo-mechanical simulations. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB133 | ||
About • | paper received ※ 21 May 2021 paper accepted ※ 15 June 2021 issue date ※ 10 August 2021 | ||
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TUPAB142 | Simulation Study of Laser Wakefield Acceleration Varying the Down-Ramp Length of a Gas Jet | electron, plasma, laser, injection | 1717 |
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In this work, particle-in-cell simulations were carried out to investigate the role of the down-ramp length of a H\textsubscript{2} gas jet in accelerating electrons ionized by the laser pulse. The laser and plasma density were chosen so that the system is operating in the self-modulated regime. Preliminary results show how the down-ramp length can control the injection of electrons in the first bubble induced in the plasma by the laser pulse. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB142 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 15 June 2021 issue date ※ 13 August 2021 | ||
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TUPAB143 | Laser Pulse Dynamics in the Self-Modulated Regime | laser, electron, plasma, wakefield | 1721 |
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In this work, particle-in-cell simulations were carried out to investigate the dynamics of a laser pulse propagating along a H2 gas jet. The laser-driven wakefield and the density of ionized electrons are analyzed during the pulse propagation through the gas jet. The laser and plasma quantities were chosen in order to have the system operating in the self-modulated regime. Results show how the self-modulation fragments the laser pulse, originating higher-amplitude pulses that can induce bubble formation with wave-breaking and particle injection. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB143 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 14 June 2021 issue date ※ 21 August 2021 | ||
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TUPAB145 | Methods for Numerical Noise Mitigation in Quasistatic Three-Dimensional Particle-in-Cell Code LCODE3D | plasma, wakefield, acceleration, electron | 1725 |
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We discuss a new quasistatic 3D particle-in-cell code LCODE3D for simulating plasma wakefield acceleration, which is a modified version of the quasistatic 2D3V code LCODE, focus on the numerical noise of the plasma solver and propose methods for reducing it. We compare different particle shape functions, as these functions affect the code stability. We also introduce the so-called dual plasma approach, which improves stability and dampens small-scale noise. After applying the proposed methods, the results of the new code closely agree with LCODE simulation results. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB145 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 17 June 2021 issue date ※ 25 August 2021 | ||
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TUPAB147 | Asymmetric Beam Driven Plasma Wakefields at the AWA | plasma, wakefield, emittance, electron | 1732 |
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Funding: This work was performed with the support of the US Department of Energy, Division of High Energy Physics under Contract No. DE-SC0017648 and DE-SC0009914 In future plasma wakefield acceleration-based scenarios for linear colliders, beams with highly asymmetric emittance are expected. In this case, the blowout region is no longer axisymmetric, but elliptical in cross-section, which implies that the focusing is not equal in the two transverse planes. In this paper, we analyze simulations for studying the asymmetries in flat-beam driven plasma acceleration using the round-to-flat-beam transformer at the Argonne Wakefield Accelerator. Beams with high charge and emittance ratios, in excess of 100:1, are routinely available at the AWA. We use particle-in-cell codes to compare various scenarios including a weak blowout, where the plasma focusing effect exhibits higher order mode asymmetry. Further, practical considerations for tunable plasma density using capillary discharge and laser ionization are compared for implementation into experimental designs. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB147 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 13 July 2021 issue date ※ 02 September 2021 | ||
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TUPAB153 | Modeling of Capillary Discharge Plasmas for Wakefield Accelerators and Beam Transport | plasma, laser, electron, GUI | 1740 |
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Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics under Award Number DE-SC0018719. Next generation accelerators demand sophisticated beam sources to reach ultra-low emittances at large accelerating gradients, along with improved optics to transport these beams without degradation. Capillary discharge plasmas can address each of these challenges. As sources, capillaries have been shown to increase the energy and quality of wakefield accelerators, and as active plasma lenses they provide orders-of-magnitude increases in peak magnetic field. Capillaries are sensitive to energy deposition, heat transfer, ionization dynamics, and magnetic field penetration; therefore, capillary design requires careful modeling. We present simulations of capillary discharge plasmas using FLASH, a publicly-available multi-physics code developed at the University of Chicago. We report on the implementation of 2D and 3D models of capillary plasma density and temperature evolution with realistic boundary and discharge conditions. We then demonstrate laser energy deposition to model channel formation for guiding intense laser pulses. Lastly, we examine active capillary plasmas with varying fill species and compare our simulations against experimental studies. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB153 | ||
About • | paper received ※ 24 May 2021 paper accepted ※ 29 July 2021 issue date ※ 30 August 2021 | ||
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TUPAB157 | Obtaining Long Accelerated Electron Bunch of Good Quality in Plasma Wakefield Accelerator at High Transformer Ratio | wakefield, plasma, electron, acceleration | 1750 |
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Funding: "This work is supported by National Research Fundation of Ukraine "Leading and Young Scientists Research Support", grant agreement # 2020.02/0299." The efficiency of electron acceleration by a wakefield, excited in a plasma by an electron bunch, is determined by the transformer ratio (see *, **). The transformer ratio is the ratio of energy acquired by the witness to energy lost by the driver. The transformer ratio can be increased by shaping driver-bunch. In this work, using a non-linear version of the 2d3v code lcode (see ***), numerical simulation of excitation of a wakefield in a plasma in blowout regime by a shaped relativistic electron bunch was performed. There is also the problem of maintaining the small dimension and small energy spread of the accelerated electron bunch while maintaining sufficient values of the accelerating gradient and the transformer ratio. Also, the question arises about the values of the limiting dimension of the witness-bunch at which the acceleration process is stable. Numerical simulation solves the problem of electron bunch acceleration of the best quality with simultaneous maximization of the transformer ratio and maximization of the witness bunch length, at which the accelerating gradient and the focusing force are constant. *Maslov V.I. et al. Problems of Atomic Science and Technology. 4 (2012) 128. **Baturin S.S., Zholents A. Phys. Rev. ST Accel. Beams. 20 (2017) 061302. ***Lotov K.V. Phys. Plasmas. 5 (1998) 785. |
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Poster TUPAB157 [1.920 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB157 | ||
About • | paper received ※ 18 May 2021 paper accepted ※ 23 June 2021 issue date ※ 30 August 2021 | ||
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TUPAB160 | Preparation for Electron-Seeding of Proton Bunch Self-Modulation in AWAKE | electron, plasma, proton, experiment | 1761 |
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The next milestone of the Advanced Wakefield Experiment (AWAKE) at CERN will be to demonstrate that the self-modulation of a long proton bunch can be seeded by a short electron bunch preceding it. This seeding method will lead to phase-reproducible self-modulation of the entire proton bunch, as required for the future AWAKE program. In the Spring of 2021, before receiving proton beams from the CERN SPS, AWAKE plans to hold a dry run of the electron seeding experiments, to commission the system and to determine the parameter scans that will be used in experiments with protons. Electron bunches of 10-20 MeV with varying charge, radius, emittance and energy will be sent in 10 m of low-density plasma. The effects of beam-plasma interactions on the amplitude of the wakefields driven by the different bunches will be studied by observing the energy spectra at the end of the plasma. This paper presents preliminary experimental results from the first two days of measurements as well as the beginning of a simulation-based study of electron propagation in plasma. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB160 | ||
About • | paper received ※ 18 May 2021 paper accepted ※ 15 June 2021 issue date ※ 27 August 2021 | ||
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TUPAB176 | ESS Proton Beam Trajectory Correction | MEBT, linac, DTL, ion-source | 1809 |
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The proton linac of the European Spallation Source (ESS) is under construction in Lund, Sweden. Beam trajectory correction is essential to mitigate the effect of accelerator element misalignment, constituting the first step to minimise beam losses. The correction will be performed using correctors distributed along the accelerator, based on the beam position monitor (BPM) readout. Three trajectory correction techniques are considered: one-to-one steering, Singular Value Decomposition (SVD), and MICADO (selecting a subset of correctors for the trajectory correction). The performance of the three methods is simulated for the ESS linac and a comparison of the outcomes is presented. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB176 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 15 June 2021 issue date ※ 27 August 2021 | ||
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TUPAB177 | Simulating Magnetized Electron Cooling for EIC with JSPEC | electron, scattering, target, HOM | 1813 |
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We present a possible electron cooling configuration for the proposed Electron Ion Collider (EIC) facility, developed using a Nelder-Mead Simplex optimization procedure built into JSPEC, an electron cooling code developed at Jefferson Lab. We show the time evolution of the emittance of the ion beam in the presence of this cooler evaluated assuming the ion distribution remains Gaussian. We also show that bi-gaussian distributions emerge in simulations of ion macro-particles. We show how intra-beam scattering can be treated with a core-tail model in simulations of ion macro-particles. The Sirepo/JSPEC* and Sirepo/Jupyter** apps will be presented, with instructions enabling the community to reproduce our simulations.
* https://www.sirepo.com/jspec ** https://www.sirepo.com/jupyter |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB177 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 15 June 2021 issue date ※ 16 August 2021 | ||
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TUPAB179 | Design of an MBEC Cooler for the EIC | electron, proton, kicker, hadron | 1819 |
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Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. Reaching maximal luminosity for the planned electron-ion collider (EIC) calls for some form of strong hadron cooling to counteract beam emittance increase from IBS. We discuss plans to use microbunched electron cooling (MBEC) to achieve this. The principle of this method is that the hadron beam will copropogate with a beam of electrons, imprinting its own density modulation on the electron beam. These electron phase space perturbations are amplified before copropogating with the hadrons again in a kicker section. By making the hadron transit time between modulator and kicker dependent on hadron energy and transverse offset, the energy kicks which they receive from the electrons will tend to reduce their longitudinal and transverse emittances. We discuss details of the analytic theory and searches for optimal realistic parameter settings to achieve a maximal cooling rate while limiting the effects of diffusion and electron beam saturation. We also place limits on the necessary electron beam quality. These results are corroborated by simulations. |
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Poster TUPAB179 [4.006 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB179 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 18 June 2021 issue date ※ 24 August 2021 | ||
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TUPAB180 | Plasma Simulations for an MBEC Cooler for the EIC | electron, hadron, kicker, proton | 1823 |
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Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. In order to reach its maximum luminosity, the electron-ion collider (EIC) is being designed to use microbunched electron cooling (MBEC) to cool the hadron beam. This involves having the hadron beam imprint on a beam of electrons, enhancing the perturbations in the electron beam using the microbunching instability, and feeding back on the original hadron beam to correct deviations in hadron energy, and, through the use of dispersion, the transverse emittances. This process has been modelled analytically in the linear regime*. However, in order to maximize the cooling rate, we wish to know how much saturation in the electron beam is acceptable before the effects of nonlinearity cause significant deviations from the analytic results. To understand this, we have developed a code to do fast one-dimensional plasma simulations of hadrons and electrons as they move through the MBEC section of the EIC. In addition to permitting us to understand the effects of saturation, other effects are included which do not fit easily in the analytic formalism. * G. Stupakov and P. Baxevanis, PRAB 22, 034401 (2019). |
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Poster TUPAB180 [1.955 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB180 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 18 August 2021 | ||
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TUPAB191 | Design and Simulation of the Axial Injection Beam Line of DC140 Cyclotron of FLNR JINR | cyclotron, injection, ECR, radiation | 1852 |
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Flerov Laboratory of Nuclear Reaction of Joint Institute for Nuclear Research carries out the works under creating of FLNR JINR Irradiation Facility based on the cyclotron DC140. The facility is intended for SEE testing of microchip, for production of track membranes and for solving of applied physics problems. The main systems of DC140 are based on the DC72 cyclotron ones that now are under reconstruction. The DC140 cyclotron is intended for acceleration of heavy ions with mass-to-charge ratio A/Z within interval from 5 to 5.5 up to two fixed energies 2.124 and 4.8 MeV per unit mass. The intensity of the accelerated ions will be about 1 pmcA for light ions (A<86) and about 0.1 pmcA for heavier ions (A>132). The injection into cyclotron will be realized from the external room temperature 18 GHz ECR ion source. The design and simulation of the axial injection system of the DC140 cyclotron is presented in this report. | |||
Poster TUPAB191 [1.090 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB191 | ||
About • | paper received ※ 14 May 2021 paper accepted ※ 28 May 2021 issue date ※ 22 August 2021 | ||
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TUPAB203 | Electromagnetic Simulations of a Novel Proton Linac Using VSim on HPC | linac, rfq, operation, controls | 1887 |
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Funding: This work is supported by the U.S. Department of Energy, award number DE-SC0019468; It used resources of the Argonne Leadership Computing Facility, contract DE-AC02-06CH11357, and from Element Aero. We discuss electromagnetic simulations of accelerating structures in a high performance computing (HPC) system. Our overarching goal is to resolve the linac operation in a large ensemble of initial beam conditions. This requires a symbiotic relation between the electromagnetic solver and HPC. The linac is being developed by Ion Linac Systems to produce a low-energy, high-current, proton beam. We use VSim, an electromagnetic solver and PIC software developed by Tech-X to determine the electromagnetic fundamental mode of operation of the accelerating structures and discuss its implementation at the THETA supercomputer in the Argonne Leadership Computing Facility. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB203 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 17 June 2021 issue date ※ 10 August 2021 | ||
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TUPAB216 | Modeling Particle Stability Plots for Accelerator Optimization Using Adaptive Sampling | network, collider, resonance, dynamic-aperture | 1923 |
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Funding: This work is partially funded by the Swiss Data Science Center (SDSC), project C18-07. One key aspect of accelerator optimization is to maximize the dynamic aperture (DA) of a ring. Given the number of adjustable parameters and the compute-intensity of DA simulations, this task can benefit significantly from efficient search algorithms of the available parameter space. We propose to gradually train and improve a surrogate model of the DA from SixTrack simulations while exploring the parameter space with adaptive sampling methods. Here we report on a first model of the particle stability plots using convolutional generative adversarial networks (GAN) trained on a subset of SixTrack numerical simulations for different ring configurations of the Large Hadron Collider at CERN. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB216 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 17 June 2021 issue date ※ 22 August 2021 | ||
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TUPAB224 | Non-Linear Variation of the Beta-Beating Measured From Amplitude | octupole, optics, resonance, target | 1949 |
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Accelerator physics needs advanced modeling and simulation techniques, for beam stability studies but also for the measurement of beam parameters like the Twiss parameters. A deeper understanding of magnetic field non-linearities effects will greatly help in the improvement of future circular collider design, performance, and diagnostics. This paper studies the variation of the \beta-beating with the action of the particle generated by non-linear Resonance Driving Terms, both from a theoretical and an experimental point of view. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB224 | ||
About • | paper received ※ 18 May 2021 paper accepted ※ 06 July 2021 issue date ※ 21 August 2021 | ||
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TUPAB226 | Study of the Third-Order Parametric Resonance Induced by RF Modulation | storage-ring, synchrotron, electron, injection | 1956 |
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There were both analytic and experimental studies on the effects of RF modulation on bunch lengthening in electron storage rings. Nevertheless, the increase of bunch energy spread will happen in the meantime. Therefore, the degradation of bunch quality may limit the potential applications of the RF modulation technique. As a consequence, we believe that the comprehensive studies of the parametric resonance induced by RF modulation are necessary for understanding the physics picture better and seeking new possibilities of applications of this technique. The studies on the beam dynamics closed to the 3vs RF phase modulation would be presented here. Based on the basic longitudinal synchrotron equations of motion, we obtained analytically the longitudinal modulated Hamiltonian and various parameters in longitudinal phase space, such as the fixed points, island tune, island width. The validity of the analytic results was checked by simulations. Furthermore, the dependence of the bunch parameters, such as energy spread and bunch length, on the modulation settings is also discussed in this paper. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB226 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 13 August 2021 | ||
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TUPAB228 | IOTA Run 2 Beam Dynamics Studies in Nonlinear Integrable Systems | optics, octupole, experiment, lattice | 1964 |
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Funding: Work supported by the U.S. NSF under award PHY-1549132, the Center for Bright Beams. Fermi Research Alliance, LLC operates Fermilab under Contract DE-AC02-07CH11359 with the US Department of Energy. Nonlinear integrable optics is a promising design approach for suppressing fast collective instabilities. To study it experimentally, a new storage ring, the Integrable Optics Test Accelerator (IOTA), was built at Fermilab. IOTA has recently completed its second scientific run, incorporating many hardware and instrumentation improvements. This report presents the results of the two integrable optics experiments - the quasi-integrable Henon-Heiles octupole system and the fully integrable Danilov-Nagaitsev system. We demonstrate tune spread and dynamic aperture in agreement with tracking simulations, and a stable crossing of the integer resonance. Based on recovered single-particle phase space dynamics, we show improved invariant jitter consistent with intended effective Hamiltonian. We conclude by outlining future plans and efforts towards proton studies and larger designs. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB228 | ||
About • | paper received ※ 31 May 2021 paper accepted ※ 23 June 2021 issue date ※ 10 August 2021 | ||
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TUPAB234 | Exploring Accelerators for Intense Beams with the IBEX Paul Trap | octupole, lattice, quadrupole, experiment | 1980 |
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Accelerators built from linear components will exhibit bounded and stable particle motion in the ideal case. However, any imperfections in field strength or misalignment of components can introduce chaotic and unstable particle motion. All accelerators are prone to such non-linearities but the effects are even more significant in high intensity particle beams with the presence of space charge effects. This work aims to explore the non-linearities which arise in high intensity particle beams using the scaled experiment, IBEX. The IBEX experiment is a linear Paul trap that allows the transverse dynamics of a collection of trapped particles to be studied by mimicking the propagation through multiple quadrupole lattice periods whilst remaining stationary in the laboratory frame. IBEX is currently undergoing a non-linear upgrade with the goal of investigating Non-linear Integrable Optics (NIO) in order to improve our understanding and utilisation of high intensity particle beams. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB234 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 18 June 2021 issue date ※ 12 August 2021 | ||
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TUPAB236 | Progress on the Electron Gun Design for a McMillan Electron Lens in the Fermilab Integrable Optics Test Accelerator (IOTA) | electron, gun, cathode, optics | 1988 |
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Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. This paper covers the progress made so far in designing the first McMillan electron lens for the Fermilab IOTA ring. The novel design allows for an increase in tune spread without limiting the dynamic aperture due to its integrability. Shown are simulations for an electron gun design to generate the specific required current density distribution for the nonlinear integrable system in IOTA. |
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Poster TUPAB236 [5.391 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB236 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 19 July 2021 issue date ※ 10 August 2021 | ||
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TUPAB244 | THE WAKEFIELD STUDY OF THE RF-SHIELDED BELLOWS AT THE ILSF STORAGE RING | impedance, wakefield, factory, vacuum | 2015 |
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The corrugated geometry of the bellows made it critical to be shielded with an RF-Shield. Different types of RF shields can be applied to the ILSF vacuum chamber to cover this component’s destructive impedance peaks. Then, the Impedance study and optimization of the RF shields can improve the impedance budget. In this article, two common types of RF shields are simulated in CST software. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB244 | ||
About • | paper received ※ 16 May 2021 paper accepted ※ 02 June 2021 issue date ※ 14 August 2021 | ||
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TUPAB245 | WAKEFIELD AND HEAT LOAD STUDY OF THE GATE VALVES AT ILSF STORAGE RING | impedance, storage-ring, wakefield, resonance | 2018 |
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As one part of the ILSF storage ring, the rf-shield of the gate valves generates considerable interest in terms of wake impedance and heat-load. Inside the gate valves, there is a vacuity, which causes low frequencies resonances, and it can lead to beam instabilities. Therefore, controlling and eliminating these frequencies will be substantial. A radio frequency rf-shield structure, which conceals this transverse gap of the gate valves, is indispensable for low emittance chambers. This paper analyzes the wake impedance and thermal behavior of a finger-band RF shield in the gate valve. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB245 | ||
About • | paper received ※ 16 May 2021 paper accepted ※ 14 June 2021 issue date ※ 13 August 2021 | ||
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TUPAB247 | Influence of the Profile of the Dielectric Structure on the Electric Fields Excited by a Laser in Dielectric Accelerators Based on Chip | electron, acceleration, laser, experiment | 2026 |
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Funding: The National Research Foundation of Ukraine, program "Leading and Young Scientists Research Support" (project # 2020.02/0299). To provide experimental researches at the NSC KIPT theoretical studies and computations of the electron acceleration in a dielectric laser accelerator have been carried out. Laser accelerator consists of two periodic quartz structures on diffraction gratings or Chips, symmetrically located along both sides of the vacuum accelerating channel. Using PIC numerical simulations, electromagnetic fields excited by laser radiation with a wavelength of 800 nm in dielectric laser accelerators were investigated. The influence of the shape and depth of the profile of diffraction gratings or Chip structures on the distribution of the electric field in the interaction space has been studied. For modeling, different types of profiles were taken, both in serial and a unique structure. In consequence of the analysis of the obtained results, estimated efficiency of acceleration was defined for each type of profile. The rectangular profile of the diffraction grating with the maximum accelerating gradient was selected as optimal for the next experiments. |
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Poster TUPAB247 [1.195 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB247 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 31 May 2021 issue date ※ 11 August 2021 | ||
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TUPAB248 | A Parallel Time Domain Thermal Solver for Transient Analysis of Accelerator Cavities | cavity, gun, background, software | 2030 |
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Funding: Work supported by US DOE under contract AC02-76SF00515. Simulation of thermal effects in accelerator cavity is normally performed assuming steady state solution where a static thermal solver suffices to evaluate temperature gradients and impacts on mechanical design. However, during the rf pulse ramp up or the machine system cool-down process, when the field in the cavity changes rapidly, transient effects need to be taken into account. A parallel time domain thermal solver has been developed in the finite element multi-physics code suite ACE3P with integrated electromagnetic, thermal and mechanical modeling capabilities. The implementation takes advantage of the parallel computation infrastructure of ACE3P and shares most of the ingredients in mesh generation, matrix assembly, time advancement scheme and postprocessing. In this paper, we will outline the finite element formulation of the transient thermal problem and verify the implementation against analytical solutions and existing numerical results. The thermal solver has also been coupled to ACE3P mechanical solver, allowing stress and strain analysis during the transient stage. Application of the transient thermal solver to realistic accelerator cavities will be presented. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB248 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 25 August 2021 issue date ※ 02 September 2021 | ||
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TUPAB250 | Axicon-Based Concentrator for Cherenkov Radiation | target, radiation, focusing, diagnostics | 2036 |
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Funding: Work supported by Russian Science Foundation (Grant No. 18-72-10137). We propose a new type of axisymmetric dielectric target - an "axicon-based concentrator" - which effectively concentrates generated Cherenkov radiation (CR) into a small vicinity of a focus point. It consists of two "glued" bodies of revolution: a hollow axicon and a hollow "lens." A theoretical investigation of the radiation field produced by a charge moving through the discussed radiator is performed for the general case where a charge trajectory is shifted with respect to the structure axis. The idea of a dielectric target with a specific profile of the outer surface and suitable analytical methods were presented and developed in our preceding papers *, **. An essential advantage of the current version of the device is that it allows the efficient concentration of CR energy from relativistic particles, making this device extremely prospective for various applications such as beam-driven THz sources and bunch diagnostic systems. * S.N. Galyamin et al., Phys. Rev. Accel. Beams 22, 083001 (2019); 22, 109901 (2019). ** A.V. Tyukhtin et al., Phys. Rev. A 102, 053514 (2020). |
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Poster TUPAB250 [1.255 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB250 | ||
About • | paper received ※ 24 May 2021 paper accepted ※ 21 June 2021 issue date ※ 12 August 2021 | ||
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TUPAB251 | Impedance Studies of a Corrugated Pipe for KARA | impedance, resonance, radiation, electron | 2039 |
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Funding: DFG project 431704792 in the ANR-DFG collaboration project ULTRASYNC and the DFG-funded Doctoral School "Karlsruhe School of Elementary and Astroparticle Physics: Science and Technology". At the KIT storage ring KARA (KArlsruhe Research Accelerator) it is planned to install an impedance manipulation structure in a versatile chamber to study and eventually control the influence of an additional impedance on the beam dynamics and the emitted coherent synchrotron radiation. For this purpose the impedance of a corrugated pipe is under investigation. In this contribution, we present first results of simulations showing the impact of different structure parameters on its impedance and wake potential. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB251 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 17 June 2021 issue date ※ 26 August 2021 | ||
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TUPAB252 | Minimization of NICA Collider Impedance | impedance, collider, space-charge, resonance | 2043 |
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The paper presents the results of the longitudinal impedance minimization for the beam tube section in the arches of the NICA collider ring, consisting of a pumping pipe, a BPM station, and a bellows assembly, and considers the contribution of the impedance of this section to the ion beam stability in the NICA collider ring. To confirm the efficiency of the optimized design, a BPM prototype was fabricated, and a test bench was built for further laboratory measurements. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB252 | ||
About • | paper received ※ 13 May 2021 paper accepted ※ 14 June 2021 issue date ※ 10 August 2021 | ||
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TUPAB256 | Investigation of Damping Effects of the Crab Cavity Noise Induced Emittance Growth | emittance, impedance, cavity, experiment | 2054 |
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Crab cavities will be installed at the two main interaction points (IP1 and IP5) of the High Luminosity LHC (HL-LHC) in order to minimize the geometric reduction of the luminosity due to the crossing angle. Two prototype crab cavities have been installed into the SPS machine and were tested with a proton beam in 2018, to study the expected emittance growth induced by RF noise. The measured emittance growth was found to be a factor 2-3 lower than predicted from the available analytical and computational models. Damping mechanisms from the transverse impedance, which is not included in the available theories, are studied as a possible explanation for the observed discrepancy. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB256 | ||
About • | paper received ※ 18 May 2021 paper accepted ※ 18 June 2021 issue date ※ 23 August 2021 | ||
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TUPAB261 | The Ferrite Loaded Cavity Impedance Simulation | cavity, impedance, MMI, synchrotron | 2070 |
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Funding: Work supported by NNSF of China: N0. U1832210 The Rapid Cycling Synchrotron of the China Spallation Neutron Source is a high-intensity proton accelerator, it accumulates the 80 MeV proton beam and accelerates it to 1.6 GeV in 20 ms. The transverse coupling bunch instability is observed in beam commissioning. The source has been investigating from the commissioning. The RF acceleration system consists of eight ferrite-loaded cavities. The impedance is simulated and there is a narrow-band impedance of the ferrite cavity at about 17 MHz |
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Poster TUPAB261 [1.145 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB261 | ||
About • | paper received ※ 13 May 2021 paper accepted ※ 31 May 2021 issue date ※ 21 August 2021 | ||
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TUPAB265 | Bunch Lengthening of the HALF Storage Ring in the Presence of Passive Harmonic Cavities | cavity, storage-ring, damping, emittance | 2082 |
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A passive 3rd harmonic RF system, being necessary for the Hefei Advanced Light Facility (HALF) storage ring under design, will be employed to lengthen the bunches for suppressing the intrabeam scattering and improving the beam lifetime. However, the transient beam loading due to the fundamental mode may significantly reduce the bunch lengthening. Since the scale of transient effects is proportional to R/Q, the effects of R/Q on bunch lengthening, in uniform fill pattern with the near-optimum condition fulfilled, are analyzed by multibunches multiparticles tracking simulation. It indicates that the passive superconducting harmonic cavity with a lower R/Q is preferred by HALF. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB265 | ||
About • | paper received ※ 16 May 2021 paper accepted ※ 18 June 2021 issue date ※ 20 August 2021 | ||
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TUPAB266 | Periodic Transient Beam Loading Effects Predicted by a Semi-Analytical Method | cavity, beam-loading, storage-ring, wakefield | 2086 |
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In this paper, we improve a semi-analytical method, which can be not only used for bunch lengthening under equilibrium conditions, but also applied to the prediction of a periodic transient beam loading effect. This periodic transient is induced by the presence of the passive harmonic cavity and might be encountered under specific conditions for a ultra-low emittance storage ring with a higher beam current. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB266 | ||
About • | paper received ※ 16 May 2021 paper accepted ※ 21 June 2021 issue date ※ 24 August 2021 | ||
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TUPAB267 | Investigation of Beam Impedance and Heat Load in a High Temperature Superconducting Undulator | undulator, impedance, laser, site | 2089 |
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The use of high temperature superconducting (HTS) materials can enhance the performance of superconducting undulators (SCU), which can later be implemented in free electron laser facilities, synchrotron storage rings and light sources. In particular, the short period < 10 mm undulators with narrow magnetic gap < 4 mm are relevant. One of the promising approaches considers a 10 cm meander-structured HTS tapes stacked one above the other. Then, the HTS tape is wound on the SCU. The idea of this jointless undulator has been proposed by, and is being further developed at KIT. Since minimizing the different sources of heat load is a critical issue for all SCUs, a detailed analysis of the impedance and heat load is required to meet the cryogenic system design. The dominant heat source is anticipated to be the resistive surface loss, which is one of the subjects of this study. Considering the complexity of the HTS tape, the impedance model includes the geometrical structure of the HTS tapes as well as the anomalous skin effect. The results of the numerical investigation performed by the help of the CST PS solver will be presented and discussed. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB267 | ||
About • | paper received ※ 18 May 2021 paper accepted ※ 26 July 2021 issue date ※ 12 August 2021 | ||
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TUPAB270 | Thermal Transition Design and Beam Heat-load Estimation for the COLDDIAG Refurbishment | vacuum, operation, cryogenics, diagnostics | 2097 |
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Funding: This work is supported by the BMBF project 05H18VKRB1 HIRING (Federal Ministry of Education and Research). The COLDDIAG (cold vacuum chamber for beam heat load diagnostics) developed at Karlsruhe Institute of Technology has been modified for more studies at cryogenic temperatures different from the previous operations at 4 K in a cold bore and at 50 K in a thermal shield. The key components in this campaign are two thermal transitions connecting both ends of the bore at 50 K with the shield at the same or higher temperature. In this paper, we present design efforts for the compact transitions, allowed heat intakes to the cooling power margin and mechanical robustness in the cryogenic environment. A manufacture scheme for the transition and its peripheral is also given. In addition, the beam heat loads in the refurbished COLDDIAG are estimated in terms of the accelerator beam parameters. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB270 | ||
About • | paper received ※ 12 May 2021 paper accepted ※ 02 June 2021 issue date ※ 12 August 2021 | ||
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TUPAB278 | The HL-LHC Beam Gas Vertex Monitor - Simulations for Design Optimisation and Performance Study | detector, target, impedance, hadron | 2120 |
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The Beam Gas Vertex (BGV) instrument is a non-invasive transverse beam profile monitor being designed as part of the High Luminosity Upgrade of the LHC (HL-LHC) at CERN. Its aim is to continuously measure bunch-by-bunch beam profiles, independent of beam intensity, throughout the LHC cycle. The primary components of the BGV monitor are a gas target and a forward tracking detector. Secondary particles emerging from inelastic beam-gas interactions are detected by the tracker. The beam profile is then inferred from the spatial distribution of reconstructed vertices of said interactions. Based on insights and conclusions acquired by a demonstrator device that was operated in the LHC during Run 2, a new design is being developed to fulfill the HL-LHC specifications. This contribution describes the status of the simulation studies being performed to evaluate the impact of design parameters on the instrument’s performance and identify gas target and tracker requirements. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB278 | ||
About • | paper received ※ 18 May 2021 paper accepted ※ 21 June 2021 issue date ※ 30 August 2021 | ||
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TUPAB281 | Gas-Mixing to Improve the Resolution of Non-Invasive Gas Jet-Based Ionization Profile Monitors | injection, electron, background, vacuum | 2132 |
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Funding: This work is supported by the HL-LHC-UK project funded by STFC and CERN and the STFC Cockcroft core grant No. ST/G008248/1. Ionization beam profile monitor using a supersonic gas jet is an attractive option for the characterization of low and medium energy beams. In this scheme, a primary beam crosses a 45-degree tilted thin gas curtain which causes ionization of gas molecules in the jet. The generated ions are then collected using an electrostatic extraction system to determine the 2D transverse profile of the primary beam. The most commonly used gases for the jet are neon and nitrogen. The signal from the gas jet is always super-imposed with the signal resulting from residual gases in the interaction chamber. CST simulations indicate that the gas jet speed is a key factor for the separation of the jet and the residual gas signals. To obtain a good signal separation, one can increase the velocity of the gas jet. This can be accomplished by generating a gas jet that mixes heavier and lighter gases. This contribution gives a general overview of the monitor design, discusses the effects of gas mixing and CST simulation results. It also presents experimental results obtained with Helium, and Nitrogen, as well as a mixture of them using different percentages and the impact on measurement resolution. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB281 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 02 June 2021 issue date ※ 13 August 2021 | ||
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TUPAB285 | Broadband Imaging of Coherent Radiation as a Single-Shot Bunch Length Monitor with Femtosecond Resolution | radiation, electron, detector, network | 2147 |
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Funding: This work is supported by the AWAKE-UK project funded by STFC and the STFC Cockcroft core grant No. ST/G008248/1 Bunch length measurements with femtosecond resolution are a key component in the optimisation of beam quality in FELs, storage rings, and plasma-based accelerators. This contribution presents the development of a novel single-shot bunch length monitor with femtosecond resolution, based on broadband imaging of the spatial distribution of emitted coherent radiation. The technique can be applied to many radiation sources; in this study the focus is coherent transition radiation (CTR) at the MAX IV Short Pulse Facility. Bunch lengths of interest at this facility are <100 fs FWHM; therefore the CTR is in the THz to Far-IR range. To this end, a THz imaging system has been developed, utilising high resistivity float zone silicon lenses and a pyroelectric camera; building upon previous results where single-shot compression monitoring was achieved. This contribution presents simulations of this new CTR imaging system to demonstrate the synchrotron radiation mitigation and imaging capability provided, alongside initial measurements and a bunch length fitting algorithm, capable of shot-to-shot operation. A new machine learning analysis method is also discussed. |
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Poster TUPAB285 [2.008 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB285 | ||
About • | paper received ※ 17 May 2021 paper accepted ※ 24 June 2021 issue date ※ 23 August 2021 | ||
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TUPAB298 | First Steps Toward an Autonomous Accelerator, a Common Project Between DESY and KIT | electron, laser, controls, operation | 2182 |
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Funding: Helmholtz Artificial Cooperation Unit Reinforcement Learning algorithms have risen in popularity in recent years in the accelerator physics community, showing potential in beam control and in the optimization and automation of tasks in accelerator operation. The Helmholtz AI project "Machine Learning toward Autonomous Accelerators" is a collaboration between DESY and KIT that works on investigating and developing RL applications for the automatic start-up of electron linear accelerators. The work is carried out in parallel at two similar research accelerators: ARES at DESY and FLUTE at KIT, giving the unique opportunity of transfer learning between facilities. One of the first steps of this project is the establishment of a common interface between the simulations and the machine, in order to test and apply various optimization approaches interchangeably between the two accelerators. In this paper we present the first results on the common interface and its application to beam focusing in ARES, and the idea of laser shaping with spatial light modulators at FLUTE. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB298 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 02 August 2021 issue date ※ 17 August 2021 | ||
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TUPAB317 | Benchmarking of the Radiation Environment Simulations for CMS Experiment at LHC | radiation, detector, experiment, neutron | 2235 |
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Radiation Simulations group of the Beam Radiation Instrumentation and Luminosity Project of the CMS experiment provide for CMS radiation environment and radiation effects simulation and benchmarking of these calculations with CMS data and other data from LHC measuring devices. We present some results of such benchmarking and the reliability analysis of the simulation procedures for radiation environment calculations at the LHC. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB317 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 16 June 2021 issue date ※ 29 August 2021 | ||
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TUPAB320 | Physical Design of the Radiation Shielding for the CMS Experiment at LHC | radiation, detector, experiment, shielding | 2246 |
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The design of the radiation shielding for the CMS experiment at the LHC requires a simulation of the radiation environment using a model of the CMS experimental setup, accelerator components and the experimental hall infrastructure. The radiation simulations are used to optimise the design of the CMS detectors components and also the interface of the CMS detector with LHC accelerator. The Beam Radiation Instrumentation and Luminosity Project of CMS is responsible for giving important input into the optimisation and upgrade of radiation shielding used in CMS and also the radiation environment simulations software infrastructure. This contribution describes the organization of this work, the simulation software environment used for this part of CMS experiment activity and recent radiation simulation results used to optimise the forward shielding for CMS. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB320 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 16 June 2021 issue date ※ 10 August 2021 | ||
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TUPAB326 | Injection Optimization and Study of XiPAF Synchrotron | injection, synchrotron, proton, experiment | 2264 |
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The synchrotron of XiPAF (Xi’an 200MeV proton application Facility) is a compact proton synchrotron, which using H- stripping injection and phase space painting scheme. Now XiPAF is under commissioning with some achievements, the current intensity after injection reach 43mA, the corresponding particle number is 2.3·1011, and the injection efficiency is 57%. The simulation results by PyOrbit show that the injection efficiency is 77%. In this paper, we report how the injection intensity and efficiency were optimized. We analyzed the difference between simulation and experiments, and quantitatively investigate the factors affecting injection efficiency through experiments. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB326 | ||
About • | paper received ※ 14 May 2021 paper accepted ※ 22 June 2021 issue date ※ 22 August 2021 | ||
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TUPAB340 | Design of the Magnetic Shielding for 166 MHz and 500 MHz Superconducting RF Cavities at High Energy Photon Source | cavity, shielding, photon, superconducting-cavity | 2289 |
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Funding: This work was supported by High Energy Photon Source, a major national science and technology infrastructure in China. Five 166 MHz quarter-wave β=1 superconducting cavities and two 500 MHz single-cell elliptical superconducting cavities have been designed for the storage ring of High Energy Photon Source (HEPS). It is necessary to shield magnetic field for superconducting cavities to reduce the residual surface resistance due to magnetic flux trapping during cavity cool down. The magnetic shielding for both 166 MHz and 500 MHz superconducting cavities have been designed. The residual magnetic field inside the cavities have been calculated by using Opera-3D simulation software. The geographic location of the cavity being installed at the HEPS site and the fringe field of the upstream magnet are considered. These are reported in this paper. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB340 | ||
About • | paper received ※ 18 May 2021 paper accepted ※ 17 June 2021 issue date ※ 10 August 2021 | ||
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TUPAB345 | Availability Modeling of the Solid-State Power Amplifiers for the CERN SPS RF Upgrade | operation, cavity, MMI, SRF | 2308 |
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Funding: This project has received funding from the Euratom research and training programme 2019-2020 under grant agreement No 945077. As part of the LHC Injector Upgrade program a complete overhaul of the Super Proton Synchrotron Radio-Frequency (RF) system took place. New cavities have been installed for which the solid-state technology was chosen to deliver a combined RF power of 2 MW from 2560 RF amplifiers. This strategy promises high availability as the system continues operation when some of the amplifiers fail. This study quantifies the operational availability that can be achieved with this new installation. The evaluation is based on a Monte Carlo simulation of the system using the novel AvailSim4 simulation software. A model based on lifetime estimations of the RF modules is compared against data from early operational experience. Sensitivity analyses have been made, that give insight to the chosen operational scenario. With the increasing use of solid-state RF power amplifiers, the findings of this study provide a useful reference for future application of this technology in particle accelerators. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB345 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 01 July 2021 issue date ※ 19 August 2021 | ||
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TUPAB349 | High Efficiency, Low Cost RF Sources for Accelerators and Colliders | cavity, klystron, controls, electron | 2322 |
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Funding: U.S. Department of Energy Calabazas Creek Research, Inc. (CCR) and its collaborators are developing high efficiency, low cost RF sources. Phase and Amplitude Controlled Magnetrons: CCR, Fermilab, and Communications & Power Industries, LLC (CPI) recently developed a 100 kW, 1.3 GHz magnetron system with amplitude and phase control. The system operated at more than 80% efficiency and demonstrated rapid control of amplitude and phase. Multiple Beam Triodes: CCR, in collaboration with CPI and JP Accelerator Works, Inc., is developing 200 kW, pulsed and CW RF sources from 350 to 700 MHz with projected efficiencies exceeding 80% and cost of $0.50/Watt. Prototype tubes are scheduled for tests in spring 2021. High Efficiency Klystrons:CCR, CPI, and Leidos, Inc. are building a 1.3 GHz, 100 kW klystron operating at 80% efficiency. High power testing is scheduled for summer 2021. Multiple Beam IOTs: CCR and Georgia Tech Research Institute are developing MBIOTs with simplified input coupling and high efficiency. Simulations indicate that 3rd harmonic drive power can increase the efficiency 8-10 %. The program is developing a prototype tube to produce 200 kW peak, 100 kW average power at 704 MHz. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB349 | ||
About • | paper received ※ 18 May 2021 paper accepted ※ 01 June 2021 issue date ※ 27 August 2021 | ||
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TUPAB350 | Design of 71 MHz Power Amplifier in a Single-ended Architecture for IRANCYC-10 Cyclotron | cyclotron, impedance, factory, SRF | 2325 |
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In this paper, the design and simulation of a high power amplifier to provide the required power of a cyclotron accelerator (IRANCYC-10) is presented step-by-step. By combining four modules of this amplifier, a power of 2.5 kW can be achieved to start the main power amplifier. The single ended designs amplifier can generate 1 kW the operating frequency of 71MHz continuous wave (CW). The purpose of choosing this type of design is simplicity to build without the need for a balun, low weight to build high power, as well as cost-effectiveness. The gain and PAE of the SSPA are 21.21 and 71%, respectively. There are also ways to reduce the size of the amplifier. | |||
Poster TUPAB350 [1.008 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB350 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 25 August 2021 issue date ※ 11 August 2021 | ||
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TUPAB356 | Electron Beam Driven Cavities | electron, cavity, linac, klystron | 2342 |
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State of the art high power feeder for RF cavities used as accelerators generally require RF amplifiers consisting of a vacuum tube, such as a klystron or Grid Tubes. In addition, a number of cost intensive RF auxiliary devices are needed: Modulator, waveguides, circulator, power dump and couplers. The equipment requires significant floor space within the linac building. Alternatively, we propose a direct driven system. Aμbunched electron beam is injected directly into the cavity. A high perveance bunched electron beam can be generated by a standard electron gun combined with a deflecting beam chopper*, an off-the-shelf IOT or klystron, respectively. The pulse rate is determined by the resonance frequency of the cavity. The resonator hereby acts like the output cavity of a klystron: Within its propagation through the cavity the beam is decelerated increasing the stored energy of the accelerator. We present 3D particle PIC simulations evaluating the geometry and beam properties in order to optimize the coupling efficiency and cavity excitation of state-of-art CH particle accelerator structures.
* S. Setzer, T. Weiland and U. Ratzinger, A Chopped Electron Beam Driver for H-Type Cavities, 20th ‘International Linac Conference, Monterey, California, August 21-25, 2000, pp. 1001-1003 |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB356 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 11 August 2021 | ||
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TUPAB362 | Physical Design of Electrostatic Deflector in CSNS Muon Source | positron, high-voltage, emittance, operation | 2360 |
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CSNS will build a muon source at the end of the RTBT. In the current design, the muon source propose two schemes, namely the baseline scheme and the baby scheme. High voltage electrostatic deflectors (ESD) are used to deflect the beam in the two schemes. A three-channel ESD with 400 kV HV is employed in the baseline scheme and a 210 kV dual-channel ESD in the simplified scheme. According to physical requirements, the electric field concentration factor is introduced, and the electrode of ESD is theoretically designed. 2D and 3D simulations are carried out to analyze the characteristics of electric field distribution by OPERA. The geometry of the electrodes also met the requirements of electric field uniformity, high voltage resistance and mechanical strength at the same time. In the baseline scheme and the baby scheme, the ESD electric field concentration factors are 1.36 and 1.53, and the maximum electric field is 6.78MV/m and 4.6MV/m, respectively. The design meets the requirements and is reasonably feasible. | |||
Poster TUPAB362 [2.214 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB362 | ||
About • | paper received ※ 13 May 2021 paper accepted ※ 09 June 2021 issue date ※ 22 August 2021 | ||
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TUPAB363 | Feasibility Study for the Novel CERN PS Fast Extraction Septum | septum, extraction, HOM, emittance | 2363 |
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In the framework of accelerator consolidation, a feasibility study for a novel CERN PS extraction septum has been conducted. Functional requirements have been established and, accordingly, a system of two septa magnets and their associated pulse generator is proposed. The magnetic septum design is based on eddy current topology. Magnetic simulations in Flux 2D and Opera 3D of a conceptual design have been carried out. The short length and high amplitude of the current pulse required to drive the eddy current septa imply that none of the power converters currently used for septa magnets at CERN will be suitable. Pulse generator topologies derived from kicker generators have therefore been explored and simulated in Spice. The conceptual magnet and generator design along with simulation results are presented in this paper. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB363 | ||
About • | paper received ※ 18 May 2021 paper accepted ※ 17 June 2021 issue date ※ 10 August 2021 | ||
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TUPAB364 | Dipole CR FAIR | dipole, HOM, storage-ring, experiment | 2367 |
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The design of CR dipole magnets (24+2 pieces) for the FAIR project in Germany began in 2014 at BINP. CR is a special storage ring where the main emphasis is placed on efficient stochastic pre-cooling of intense beams of stable ions, rare isotopes, or antiprotons. This type of magnet is an iron-based electromagnet with a straight pole, sector form is realized by cutting ends. The maximum field value is 1.6 T. The integrated over the length of the magnet field quality as a function of radius is dBl/Bl = ± 10-4 with 190 mm good field region as required from the beam dynamics simulations. This challenging field quality is necessary mainly for precise experiments with ion beam in the ISO regime. Below 1.6 T the value dBl/Bl can be higher with a linear approximation up to ± 2.5× 10-4 at the field level of 0.8 T. The first prototype has been manufactured at the end of 2020. Here we describe features of the dipole, 3D calculations, and measurements of the magnetic field. | |||
Poster TUPAB364 [1.587 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB364 | ||
About • | paper received ※ 09 May 2021 paper accepted ※ 31 May 2021 issue date ※ 28 August 2021 | ||
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TUPAB366 | Design and Realization of New Solenoids for High Brightness Electron Beam Injectors | solenoid, gun, electron, cathode | 2374 |
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High-brightness, high-current electron beams are the main requirement for fourth generation light sources such as free-electron lasers (FELs), energy recovery Linacs (ERLs) and high-energy linear colliders. The most successful device for producing such beams is the Radio-Frequency photoinjector where a key element is the gun solenoid. Its main task is to limit the beam emittance growth in the first acceleration stages by imposing a spiraling motion to the beam. This paper is focused on two magnets: the first one is the solenoid gun for the new photoinjector at INFN-LNF SPARC_LAB test facility. The design, the realization, and all the measurements performed at the factory and at LNF are shown. Moreover, the design of a solenoid for a novel C-band gun for CompactLight project is presented. Both magnets have been designed with the goal to reach the same integrated field of the gun solenoid currently installed at SPARC_LAB, with an integrated field quality of 5·10-4 in a good field radius of 30mm and 10mm radius respectively for SPARC_LAB and CompactLight solenoid. This one is equipped with a bucking coil to limit the field on cathode that could led to an undesired emittance growth. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB366 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 18 June 2021 issue date ※ 15 August 2021 | ||
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TUPAB378 | Superconducting Dipole Magnets for the SIS100 Synchrotron | dipole, synchrotron, multipole, operation | 2401 |
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The Facility for Antiproton and Ion Research (FAIR) is currently under construction at GSI Darmstadt, Germany. For its main accelarator, the SIS100 synchrotron, 110 superconducting dipole magnets has been produced and extensively tested. The fast-ramped Nuclotron-type superferric dipoles were manufactured with high effort regarding a precise magnetic field which could be proven by magnetic field measurements with high accuracy. Stable operation conditions at 4.5 K were achieved including an excellent quench behaviour and precise geometrical and electrical properties. An overview on design, production, operation, tests and measurement results will be given. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB378 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 10 August 2021 | ||
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TUPAB389 | High Precision Four Quadrant Converter with GaN Technology | controls, operation, power-supply, damping | 2431 |
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New proton therapy facilities for the cure of tumors as well as high-energy photon sources are currently being installed all around the world. In this field, the request for special power supplies for corrector, scanning, and quadrupole magnets are increasing. For these applications, mandatory requirements are high bandwidth and current stability as well as low output ripple which are conflicting constraints. A feasibility study, prototype development, measurements, and investigations on the control methodology of a wide-bandgap GaN semiconductor-based power module is presented in the paper. The developed power module features the following characteristics: Eurocard standard PCB, bipolar 4Q operation, minimum switching frequency 100 kHz, bandwidth 5 kHz, output voltage and current up to 200 V / 8 A, output current ripple <20 ppm. The enlisted characteristics make it suitable for high inductive loads requiring fast transients (scanning magnets). An RST controller will be developed and a system identification approach to the transfer function of two parallel-connected power modules will be presented along with simulations assessing the performance. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB389 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 25 June 2021 issue date ※ 21 August 2021 | ||
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TUPAB391 | Cryopanels in the Room Temperature Heavy Ion Synchrotron SIS18 | vacuum, cryogenics, quadrupole, heavy-ion | 2435 |
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The FAIR complex at the GSI Helmholtzzentrum will generate heavy ion beams of ultimate intensities. To achieve this goal, medium charge states have to be used. However, the probability for charge exchange in collisions with residual gas particles of such ions is much higher than for higher charge states. In order to lower the residual gas density to extreme high vacuum conditions, 65% of the circumference of SIS18 are already coated with NEG, which provides high and distributed pumping speed. Nevertheless, nobel and nobel-like components, which have very high ionization cross sections, do not get pumped by this coating. A cryogenic environment at moderate temperatures, i.e. at 50-80K, provides high pumping speed for all heavy residual gas particles. The only typical residual gas species, that cannot be pumped at this temperature is hydrogen. With an additional NEG coating the pumping will be optimized for all residual gas particles. The installation of cryogenic surfaces in the existing room temperature synchrotron SIS18 at GSI has been investigated. A prototype quadrupole chamber with cryogenic surfaces, first measurements, and simulations of the adapted accelerator are presented. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB391 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 31 August 2021 issue date ※ 25 August 2021 | ||
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TUPAB407 | A Novel Beam Optics Concept to Maximize the Transmission Through Cyclotron-based Proton Therapy Gantries | optics, proton, emittance, quadrupole | 2477 |
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Funding: This work is funded by a PSI inter-departmental funding initiative (CROSS). Most of the conventional beam optics of cyclotron-based proton gantries were designed to provide point-to-point focus in both planes with an imaging factor between 1 and 2 from the entrance of the gantry to the patient. This means that a small beam size at the gantry entrance is required to achieve the required small beam size at the patient. Due to the typically used beam emittance, this in turn results in large beam divergence at the gantry entrance, increasing the possibility of beam losses along the gantry as the beam envelope gets close to the apertures. To maximize transmission through the gantry, we propose a novel beam optics concept using 3:1 imaging. It reduces the beam divergence at the gantry entrance by factor 3 while still achieving a small beam size at the patient. The beam envelope is better controlled and keeps clear of the apertures compared to the 1:1 or 1:2 imaging beam envelope. For PSI Gantry 2, the novel 3:1 imaging beam optics increase the proton beam transmission for lower energies by 40% compare to 1:1 imaging beam optics. The usage of small imaging factors can help to maximize transmission for different gantry lattices, thus reducing treatment times. |
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Poster TUPAB407 [1.347 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB407 | ||
About • | paper received ※ 10 May 2021 paper accepted ※ 02 June 2021 issue date ※ 29 August 2021 | ||
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TUPAB409 | FLUKA and Geant4 Monte Carlo Simulations of a Desktop, Flat Panel Source Array for 3D Medical Imaging | photon, electron, experiment, detector | 2483 |
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Funding: Funded by the Accelerators for Security, Healthcare and Environment CDT from the United Kingdom Research and Innovation Science and Technology Facilities Council, reference ID ST/R002142/1 Digital tomosynthesis (DT) is a 3D imaging modality with a lower cost and lower dose than computed tomography. A DT system made of a flat panel array with 45 X-ray sources, but compact enough to fit on the desktop is near market realisation by the company Adaptix Ltd. This work presents a framework of FLUKA and Geant4 Monte Carlo (MC) simulations of the Adaptix system including the X-ray beam generation and the final image quality. The results show that MC methods offer an insight into the performance details of such an innovative device at different levels between the X-ray emitter array and the detector. As such, a large portion of the design and optimisation of such novel X-ray imaging systems can be done with a single toolkit. Finally, the modularity of the approach allows other tools to be imported at various steps within the framework and thus provide answers to questions that cannot be addressed by general-purpose MC codes. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB409 | ||
About • | paper received ※ 17 May 2021 paper accepted ※ 31 May 2021 issue date ※ 24 August 2021 | ||
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TUPAB416 | Depth-Dose Distribution Dependence on the Energy Profile of Linear and Laser Wakefield Accelerator Electron Beams | electron, radiation, linac, HOM | 2502 |
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The depth-dose distributions of 10 MeV electron beams used for food irradiation and sterilization purposes at Research and Development Center for Radiation Technology, HCMC, Vietnam are measured and the results are well reproduced by the MCNP simulations. We extend the simulations to predict the dose depth distribution for 10 MeV electron beams with the energy profiles of a model Laser Wake Field accelerator (LWFA). The dosimetry and simulation results show that the maximum dose of the depth-dose curve inside the product is 1.4 times surface dose with an area density limit of 8.6 g/cm2 for two-sided irradiation with nearly mono-energetic beams from the linear accelerator and the corresponding parameters for LWFA are 1.2 times surface dose and 13.0 g/cm2, respectively. | |||
Poster TUPAB416 [1.506 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB416 | ||
About • | paper received ※ 17 May 2021 paper accepted ※ 11 June 2021 issue date ※ 31 August 2021 | ||
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TUPAB417 | Pushing Spatial Resolution Limits In Single-Shot Time-Resolved Transmission Electron Microscopy at the UCLA Pegasus Laboratory | electron, space-charge, gun, cavity | 2506 |
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Funding: This work was supported by DOESTTR grant No. DE-SC0013115 and by by the National Science Foundation under STROBE Science and Technology Center Grant No. DMR-1548924 We present the design of a high-speed single shot relativistic electron microscope planned for implementation at the UCLA PEGASUS Laboratory capable of imaging with less than 30~nm spatial resolution and image acquisition time on the order of 10~ps. This work is based on a multi-cavity acceleration scheme for producing relativistic beams (3.75 MeV) with suppressed rms energy spread (σδ ≈5e-5), and a means to reduce smooth space charge aberrations by generating a quasi-optimal 4D particle distribution at the sample plane. start-to-end simulation results are used to validate the entire setup. Ultimately, a feasible working point is demonstrated. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB417 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 28 July 2021 issue date ※ 01 September 2021 | ||
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WEXC04 | Simulations of Beam Strikes on Advanced Photon Source Upgrade Collimators using FLASH, MARS, and elegant | electron, photon, storage-ring, radiation | 2562 |
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Funding: Work supported by the U.S. D.O.E.,Office of Science, Office of Basic Energy Sciences, under contract number DE-AC02- 06CH11357. Modeling of high-energy-density electron beams on collimators proposed for the Advanced Photon Source Upgrade (APS-U) storage ring (SR) is carried out with codes FLASH, MARS, and elegant. Code results are compared with experimental data from two separate beam dump studies conducted in the present APS SR. Whole beam dumps of the 6-GeV, 200 mA, ultra-low emittance beam will deposit acute doses of 30 MGy within 10 to 20 microseconds, leading to hydrodynamic behavior in the collimator material. Goals for coupling the codes include accurate modeling of the hydrodynamic behavior, methods to mitigate damage, and understanding the effects of the resulting shower downstream of the collimator. Relevant experiments, though valuable, are difficult and expensive to conduct. The coupled codes will provide a method to model differing geometries, materials, and loss scenarios. Efforts thus far have been directed toward using FLASH to reproduce observed damage seen in aluminum test pieces subjected to varying beam strike currents. Stabilizing the Eulerian mesh against large energy density gradients as well as establishing release criteria from solid to fluid forms are discussed. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEXC04 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 23 July 2021 issue date ※ 30 August 2021 | ||
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WEPAB006 | EIC Crab Cavity Multipole Analysis | cavity, multipole, dynamic-aperture, collider | 2589 |
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Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. Crab cavities are specialized RF devices designed for colliders targeting high luminosities. It is a straightforward solution to retrieve head-on collision with crossing angle existing to fast separate both beams after collision. The Electron Ion Collider (EIC) has a crossing angle of 25 mrad, and will use local crabbing to minimize the dynamic aperture requirement throughout the rings. The current crab cavity design for the EIC lacks axial symmetry. Therefore, their higher order components of the fundamental deflecting mode have a potential of affecting the long-term beam stability. We present here the multipole analysis and preliminary particle tracking results from the current crab cavity design. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB006 | ||
About • | paper received ※ 18 May 2021 paper accepted ※ 25 June 2021 issue date ※ 16 August 2021 | ||
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WEPAB008 | Numerical Noise Study in EIC Beam-Beam Simulations | electron, proton, emittance, resonance | 2592 |
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In the Electron-Ion Collider (EIC) design, a flat beam collision scheme is adopted to achieve 1e34 luminosity. We found that the vertical growth of the proton beam is much larger than of the round beam. In this article we present the numerical noise study about the number of macroparticles, the electron slice number, and the electron bunch length. Both weak-strong and strong-strong simulation methods are used. It turns out the proton emittance growth in the strong-strong simulation mainly comes from the numberical noise. This study helps us to perform beam-beam simulation correctly for EIC. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB008 | ||
About • | paper received ※ 17 May 2021 paper accepted ※ 31 August 2021 issue date ※ 31 August 2021 | ||
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WEPAB009 | Study of Harmonic Crab Cavity in EIC Beam-Beam Simulations | cavity, resonance, betatron, electron | 2595 |
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In the Electron-Ion Collider (EIC) design, crab cavities are adopted to compensate the geometric luminosity loss from the crossing angle. From previous studies, higher-order synchro-betatron resonances are excited since the hadron beam is long and the crossing angle is large. To reduce the luminosity degradation rate, different combinations of harmonic crab cavities are studied with both weak-strong and strong-strong simulation methods. The frequency map analysis (FMA) is also used for comparison. This study helps determine the crab cavity parameters for the future EIC. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB009 | ||
About • | paper received ※ 17 May 2021 paper accepted ※ 23 June 2021 issue date ※ 28 August 2021 | ||
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WEPAB010 | Full Range Tune Scan Studies Using Graphics Processing Units with CUDA in EIC Beam-Beam Simulations | resonance, betatron, GPU, cavity | 2598 |
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The hadron beam in the Electron-Ion Collider (EIC) suffers high order betatron and synchro-betatron resonances. In this paper, we present a weak-strong full range (0.0~0.5) fractional tune scan with a step size as small as 0.001. Multiple Graphics Processing Units (GPUs) are used to speed up the simulation. A code parallelized with MPI and CUDA is implemented. The good tune region from weak-strong scan is further checked by the self-consistent strong-strong simulation. This study provides beam dynamics guidance in choosing proper working points for the future EIC. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB010 | ||
About • | paper received ※ 17 May 2021 paper accepted ※ 23 June 2021 issue date ※ 12 August 2021 | ||
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WEPAB013 | A New Algorithm for Positron Source Parameter Optimisation | positron, target, electron, linac | 2609 |
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In this report, we proposed a new simple and efficient algorithm for positron source parameter optimisation, which is based on iterations of scan of free parameters in the simulation. The new algorithm is fast, simple and convincing since the results can be visually drawn and flexibly tuned and it has an advantage that it can easily handle realistic parametric problems with more than one objective quantities to optimise. The optimisation of the main parameters of the CLIC positron source at the 380 GeV stage is presented as an example to demonstrate how the algorithm works. | |||
Poster WEPAB013 [1.352 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB013 | ||
About • | paper received ※ 15 May 2021 paper accepted ※ 24 June 2021 issue date ※ 17 August 2021 | ||
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WEPAB014 | Optimisation of the CLIC Positron Source | positron, target, linac, electron | 2613 |
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In this report, we reoptimised the CLIC positron source at all collision energy stages. Simulation, optimisation algorithm and results were all improved compared with previous studies. Two different target schemes were studied and compared in terms of the advantages and disadvantages. The spot size of the injected electron beam was also optimised to achieve a compromise between large positron yields and safe energy deposition. The matching device for the capture of positrons was simulated and optimised with both improved analytic and realistic field maps. Conical aperture and front and rear gaps of the matching device were also considered for the first time. The optimised positron source is expected to have the lowest cost. | |||
Poster WEPAB014 [1.825 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB014 | ||
About • | paper received ※ 15 May 2021 paper accepted ※ 21 June 2021 issue date ※ 25 August 2021 | ||
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WEPAB015 | Comparison of Different Matching Device Field Profiles for the FCC-ee Positron Source | positron, target, linac, electron | 2617 |
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In this report, we compared different matching device field profiles for the FCC-ee positron source. The matching device is used to capture positrons with magnetic field. A flux concentrator was designed with a conical inner chamber. A smaller aperture and a larger aperture were studied. An analytic field profile was also studied using an adiabatic formula. The peak field of the analytic profile as well as beam and target parameters was optimised to achieve a maximum positron yield. A safe energy deposition in the target was guaranteed by requiring a constraint on the deposited power and peak energy deposition density. | |||
Poster WEPAB015 [3.066 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB015 | ||
About • | paper received ※ 15 May 2021 paper accepted ※ 23 June 2021 issue date ※ 30 August 2021 | ||
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WEPAB020 | The Relation Between Field Flatness and the Passband Frequency in the Elliptical Cavities | cavity, SRF, gun, accelerating-gradient | 2636 |
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A technique that predicts the field flatness of the operating pi-mode based on the passband frequency is highly desirable when the direct measurement of the field is not available. Such a technique was developed for the SNS-PPU cavity, a 6-cell SRF cavity whose field flatness is important for cold operation. In this paper, we will present the theory on the relations between field profile and passband frequencies of the arbitrary deformed cavities, the simulation studies, and comparison with the experimental measurements. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB020 | ||
About • | paper received ※ 17 May 2021 paper accepted ※ 24 June 2021 issue date ※ 20 August 2021 | ||
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WEPAB024 | Release of Crystal Routine for Multi-Turn Proton Simulations within SixTrack v5 | collimation, proton, collider, hadron | 2648 |
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Crystal collimation is studied as a possible scheme to further improve the efficiency of ion collimation at the High Luminosity Large Hadron Collider (HL-LHC), as well as for possible applications in the CERN program of Physics Beyond Colliders. This concept relies on the use of bent crystals that can deflect high-energy halo particles at large angles, of the order of tens of urad. In order to reproduce key experimental results of crystal collimation tests and predict the performance of this system when applied to present and future machines, a dedicated simulation routine was developed. This routine is capable of modeling both coherent and incoherent interactions of beam particles with crystal collimators, and is fully integrated into the magnetic tracking and collimator modeling provided by the single-particle tracking code SixTrack. This paper describes the implementation of the routine in the latest version of SixTrack and its most recent improvements, in particular regarding the treatment of the crystal miscut angle. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB024 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 23 June 2021 issue date ※ 14 August 2021 | ||
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WEPAB025 | Collimation Strategies for Secondary Beams in FCC-hh Ion-Ion Operation | secondary-beams, collider, site, heavy-ion | 2652 |
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The target peak luminosity of the CERN FCC-hh during Pb-Pb collisions is more than a factor of 50 greater than that achieved by the LHC in 2018. As a result, the intensity of secondary beams produced in collisions at the interaction points will be significantly higher than previously experienced. With up to 72 kW deposited in a localised region by a single secondary beam type, namely the one originated by Bound Free Pair Production (BFPP), it is essential to develop strategies to safely intercept these beams, including the ones from ElectroMagnetic Dissociation (EMD), in order to ensure successful FCC-hh Pb-Pb operation. A series of beam tracking and energy deposition simulations were performed to determine the optimal solution for handling the impact of such beams. In this contribution the most advanced results are presented, with a discussion of different options. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB025 | ||
About • | paper received ※ 18 May 2021 paper accepted ※ 02 July 2021 issue date ※ 18 August 2021 | ||
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WEPAB028 | MAD-X for Future Accelerators | solenoid, radiation, lattice, collider | 2664 |
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The feasibility and performance of the future accelerators must, to a large extent, be predicted by simulation codes. This implies that simulation codes need to include effects that previously played a minor role. For example, in large electron machines like the FCC-ee the large energy variation along the ring requires that the magnets strength is adjusted to the beam energy at that location, normally referred to as tapering. In this article, we present new features implemented in the MAD-X code to enable and facilitate simulations of future colliders. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB028 | ||
About • | paper received ※ 17 May 2021 paper accepted ※ 06 July 2021 issue date ※ 27 August 2021 | ||
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WEPAB029 | Challenges for the Interaction Region Design of the Future Circular Collider FCC-ee | photon, detector, background, collider | 2668 |
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Funding: This work was partially supported by the EC HORIZON 2020 project FCC-IS, grant agreement n.951754, and by the U. S. Department of Energy, Office of Science, under Contract No. DE-AC02-76SF-00515. The FCC-ee is a proposed future high-energy, high-intensity and high precision lepton collider. Here, we present the latest developments for the FCC-ee interaction regions, which shall ensure optimum conditions for the particle physics experiments. We discuss measures of background reduction and a revised interaction region layout including a low impedance compact beam chamber design. We also discuss the possible impact of the radiation generated in the interaction region including beamstrahlung. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB029 | ||
About • | paper received ※ 11 May 2021 paper accepted ※ 23 June 2021 issue date ※ 30 August 2021 | ||
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WEPAB031 | Frequency Dependence of Plasma Cascade Amplification | electron, plasma, distributed, hadron | 2672 |
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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 new type of amplifier, plasma cascade amplifier (PCA) has been proposed for a coherent electron cooling (CeC) system. Previously, the 1D model for PCA assumes that the transverse distribution of the density perturbation in the electrons is uniform and consequently, the plasma frequency does not depend on the wavelength of the perturbation. This assumption is valid if the longitudinal wavelength of the beam frame is much shorter than the transverse width of perturbation. In this work, we explore the PCI gain at a long wavelength by assuming the perturbation in the electron density has a non-uniform transverse profile. Specifically, we solve the 3D Poisson equation for given charge distribution (longitudinal sinusoidal, transversely Gaussian, or Beer-can), average the electric field over the transverse plane, and then apply it to 1D Vlasov equation. Similar to the previous calculation, the Vlasov equation can be reduced to a Hill’s equation but the plasma frequency now depends on the longitudinal wavelength of the density perturbation in the electrons. By numerically solving Hill’s equation, we obtain the gain of a PCA and compare it with the results from 3D SPACE simulations. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB031 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 23 June 2021 issue date ※ 27 August 2021 | ||
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WEPAB032 | Studies of the Short-Range Wakefields for the Electron Storage Ring in the Electron Ion Collider | electron, vacuum, wakefield, dipole | 2675 |
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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. During the estimates of impedance budget for the Electron Storage Ring (ESR) of Electron-Ion Collider (EIC), various codes, including GdfidL, CST and ECHO3D, have been used to calculate the short-range wake-fields due to the vacuum components. The ECHO 3D code demonstrates more reliable results for the tapered type of structures rather than the GdfidL code, where the stepsize needs to be dramatically decreased to achieve a high-performance calculation. Impedance of the following components are discussed and compared in details: Interaction Region (IR) chamber, bellows, and synchrotron radiation mask (flange absorber). |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB032 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 10 June 2021 issue date ※ 24 August 2021 | ||
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WEPAB056 | Advanced Photoinjector Development at the UCLA SAMURAI Laboratory | FEL, emittance, gun, linac | 2728 |
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Funding: This work was supported by the US Department of Energy under the contract No. DE-SC0017648, DE-SC0009914, and DE-SC0020409, and by National Science Foundation Grant No. PHY-1549132 UCLA has recently constructed SAMURAI, a new radiation bunker and laser infrastructure for advanced accelerator research. In its first phase, we will build a 30 MeV photoinjector with an S-band hybrid gun. The beam dynamics simulation for this beamline showed the generation of the beam with the emittance 2.4 um and the peak current 270 A. FIR-FEL experiments are planned in this beamline. The saturation peak power was expected at 170 MW. |
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Poster WEPAB056 [0.939 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB056 | ||
About • | paper received ※ 28 May 2021 paper accepted ※ 01 July 2021 issue date ※ 11 August 2021 | ||
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WEPAB063 | Status of the Polarized Source and Beam Preparation System at MESA | laser, electron, experiment, emittance | 2736 |
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Funding: This work is supported by the DFG excellence initiative PRISMA+. The MESA Low-energy Beam Apparatus (MELBA) connects the DC photoemission source STEAM with the injector accelerator MAMBO. MELBA is capable of adjusting the longitudinal phase space for the requirements of the pre-acceleration by using a chopper and buncher while providing small transverse emittances. Measurements of the transverse phase space and longitudinal beam dimension taken at a test setup are presented. These results serve now for further improvements, e.g design changes in our corrector magnets. In addition, the revised MELBA will include two Wien filters and a solenoid for spin manipulation. A double scattering Mott polarimeter for spin diagnostics and a second source for the extraction of high bunch charges is foreseen using a branched off beam line. RF-synchronized laser diodes will be used with infrared wavelength as a driver for the spin-polarized photoemission. In this report we present the latest layout of MELBA and simulation results. |
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Poster WEPAB063 [1.752 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB063 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 16 July 2021 issue date ※ 28 August 2021 | ||
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WEPAB072 | PAX: A Plasma-Driven Attosecond X-Ray Source | plasma, electron, experiment, FEL | 2755 |
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Funding: Work supported by the U.S. Department of Energy under contract number DE-AC02-76SF00515. This work was also partially supported by DOE grant DESC0009914 Plasma accelerators can generate ultra high brightness electron beams which open the door to light sources with smaller physical footprint and properties unachievable with conventional accelerator technology. In this work * we show that electron beams from Plasma WakeField Accelerators (PWFAs) can generate coherent tunable soft X-ray pulses with TW peak power and duration of tens of attoseconds in a meter-length undulator. These X-ray pulses are an order of magnitude more powerful, shorter and can be produced with better stability than state-of-the-art X-ray Free Electron Lasers (XFELs). The X-ray emission in this approach is driven by coherent radiation from a pre-bunched, near Mega Ampere (MA) current electron beam of attosecond duration rather than the SASE FEL process starting from noise. This approach significantly relaxes the restrictive requirements on emittance, energy spread, and pointing stability which has thus far hindered the realization of a high-gain FEL driven by a plasma accelerator. We discuss the approach and progress towards the experimental realization of this concept at the FACET-II accelerator facility. * C. Emma, X. Xu, A. Fisher, J. P. MacArthur, J. Cryan, M. J. Hogan, P. Musumeci, G. White, A. Marinelli, "Terawatt attosecond X-ray source driven by a plasma accelerator", arXiv:2011.07163 (2020) |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB072 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 24 June 2021 issue date ※ 31 August 2021 | ||
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WEPAB075 | Xenos: X-Ray Monte Carlo Code Suite | electron, positron, photon, operation | 2766 |
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Xenos is an integrated 3D code suite for the design of X-ray sources and electron beam devices. The component programs run under all versions of Windows. This paper describes unique features of Xenos compared to other Monte Carlo packages: 1) representation of geometry and deposited dose on a finite-element mesh supported by an interactive mesh generator, 2) inclusion of full 3D electric and magnetic fields in Monte Carlo simulations, 3) an integrated user environment for input and output calculations (e.g., electron gun design, target heating, …) and 4) extended parallel-computing support for high-accuracy solutions. Xenos employs the full capabilities of multi-core computers and allows parallel computations on an unlimited number of independent computers.
* Sempau J., et.al. (2003), "Experimental benchmarks of the Monte Carlo code PENELOPE", Nucl. Instrum. Meth. B 207, 107-123. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB075 | ||
About • | paper received ※ 10 May 2021 paper accepted ※ 23 June 2021 issue date ※ 25 August 2021 | ||
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WEPAB082 | Single Bunch Instability Simulations in the Storage Ring of the ALS-U Project | impedance, cavity, storage-ring, operation | 2783 |
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As the broad-band impedance modeling and the vacuum chamber design of the new Advanced Light Source storage ring (ALS- U) reach maturity, we report on progress in single-bunch collective effects studies. A pseudo-Green function wake representing the entire ring was earlier obtained by numerical and analytical methods. Macroparticle simulations using the computer code "elegant" and this wake function are used to determine the instability thresholds for longitudinal and transverse motion. We consider various operating conditions, such as without/with higher-harmonic RF cavities, zero/finite linear chromaticity, and without/with a transverse bunch-by-bunch feedback system. Results show enough margin for the broadband impedance budget when the single-bunch instability thresholds are compared with the design bunch charge. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB082 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 01 July 2021 issue date ※ 12 August 2021 | ||
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WEPAB083 | Effect of Negative Momentum Compaction Operation on the Current-Dependent Bunch Length | operation, bunching, synchrotron, storage-ring | 2786 |
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Funding: Funded by the European Union’s Horizon 2020 Research and Innovation programme, Grant Agreement No 730871. P.S, T.B are supported by DFG-funded Karlsruhe School of Elementary and Astroparticle Physics. New operation modes are often considered during the development of new synchrotron light sources. An understanding of the effects involved is inevitable for a successful operation of these schemes. At the KIT storage ring KARA (Karlsruhe Research Accelerator), new modes can be implemented and tested at various energies, employing a variety of performant beam diagnostics devices. Negative momentum compaction optics at various energies have been established. Also, the influence of a negative momentum compaction factor on different effects has been investigated. This contribution comprises a short report on the status of the implementation of a negative momentum compaction optics at KARA. Additionally, first measurements of the changes to the current-dependent bunch length will be presented. |
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Poster WEPAB083 [1.129 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB083 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 01 July 2021 issue date ※ 26 August 2021 | ||
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WEPAB092 | Redesign of the Jefferson Lab -300 kV DC Photo-Gun for High Bunch Charge Operations | cathode, gun, high-voltage, electron | 2802 |
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Funding: The U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177, JSA initiatives fund program and Laboratory Directed Research and Development program. Production of high bunch charge beams for the Electron-Ion Collider (EIC) is a challenging task. High bunch charge (a few nC) electron beam studies at Jefferson Lab using an inverted insulator DC high voltage photo-gun showed evidence of space charge limitations starting at 0.3 nC, limiting the maximum delivered bunch charge to 0.7 nC for beam at -225 kV, 75 ps (FWHM) pulse width, and 1.64 mm (rms) laser spot size. The low extracted charge is due to the modest longitudinal electric field (Ez) at the photocathode leading to beam loss at the anode and downstream beam pipe. To reach the few nC high bunch charge goal, and to correct the beam deflection exerted by the non-symmetric nature of the inverted insulator photo-gun the existing photo-gun was modified. This contribution discusses the electrostatic design of the modified photo-gun obtained using CST Studio Suite’s electromagnetic field solver. Beam dynamics simulations performed using General Particle Tracer (GPT) with the resulting electrostatic field map obtained from the modified electrodes confirmed the validity of the new design. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB092 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 02 June 2021 issue date ※ 17 August 2021 | ||
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WEPAB097 | Initial Nanoblade-Enhanced Laser-Induced Cathode Emission Measurements | electron, laser, cathode, experiment | 2814 |
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Funding: This work was supported by the Center for Bright Beams, National Science Foundation Grant No. PHY-1549132 and DOE HEP Grant DE-SC0009914 Nanostructured photocathodes offer a unique functionality not possible in traditional photocathodes, increasing beam brightness by reducing the effective emission area. Inspired by field emitter tips, we examine a possible extension for higher current operation, an extended nanoblade capable of producing asymmetric emittance electron beams. A full understanding of emission is necessary to establish the effectiveness of nanoblades as usable cathode for electron accelerators. Utilizing wet etching of silicon wafers, we arrive at a robust sample capable of dissipating incident laser fields in excess of 20 GV/m without permanent damage. Initial predictions and experiments from the nanotip case predict energies up to the keV scale from electron rescattering and fine features on the order of the photon quantum. We will present initial electron data from 800 nm Ti:S laser illumination and measurements of a focused 1 keV beam. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB097 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 24 June 2021 issue date ※ 15 August 2021 | ||
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WEPAB104 | Improving the Operational Lifetime of the CEBAF Photo-Gun by Anode Biasing | cathode, laser, electron, gun | 2840 |
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Funding: U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177. The operating lifetime of GaAs-based photocathodes in DC high voltage electron photo-guns is dominated by the ionization rate of residual beamline gas molecules. In this work, experiments were performed to quantify the improvement in photocathode charge lifetime by biasing the photo-gun anode with a positive voltage, which repels ions generated downstream of the anode. The photo-cathode charge lifetime improved by almost a factor of two when the anode was biased compared to the usual grounded configuration. Simulations were performed using the particle tracking code General Particle Tracer (GPT) with a new custom element. The simulation results showed that both the number and energy of ions play a role in the pattern of QE degradation. The experiment results and conclusions supported by GPT simulations will be presented. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB104 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 02 June 2021 issue date ※ 18 August 2021 | ||
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WEPAB105 | Simulating Electron Impact Ionization Using a General Particle Tracer (GPT) Custom Element | electron, gun, cathode, high-voltage | 2843 |
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Funding: U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177, Consejo Nacional de Ciencia y Tecnología (CONACYT). A new C++ custom element has been developed with the framework of General Particle Tracer (GPT) to simulate electron impact ionization of residual gas molecules. The custom element uses Monte-Carlo routines to determine both the ion production rate and the secondary electron kinetic energy based on user-defined gas densities and theoretical values for the ionization cross section and the secondary electron differential cross section. It then uses relativistic kinematics to track the secondary electron, the scattered electron, and the newly formed ion after ionization. The ion production rate and the secondary electron energy distribution determined by the custom element have been benchmarked against theoretical calculations and against simulations made using the simulation package IBSimu. While the custom element was originally built for particle accelerator simulations, it is readily extensible to other applications. The custom element will be described in detail and examples of applications at the Thomas Jefferson National Accelerator Facility will be presented for ion production in a DC high voltage photo-gun. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB105 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 25 June 2021 issue date ※ 19 August 2021 | ||
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WEPAB110 | Solid-State Driven X-Band Linac for Electron Microscopy | electron, cavity, linac, gun | 2853 |
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Funding: This work was supported by the Department of Energy Contract No. DE-AC02-76SF00515. Microcrystal electron diffraction (MicroED) is a technique used by scientists to image molecular crystals with cryo-electron microscopy (cryo-EM)*. However, cryo-EMs remain expensive, limiting MicroED’s accessibility. Current cryo-EMs accelerate electrons to 200-300 keV using DC electron guns with a nA of current and low emittance. However at higher voltages these DC guns rapidly grow in size. Replacing these electron guns with a compact linac powered by solid-state sources could lower cost while maintaining beam quality, thereby increasing accessibility. Utilizing compact high shunt impedance X-band structures ensures that each RF cycle contains at most a few electrons, preserving beam coherence. CW operation of the RF linac is possible with distributed solid-state architectures** that use 100W solid-state amplifiers at X-band frequencies. We present an initial design for a prototype low-cost CW RF linac for high-throughput MicroED producing 200 keV electrons with a standing-wave architecture where each cell is individually powered by a solid-state amplifier. This design also provides an upgrade path for future compact MeV-scale sources on the order of 1 meter in size. * Jones, C. G. et al. ACS central science 4, 1587-1592 (2018). ** D. C. Nguyen et al, Proc. 9th International Particle Accelerator Conference (IPAC’18), no. 9, pp. 520-523 |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB110 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 24 June 2021 issue date ※ 10 August 2021 | ||
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WEPAB115 | Beam Preparation with Temporally Modulated Photocathode Laser Pulses for a Seeded THz FEL | FEL, laser, cathode, electron | 2866 |
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The need for carrier-envelope-phase (CEP) stable THz pump pulses is recognized at many pump-probe experiments at the European XFEL. At the Photo Injector Test Facility at DESY in Zeuthen (PITZ), a proof-of-principle experiment of an accelerator-based THz FEL source is in preparation. Since the CEP stability of FEL pulses is not guaranteed in the SASE regime, a seeding scheme is needed. A common scheme for seeding is to drive the microbunching process with external laser pulses, which are power-limited in the THz range. Alternatively, a pre-bunched beam, generated for example by applying a temporally modulated photocathode laser pulse, can be used to drive the FEL. The beam dynamics with such a seeding method are studied with ASTRA tracking code simulations with space-charge forces as well as experimentally. The results of these studies are shown and discussed. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB115 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 27 July 2021 issue date ※ 26 August 2021 | ||
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WEPAB117 | Injection Feedback for a Storage Ring | injection, HOM, feedback, kicker | 2870 |
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Funding: Research Agency under the Equipex convention ANR-10-EQPX-0051. We report on an injection feedback scheme for the ThomX storage ring project. ThomX is a 50-MeV-electron accelerator prototype which will use Compton backscattering in a storage ring to generate a high flux of hard X-rays. Given the slow beam damping (in the ring), the injection must be performed with high accuracy to avoid large betatron oscillations. A homemade analytic code is used to compute the corrections that need to be applied before the beam injection to achieve a beam position accuracy of a few hundred micrometers in the first beam position monitors (BPMs). In order to do so the code needs the information provided by the ring’s diagnostic devices. The iterative feedback system has been tested using MadX simulations. Our simulations show that a performance that matches the BPMs’ accuracy can be achieved in less than 50 iterations in all cases. Details of this feedback algorithm, its efficiency and the simulations are discussed. |
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Poster WEPAB117 [2.422 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB117 | ||
About • | paper received ※ 28 May 2021 paper accepted ※ 01 July 2021 issue date ※ 25 August 2021 | ||
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WEPAB121 | Design and Simulation of Transparent Injection Upgrade for the CLS Storage Ring | injection, storage-ring, kicker, sextupole | 2885 |
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The Canadian Light Source (CLS) synchrotron uses four fast kicker magnets to inject electrons into the storage ring from a 2.9 GeV booster ring. The injection occurs over several turns of the stored beam, which is also perturbed by the injection kickers. The resultant oscillations of the stored beam can negatively affect beamline experiments, so it is desirable to implement an injection scheme which does not disturb the stored beam. Injection schemes of this type allow for transparent injection and are beneficial for planned top-up operations of the CLS storage ring. Many alternative injection techniques were examined as they apply to the CLS storage ring. Pulsed multipole magnets and a non-linear kicker (NLK) are the most viable options for integration with the current ring. Non-linear kicker designs are also being considered for the proposed CLS2 and studying the NLK in the limitations of the current machine provides insight to guide the work on the new machine. Simulation with the accelerator code ELEGANT shows the viability of the non-linear kicker design as developed at BESSY, MAX IV and SOLEIL for transparent injection at the CLS. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB121 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 16 July 2021 issue date ※ 01 September 2021 | ||
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WEPAB123 | Multi-Bunch Resistive Wall Wake Field Tracking via Pseudomodes in the ALS-U Accumulator Ring | injection, damping, feedback, kicker | 2893 |
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For the ALS-U project, particles will be injected from the booster to the accumulator ring utilizing an injection scheme that leaves the stored and injected particles with a non-trivial transient. This transient requires that multibunch feedback be masked for those buckets into which charge is injected. The masking significantly diminishes the damping capability of the multibunch feedback system. This problem is exacerbated by the large injection transient. The higher order resistive wall wake fields in the accumulator ring exceed the radiation damping time. To study whether the beam will remain multibunch stable during an injection cycle, a multibunch tracking simulation is used that simulates the multibunch feedback system and also pseudomode representation of resistive wall wake fields. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB123 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 01 September 2021 issue date ※ 23 August 2021 | ||
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WEPAB125 | Acceptance Analysis Method for the Scheme Design of Multipole Kicker Injection | injection, kicker, multipole, storage-ring | 2900 |
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A pulsed multipole kicker has zero magnetic field at the center, consequently, this injection scheme can be transparent to the stored beam and users. In general, multipole kicker injection schemes are derived from the method of phase space analysis. In this paper, a new method of acceptance analysis based on multi-particles tracking is proposed. Using this method, we can quickly obtain multiple kicker injection schemes and easily make adjustments to them. The details of this method are presented and we apply it to the HALF storage ring as an example. A series of tracking simulations are carried out and results are also discussed. | |||
Poster WEPAB125 [0.930 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB125 | ||
About • | paper received ※ 18 May 2021 paper accepted ※ 09 June 2021 issue date ※ 13 August 2021 | ||
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WEPAB133 | First Numerical Wakefield Studies of New In-Vacuum Cryogenic and APPLE II Undulators for BESSY II | impedance, vacuum, undulator, factory | 2925 |
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While the new in-vacuum cryogenic undulator is in its last commissioning stages, a worldwide new in-vacuum APPLE II undulator is being designed and constructed for BESSY II storage ring. Besides the challenging mechanical design of these small-gap and short-period undulators, challenges arise due to interaction with the electron beam. Therefore, detailed studies of this interaction is required to minimize the adverse effects on beam dynamics and the device itself. For this purpose, the wakefield effects have been computed numerically for critical parts of these devices i.e. the RF-shields, flexible tapers and taper sections. A brief overview of simulation results and discussions are presented in this paper. | |||
Poster WEPAB133 [0.795 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB133 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 23 July 2021 issue date ※ 23 August 2021 | ||
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WEPAB139 | Beam Tracking Simulations for Stage 1 of the Laser-Hybrid Accelerator for Radiobiological Applications (LhARA) | laser, proton, target, plasma | 2939 |
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The Laser-hybrid Accelerator for Radiobiological Applications (LhARA) is a unique and flexible facility proposed for radiobiological studies. The first stage of LhARA consists of an intense laser source interacting with a thin foil target producing a large flux of protons with energies up to 15 MeV. Particles will propagate through a combination of plasma (Gabor) lenses and magnetic elements to an achromat arc delivering the beam vertically to an in-vitro end station. An end-to-end simulation from the laser source to the end station is required to verify the conceptual design of the beamline. The laser-plasma interaction is simulated with Smilei (a particle-in-cell code) to produce a two-dimensional (2D) distribution of particles. Whilst it is possible to simulate the laser-plasma interaction in three dimensions (3D), access to the computing resources needed to run highly resolved simulations was not available. A sampling routine will be described which samples the 2D distribution to generate a 3D beam. The Monte Carlo simulation programs BDSIM and GPT were used to track the beam. Results of the simulations will be shown and compared to the results of an idealized Gaussian beam. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB139 | ||
About • | paper received ※ 18 May 2021 paper accepted ※ 01 July 2021 issue date ※ 10 August 2021 | ||
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WEPAB141 | Preliminary Simulation of CERN’s Linac4 H− Source Beam Formation | plasma, electron, extraction, linac | 2947 |
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Linac4 is the new (H−) linear injector of CERN’s accelerator complex. This contribution describes the modelling activities required to get insight into H− beam formation processes and their impact on beam properties. The simulation region starts from a homogeneous hydrogen plasma, the plasma then expands through the magnetic filter field. H− ions and electrons are electrostatically extracted through the meniscus (line of separation between the plasma and the extracted beam) and eventually accelerated. The physics is simulated via the 3D PIC code ONIX. This code, originally dedicated to ITER’s neutral injector sources, has been modified to match single aperture sources. A new type of boundary condition is described, as well as the field distribution and geometry of the standard IS03 and a dedicated proto-type of CERN’s Linac4 H− source. A plasma electrode prototype designed to provide metallic boundary conditions was produced and tested. This plasma electrode geometry enables Optical Emission Spectroscopy in the region closest to meniscus. A set of plasma parameters was chosen as input characterizing the plasma. Preliminary simulation results of beam formation region are presented. | |||
Poster WEPAB141 [0.710 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB141 | ||
About • | paper received ※ 18 May 2021 paper accepted ※ 02 June 2021 issue date ※ 31 August 2021 | ||
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WEPAB143 | Sub-MeV Ion Generation by Standing Wave Excitation of Ionized Gases | electron, acceleration, plasma, laser | 2951 |
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Funding: Hungarian Scientific Research Fund (OTKA) (125808, 129134) ÚNKP-20-3 New National Excellence Program of the Ministry for Innovation and Technology from the source of the National Research Many ion acceleration techniques have been suggested and thoroughly studied in the last two decades*. One of the promising techniques is the Coulomb explosion acceleration (CEA)**. Using CEA in clusters could result in symmetric acceleration if there are not any other significant mechanisms. We proposed a THz-driven accelerator scheme that is based on CEA in proton, deuterium and heavy water gas plasmas. Two counter-propagating THz pulses are focused to the ionized region of the gas jet. Following the ripping of the electrons from the gas plasmas by ultrafast standing waves, the Coulomb explosion accelerates the positive ions. According to our calculation, using 2 x 34 mJ THz pulses electrons and protons with 1.1 nC charge are accelerated up to 0.4 MeV and 0.1 MeV, respectively. The total energy of the particles is 0.7 % of the energy of the THz pulses. We examined the effect of the initial bunch charge, bunch size and shape on the final energy spectra and the directional distribution of the particles. Our presented technique is scalable from a few µm to a few thousand µm driving wavelengths and can be used for electron and heavy-ion acceleration. *J. Badziak, IOP Conf. Series: J Phys: Conf. Series 959, 012001 (2018). ** M. Murakami and K. Mima, Phys. of Plasmas 16, 103108 (2009). |
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Poster WEPAB143 [3.467 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB143 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 07 June 2021 issue date ※ 15 August 2021 | ||
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WEPAB147 | Simulations of Nanoblade-Enhanced Laser-Induced Cathode Emissions and Analyses of Yield, MTE, and Brightness | electron, laser, space-charge, brightness | 2957 |
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Funding: This work was supported by the Center for Bright Beams, National Science Foundation Grant No. PHY-1549132 and DOE HEP Grant DE-SC0009914. Laser-induced field emission of electrons from metallic nanotips has been well studied. Unfortunately, nanotips suffer low damage thresholds with enhanced fields around 10 GV/m. The nanoblade, akin to a nanotip extruded in one lateral dimension, may reach upwards of 40 GV/m due to its robust thermomechanical properties. This increased surface field promises brighter electron emissions. We perform simulations of strong-field emissions from metallic nanoblades via the 1-D time-dependent Schr\"odinger equation with effective Jellium and nonlinear collective image charge potentials, including the strong field gradients induced by the nanostructure. We measure spectra and yields and compare to recent experiments. Potential analytical forms of image potential limited yield for a spectrally rich emission are presented. Calculations of mean transverse energy are provided as well as a prospective method of mitigation with the goal of increasing brightness. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB147 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 06 July 2021 issue date ※ 01 September 2021 | ||
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WEPAB174 | Study of the Electron Seeded Proton Self-Modulation Using FBPIC | plasma, proton, wakefield, electron | 3008 |
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Funding: This work is supported by the Cockcroft Institute Core Grant and the STFC AWAKE Run 2 grant ST/T001917/1 In order to make a full use of the whole proton bunch to drive large amplitude plasma wakefields and suppress the uncontrolled growth of any possible instabilities at the head of the proton bunch, the AWAKE Run 2 experiment plans to use an electron bunch to seed the formation of the proton bunch self-modulation. Additionally, a density step in the plasma channel will be used to freeze the selfmodulation process to keep the wakefield amplitude. In this work, numerical simulations performed with FBPIC are used to investigate the electron seeded proton self-modulation and the effect of the plasma density step as well. |
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Poster WEPAB174 [1.751 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB174 | ||
About • | paper received ※ 10 May 2021 paper accepted ※ 28 June 2021 issue date ※ 24 August 2021 | ||
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WEPAB177 | Consideration of Triple-Harmonic Operation for the J-PARC RCS | operation, bunching, injection, cavity | 3020 |
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The wideband magnetic alloy (MA) cavities are employed in the J-PARC RCS. The dual-harmonic operation, in which each MA cavity is driven by superposition of the fundamental accelerating voltage and the second harmonic voltage, significantly improves the bunching factor and is indispensable for acceleration of the high intensity beams. The original LLRF control system was replaced with the new system in 2019, which can control the amplitudes of the higher harmonics as well as the fundamental and second harmonics. Therefore we consider to use additionally the third harmonic voltage for further improvement of the bunching factor during acceleration. By the triple-harmonic operation, the flat RF bucket can be realized with a higher synchronous phase and improvement of the bunching factor is expected. In this presentation, we describe the longitudinal simulation studies of the triple-harmonic operation. Also the preliminary test results are presented. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB177 | ||
About • | paper received ※ 18 May 2021 paper accepted ※ 25 June 2021 issue date ※ 19 August 2021 | ||
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WEPAB186 | Studies for the K12 High-Intensity Kaon Beam at CERN | detector, experiment, target, kaon | 3049 |
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The NA62 experiment is a fixed target experiment located in the North Area of CERN and has as main goal the measurement of the branching ratio of the rare decay K±>pi+vv. The primary proton beam from the SPS accelerator interacts with the T10 beryllium target and the generated 75 GeV/c secondary particles, containing about 6% of positive kaons, are transported by the K12 beamline to the NA62 experiment. Studies in this paper present detailed simulations of the K12 beamline developed in both FLUKA and BDSIM codes, which reproduce the current configuration of K12 for the NA62 experiment. The beam optics parameters of K12 are studied in BDSIM and compared to MADX optics and tracking calculations. The models in FLUKA and BDSIM are used for beam studies and muon production at various locations along the beamline, and the parameters obtained from simulations are benchmarked against data recorded by the experiment. The impact of the Cherenkov kaon tagging detector (CEDAR) on the beam quality is calculated for two different gas compositions in view of a possible upgrade of the detector. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB186 | ||
About • | paper received ※ 17 May 2021 paper accepted ※ 01 July 2021 issue date ※ 27 August 2021 | ||
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WEPAB190 | DC Break Design for a 2.45 GHz ECR Ion Source | GUI, site, ECR, high-voltage | 3064 |
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New 2.45 GHz Electron Cyclotron Resonance Ion Source (ECRIS) is under development at NRNU MEPhI. The transmission line is designed for transmitting the microwave power into the ECRIS. A DC break up to 80 kV was designed for the electrical insulation between the microwave supply system and the plasma chamber applied to high DC voltage. Current study considers the investigation results as well as the optimization of numerical simulations of the 2.45 GHz DC break with low losses and low emission into the surrounding space. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB190 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 08 June 2021 issue date ※ 30 August 2021 | ||
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WEPAB192 | Simulation Study on Double Diffuser for Loss Reduction in Slow Extraction at J-PARC Main Ring | extraction, operation, proton, scattering | 3069 |
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J-PARC (Japan Proton Accelerator Research Complex) Main Ring delivers slow-extracted 30~GeV proton beam to various nuclear and particle physics experiments. In the slow extraction the beam loss at the electrostatic septum (ESS) is inevitable, and the beam loss reduction is a key issue to realize the high-intensity beam delivery. We carried out simulation studies on the effectiveness of the beam diffusers at the upstream of the ESS for the beam loss reduction with various materials and dimensions of the diffusers. We found out that putting two diffusers simultaneously on the beam was effective for the beam loss reduction, and the expected beam loss was 0.35 times as high as the operation without diffusers. According to the simulation results we installed the diffusers in the J-PARC Main Ring. We performed beam test with one diffuser and beam loss reduction of 60% was observed, which was in good agreement with the simulation results. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB192 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 28 June 2021 issue date ※ 21 August 2021 | ||
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WEPAB193 | Optimization of the Hadron Ring Stripline Injection Kicker for the EIC | kicker, impedance, injection, wakefield | 3073 |
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Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy The Electron-Ion Collider (EIC) at Brookhaven National Laboratory is a high luminosity, ( ∼ 1034 \textrm{cm}-2 \textrm{s}-1 ) accelerator facility colliding polarized electron beam with different ion species ranging from lighter nuclei (proton, deuterium) to heavier nuclei (gold, uranium). Design of a stripline injection kicker for the Hadron Storage Ring (HSR) of EIC for beams with the rigidity of ∼ 81 T-m poses some technical challenges due to expected shorter bunch spacing and higher peak current of EIC. This paper focuses on the optimization of the EIC hadron ring injection kicker. Starting from the 2D cross-section design which includes the selection of electrodes shape, we describe the optimization of the kicker’s cross-section. Then we discuss converting this 2D geometry to 3D by adding essential components for the stripline kicker and the 3D optimization techniques that we employed. Finally, we show simulation results for the optimized geometry including wakefields and Time Domain Reflection (TDR) from one feedthrough to another. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB193 | ||
About • | paper received ※ 21 May 2021 paper accepted ※ 28 June 2021 issue date ※ 14 August 2021 | ||
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WEPAB194 | Feasibility of Using the Existing RHIC Stripline BPMs for the EIC | shielding, impedance, hadron, site | 3077 |
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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 design of the Electron-Ion Collider (EIC) at Brookhaven National Laboratory (BNL) will utilize portions of the existing Relativistic Heavy Ion Collider (RHIC) for the EIC hadron ring. The EIC design calls for up to 10-times shorter ion bunches compared to the present RHIC operation. Higher single bunch peak currents will result in higher voltages to the output ports of the BPMs consequently producing more heating of the cryogenic signal cables connected to these output ports. Therefore, the existing stripline BPMs should be either upgraded or replaced with new ones. In this paper, we explore the potentially cost-effective approach by incorporating an RF-shielding piece into the existing BPMs as opposed to replacing them completely. Starting with the power delivered to the output ports, we present the proposed BPM modification with the RF-shielding piece. Then we discuss in detail the RF-shielding piece geometry including the dimension of RF slot and RF-fingers configuration. Finally, we present the optimization of the shielding piece and the mechanical tolerances required for its fabrication. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB194 | ||
About • | paper received ※ 21 May 2021 paper accepted ※ 28 June 2021 issue date ※ 15 August 2021 | ||
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WEPAB195 | Design and Optimization of a Low Frequency RF-Input Coupler for the IsoDAR RFQ | rfq, coupling, cyclotron, multipactoring | 3081 |
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Funding: The RFQ-DIP project is supported by National Science Foundation grant \# PHY-1626069 and the Heising-Simons Foundation. The Isotope Decay-At-Rest experiment (IsoDAR) is a proposed underground experiment which is expected to be a definitive search for sterile neutrinos. IsoDAR uses an especially designed low-frequency spilt-coaxial radio frequency quadrupole (RFQ) to accelerate H2+ ions directly from the ion source into the main cyclotron accelerator. This paper mainly focuses on the design and optimization of a low frequency (32.8 MHz) RF-input coupler for the IsoDAR RFQ. Starting with a basic design, we determine its appropriate position for this coupler in the RFQ. Finally, we optimized the design to lower the input power without compromising the coupling efficiency. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB195 | ||
About • | paper received ※ 21 May 2021 paper accepted ※ 30 June 2021 issue date ※ 29 August 2021 | ||
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WEPAB198 | Beam Dynamics Design of a Synchrotron Injector with Laser-Accelerated Ions | laser, emittance, synchrotron, quadrupole | 3085 |
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We present, in this paper, the beam dynamics design of a linac injector with laser-accelerated carbon-ions for a medical synchrotron. In the design, the initial transverse divergence is reduced by two apertures. The beam is focused transversely through a quadrupole triplet lens downstream the apertures. The output energy spread of the extracted beam at the exit of the injector is compressed from ±6% to ±0.6% by a debuncher and a bend magnet system to meet the injection requirement for the synchrotron. By changing the width of imaging slit of the bend magnet system, the beam with energy of 4±0.024 MeV/u is extracted, and the particle number per shot and transverse emittances of the beam at the exit of the injector can be regulated through adjusting the slit height. The dynamics design can pave the way for the future concept research of the synchrotron injector. | |||
Poster WEPAB198 [1.034 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB198 | ||
About • | paper received ※ 16 May 2021 paper accepted ※ 16 June 2021 issue date ※ 18 August 2021 | ||
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WEPAB200 | Study on the Measurement and Residual Dose of the CSNS Stripping Foil | injection, scattering, MMI, neutron | 3093 |
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Funding: This work was supported by National Natural Science Foundation of China (Project Nos. 12075134 and U1832210). In this paper, firstly, the application and service life of the main stripping foil for the China Spallation Neutron Source (CSNS) were introduced. The stripping efficiency of the main stripping foil have been measured and studied. Then, by using the codes FLUKA and ORBIT, the particle scattering of the main stripping foil has been simulated and the theoretical residual doses in the injection region caused by the foil scattering were obtained. By weekly measurement of the residual doses in the injection region, the actual residual doses near the main stripping foil were given. The residual doses comparison results have confirmed that the particle scattering of the main stripping foil is the most important source of the residual doses in the injection region. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB200 | ||
About • | paper received ※ 09 May 2021 paper accepted ※ 25 August 2021 issue date ※ 23 August 2021 | ||
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WEPAB202 | Thermal Analysis of a Compact Split-Coaxial CW RFQ for the IsoDAR RFQ-DIP | rfq, cyclotron, injection, target | 3097 |
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The RFQ direct injection project (RFQ-DIP) for the neutrino physics experiment IsoDAR aims at an efficient injection of a high-current H2+ beam into the dedicated 60 MeV driver cyclotron. Therefore, it is intended to use a compact 32.8 MHz RFQ structure of the split-coaxial type as a pre-buncher. To determine the thermal elongation of the 1.4 m long electrode rods as well as the thermal frequency detuning of the RF structure at a maximum nominal power load of 3.6 kW, an extensive thermal and structural mechanical analysis using COMSOL Multiphysics was conducted. The water heating along the cooling channels as well as the properties of heat transfer from the copper structure to the cooling water were taken into account, which required CFD simulations of the cooling water flow in the turbulent regime. Here we present the methods and results of the sophisticated thermal and structural mechanical simulations using COMSOL and provide a comparison to more simplistic simulations conducted with CST Studio Suite. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB202 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 01 July 2021 issue date ※ 14 August 2021 | ||
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WEPAB203 | RFQ Beam Dynamics Optimization Using Machine Learning | rfq, focusing, network, quadrupole | 3100 |
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To efficiently inject a high-current H2+ beam into the 60 MeV driver cyclotron for the proposed IsoDAR project in neutrino physics, a novel direct-injection scheme is planned to be implemented using a compact radio-frequency quadrupole (RFQ) as a pre-buncher, being partially inserted into the cyclotron yoke. To optimize the RFQ beam dynamics design, machine learning approaches were investigated for creating a surrogate model of the RFQ. The required sample datasets are generated by standard beam dynamics simulation tools like PARMTEQM and RFQGen or more sophisticated PIC simulations. By reducing the computational complexity of multi-objective optimization problems, surrogate models allow to perform sensitivity studies and an optimization of the crucial RFQ beam output parameters like transmission and emittances. The time to solution might be reduced by up to several orders of magnitude. Here we discuss different methods of surrogate model creation (polynomial chaos expansion and neural networks) and identify present limitations of surrogate model accuracy. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB203 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 01 July 2021 issue date ※ 30 August 2021 | ||
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WEPAB204 | Layout of the New Septum Magnets for Fast Extraction in J-PARC Main Ring | septum, extraction, operation, emittance | 3103 |
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At J-PARC Main Ring (MR), we are pursuing to improve the beam power from 500 kW to 1.3 MW by reducing the repetition cycle from 2.48 to 1.16 seconds (1 Hz operation). Additionally, we are considering the beam particles increasing by selecting a more optimal tune. The fast extraction (FX) equipment to the neutrino facility (NU) is needed to upgrade for the 1 Hz operation. We plan to replace most FX septum magnets with new ones in 2021. We report a layout of the FX line in confirmation of new beam optics and mention the beam loss during the fast extraction. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB204 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 09 June 2021 issue date ※ 27 August 2021 | ||
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WEPAB210 | Beam Commissioning of the New 160 MeV H− Injection System of the CERN PS Booster | injection, emittance, scattering, brightness | 3116 |
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A key component to meeting the brightness targets of the LHC Injectors Upgrade (LIU) project at CERN is the new 160 MeV H− charge exchange injection system into the Proton Synchrotron Booster. This system has been in beam commissioning since December 2020, optimizing the beam production schemes for tailoring different beams to the respective user-defined brightness targets. In this paper, selected measurements from the beam commissioning period are presented, characterizing the system’s flexibility to produce the required wide range of transverse emittances. The discussion focuses on the essential optimization of the injection set-up to minimize space charge driven emittance blow-up and injection errors. The results are completed by selected comparisons with multi-particle simulation models of the injection process. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB210 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 19 July 2021 issue date ※ 29 August 2021 | ||
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WEPAB212 | Physics Studies for the LBNF Graphite Target Design | target, focusing, detector, proton | 3123 |
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We present the simulated physics performance of the Long-Baseline Neutrino Facility (LBNF) graphite target that is being designed by the RAL High Power Targets Group for the Deep Underground Neutrino Experiment (DUNE). We first compare three conceptual cylindrical target design options as a function of target length (up to 2.2 m): downstream supported, two individual targets and an upstream-supported cantilever. Choosing the cantilever design as the baseline, we show the effect of widening the upstream inner conductor of the first focusing horn to provide extra space for supporting the target. We also give estimates of the expected performance of the 1.5 m prototype and 1.8 m production cantilevered targets. Furthermore, we show the effects of the main engineering updates made to the other two focusing horns since the DUNE TDR. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB212 | ||
About • | paper received ※ 17 May 2021 paper accepted ※ 05 July 2021 issue date ※ 26 August 2021 | ||
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WEPAB213 | Optimization of Antiproton-Atom Collision Studies Using GEANT4 | proton, antiproton, experiment, bunching | 3126 |
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Funding: This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 721559. The interaction between antiprotons and hydrogen or helium atoms is a fundamental problem in many-particle atomic physics, attracting strong interest from both theory and experiments. Atomic collisions are ideal to study the three and four-body Coulomb problem as the number of possible reaction channels is limited. Currently, only the total cross-sections of such interactions have been measured in an energy range between keV and a few MeV. This contribution investigates the discrepancies between different theories and available experimental data. It also describes a pathway for obtaining differential cross-sections. A purpose-designed experimental setup is presented and detailed Geant4 simulations provide an insight into the interaction between short (ns) antiproton bunches and a dense gas-jet target. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB213 | ||
About • | paper received ※ 23 May 2021 paper accepted ※ 30 June 2021 issue date ※ 24 August 2021 | ||
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WEPAB214 | Realistic Simulations of Stray Field Impact on Low Energy Transfer Lines | solenoid, experiment, proton, antiproton | 3130 |
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Funding: This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 721559. Low energy (~100 keV) facilities working with antiprotons, heavy ions, or charged molecules may experience severe beam transport instabilities caused by field imperfections. For example, long (~10 m), unshielded beamlines will not be able to transfer particles due to the natural Earth magnetic field or stray fields from closely located experiments. Currently, only a limited number of simulation codes allow a simplified representation of such field errors, limiting capabilities for beam delivery optimization. In this contribution, a new simulation approach is presented that can provide detailed insight into 4D beam transport. It illustrates the impact of imperfections and stray fields on beam stability and quality through simulations of two antiproton experiments located in the Antimatter Factory (AD) at CERN in Geneva, Switzerland. Magnetic field imperfections are examined in two different ways, providing greater flexibility and an opportunity to benchmark all outcomes. Simulation performance is analyzed as a function of the level of detail and efficiency. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB214 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 12 July 2021 issue date ※ 18 August 2021 | ||
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WEPAB215 | Simulation of Intra-Beam Scattering in PyHEADTAIL | scattering, emittance, space-charge, proton | 3134 |
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Funding: This project has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No 721559 High-intensity beams in low-energy synchrotrons are subject to space charge as well as intra-beam scattering (IBS). Accurate modelling of both effects becomes essential when the transverse emittances and minimum bunch length are determined through heating processes and resonances induced by machine errors. To date, only very few tools available to the general public allow to simultaneously study space charge and IBS in self-consistent simulations. In this contribution, we present our recent development of an IBS module for PyHEADTAIL, an open-source 6D multi-particle tracking tool, which already includes various 2.5D and 3D space-charge models based on the self-consistent particle-in-cell algorithm. A simulation example of high-intensity bunch rotation demonstrates the joint impact of applied heating effects. Our model is based on the Martini and Bjorken-Mitingwa theories. Benchmarks of our implementation against IBS modules provided in the MAD-X and JSPEC codes are shown. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB215 | ||
About • | paper received ※ 23 May 2021 paper accepted ※ 14 July 2021 issue date ※ 13 August 2021 | ||
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WEPAB225 | Transverse and Longitudinal Single Bunch Instabilities in FCC-ee | wakefield, impedance, collider, coupling | 3153 |
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Improving the accuracy of the impedance model of an accelerator is important for keeping beam instabilities and power loss under control. Here, by means of the PyHEAD- TAIL tracking code, we first review the longitudinal mi- crowave instability threshold for FCC-ee by taking into ac- count the longitudinal impedance model evaluated so far. Moreover, we present the results of beam dynamics simula- tions, including both the longitudinal and transverse wake- fields due to the resistive wall, in order to evaluate the influ- ence of the bunch length on the transverse mode coupling instability. The results of the transverse beam dynamics are also compared with the Vlasov solver DELPHI. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB225 | ||
About • | paper received ※ 10 May 2021 paper accepted ※ 01 July 2021 issue date ※ 18 August 2021 | ||
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WEPAB226 | Investigation of Vlasov Systems with a Certain Class of Linearly-Collective Hamiltonians | bunching, collective-effects, linear-dynamics, distributed | 3157 |
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In many cases the Vlasov equation cannot be solved exactly due its inherent non-linearity arising from collective terms in the Hamiltonian. Based on the analysis of the Hamiltonian’s dependence on the phase-space density and the requirement for self-consistency in this contribution a class of Hamiltonians is defined and characterized. For members of this class the corresponding expansion of the Vlasov equation terminates. The new, potentially non-autonomous, Hamiltonian of the resulting Liouville equation depends only on the initial condition of the phase-space density. Prominent members of this class are Poisson-type kick-Hamiltonians, which we show as an example. We expect these investigations to be a potential starting point for the analysis and conception of operator-splitting schemes or splitting-free methods for beam-dynamics simulation codes. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB226 | ||
About • | paper received ※ 18 May 2021 paper accepted ※ 01 July 2021 issue date ※ 17 August 2021 | ||
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WEPAB227 | Mechanism of Longitudinal Single-Bunch Instability in the CERN SPS | impedance, synchrotron, coupling, emittance | 3161 |
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Understanding the origin of beam instabilities is essential for reaching the highest performance of proton synchrotrons. In the present work, the Oide-Yokoya eigenvalue method of solving the linearised Vlasov equation was used to shed light on the mechanism of longitudinal single-bunch instability in the CERN SPS. In particular, semi-analytical calculations were done for the full longitudinal impedance model, taking into account the RF nonlinearity. The obtained results agree well with macro-particle simulations and are consistent with available beam measurements. For the first time, the instability has been interpreted as a coupling of radial modes within a single azimuthal mode, due to a strong potential-well distortion of the synchrotron-frequency distribution. To avoid this instability, a higher RF voltage is required at a given emittance. Thus, the instability mechanism is very different from the loss of Landau damping, which, in contrast, is mitigated by a lower RF voltage. This understanding also allowed us to optimise the RF voltage programmes during the acceleration cycle for high-intensity bunches used in the AWAKE experiment at CERN. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB227 | ||
About • | paper received ※ 12 May 2021 paper accepted ※ 01 July 2021 issue date ※ 15 August 2021 | ||
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WEPAB229 | Transverse Density Pileup and Pattern Formation in Dense Ultracold Electron Beamlets under Coulomb Expansion | electron, ECR, FEL, damping | 3169 |
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Funding: This work was sponsored by the US Department of Energy Office of Science under Grant DE-SC0020241. Dynamic Coulomb expansion of dense particle bunches can lead to transverse density shock-like propagation for nonuniform bunch distributions. Furthermore, under favorable circumstances, multiple bunches in close proximity can collide without crossing to form wheel-and-spoke patterns. This process has been observed experimentally for Rubidium ions, but not yet for electrons, where the dynamics occur over far shorter length scales. We simulate the interaction of electron bunches while varying the initial transverse temperature and density profiles to determine the thresholds that characterize this pattern formation. Additionally, we consider the effects of asymmetries and the impact of a low-density halo on the overall process. The simulations are conducted using a novel high-fidelity algorithm for collisional particle dynamics. |
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Poster WEPAB229 [7.411 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB229 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 02 July 2021 issue date ※ 13 August 2021 | ||
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WEPAB234 | Simulating Two Dimensional Coherent Synchrotron Radiation in Python | emittance, radiation, synchrotron-radiation, electron | 3177 |
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Coherent Synchrotron Radiation (CSR) in bending magnets poses an important limit for electron beams to reach high brightness in novel accelerators. While the longitudinal wakefield has been well studied in one-dimensional CSR theory and implemented in various simulation codes, transverse wakefields have received less attention. Following the recently developed two-dimensional CSR theory, we developed a Python code simulating the steady-state two-dimensional CSR effects. The computed CSR wakes have been benchmarked with theory and other simulation codes. To speed up computation speed, the code applies vectorization, parallel processing, and Numba in Python. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB234 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 01 July 2021 issue date ※ 20 August 2021 | ||
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WEPAB235 | TMCI Theory of Flat Chambers Revisited | impedance, coupling, storage-ring, vacuum | 3181 |
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By accounting for the transverse impedance’ quadrupolar component according to the work of R.Lindberg *, no TMCI-instability can be observed in case of a pure horizontal resistive wall impedance of flat vacuum chambers. In order to study this effect more closely, TMCI-theory is reviewed and Lindberg’s work is further developed by including the resonator model as impedance type. The theory is applied to the ALBA-impedance model for the calculation of horizontal TMCI-detuning and threshold. Moreover, a couple of example cases are presented including vertical TMCI-detuning and threshold. Results on both planes are compared to simpler descriptions which account for the quadrupolar impedance effect only by tune shift.
* Ryan Lindberg, Fokker-Planck analysis of transverse collective instabilities in electron storage rings, Phy. Rev. Acc. Beams 19, 124402 (2016) |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB235 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 01 July 2021 issue date ※ 19 August 2021 | ||
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WEPAB243 | Longitudinal Microwave Instability Study at Transition Crossing with Ion Beams in the CERN PS | impedance, emittance, controls, proton | 3197 |
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The luminosity of lead ion collisions in the Large Hadron Collider (LHC) was significantly increased during the 2018 ion run by reducing the bunch spacing from 100 ns to 75 ns, allowing to increase the total number of bunches. With the new 75 ns variant, three instead of four bunches are generated each cycle in the Low Energy Ion Ring (LEIR) and the Proton Synchrotron (PS) with up to 30% larger intensity per bunch. The beam was produced with satisfactory quality but at the limit of stability in the injectors. In particular, the minimum longitudinal emittance in the PS is limited by a strong longitudinal microwave instability occurring just after transition crossing. The uncontrolled blow-up generates tails, which translate into an unacceptably large satellite population following the RF manipulations prior to extraction from the PS. In this paper, instability measurements are compared to particle simulations using the latest PS impedance model to identify the driving impedance sources. Moreover, means to mitigate the instability are discussed. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB243 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 06 July 2021 issue date ※ 29 August 2021 | ||
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WEPAB244 | Optimization and Machine Learning Applied to the RF Manipulations of Proton Beams in the CERN PS | beam-loading, operation, extraction, cavity | 3201 |
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The 25 ns bunch spacing in the LHC is defined by a sequence of RF manipulations in the Proton Synchrotron (PS). Multiple RF systems covering a large range of revolution harmonics (7 to 21, 42, 84, 168) allow performing RF manipulations such as beam splitting, and non-adiabatic bunch shortening. For the nominal beam sent to LHC, each bunch is split in 12 in the PS. The relative amplitude and phase settings of the RF systems need to be precisely adjusted to minimize the bunch-by-bunch variations in intensity, longitudinal emittance, and bunch shape. However, due to transient beam-loading, the ideal settings, as well as the best achievable beam quality, vary with beam intensity. Slow drifts of the hardware may also affect beam quality. In this paper, automatized optimization routines based on particle simulations with intensity effects are presented, together with the first considerations of machine learning. The optimization routines are used to assess the best achievable longitudinal beam quality expected with the PS RF systems upgrades, in the framework of the LHC Injector Upgrade project. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB244 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 01 July 2021 issue date ※ 24 August 2021 | ||
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WEPAB245 | A Possible Modification of Ceramic Chambers in the Injection Area at the RCS in J-PARC | impedance, injection, dipole, proton | 3205 |
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The J-PARC RCS is composed of ceramic chambers covered over copper stripes to suppress the eddy current on the chamber. The inductance, comprising the copper stripes and flanges, in combination with the capacitors makes an LCR electric circuit with the chamber and can cause field modulation in the chamber. Though most chambers are not harmful at the RCS, the chambers at the injection area excite beam losses, because a trapezoid field pattern is excited to accumulate LINAC beam during the injection period. In this report, we consider several types of ceramic chambers to suppress the field modulation. One type is a ceramic chamber covered over copper stripes in parallel with damping resistors. Another is that covered over spiral copper stripes with only capacitors. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB245 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 01 July 2021 issue date ※ 18 August 2021 | ||
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WEPAB248 | Kurth Vlasov-Poisson Solution for a Beam in the Presence of Time-Dependent Isotropic Focusing | focusing, emittance, space-charge, proton | 3213 |
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Funding: This work was supported by the Director, Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. The well-known K-V distribution provides an exact solution of the self-consistent Vlasov-Poisson system describing an unbunched charged particle beam with nonzero temperature in the presence of time-dependent linear transverse focusing. We describe a lesser-known exact solution of the Vlasov-Poisson system that is based on the work of Kurth in stellar dynamics. Unlike the K-V distribution, the Kurth distribution is a true function of the phase space variables, and the solution may be constructed on either the 4D or 6D phase space, for the special case of isotropic linear focusing. Numerical studies are performed for benchmarking simulation codes, and the stability properties of a 4D Kurth distribution are compared with those of a K-V distribution. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB248 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 14 July 2021 issue date ※ 02 September 2021 | ||
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WEPAB252 | Transient Beam-Beam Effect During Electron Bunch Replacement in the EIC | electron, emittance, proton, injection | 3228 |
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The high luminosity, high polarization electron-ion collider (EIC) will provide great opportunities in nuclear physics study. In order to maintain high polarization, the electron beam will be replaced every few minutes during the collider operation. This frequent replacement of electron beams can affect proton beam quality during the collision. In this paper, we report on the study of the transient effect of electron beam replacement on proton beam emittance growth through strong-strong beam-beam simulation. The effect of electron beam injection imperfection will be included in the study. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB252 | ||
About • | paper received ※ 17 May 2021 paper accepted ※ 21 June 2021 issue date ※ 02 September 2021 | ||
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WEPAB255 | Simulation Studies on the Interactions of Electron Beam with Wastewater | electron, radiation, photon, target | 3236 |
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Funding: Jefferson Lab LDRD The manufactured chemical pollutants, like 1,4 dioxane and PFAS (per- and polyfluroralkyl substances), found in the underground water and/or drinking water are challenging to be removed or biodegraded. Energetic electrons are capable of mediating and removing them. This paper utilizes FLUKA code to evaluate the beam-wastewater interaction effects with different energy, space and divergence distributions of the electron beam. With 8 MeV average energy, the electron beam exits from a 0.0127 cm thick titanium window, travels through a 4.3 cm distance air and a second 0.0127 cm thick stainless water container window with 2.43 cm radius, and finally is injected into the water area, where the volume of water is around 75 cubic cm. The distribution parameters of the electron beam are from the GPT (General Particle Tracer) simulations for UITF (Upgraded Injector Test Facility) in Jefferson lab. By varying the distributions, several measurements including the dose (or energy deposition) distribution, electron fluence, photon fluence are scored and compared. Taking the comparisons into consideration, this paper is aiming to find better electron beams for the wastewater irradiation. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB255 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 25 June 2021 issue date ※ 14 August 2021 | ||
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WEPAB256 | Three-Dimensional Space Charge Oscillations in a Hybrid Photoinjector | emittance, plasma, electron, cathode | 3240 |
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Funding: This work supported by DARPA GRIT under contract no. 20204571 and partially by INFN National committee V through the ARYA project. A new hybrid C-band photo-injector, consisting of a standing wave RF gun connected to a traveling wave structure, operating in a velocity bunching regime, has shown to produce an extremely high brightness beam with very low emittance and a very high peak current through a simultaneous compression of the beam in the longitudinal and transverse dimensions. A beam slice analysis has been performed in order to understand the evolution of the relevant physical parameters of the beam in the longitudinal and transverse phase spaces along the structure. A simple model for the envelope equation has been developed to describe the beam behavior in this particular dynamics regime that we term "triple waist", since all three dimensions reach a minimum condition almost simultaneously. The model analyzes the transverse envelope dynamics at the exit of the hybrid photo-injector, in the downstream drift where the triple waist occurs. The analytical solutions obtained from the envelope equation are compared with the simulations, showing a good agreement. Finally, these results have been analyzed also in terms of plasma oscillation to obtain a further physical interpretation of the beam dynamics. |
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Poster WEPAB256 [1.162 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB256 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 21 July 2021 issue date ※ 13 August 2021 | ||
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WEPAB265 | Simulations of Cooling Rate for Coherent Electron Cooling with Plasma Cascade Amplifier | electron, kicker, plasma, hadron | 3261 |
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Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. Coherent electron cooling (CeC) is a novel technique for rapidly cooling high-energy, high-intensity hadron beams. A plasma cascade amplifier (PCA) has been proposed for the CeC experiment in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL). The cooling rate of CeC experiment with PCA has been predicted in 3D start-to-end CeC simulations using code SPACE. |
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Poster WEPAB265 [1.507 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB265 | ||
About • | paper received ※ 13 May 2021 paper accepted ※ 10 June 2021 issue date ※ 18 August 2021 | ||
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WEPAB266 | Simulation Studies of Plasma Cascade Amplifier | electron, plasma, emittance, experiment | 3265 |
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Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. Plasma cascade amplifier (PCA) is an advanced design of amplifier for the coherent electron cooling (CeC) experiment in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL). Working principle of PCA is the new plasma cascadeμbunching instability occurring in electron beams propagating along a straight trajectory. PCA is cost-effective as it does not require separating electron and hadron beams. SPACE, a parallel, relativistic 3D electromagnetic Particle-in-Cell (PIC) code, has been used for simulation studies of PCA. |
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Poster WEPAB266 [2.317 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB266 | ||
About • | paper received ※ 13 May 2021 paper accepted ※ 10 June 2021 issue date ※ 31 August 2021 | ||
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WEPAB270 | Characterization and Simulation of Optical Delay System for the Proof-of-Principle Experiment of Optical Stochastic Cooling at IOTA | undulator, radiation, experiment, kicker | 3269 |
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Funding: CBB NSF-PHY-1549132 DOE DE-SC0018656 DOE DE-AC02-07CH11359 The Optical Stochastic Cooling (OSC) experiment at Fermilab’s IOTA storage ring uses two undulators to cool the beam over many turns. The radiation emitted by electrons in the first undulator is delayed and imaged in the second undulator where it applies a corrective energy kick on the electrons. Imperfections in the manufacturing of the delay plates can lead to a source of error. This paper presents the experimental characterization of the absolute thickness of these delay plates using an interferometric technique. The measured "thickness maps" are implemented in the Synchrotron Radiation Workshop (SRW) program to assess their impact on the delayed radiation pulse. |
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Poster WEPAB270 [2.578 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB270 | ||
About • | paper received ※ 16 May 2021 paper accepted ※ 05 July 2021 issue date ※ 22 August 2021 | ||
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WEPAB271 | Numerical Modelling of the Optical Stochastic Cooling Experiment at IOTA | radiation, damping, undulator, emittance | 3273 |
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Funding: CBB NSF-PHY-1549132 DOE DE-SC0018656 DOE DE-AC02-07CH11359 A proof-of-principle optical-stochastic cooling (OSC) experiment is currently in its commissioning phase at the Fermilab’s IOTA ring. In support of this experiment, we recently implemented an OSC element in the ELEGANT tracking program. The model, based on a semi-analytic description of OSC [*], supports the simulation of a large number of macroparticles (104-106) over many turns (106). This paper showcases the simulation capabilities to investigate the beam dynamics in the presence of cooling (or self-interacting radiation field in general) and quantify the impact of various sources of error (e.g. transverse and phase jitter), guide data analysis. * B. Andorf, V. A. Lebedev, J. Jarvis, and P. Piot Rev. Accel. Beams 21, 100702 (2018) |
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Poster WEPAB271 [1.649 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB271 | ||
About • | paper received ※ 16 May 2021 paper accepted ※ 06 July 2021 issue date ※ 13 August 2021 | ||
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WEPAB274 | Numerical Study of Beam Dynamics in PITZ Bunch Compressor | laser, booster, FEL, gun | 3285 |
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A magnetic bunch compressor has been recently designed for an accelerator-based THz source which is under development at the Photo Injector Test facility at DESY in Zeuthen (PITZ). The THz source is assumed to be a prototype for an accelerator-based THz source for pump-probe experiments at the European XFEL. As an electron bunch is compressed to achieve higher bunch currents for the THz source, we investigate the beam dynamics in the bunch compressor by numerical simulations. A start-to-end simulation optimizer has been developed by combining the use of ASTRA, IMPACT-T, and OCELOT to support the design of the THz source prototype. Coherent synchrotron radiation effects degrade the compression performance for our study cases with bunch charges up to 4 nC and beam energy of 17 MeV at a bending angle of 19 degrees. Simulation and preliminary beam characteristic results will be presented in this paper. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB274 | ||
About • | paper received ※ 11 May 2021 paper accepted ※ 06 July 2021 issue date ※ 23 August 2021 | ||
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WEPAB292 | Application of Machine Learning to Predict the Response of the Liquid Mercury Target at the Spallation Neutron Source | target, neutron, proton, experiment | 3340 |
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Funding: Basic Energy Sciences U.S. Department of Energy SC-22/Germantown Building 1000 Independence Avenue., SW Washington, DC 20585 P: (301) 903 - 3081 F: (301) 903 - 6594 The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory is currently the most powerful accelerator-driven neutron source in the world. The intense proton pulses strike on SNS’s mercury target to provide bright neutron beams, which also leads to severe fluid-structure interactions inside the target. Prediction of resultant loading on the target is difficult particularly when helium gas is intentionally injected into mercury to reduce the loading and mitigate the pitting damage on the target’s internal walls. Leveraging the power of machine learning and the measured target strain, we have developed machine learning surrogates for modeling the discrepancy between simulations and experimental strain data. We then employ these surrogates to guide the refinement of the high-fidelity mercury/helium mixture model to predict a better match of target strain response. |
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Poster WEPAB292 [0.930 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB292 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 02 July 2021 issue date ※ 10 August 2021 | ||
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WEPAB302 | COSY Machine-Model Optimization | dipole, operation, betatron, optics | 3375 |
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Funding: Helmholtz Association Successful operation of a particle accelerator requires accompanying model calculations. The model helps in understanding the machine and predicts the impact of a change in the settings (e.g. current of magnetic elements). For the COoler SYnchrotron (COSY) at Research Center Jülich the accelerator simulation software MAD-X is used to model the machine. The model parameters are steadily being improved based on various manual adjustments and analytical studies, however are hardly optimized all at once. This can be improved with machine learning methods. The model is used to predict measurable quantities, like Orbit Response Matrix (ORM) or betatron tunes. Several observables for different particle energies have been measured recently and the corresponding machine settings are available. We describe the effort to improve the agreement between measured and calculated ORMs and hence improve the agreement between model and (real) machine and report on the optimization using a multivariate algorithm (e.g. genetic algorithm). This facilitates the setup of COSY and will allow to perform high precision experiments e.g. a measurement of an electric dipole moment of deuterons at COSY. |
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Poster WEPAB302 [1.905 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB302 | ||
About • | paper received ※ 14 May 2021 paper accepted ※ 28 July 2021 issue date ※ 20 August 2021 | ||
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WEPAB303 | Machine Learning Applied to Automated Tunes Control at the 1.5 GeV Synchrotron Light Source DELTA | storage-ring, quadrupole, controls, operation | 3379 |
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Machine learning (ML) driven algorithms are finding more and more use cases in the domain of accelerator physics. Apart from correlation analysis in large data volumes, low and high level controls, like beam orbit correction, also non-linear feedback systems are possible application fields. This also includes monitoring the storage ring betatron tunes, as an important task for stable machine operation. For this purpose classical, shallow (non-deep), feed-forward neural networks (NNs) were investigated for automated adjusting the storage ring tunes. The NNs were trained with experimental machine data as well as with simulated data based on a lattice model of the DELTA storage ring. With both data sources comparable tune correction accuracies were achieved, both, in real machine operation and for the simulated storage ring model. In contrast to conventional PID methods, the trained NNs were able to approach the desired target tunes in fewer steps. The report summarizes the current status of this machine learning project and points out possible future improvements as well as other possible applications. | |||
Poster WEPAB303 [1.575 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB303 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 05 July 2021 issue date ※ 25 August 2021 | ||
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WEPAB304 | Multi-Objective Multi-Generation Gaussian Process Optimizer | operation, framework, network, storage-ring | 3383 |
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Funding: DOE, Office of Science, Office of Basic Energy Sciences, DE-AC02-76SF00515 and FWP 2018-SLAC-100469 Computing Science, Office of Advanced Scientific Computing Research, FWP 2018-SLAC-100469ASCR. We present a multi-objective evolutionary optimization algorithm that uses Gaussian process (GP) regression-based models to select trial solutions in a multi-generation iterative procedure. In each generation, a surrogate model is constructed for each objective function with the sample data. The models are used to evaluate solutions and to select the ones with a high potential before they are evaluated on the actual system. Since the trial solutions selected by the GP models tend to have better performance than other methods that only rely on random operations, the new algorithm has much higher efficiency in exploring the parameter space. Simulations with multiple test cases show that the new algorithm has a substantially higher convergence speed and stability than NSGA-II, MOPSO, and some other recent preselection-assisted algorithms. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB304 | ||
About • | paper received ※ 17 May 2021 paper accepted ※ 12 July 2021 issue date ※ 28 August 2021 | ||
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WEPAB306 | Applying Machine Learning to Optimization of Cooling Rate at Low Energy RHIC Electron Cooler | electron, network, experiment, emittance | 3391 |
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Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. The Low Energy RHIC electron Cooler (LEReC) is a novel, state-of-the-art, electron accelerator for cooling RHIC ion beams, which was recently built and commissioned. Optimization of cooling with LEReC requires fine-tuning of numerous LEReC parameters. In this work, initial optimization results of using Machine Learning (ML) methods - Bayesian Optimization (BO) and Q-learning are presented. Specially, we focus on exploring the influence of the electron trajectory on the cooling rate. In the first part, simulations are conducted by utilizing a LEReC simulator. The results show that both methods have the capability of deriving electron positions that can optimize the cooling rate. Moreover, BO takes fewer samples to converge than the Q-learning method. In the second part, Bayesian optimization is further trained on the historical cooling data. In the new samples generated by the BO, the percentage of larger cooling rates data is greatly enhanced compared with the original historical data. |
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Poster WEPAB306 [1.083 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB306 | ||
About • | paper received ※ 12 May 2021 paper accepted ※ 01 July 2021 issue date ※ 24 August 2021 | ||
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WEPAB308 | Measurement-Based Surrogate Model of the SLAC LCLS-II Injector | laser, network, controls, cathode | 3395 |
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Funding: This project was funded by the DOE SCGSR Program. There is significant effort within particle accelerator physics to use machine learning methods to improve modeling of accelerator components. Such models can be made realistic and representative of machine components by training them with measured data. These models could be used as virtual diagnostics or for model-based control when fast feedback is needed for tuning to different user settings. To prototype such a model, we demonstrate how a machine learning based surrogate model of the SLAC LCLS-II photocathode injector was developed. To create machine-based data, laser measurements were taken at the LCLS using the virtual cathode camera. These measurements were used to sample particles, resulting in realistic electron bunches, which were then propagated through the injector via the Astra space charge simulation. By doing this, the model is not only able to predict many bulk electron beam parameters and distributions which are often hard to measure or not usually available to measure, but the predictions are more realistic relative to traditionally simulated training data. The methods for training such models, as well as model capabilities and future work are presented here. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB308 | ||
About • | paper received ※ 26 May 2021 paper accepted ※ 27 July 2021 issue date ※ 24 August 2021 | ||
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WEPAB310 | Study and Design of a High-Performance Computing Infrastructure for Iranian Light Source Facility Based on the Accelerator Physicists and Engineers’ Applications Requirements | software, network, hardware, Ethernet | 3402 |
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Synchrotron design and operation are one of the complex tasks which requires a lot of precise computation. As an example, we could mention the simulations done for calculating the impedance budget of the machine which requires a notable amount of computational power. In this paper we are going to review different HPC scenarios suitable for this matter then we will present our design of a suitable HPC based on the accelerator physicists and engineers’ needs. Going through different HPC scenarios such as shared memory architectures, distributed memory architectures, cluster, grid and cloud computing we conclude implementation of a dedicated computing cluster can be desired for ILSF. Cluster computing provides the opportunity for easy and saleable scientific computation for ILSF also another advantage is that its resources can be used for running cloud or grid computing platforms as well. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB310 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 19 July 2021 issue date ※ 12 August 2021 | ||
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WEPAB318 | Prediction and Clustering of Longitudinal Phase Space Images and Machine Parameters Using Neural Networks and K-Means Algorithm | FEL, network, electron, ECR | 3417 |
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Machine learning algorithms were used for image and parameter recognition and generation with the aim to optimise the CLARA facility at Daresbury, using start-to-end simulation data. Convolutional and fully connected neural networks were trained using TensorFlow-Keras for different instances, with examples including predicting Longitudinal Phase Space (LPS) images with machine parameters as input and FEL parameter prediction (e.g. pulse energy) from LPS images. The K-means clustering algorithm was used to cluster the LPS images to highlight patterns within the data. Machine learning techniques can enhance the way large amounts of data are processed and analysed and so have great potential for application in accelerator science R&D. | |||
Poster WEPAB318 [1.062 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB318 | ||
About • | paper received ※ 17 May 2021 paper accepted ※ 05 July 2021 issue date ※ 21 August 2021 | ||
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WEPAB327 | Sheet Electron Probe for Beam Tomography | electron, proton, diagnostics, cathode | 3437 |
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Funding: Work is funded by DOE SBIR grant DE-SC0021581 An electron beam probe has been successfully used for the determination of accelerated particle density distributions. However, the apparatus used for this diagnostic had a large size and complex design which limit the broad use of this diagnostic for tomography of accelerated bunches. We propose a new approach to electron beam tomography: we will generate a continuous sheet of electrons. As the ion beam bunches pass through the sheet, they cause distortions in the distribution of sheet electrons arriving at CCD device on the other side of the beam that is interpreted to give a continuous measurement of the beam profile. The apparatus to generate the sheet beam is a strip cathode, which, compared to the scanning electron beam probe, is smaller, has a simpler design and less expensive manufacturing, has better magnetic shielding, has higher sensitivity, higher resolution, has better accuracy of measurement and better time resolution. With this device, it is possible to develop almost ideal tomography diagnostics of bunches in linear accelerators and in circular accelerators and storage rings. |
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Poster WEPAB327 [0.640 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB327 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 15 July 2021 issue date ※ 20 August 2021 | ||
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WEPAB329 | LCLS-II Average Current Monitor | cavity, vacuum, coupling, network | 3443 |
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The LCLS-II project at SLAC is a high power upgrade to the existing free-electron laser facility. The LCLS-II Accelerator System will include a new 4 GeV continuous-wave superconducting linear accelerator in the first kilometer of the SLAC linear accelerator tunnel and supplements the existing low power pulsed linac. Average Current Monitors (ACMs) are needed to protect against excessive beam power which might otherwise cause damage to the beam dumps. The ACM cavities are pillbox-shaped stainless steel RF cavity with two radial probe ports with couplers, one radial test port with a coupler, and a mechanism for mechanically fine-tuning the cavity resonant frequency. The ACM RF cavities will be located at points of known or constrained beam energy and will monitor the beam current, a safety system will trip off the beam if the beam power exceeds the allowed value. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB329 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 16 June 2021 issue date ※ 22 August 2021 | ||
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WEPAB340 | Pressure Simulations for the EIC Interaction Region | vacuum, photon, electron, detector | 3483 |
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Background detector rates in the Electron Ion Collider depend in part on the pressure in the interaction region. Materials choice, synchrotron radiation induced desorption, conditioning time and pumping configuration all affect the pressure in the system. Simulations of the region using Synrad and Molflow+ coupled simulation codes will be presented for various configruations and conditioning times. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB340 | ||
About • | paper received ※ 18 May 2021 paper accepted ※ 20 July 2021 issue date ※ 11 August 2021 | ||
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WEPAB342 | Beam Induced Power Deposition in CERN SPS Injection Kickers | impedance, HOM, kicker, coupling | 3490 |
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The SPS injection kicker magnets (MKP) were developed in the 1970’s, before beam power deposition was considered an issue and before any advanced tools for analysing beam coupling impedance were available in their current form. These magnets are very lossy from a beam impedance perspective, and the beam induced power deposition is highly non-uniform. This is expected to be an issue during SPS operation with the higher intensity beams needed in the future for HL-LHC. There is an existing design, with serigraphy, that will mitigate the heating issues, which is presently being implemented on a prototype for test and measurement. Models have been developed to aid in predicting the safe operating regions until the upgraded MKPs are installed in the SPS: these are reported herein. A novel measurement technique is also presented to confirm the non-uniform power deposition in the ferrite yoke. Beam coupling impedance, power deposition, field rise time and field uniformity data are also presented for an upgraded, prototype, MKP. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB342 | ||
About • | paper received ※ 16 May 2021 paper accepted ※ 02 July 2021 issue date ※ 25 August 2021 | ||
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WEPAB343 | Inductive Adder Prototype for FCC-hh Injection Kicker System | kicker, injection, flattop, collider | 3494 |
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The future circular collider (FCC) requires a highly reliable injection kicker system. Present day kicker systems often rely on thyratron-based pulse generators and a pulse forming network or line: the thyratron is susceptible to self-triggering. Hence, an alternative pulse generator topology, based on fast semiconductor switches, is considered for the FCC. One possibility is an inductive adder (IA). A prototype IA has been designed and built: the main challenges are the fast rise time, high output current, low system impedance and a 2.3 us pulse duration combined with low droop. This paper presents the results of measurements on the prototype IA where the rated output current and output voltage were achieved separately. Suggested improvements to the IA hardware are identified and proposals are presented that could help improve the kicker system performance. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB343 | ||
About • | paper received ※ 16 May 2021 paper accepted ※ 01 July 2021 issue date ※ 17 August 2021 | ||
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WEPAB344 | Studies for Mitigating Flashover of CERN-LHC Dilution Kicker Magnets | electron, kicker, vacuum, high-voltage | 3498 |
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The LHC beam dump system is used for extracting beam from the LHC and, as such, is a safety critical system whose proper functionality must be assured. Dilution kicker magnets (MKBs) sweep the extracted beam over the cross-sectional area of a dump block as the energy density would otherwise be too high and damage the block. In 2018, a high voltage flashover occurred in a vertical MKB (MKBV) vacuum tank, during a beam dump, which resulted in non-ideal sweep of the beam over the block. The location of the flashover could not be identified during a subsequent inspection of the magnet. Hence, electrical field simulations have been carried out to identify potentially critical regions, to determine the most probable region of the flashover. One potentially critical region is a rectangular beam pipe (RBP) between the end of the tank and the MKBV magnet, whose purpose is to reduce plasma propagation to the adjacent tank in the event of a flashover. Mitigating measures were studied and are reported in this paper. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB344 | ||
About • | paper received ※ 16 May 2021 paper accepted ※ 06 July 2021 issue date ※ 22 August 2021 | ||
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WEPAB345 | Impedance and Thermal Studies of the LHC Injection Kicker Magnet Upgrade | kicker, impedance, injection, coupling | 3502 |
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The bunch intensities of High Luminosity (HL) LHC are predicted to lead to heating of the ferrite yokes of the LHC injection kicker magnets (MKI), in their current configuration, to their Curie temperature. Hence, the MKIs are being upgraded to meet the requirements of HL-LHC, which is planned to start in the mid-2020s. The upgraded design features an RF damping ferrite loaded structure at the upstream end of each magnet, which will absorb a large portion of the beam induced power deposition of the magnet. The ferrite damper is cooled via a copper sleeve, brazed to the ferrite, and a set of water pipes. The thermal contact conductance (TCC) between ferrite and copper is very important, as are the properties of the ferrite. In this paper, we present measurements of the TCC and ferrite properties. This data is used to predict temperatures during operation of the LHC. In addition, a measurement and prediction is shown for the longitudinal impedance of the magnet. The models developed in this study will be benchmarked during run III of the LHC. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB345 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 06 July 2021 issue date ※ 13 August 2021 | ||
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WEPAB346 | Electromagnetic Modelling of Kicker Magnets to Derive Equivalent Circuits | kicker, coupling, impedance, extraction | 3506 |
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An equivalent circuit model of a kicker magnet system is an invaluable tool for predicting the performance, studying possible modifications and for helping to diagnose faults. The frequency content of pulses associated with a ferrite loaded transmission line kicker magnet generally extend up to a few tens of MHz: hence, it is feasible to accurately model such a kicker magnet using lumped elements. This modelling technique is powerful since it in general has a run time several orders of magnitude shorter than a full wave electromagnetic simulation. In this paper, we determine values, including those of parasitic components, using modern simulation tools, for use in the lumped equivalent circuit models. In addition, the paper describes a method to simulate coupling between beam and the electrical circuit of a kicker magnet at relatively low frequencies: this allows one to use circuit analysis tools to study means of mitigating beam induced resonances. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB346 | ||
About • | paper received ※ 16 May 2021 paper accepted ※ 02 July 2021 issue date ※ 14 August 2021 | ||
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WEPAB349 | Design of a Circular Waveguide TM01 Mode Launcher with Wire Loop Feed | GUI, coupling, experiment, detector | 3517 |
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In Accelerator technology, RF power couplers are important component to couple RF signal to travelling wave structure. Circular waveguide TM01 mode is one of the symmetric modes, that is suitable to use for RF coupling. TM01 mode launcher is used as an RF coupler in Accelerator technology*. Design of a compact circular waveguide TM01 mode-launcher is presented in this paper. The design is based on the principle of magnetic field coupling between a wire loop and TM01 mode of circular waveguide. The mode launcher exhibits high efficiency and 3.1% bandwidth at 3.2 GHz frequency with both circular and elliptical loop. Performance of the mode launcher is experimentally verified and simulated S-parameters agree with the measured results. The mode launcher is of compact size and is suitable for efficient excitation of TM01 mode in circular waveguide and travelling wave structures. The launcher is also useful for cold testing of high power microwave antennas and Radars.
* M. Forno, "Design of a high power TM01 mode launcher optimized for manufacturing by milling." 2016. |
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Poster WEPAB349 [1.135 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB349 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 20 August 2021 | ||
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WEPAB351 | Requirements for an Inductive Voltage Adder as Driver for a Kicker Magnet with Short Circuit Termination | kicker, impedance, timing, flattop | 3521 |
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At CERN pulse generators based on Thyratron switches and SF6 gas filled pulse forming lines, used for driving kicker magnets, are to be replaced with semiconductor technology. Preliminary investigations show the inductive voltage adder is suitable as a pulse generator for this application. To increase the magnetic field without raising the system voltage, a short-circuit termination is often applied to a kicker magnet. Because of the electrical length of a transmission line magnet, wave propagation needs to be considered. To allow for the wavefront reflected from the short-circuit termination back to the generator, a novel approach for an inductive adder architecture has been investigated. It is based on a modified generator interface, circulating the current back into the load, until the stored energy is absorbed at the end of the pulse. This approach allows for a smaller magnetic core size compared to a conventional design with a matched load. Moreover, it enables more energy-efficient operation involving smaller storage capacitors. This paper summarizes the conceptual design features and furthermore gives an overview of the parameter space for possible applications at CERN. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB351 | ||
About • | paper received ※ 18 May 2021 paper accepted ※ 11 June 2021 issue date ※ 17 August 2021 | ||
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WEPAB356 | Proposal of an Alignment System for HALF: The Reference Network of Alignment | alignment, monitoring, real-time, network | 3533 |
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As a fourth-generation light source based on the diffraction-limited storage ring, Hefei Advanced Light Facility (HALF) has higher requirements for magnets alignment in accuracy, efficiency, and reliability. In this paper, the Reference Network of Alignment (RNA) system is proposed to improve the magnetic axis alignment accuracy on the radial direction of the beamline. Herein, we mainly introduce the concept design and the theoretical analysis of the RNA system, which center on the novel fusion method of sensors. A simulation result shows that it is credible to assume the RNA system can achieve an alignment installation accuracy of 20 µm and a displacement monitoring accuracy of 10 µm. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB356 | ||
About • | paper received ※ 16 May 2021 paper accepted ※ 21 June 2021 issue date ※ 31 August 2021 | ||
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WEPAB363 | Dynamic Response of Spallation Volume to Beam Raster on the European Spallation Source Target | target, resonance, operation, proton | 3552 |
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To achieve a desirably low beam intensity on the target, the European Spallation Source (ESS) adopted a beam raster system at the high beta beam transport part of the linac. The raster system paints the beam on the target with frequencies up to 40 kHz within the 2.86 ms beam pulse, to form a uniformly expanded beam footprint. While the beam raster reduces the time-averaged beam current density to a level that the 5 years of design lifetime of the target system can be achieved with a high operational reliability, it could potentially induce deleterious dynamic excitations in the spallation volume made of tungsten. The stress wavelets created by raster sweeps can be amplified if the sweep frequency is in tune with a resonance mode of the tungsten volume. This coherent interference of the wavelets could lead to a high dynamic stress in tungsten, posing a risk of premature failure of the target. In this paper, the dynamic response of the spallation volume of the ESS target to different beam raster frequencies has been analysed, using multi-physics simulations based on measured material data. Finally, a safe operational range of the beam raster frequency band is proposed. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB363 | ||
About • | paper received ※ 12 May 2021 paper accepted ※ 02 July 2021 issue date ※ 01 September 2021 | ||
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WEPAB371 | Numerical Analysis on Nitrogen Injection Fire Extinguishing System in the LINAC Area at TPS | linac, injection, GUI, gun | 3578 |
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The Linear accelerator (LINAC) of Taiwan Photon Source (TPS) could generate electrons to 150 MeV. The main subsystems including an electron gun, buncher, accelerating sections, vacuum system, and focusing and steering magnets are located in the LINAC area of 223.5 m2 and 3 m in height. We designed a nitrogen injection fire extinguishing system for the LINAC area and performed Computational Fluid Dynamic (CFD) simulation to analyse the fire extinguishing performance with and without fresh air supplied from the air conditioning system. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB371 | ||
About • | paper received ※ 16 May 2021 paper accepted ※ 21 June 2021 issue date ※ 20 August 2021 | ||
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WEPAB381 | Multipactor Simulations for MYRRHA Spoke Cavity: Comparison Between SPARK3D, MUSICC3D, CST PIC and Measurement | multipactoring, electron, cavity, niobium | 3606 |
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The multipactor effect can lead to thermal breakdown (quench), high field emission and limited accelerating gradient in superconducting accelerator devices. To determine the multipactor breakdown power level, multipactor simulations can be performed. The objective of this study is to compare the results given by different simulation codes with the results of vertical testing of SRF cavities. In this paper, Spark3D, MUSICC3D and CST Studio PIC solver have been used to simulate the multipactor effect in Spoke cavity developed within the framework of MYRRHA project. Then, a benchmark of these three simulation codes has been made. The breakdown power level, the multipactor order and the most prominent location of multipactor are presented. Finally, the simulation results are compared with the measurements done during the vertical tests. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB381 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 24 June 2021 issue date ※ 25 August 2021 | ||
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WEPAB383 | An Evolutionary Algorithm Approach to Multi-Pass ERL Optics Design | linac, optics, quadrupole, focusing | 3610 |
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Funding: This material is based upon work supported by the U.S. Department of Energy under contract DE-AC05-06OR23177. An Energy Recovery Experiment at CEBAF (ER@CEBAF) is aimed at demonstrating high energy, low current, multi-pass energy recovery at the existing 12 GeV CEBAF accelerator. The beam break-up instability, limiting the maximum beam current, can be controlled through minimizing beta functions for the lowest energy pass, which gives a preference to strongly focusing optics, e.g. a semi-periodic FODO lattice. On the other hand, one needs to limit beta function excursions, caused by under focusing, at the higher energy passes, which in turn favors weakly focusing linac optics. Balancing both effects is the main objective of proposed multi-pass linac optics optimization. Here, we discuss an optics design process for ER@CEBAF transverse optics using a genetic algorithm. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB383 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 02 July 2021 issue date ※ 15 August 2021 | ||
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WEPAB384 | Design and Beam Dynamics of the Electron Lens for Space Charge Compensation in SIS18 | electron, space-charge, solenoid, dipole | 3614 |
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An electron lens for space charge compensation is being developed at GSI to increase the ion beam intensities in SIS18 for the FAIR project. It uses an electron beam of 10A maximum current at 30keV. The maximum magnetic field on-axis is 0.6T, considerably higher than the field of the existing electron cooler. The magnetic system of the lens consists of solenoids and toroids. The toroids’ vertical field component creates a significant horizontal orbit deflection in the circulating low rigidity ion beam. To correct this deflection, four correction dipoles have been introduced. As common for electron lenses, the high-power electron beam is not dumped at ground potential, but rather in a collector with a small bias potential with respect to the cathode. The present design foresees a collector at -27kV, leading to a power dissipation of 30kW, distributed over a large surface area by placing the collector in an appropriately shaped magnetic field of a pre-collector solenoid. This contribution reports on the design of the lens and presents the results of beam transport simulations for the electron beam (with space charge) and a representative ion beam, performed using the 3D CST STUDIO. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB384 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 05 July 2021 issue date ※ 31 August 2021 | ||
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WEPAB396 | First Measurements on Multipactor Study | multipactoring, electron, vacuum, ECR | 3633 |
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Multipactor (MP) is an undesired phenomenon of resonant electron build up encountered on particle accelerators. It can induce anomalous thermal losses, higher than the Joule losses, inducing a decrease of the superconducting cavities quality factor, it can even lead to a cavity quench. On couplers, it can produce irreversible damages or generate a breakdown of their vacuum window. Multipactor may lead to Electron Cloud build up as well. The accelerator group at LPSC has developed a test bench dedicated to the multipactor studies. This paper presents the experimental set-up and its first measurements. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB396 | ||
About • | paper received ※ 18 May 2021 paper accepted ※ 14 July 2021 issue date ※ 17 August 2021 | ||
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WEPAB397 | Design of the Two-Layer Girder for Accelerating Tube | neutron, ECR, acceleration, operation | 3636 |
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An accelerating tube is one kind of important acceleration equipment of a linear accelerator. It is often made up of oxygen-free copper with a long tubular structure. It’s easy to suffer from deformation. Based on support requirements, the reasonable structure of the girder was obtained. Four supporting blocks were installed on the top surface of aluminum profile with the uniform distribution along the beam direction. The support strength with static condition and different working conditions were checked by ANSYS simulation calculation to ensure the stable operation of the girder. The two-layer girder can be used as a reference for other similar slender part for its simple structure and reliable support. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB397 | ||
About • | paper received ※ 14 May 2021 paper accepted ※ 01 September 2021 issue date ※ 22 August 2021 | ||
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WEPAB400 | Forced Coupling Resonance Driving Terms | coupling, dipole, optics, resonance | 3646 |
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At the LHC, coupling is routinely measured using forced oscillations of the beam through excitation with an AC-dipole. The driving of the particle motion has an impact on the measurement of resonance driving terms. Recent findings suggest that the current models describing the forced motion are neglecting a local effect of the AC-dipole, creating a jump of the amplitude of the resonance driving terms. This work presents a study of the improvement of coupling measurements for typical LHC optics as well as its upgrade project HL-LHC, by using the new model. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB400 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 02 August 2021 issue date ※ 20 August 2021 | ||
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WEPAB401 | Study for Alternative Cavity Wall and Inductive Insert Material | proton, storage-ring, impedance, experiment | 3650 |
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Funding: Contract No. 89233218CNA000001, supported by the U.S. Department of Energy’s National Nuclear Security Administration (NNSA), for the management and operation of Los Alamos National Laboratory (LANL). The goal of this work was to develop a solution to the problem of longitudinal beam instability. Beam instability has been a significant problem with storage rings’ performance for many decades. The proton storage ring (PSR) at the Los Alamos Neutron Science Center (LANCE) is no exception. To mitigate the instability, it was found that ferrite inductive inserts can be used to bunch the protons that are diverging due to the electron background. The PSR was the first storage ring to successfully use inductive inserts to mitigate the longitudinal instability with normal production beams. However, years later new machine upgrades facilitate shorter, more intense beams to meet the needs of researchers. The ferrite inserts used to reduce the transverse instabilities induce a microwave instability with the shorter more intense proton beam. This study investigates alternative magnetic materials for inductive inserts in particle beam storage rings, including the necessary engineering for maintaining the ideal temperature during operation. ’ tjschaub@unm.edu |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB401 | ||
About • | paper received ※ 29 May 2021 paper accepted ※ 02 July 2021 issue date ※ 15 August 2021 | ||
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WEPAB410 | Finite Element Analyses of Synchrotron Radiation Induced Stress in Beryllium Synch-Light Mirrors | dipole, synchrotron, scattering, operation | 3664 |
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Funding: Air Force Research Laboratory Directorate for Mathematical and Physical Sciences National Institute of General Medical Sciences Empire State Development - NYSTAR Mirrors made of high purity beryllium are used in particle accelerators to extract synchrotron radiation (SR) in the visible range for transverse and longitudinal particle beam profile measurements. Be is a high-strength, high thermal conductivity material. As a low-Z metal, it allows high-energy photons to penetrate the mirror body, so that majority of the SR power is dissipated, resulting in a significantly reduced thermal stress and distortion on the mirror surface. In this paper, we describe a Finite Element Analysis method of accurately simulating the SR-induced thermal stress on the beryllium mirrors at the Cornell Electron Storage Ring at various particle beam conditions. The simulations consider the energy dependence of X-ray attenuation in beryllium. The depth-dependent distribution of the power absorbed by the mirror is represented by separate heating zones within the mirror model. The results help set the operational safety limit for the mirrors-ensuring that the SR-induced thermal stress is below the elastic deformation limit and estimate the mirror surface distortion at high beam currents. The simulated surface distortion is consistent with optical measurements. |
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Poster WEPAB410 [0.942 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB410 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 24 June 2021 issue date ※ 02 September 2021 | ||
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THXA01 | Beyond RMS: Understanding the Evolution of Beam Distributions in High Intensity Linacs | rfq, quadrupole, MEBT, space-charge | 3681 |
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Funding: This work has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. Understanding the evolution of beams with space charge is crucial to design and operation of high intensity linacs. While the community holds a broad understanding of the mechanisms leading to emittance growth and halo formation, there is outstanding discrepancy between measurements and beam evolution models that precludes prediction of halo losses. This may be due in part to insufficient information of the initial beam distribution. This talk will describe work at the SNS Beam Test Facility to directly measure the 6D beam distribution. Full-and-direct 6D measurement has revealed hidden but physically significant dependence between the longitudinal distribution and transverse coordinates. This nonlinear correlation is driven by space charge and reproduced by self-consistent simulation of the RFQ. Omission of this interplane correlation, common when bunches are reconstructed from lower-dimensional measurements, degrades downstream predictions. This talk will also describe the novel diagnostics supporting this work. This includes ongoing improvements to efficiency of the 6D phase space measurement as well as recent achievement of six orders of dynamic range in 2D phase space. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THXA01 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 23 July 2021 issue date ※ 17 August 2021 | ||
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THXA02 | Overview of the Micro-Bunching Instability in Electron Storage Rings and Evolving Diagnostics | operation, bunching, electron, diagnostics | 3686 |
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The micro-bunching instability is a longitudinal instability that leads to dynamical deformations of the charge distribution in the longitudinal phase space. It affects the longitudinal charge distribution, and thus the emitted coherent synchrotron radiation spectra, as well as the energy distribution of the electron bunch. Not only the threshold in the bunch current above which the instability occurs, but also the dynamics above the instability threshold strongly depends on machine parameters, e.g., natural bunch length, accelerating voltage, momentum compaction factor, and beam energy. All this makes the understanding and potential mitigation or control of the micro-bunching instability an important topic for the next generation of light sources and circular e+/e− colliders. This presentation will give a review on the micro-bunching instability and discuss how technological advances in the turn-by-turn and bunch-by-bunch diagnostics are leading to a deeper understanding of this intriguing phenomenon. | |||
Slides THXA02 [23.626 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THXA02 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 23 July 2021 issue date ※ 31 August 2021 | ||
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THXA04 | Microbunching Instability in the Presence of Intrabeam Scattering for Single-Pass Accelerators | electron, bunching, scattering, FEL | 3692 |
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Funding: This work is supported by the Fundamental Research Funds for the Central Universities under Project No. 5003131049 and National Natural Science Foundation of China under project No. 11905073. Intrabeam scattering (IBS) has long been studied in lepton or hadron storage rings as a slow diffusion process, while the effects of IBS on single-pass or recirculating electron accelerators have drawn attention only in the recent two decades due to the emergence of linac-based or ERL-based 4th-generation light sources, which require high-quality electron beams during the beam transport. Recent experimental measurements indicate that in some parameter regimes, IBS can have a significant influence on microbunched beam dynamics. Here we develop a theoretical formulation* of microbunching instability (MBI) in the presence of IBS for single-pass accelerators. We start from the Vlasov-Fokker-Planck (VFP) equation, combining both collective longitudinal space charge and incoherent IBS effects. The linearized VFP equation with the corresponding coefficients is derived. The evolutions of the phase space density and energy modulations are formulated as a set of coupled integral equations. The formulation** is then applied to a simplified single-pass transport line. The results from the semi-analytical calculation are compared and show good agreement with particle tracking simulations. * C.-Y. Tsai et al., Phys. Rev. Accel. Beams 23, 124401 (2020) ** C.-Y. Tsai and W. Q, Phys. Plasmas (2021), accepted for publication |
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Slides THXA04 [2.699 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THXA04 | ||
About • | paper received ※ 13 May 2021 paper accepted ※ 19 July 2021 issue date ※ 13 August 2021 | ||
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THXA06 | The Effect of Beam Velocity Distribution on Electron-Cooling at Elena | electron, proton, emittance, antiproton | 3700 |
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Funding: Work supported by EU Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 721559. ELENA is a novel storage ring at CERN, designed to deliver low energy, high-quality antiprotons to antimatter experiments. The electron cooler is a key component of this decelerator, which counters the beam blow-up as the antiproton energy is reduced from 5.3 MeV to 100 keV. Typical numerical approximations on electron cooling processes assume that the density distribution of electrons in analytical form and the velocity distribution space to be Maxwellian. However, it is useful to have an accurate description of the cooling process based on a realistic electron distribution. In this contribution, BETACOOL simulations of the ELENA antiproton beam phase space evolution were performed using uniform, Gaussian, and "hollow beam" electron velocity distributions. The results are compared with simulations considering a custom electron beam distribution obtained with G4beamline. The program was used to simulate the interaction of an initially Gaussian electron beam with the magnetic field measured inside the electron cooler interaction chamber. The resulting beam lifetime and equilibrium parameters are then compared with measurements. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THXA06 | ||
About • | paper received ※ 18 May 2021 paper accepted ※ 01 July 2021 issue date ※ 14 August 2021 | ||
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THXC05 | Simulation of Imaging Using Accelerated Muon Beams | acceleration, linac, radio-frequency, scattering | 3740 |
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Muons are elementary particles with strong penetrating power and cosmic-ray muons have been utilized to see through large structures such as the pyramids. Recently, we have succeeded in accelerating muons using a radio-frequency accelerator, opening the door to new imaging techniques using accelerated muon beams. Currently, imaging with cosmic-ray muons is limited in imaging time and resolution by their intensity and energy fluctuations. The muon beams can have high intensity and monochromatic energy, allowing for better resolution imaging in less time. In this poster, imaging of spent nuclear fuel in casks using cosmic rays and muon beams, as well as imaging in other cases, will be evaluated and compared. | |||
Poster THXC05 [2.560 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THXC05 | ||
About • | paper received ※ 16 May 2021 paper accepted ※ 19 July 2021 issue date ※ 15 August 2021 | ||
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THPAB001 | Reaching the Sub Per Mil Level Coupling Corrections in the LHC | coupling, quadrupole, dipole, operation | 3752 |
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The High Luminosity LHC (HL-LHC) is requiring sub per mil coupling correction, as defined by the closest tune approach. In this article, the current coupling correction strategy is analyzed in order to understand if it can robustly correct to these very low levels. The impact of realistic errors on the coupling correction is investigated with MAD-X simulations, including the influence of local coupling on the global coupling correction. Through simulations and measurements in the LHC, the effect of BPM noise on the coupling correction is analyzed. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB001 | ||
About • | paper received ※ 11 May 2021 paper accepted ※ 28 July 2021 issue date ※ 23 August 2021 | ||
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THPAB011 | Monte Carlo Driven MDI Optimization at a Muon Collider | detector, collider, optics, interaction-region | 3769 |
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A Muon Collider represents a very interesting possibility for a future machine to explore the energy frontier in particle physics. However, to reach the needed luminosity, beam intensities of the order of 109–1012 muons per bunch are needed. In this context, the Beam-Induced Background must be taken into account for its effects on magnets and detector. Several mitigation strategies can however be conceived. In this view, it is of crucial importance to develop a flexible tool that allows to easily reconstruct the machine geometry in a Monte Carlo code, allowing to simulate in detail the interaction of muon decay products in the machine, while being able to change the machine optics itself to find the best configuration. In this contribution, a possible approach to such a purpose is presented, based on FLUKA for the Monte Carlo simulation and on LineBuilder for the geometry reconstruction. Results based on the 1.5 TeV machine optics developed by the MAP collaboration are discussed, as well as a first approach to possible mitigation strategies. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB011 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 13 July 2021 issue date ※ 01 September 2021 | ||
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THPAB013 | Magnetic Measurements at Warm of the First FCC-ee Final Focus Quadrupole Prototype | multipole, quadrupole, induction, factory | 3777 |
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The first FCC-ee final focus quadrupole prototype has been designed, manufactured, assembled and tested at warm. The prototype is a single aperture quadrupole magnet of the CCT type. One edge of the magnet was designed with local multipole cancellation, whereas the other was left with the conventional design. An optimized rotating induction-coil sensor was used. A technique was developed to take into account field distortions due to the environment of the test and distinguish them from magnet effects, demonstrating an excellent field quality for the prototype. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB013 | ||
About • | paper received ※ 11 May 2021 paper accepted ※ 28 July 2021 issue date ※ 16 August 2021 | ||
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THPAB014 | Matlab Simulations of the Helium Liquefier in the FREIA Laboratory | HOM, cavity, interface, coupling | 3781 |
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We describe simulations that track a state vector with pressure, temperature, and gas flow through the helium liquefier in the FREIA laboratory. Most components, including three-way heat exchangers, are represented by matrices that allow us to track the state through the system. The only non-linear element is the Joule-Thomson valve, which is represented by a non-linear map for the state variables. Realistic properties for the enthalpy and other thermodynamic quantities are taken into account with the help of the Coolprop library. The resulting system of equations is rapidly solved by iteration and shows good agreement with the observed LHe yield with and without nitrogen pre-cooling. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB014 | ||
About • | paper received ※ 13 May 2021 paper accepted ※ 14 July 2021 issue date ※ 26 August 2021 | ||
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THPAB028 | Beam-Beam Related Design Parameter Optimization for the Electron-Ion Collider | proton, electron, betatron, luminosity | 3808 |
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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 design luminosity goal for the Electron-Ion Collider (EIC) is 1e34 cm-2s−1. To achieve such a high luminosity, the EIC design adopts high bunch intensities, flat beams at the interaction point (IP) with a small vertical β*-function, and a high collision frequency, together with crab cavities to compensate the geometrical luminosity loss due to the large crossing angle of 25mrad. In this article, we present our strategies and approaches to obtain the design luminosity by optimizing some key beam-beam related design parameters. Through our extensive strong-strong and weak-strong beam-beam simulations, we found that beam flatness, electron and proton beam size matching at the IP, electron and proton working points, and synchro-betatron resonances arising from the crossing angle collision play a crucial role in proton beam size growth and luminosity degradation. After optimizing those parameters, we found a set of beam-beam related design parameters to reach the design luminosity with an acceptable beam-beam performance. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB028 | ||
About • | paper received ※ 17 May 2021 paper accepted ※ 28 July 2021 issue date ※ 25 August 2021 | ||
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THPAB035 | Study of the Tolerances for Superconducting Undulators at the European XFEL | undulator, FEL, electron, photon | 3819 |
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European XFEL is investing in the development of superconducting undulators (SCUs) for future upgrade of its beamlines SCUs made of NbTi, working at 2K, with a period length of 15 mm and a vacuum gap of 5 mm allow covering a range between 54 keV and 100 keV for 17.5 GeV electron energy. The effect of mechanical errors in the distribution of K along the undulators is more relevant for working points at lower photon energy, which are obtained using a higher magnetic field in the undulator. In this article we investigate the effect of error distribution in the K-parameter for a working point at 50keV photon energy obtained injecting an electron beam with 16.5 GeV energy from the XFEL linear accelerator in a undulator line composed by SCUs with 1.58 T peak magnetic field. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB035 | ||
About • | paper received ※ 12 May 2021 paper accepted ※ 05 July 2021 issue date ※ 18 August 2021 | ||
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THPAB045 | Design of a Short Period Helical Superconducting Undulator | undulator, FEL, electron, photon | 3844 |
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Superconducting technology provides the possibility to develop short period, small bore undulators that can generate much larger magnetic fields than alternative technologies. This may allow an XFEL with optimised superconducting undulators to cover a broader range of wavelengths than traditional undulators. At STFC, we have undertaken work to design and build a prototype helical superconducting undulator (HSCU) module with parameters suitable for use on a future XFEL facility. This work includes the design of a full 2 m long undulator module, including an undulator with 13 mm period and 5 mm inner winding diameter, the supporting cryogenic and vacuum systems required for operation, and quadrupoles, phase shifters and correction magnets for use between undulator sections. We present here the magnetic and mechanical design of the HSCU. The choice of undulator parameters and their influence on the design is discussed. A turnaround scheme to allow continuous winding of the undulator without the need for superconducting joints is also presented. Techniques for winding the undulator are currently being investigated and a short prototype will soon be wound and tested. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB045 | ||
About • | paper received ※ 17 May 2021 paper accepted ※ 18 June 2021 issue date ※ 21 August 2021 | ||
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THPAB048 | Design and Fabrication Concepts of a Compact Undulator with Laser-Structured 2G-HTS Tapes | undulator, laser, FEL, impedance | 3851 |
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To produce small-scale high-field undulators for table-top free electron lasers (FELs), compact designs have been proposed using high temperature superconducting (HTS) tapes, which show both large critical current densities and high critical magnetic fields with a total tape thickness of about 50 μm and a width of up to 12 mm. Instead of winding coils, a meander structure can be laser-scribed directly into the superconductor layer, guiding the current path on a quasi-sinusoidal trajectory. Stacking pairs of such scribed tapes allows the generation of the desired sinusoidal magnetic fields above the tape plane, along the tape axis. Two practically feasible designs are presented, which are currently under construction at KIT: A coil concept wound from a single structured tape with a length of 15 m, which is a progression of a design that has been presented already in the past, as well as a novel stacked and soldered design, made from 25 cm long structured tapes, soldered in a zig-zag-pattern. In this contribution the designs are briefly recapped and the experimental progress is presented. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB048 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 12 July 2021 issue date ※ 15 August 2021 | ||
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THPAB049 | Modeling the Magnetic Field of the LCLS-I Undulator for THz@PITZ | undulator, FEL, vacuum, experiment | 3855 |
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Funding: This work was supported by the European XFEL research and development program An accelerator-based THz source for pump-probe experiments at the European XFEL is under development at the Photo Injector Test Facility at DESY in Zeuthen (PITZ). For the proof-of-principle experiments an LCLS-I undulator is planned to be installed downstream of the PITZ accelerator. The fields of the undulator module 26 have been re-measured at DESY in Hamburg and the results are consistent with earlier SLAC measurements. A model for 3D field reconstruction based on the undulator magnetic measurements has been developed. It includes also a horizontal gradient of the vertical field. Tracking of the 17 MeV/c beam has revealed that the transverse gradient will lead to a significant off-axis trajectory in the horizontal plane. This offset has to be corrected with a steering coil, the design of which is also presented. The performance of the THz generation with the correction coil is discussed as well. |
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Poster THPAB049 [1.409 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB049 | ||
About • | paper received ※ 12 May 2021 paper accepted ※ 12 July 2021 issue date ※ 02 September 2021 | ||
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THPAB051 | Vertical Septum Magnet Design for the APS Upgrade | septum, electron, magnet-design, photon | 3862 |
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The vertical injection scheme proposed for the APS Upgrade (APS-U) Project requires a challenging septum magnet that must meet stringent beam physics, magnetic field leakage, and vacuum requirements. The current iteration of this magnet design includes an enlarged stored-beam chamber aperture of 9 mm x 12 mm and a reduction of the septum thickness to 1.5 mm. The enlarged aperture accommodates a non-evaporable getter (NEG)-coated stored beam chamber to better achieve the required vacuum. A prototype septum magnet has been built and measurements confirm the cancellation of a peak leakage field even though the value is six times larger than the design. The leakage field measured at the upstream (US) end cancels the downstream (DS) end as was expected by design. The measured and simulated leakage field and the stored beam trajectories are reported. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB051 | ||
About • | paper received ※ 14 May 2021 paper accepted ※ 01 September 2021 issue date ※ 27 August 2021 | ||
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THPAB055 | Reconstruction of Linear Optics Observables Using Supervised Learning | optics, target, operation, MMI | 3875 |
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In the LHC, most of the optical functions can be obtained from turn-by-turn beam centroid data. However, the measurement of such observables as β* and the dispersion function require special dedicated techniques and additional operational time. In this work, we propose an alternative approach to estimate these observables using supervised machine learning, in case the dedicated measurements are not available but turn-by-turn data are. The performance of developed estimators is demonstrated on LHC simulations. Comparison to traditional techniques for the computation of beta-function will be also provided. | |||
Poster THPAB055 [0.713 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB055 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 19 July 2021 issue date ※ 15 August 2021 | ||
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THPAB060 | Dispersion Controlled Temporal Shaping of Photoinjector Laser Pulses for Electron Emittance Reduction in X-Ray Free Electron Lasers | laser, electron, emittance, bunching | 3886 |
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Funding: Office of Science DE-SC0014664 Temporal shaping of photocathode excitation laser pulses is a long-sought-after challenge to tailor the phase-space of electrons. The temporal profile of lasers, typically up-converted from infrared to ultraviolet, have significant impact on the distribution and time-evolution of the collective electron bunches. Towards this end, we present a method combining efficient nonlinear up-conversion with simultaneous and adaptable temporal profile shaping through dispersion-controlled sum-frequency generation* resulting in temporal profiles with sharp rise-fall times and flat top profiles. Using the LCLS-II photoinjector as a case study, we demonstrate a reduction in generated electron transverse emittance by upwards of 30% over conventionally implemented temporal profiles. Additionally, we discuss the ongoing experimental implementation of this method and preliminary results. * R. Lemons, et al. arXiv:2012.00957 [physics.optics] (2020) |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB060 | ||
About • | paper received ※ 17 May 2021 paper accepted ※ 08 July 2021 issue date ※ 26 August 2021 | ||
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THPAB062 | Long-Wave IR Terawatt Laser Pulse Compression to Sub-Picoseconds | laser, experiment, FEM, plasma | 3893 |
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Funding: U.S. Department of Energy under contract DE-SC0012704 We report an experiment and simulations on post-compression of 2 ps, 0.15 TW CO2 laser pulses to 480 fs, ~0.25 TW by means of a self-phase modulation accompanied by a negative group dispersion in KCl and BaF2 optical slabs. In addition, down to 130 fs fine pulse structure, but at lower conversion efficiency, has been observed through self-compression in a bulk NaCl crystal. The obtained results surpass by far previous achievements in the ultra-fast long-wave IR laser technology |
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Poster THPAB062 [2.675 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB062 | ||
About • | paper received ※ 12 May 2021 paper accepted ※ 18 June 2021 issue date ※ 24 August 2021 | ||
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THPAB066 | Ground Diffusion Measurement and Its Effect on APS-U Orbit Stability | ground-motion, electron, alignment, quadrupole | 3907 |
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Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. Spatial and temporal ground diffusion can be approximately described by the ATL law*,**. Ground diffusion can have an important effect on the long-term stability of the accelerator alignment. To estimate the possible consequences of the ground diffusion on the APS Upgrade performance, the ground diffusion constant of the existing APS tunnel was measured using historical data of the orbit correction effort and then used to estimate the ground diffusion effect on the orbit stability of the APS Upgrade. In this paper, we will describe the diffusion constant measurement and present the estimations of the expected APS-U alignment and orbit stability. * B.A. Baklakov et. al., Technical Physics, v.38(10), pp.894-898(1993) ** V. Shiltsev, Physical Review Letters, 104(23), p.238501 (2010). |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB066 | ||
About • | paper received ※ 12 May 2021 paper accepted ※ 13 July 2021 issue date ※ 24 August 2021 | ||
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THPAB067 | Simulation of the APS-U Orbit Motion Due to RF Noise | synchrotron, resonance, cavity, photon | 3911 |
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Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. APS Upgrade storage ring will keep the same rf system that is presently used at APS. This rf system has amplitude and phase noise dominated by the lines at 60, 180, and 360 Hz. APS presently operates with synchrotron frequency close to 2 kHz, which is far away from the rf noise frequencies, and still the rf system noise contributes over 2 micrometers rms into the horizontal orbit noise due to beam energy variation. APS-U will operate with a bunch-lengthening cavity, which will lower the synchrotron frequency down to about 200 Hz. This could potentially lead to large orbit noise and other negative consequences due to energy variation caused by the rf system noise. In this paper, we will present simulations of the rf noise-induced orbit motion at APS and APS-U and define the rf amplitude and phase noise requirements that need to be achieved for APS-U operation. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB067 | ||
About • | paper received ※ 12 May 2021 paper accepted ※ 13 July 2021 issue date ※ 23 August 2021 | ||
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THPAB068 | Denoising of Optics Measurements Using Autoencoder Neural Networks | optics, network, MMI, controls | 3915 |
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Noise artefacts can appear in optics measurements data due to instrumentation imperfections or uncertainties in the applied analysis methods. A special type of semi-supervised neural networks, autoencoders, are widely applied to denoising tasks in image and signal processing as well as to generative modeling. Recently, an autoencoder-based approach for denoising and reconstruction of missing data has been developed to improve the quality of phase measurements obtained from harmonic analysis of LHC turn-by-turn data. We present the results achieved on simulations demonstrating the potential of the new method and discuss the effect of the noise in light of optics corrections computed from the cleaned data. | |||
Poster THPAB068 [0.881 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB068 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 13 July 2021 issue date ※ 02 September 2021 | ||
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THPAB075 | Collective (In)stability Near the Coupling Resonance | wakefield, coupling, resonance, impedance | 3933 |
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Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. We show how to treat transverse collective instabilities when operating in the vicinity of the coupling (or tune difference) resonance. We begin by defining the approximate independent degrees of freedom including both linear coupling and chromatic effects. We then show how the destabilizing force due to wakefields and the stabilizing chromatic effects can be described by a linear combination of the horizontal and vertical motion that depends upon how close one is to the resonance. The theory agrees well with tracking studies, and will be relevant for those next-generation storage rings that plan to operate near the coupling resonance to produce nearly round beams, including the multi-bend achromat upgrade for the Advanced Photon Source. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB075 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 27 July 2021 issue date ※ 01 September 2021 | ||
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THPAB076 | Effects of Chromaticity and Synchrotron Emission on Coupled-Bunch Transverse Stability | damping, synchrotron, wakefield, coupling | 3937 |
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Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. We present a theory that can compute the transverse coupled-bunch instability growth rates at any chromaticity and for any longitudinal potential provided only that the long-range wakefield varies slowly over the bunch. The theory is expressed in terms of the usual coupled-bunch eigenvalues at zero chromaticity, and when the longitudinal motion is simple harmonic our solution only requires numerical root-finding that is easy to implement and fast to solve; the more general case requires some additional calculations but is still relatively fast. The theory predicts that the coupled-bunch growth rates can be significantly reduced when the chromatic betatron tune spread is larger than the coupled-bunch growth rate at zero chromaticity. Our theoretical results are compared favorably with tracking simulations for the long-range resistive wall instability, and we also indicate how damping and diffusion from synchrotron emission can further reduce or even stabilize the dynamics. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB076 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 26 July 2021 issue date ※ 26 August 2021 | ||
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THPAB077 | Magnetic Shims Studies for APS-U Hybrid Permanent Magnet Undulators | undulator, multipole, GUI, quadrupole | 3941 |
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Funding: Work supported by U.S. Department of Energy, Office of Science, under contract number DE-AC02-06CH11357 For the newly designed and fabricated APS Upgrade (APS-U) hybrid permanent magnet undulators (HPMUs), the development of magnetic shims has been critical to successfully tuning the undulators to meet the tight APS-U physics requirements. Different types of side and surface shims have been developed and applied for this purpose. The side shims are primarily used for trajectory tuning, and the surface shims are for phase and multipole tuning as well as trajectory tuning. Current design, applications, and measurement of the shims for the newly designed and fabricated APS28 (28 mm period) undulators are presented in this paper. |
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Poster THPAB077 [0.531 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB077 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 18 June 2021 issue date ※ 27 August 2021 | ||
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THPAB121 | Plasma Muon Beam Cooling for HEP | plasma, focusing, cavity, emittance | 3999 |
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Ionization cooling has the potential to shrink the phase space of a muon beam by a factor of 106 within the muons’ short lifetime (2.2 µs) because the collision frequency in a cooling medium is extremely high compared to conventional beam cooling methods. It has been realized that ionization cooling inherently produces a plasma of free electrons inside the absorber material, and this plasma can have an important effect on the muon beam. In particular, under the right circumstances, it can both improve the rate of cooling and reduce the equilibrium emittance of the beam. This has the potential to improve the performance of muon facilities based on muon cooling; in particular a future muon collider. We describe how this project will integrate Plasma muon beam cooling into both the basic Helical Cooling Channel (HCC) and extreme Parametric-resonance Ionization Cooling (PIC) techniques. This potentially whole new approach to muon cooling has exciting prospects for significantly reduced muon beam emittance. | |||
Poster THPAB121 [1.214 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB121 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 12 July 2021 issue date ※ 11 August 2021 | ||
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THPAB123 | Pytomic: A Python Tool for Polarized Atomic Beam Tracking | detector, sextupole, polarization, target | 4002 |
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Funding: This work was supported by the U.S. DOE under Contract No. DE-AC02-06CH11357 through ANL’s LDRD program. Pytomic is a new tool for the simulation and analysis of atomic beams through magnetic systems. It is written in Python and based on the same fundamentals as other particle tracking codes but for atomic beams instead of charged beams. In this case, the manipulation and control of neutral atomic beams is via a force due to the spin interacting with a magnetic field gradient. An object-oriented tool was developed to aid in the design of a beamline through the manipulation of modular elements. The Python language allowed for a smooth implementation and kept the code clear and simple. The primary purpose of developing this code was to have a tool to design, simulate, and optimize a Breit-Rabi Polarimeter to measure the polarization of an atomic beam. Therefore, different set-ups with different magnets need to be simulated and optimized for direct comparison. In addition to simulation and tracking modules, a new data analysis module was developed to be able to quickly analyze simulation results, gaining insight from each iteration of the simulation, leading to an efficient and rapid design process. Example applications to design polarimeters for atomic beams will be presented. |
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Poster THPAB123 [7.765 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB123 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 21 June 2021 issue date ※ 27 August 2021 | ||
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THPAB130 | Design of a Very Low Energy Beamline for NA61/SHINE | target, experiment, hadron, optics | 4017 |
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A new, low-energy beamline branch is currently under consideration for the H2 beamline at the CERN North Area. This new branch would extend the capabilities of the current infrastructure enabling the study of particles in the very low, 1-13 GeV/c, momentum range. The design of this new beamline involves various stages. Firstly, a study of the secondary targets to maximise the yield of secondary hadrons. Secondly, the development of high acceptance transverse optics with high momentum resolution on the order of a few %. Finally, we discuss the first considerations on instrumentation to enable particle identification and background rejection. The first experiment to profit from this new line could be NA61/SHINE, but other possible future fixed target experiments or test-beams installed in the downstream zones could also use the low-energy particles provided. The aim is to arrive at a complete design of this branch by the end of 2021, which, pending the approval of the CERN scientific committees, could be envisaged for construction after 2024. This timescale is compatible with requests for measurements by various large international collaborations, in the next 10-year horizon. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB130 | ||
About • | paper received ※ 15 May 2021 paper accepted ※ 27 July 2021 issue date ※ 27 August 2021 | ||
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THPAB134 | Development and Analysis of Software for the Numerical Simulation of Field Emission Electron Sources | electron, injection, software, electronics | 4024 |
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Funding: The reported study was funded by RFBR, project number 20-07-01086. The open-source DAISI C++ package (Design of Accelerators, optImizations and SImulations) is extended with the ability to simulate the operation of electron sources in the field emission mode, with the user-defined initial distribution of emitted electrons velocities, as a model parameter, and with the automated calculation of current-voltage characteristics. Particles injection scheme is suggested. Computational experiments are performed for silicon carbide field emission electron source nanostructure with bimodal energy spectrum, revealed from experimental study, and comparative analysis with Maxwell distribution is presented. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB134 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 27 July 2021 issue date ※ 17 August 2021 | ||
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THPAB140 | Modelling Seeded Self Modulation of Long Elliptical Bunches in Plasma | plasma, wakefield, proton, emittance | 4030 |
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Funding: This work was supported by STFC Centre for Doctoral Training in Data-Intensive Science (LIV. DAT) under grant ST/P006752/1 and the STFC Scientific Computing Department’s SCARF cluster. The stability of particle bunches undergoing seeded self-modulation (SSM) over tens or hundreds of meters is crucial to the generation of GV/m wakefields that can accelerate electron beams as proposed for use in several high energy plasma-based linear colliders. Here, 3D particle-in-cell simulations using QuickPIC are compared to an analytical model of seeded self-modulation (SSM) of elliptical beam envelopes using linear wakefield theory. It is found that there is quantitative agreement between simulations and analytical predictions for the envelope in the early growth of the SSM. A scaling law is derived for the reduction of the maximum overall modulation growth rate with aspect ratio and is found to match well with simulation. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB140 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 22 July 2021 issue date ※ 31 August 2021 | ||
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THPAB141 | Novel Design of a HVDC Magnetized Electron Source | cathode, solenoid, permanent-magnet, gun | 4034 |
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Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. The hadron beam in EIC is flat with a transverse size ratio of about 1:3. The cooling rate of the hadron beam can be maximized if the electron beam from the strong hadron cooler fully overlaps with the hadron beam. Therefore, generating a flat electron beam is essential. The most efficient way to generate a flat electron beam is to produce a magnetized beam first, and then convert it to flat to the desired transverse size ratio. Using a Magnetized electron beam is a promising way to cool high-energy hadrons. One of the major challenges in producing magnetized beams is fine-tuning the longitudinal magnetic field on the cathode surface and maintaining the desired field uniformity over the emission area. In this paper, we discuss the design of a novel high voltage DC gun capable of fine-tuning the B field on the cathode. This is achieved by installing a permanent magnet inside the cathode puck, with a solenoid field at the front of the cathode. We show magnetostatic simulation to prove the feasibility of this idea. We also show preliminary beam dynamics simulations showing emittance from the gun as the permanent magnet and solenoidal fields are tuned for minimum emittance. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB141 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 02 August 2021 issue date ※ 17 August 2021 | ||
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THPAB145 | Cold Test of a Novel S-Band 1.6 Cell Photocathode RF Gun | gun, cavity, coupling, cathode | 4045 |
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Funding: Work supported by National Natural Science Foundation of China(Grant No. 11805199 and U1832135) and Fundamental Research Funds for the Central Universities (Grant No. WK2310000072) The photocathode RF gun is one of the most critical components for high quality electron beam sources. The asymmetric multi-pole field contributes to the transverse emittance growth and degrades the beam quality. In order to overcome the problem, we propose a novel rotationally symmetric 1.6 cell RF gun to construct the symmetric field in this paper. The concrete proposal is that a coaxial cell cavity with a symmetrical distribution of four grooves is concatenated to the photocathode end of the traditional 0.6 cell cavity to form the novel 0.6 cell cavity. Through the detailed design study, the profile of the RF gun is optimized to improve the shunt impedance and mode separation and make the surface peak electric field at the photocathode end. Considering the filling time, a coupling slot is designed to couple input power into the RF gun. The RF cavity is machined by numerical control machine tool, and the tuning and low power RF measurement are carried out. The experimental results are consistent with the simulation results. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB145 | ||
About • | paper received ※ 09 May 2021 paper accepted ※ 02 September 2021 issue date ※ 29 August 2021 | ||
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THPAB151 | The Advantage of Cold Electron Source in Electron Diffraction | electron, experiment, FEL, ion-source | 4053 |
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In this paper, a model for discussing the influence of transverse coherence of electron beams on electron diffraction is established. With reference to Fedele’s thermal-wave model, the transverse coherence length is introduced into this model to characterize the transverse coherence of electron beams. The simulation results show that the transverse coherence of electron beams has a significant influence on electron diffraction, and the cold electron source with high transverse coherence has an obvious advantage in electron diffraction. | |||
Poster THPAB151 [0.647 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB151 | ||
About • | paper received ※ 15 May 2021 paper accepted ※ 21 June 2021 issue date ※ 25 August 2021 | ||
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THPAB153 | Design, Construction and Tests of the Cooling System with a Cryocooler for Cavity Testing | cavity, cryogenics, SRF, vacuum | 4056 |
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Cryogenically cooled normal-conducting cavities have shown higher gradients than those operated at room temperature. We are constructing a compact cooling system with a cryocooler to test C-band normal-conducting cavities and 1.3 GHz superconducting cavities. This paper describes the design, construction, and cooling test results as well as some low-power cavity Q measurement results. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB153 | ||
About • | paper received ※ 17 May 2021 paper accepted ※ 21 June 2021 issue date ※ 12 August 2021 | ||
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THPAB155 | Strong Quadrupole Wakefield Based Focusing in Dielectric Wakefield Accelerators | wakefield, controls, focusing, electron | 4059 |
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Funding: Grant number: DOE HEP Grants DE-SC0017648, DE-SC0009914, and National Science Foundation Grant No. PHY-1549132. We propose here to exploit the quadrupole wakefields in an alternating symmetry slab-based dielectric wakefield accelerator (DWA) to produce second-order focusing. The resultant focusing is found to be strongly dependent on longitudinal position in the bunch. We analyze this effect with analytical estimates and electromagnetic PIC simulations. We examine the use of this scenario to induce beam stability in very high gradient DWA, with positive implications for applications in linear colliders and free-electron lasers. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB155 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 27 July 2021 issue date ※ 19 August 2021 | ||
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THPAB167 | Technical Design of an RFQ Injector for the IsoDAR Cyclotron | rfq, cyclotron, cavity, coupling | 4075 |
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For the IsoDAR (Isotope Decay-At-Rest) experiment, a high intensity (10 mA CW) primary proton beam is needed. To generate this beam, H2+ is accelerated in a cyclotron and stripped into protons after extraction. An RFQ, partially embedded in the cyclotron yoke, will be used to bunch and axially inject H2+ ions into the main accelerator. The strong RFQ bunching capabilities will be used to optimize the overall injection efficiency. To keep the setup compact the distance between the ion source and RFQ can be kept very short as well. In this paper, we describe the technical design of the RFQ. We focus on two critical aspects: 1. The use of a split-coaxial structure, necessitated by the low frequency of 32.8 MHz (matching the cyclotron RF) and the desired small tank diameter; 2. The high current, CW operation, requiring a good cooling concept for the RFQ tank and vanes. | |||
Poster THPAB167 [2.162 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB167 | ||
About • | paper received ※ 14 May 2021 paper accepted ※ 27 July 2021 issue date ※ 21 August 2021 | ||
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THPAB170 | RF Deflector Design for Rapid Proton Therapy | proton, cavity, polarization, quadrupole | 4086 |
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Funding: This work is supported by US Department of Energy Contract No. DE-AC02-76SF00515. Pencil beam scanning of charged particle beams is a key technology enabling high dose rate cancer therapy. The potential benefits of high-speed dose delivery include not only a reduction in total treatment time and improvements to motion management during treatment but also the possibility of enhanced healthy tissue sparing through the FLASH effect, a promising new treatment modality. We present here the design of an RF deflector operating at 2.856 GHz for the rapid steering of 150 MeV proton beams. The design utilizes a TE11-like mode supported by two posts protruding into a pillbox geometry to form an RF dipole. This configuration provides a significant enhancement to the efficiency of the structure, characterized by a transverse shunt impedance of 68 MOhm/m, as compared to a conventional TM11 deflector. We discuss simulations of the structure performance for several operating configurations including the addition of a permanent magnet quadrupole to amplify the RF-driven deflection. In addition to simulation studies, we will present preliminary results from a 3-cell prototype fabricated using four copper slabs to accommodate the non-axially symmetric cell geometry. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB170 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 14 July 2021 issue date ※ 27 August 2021 | ||
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THPAB171 | mm-Wave Linac Design for Next Generation VHEE Cancer Therapy Systems | linac, electron, impedance, coupling | 4090 |
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Direct electron therapy offers an attractive method for providing the high dose rates necessary for FLASH radiation therapy, a new treatment modality with the potential for enhanced healthy tissue sparing. Direct electron therapy has been limited by the low beam energies, up to 20 MeV, provided by today’s medical linacs, restricting the achievable dose depth to superficial tumors. Very High Energy Electron (VHEE) therapy could reach deep-seated tumors throughout the body. A clinically viable VHEE system must provide electron energies of around 100 MeV in a compact footprint, roughly 1 to 2 meters, with modest power requirements. We investigate the development of mm-wave linacs to provide the necessary beam energies on the sub-meter scale, taking advantage of the favorable scaling of high-frequency operation to support gradients well above 100 MeV/m. We discuss the design parameters necessary for high-efficiency structures, with shunt impedance on the order of 1 GOhm/m, producing high gradients with only a few megawatts of power. We present simulations of cavity performance in the mm-wave operating regime, with an emphasis on compatibility with the requirements of VHEE therapy. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB171 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 26 July 2021 issue date ※ 15 August 2021 | ||
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THPAB173 | Fundamental Study on Electromagnetic Characteristics of Half-Wave Resonator for 200 MeV Energy Upgrade of KOMAC Proton Linac | cavity, linac, proton, SRF | 4098 |
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Funding: This work has been supported through KOMAC operation fund of KAERI by the Korea government (MSIT). A superconducting linac has been developed at KOrea Multi-purpose Accelerator Complex (KOMAC). A goal of the SRF linac is to increase proton beam energy from 100 MeV to 200 MeV. 350 MHz medium beta half-wave resonator (HWR) should provide 3.6 MV accelerating voltage to achieve the energy upgrade. An electromagnetic (EM) analysis on the parametrically designed HWR cavity was conducted. The cavity design was optimized to reduce a peak electric field and a peak magnetic field while satisfying the required acerating voltage. In addition, a mechanical-EM coupled simulation was conducted to estimate a helium pressure sensitivity. Also, Lorentz force detuning was simulated. The design is being optimized to minimize the frequency detuning due to the helium pressure and Lorentz force. |
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Poster THPAB173 [0.800 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB173 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 23 August 2021 | ||
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THPAB176 | Studies on Beam Collimation System for the ESSnuSB Accumulator | collimation, scattering, proton, linac | 4107 |
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Funding: This work is supported by the European Union Horizon 2020 research and innovation program under grant agreement No 777419. The ESSnuSB, a neutrino facility based on the European Spallation Source, aims at measuring, with precision, the charge-parity (CP) violating lepton phase at the 2nd oscillation maximum. The ESS linac will have to be upgraded to provide an additional 5 MW beam for the ESSnuSB to produce an unprecedented high-intensity neutrino beam. An accumulator ring is employed to compress the 2.86 ms long pulse from the linac to around 1.5 µs in order to satisfy the target requirements and improve the physics performance. In the operation of a high-intensity proton accumulator, the most important issue is to minimize the uncontrolled beam loss to reduce component activation to make hands-on maintenance possible. For this purpose, a two-stage collimation system is designed, which consists of a thin scraper to scatter halo particles and secondary collimators to absorb those scattered particles. Phase advances between scraper and secondary collimators, together with the material, the thickness of collimators, have been detailed studied and numerical simulations have been performed to evaluate the performance of the collimation system. This paper presents the design of the collimation system. |
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Poster THPAB176 [5.022 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB176 | ||
About • | paper received ※ 11 May 2021 paper accepted ※ 21 June 2021 issue date ※ 01 September 2021 | ||
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THPAB177 | Simulation Model Improvements at the Cooler Synchrotron COSY Using the LOCO Algorithm | storage-ring, quadrupole, dipole, polarization | 4111 |
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Funding: ERC Advanced Grant (srEDM #694340) of the European Union The JEDI (Jülich Electric Dipole moment Investigations) collaboration is searching for Electric Dipol Moments (EDMs) of charged particles in storage rings. In a stepwise approach, a first direct deuteron EDM measurement was performed at the Cooler Synchrotron COSY and design studies for a dedicated proton EDM storage ring are underway. In an experiment with a polarized beam in a storage ring, an EDM leads to a vertical polarization buildup. However, the vertical polarization component is also induced by systematic effects such as magnet misalignments. To investigate systematic effects individually and to support data analysis, a realistic simulation model of the storage ring is needed. In this paper, the development of such a model based on the Bmad software library is presented. Furthermore, various systematic effects and their impact on the spin motion in COSY are investigated and quantified by means of beam and spin tracking simulations. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB177 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 27 July 2021 issue date ※ 12 August 2021 | ||
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THPAB180 | Simulation of 4D Emittance Measurement at the Spallation Neutron Source | emittance, quadrupole, space-charge, optics | 4119 |
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Similar to the KV distribution, the Danilov distribution has an elliptical shape and uniform density in the transverse plane and maintains these properties under any linear transport. Efforts are underway at the Spallation Neutron Source (SNS) to paint a Danilov distribution in the accumulator ring. After the beam has been painted, the level to which it approximates an ideal Danilov distribution must be quantified. One way to do this is to measure the four-dimensional emittance, which is ideally zero due to linear relationships between the phase space variables. To measure this emittance, we will utilize a standard method of reconstructing the covariance matrix using various optics settings in conjunction with beam profile measurements. We present the results of preliminary simulations which aim to optimize this measurement scheme for the SNS Ring to Target Beam Transport (RTBT) line. | |||
Poster THPAB180 [2.525 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB180 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 12 July 2021 issue date ※ 25 August 2021 | ||
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THPAB181 | AI-ML Developments for the ATLAS Ion Linac Facility | rfq, operation, linac, experiment | 4122 |
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Funding: This work was supported by the U.S. Department of Energy, under Contract No. DE-AC02-06CH11357. This research used the ATLAS facility, which is a DOE Office of Nuclear Physics User Facility. ATLAS is a DOE/NP User Facility for the study of low-energy nuclear physics with heavy ions. It operates ~6000 hours per year. In addition to delivering any stable beam from proton to uranium, the facility also provides radioactive beams from the CARIBU source or via the in-flight radioactive ion separator, RAISOR. The facility uses 3 ion sources and services 6 target areas at energies from ~1-15 MeV/u. To accommodate the large number and variety of approved experiments, ATLAS reconfigures once or twice per week over 40 weeks of operation per year. The startup time varies from ~12-48 hours depending on the complexity of the tuning, which will increase with the upcoming Multi-User Upgrade to deliver beam to two experimental stations simultaneously. DOE/NP has recently approved a project to use AI/ML to support ATLAS operations. The project aim is to significantly reduce the accelerator tuning time and improve machine performance by developing and deploying artificial intelligence methods. These improvements will increase the scientific throughput of the facility and the quality of the data collected. Our recent developments and future plans will be presented and discussed. |
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Poster THPAB181 [1.034 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB181 | ||
About • | paper received ※ 06 June 2021 paper accepted ※ 28 July 2021 issue date ※ 12 August 2021 | ||
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THPAB186 | Review of Proton Linac Beam Dynamic Simulation Code | linac, proton, space-charge, software | 4137 |
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CSNS-II project design a linac accelerates 40 mA H− beam from 3.8 MeV to 300 MeV, which should not only overcome the space-charge effect at low energy but also have high efficiency at high energy. Therefore, lots of simulation studies should be done on a variety of codes. Each of them has its own characteristics. For example, MAD can easily match quadrupole fast while it couldn’t do the multiparticle calculation. This paper will introduce some common and efficient code used to design linac and study beam dynamic performance. | |||
Poster THPAB186 [0.880 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB186 | ||
About • | paper received ※ 17 May 2021 paper accepted ※ 08 July 2021 issue date ※ 11 August 2021 | ||
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THPAB189 | New Techniques to Compute the Linear Tune | collider, damping, betatron, experiment | 4142 |
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Tune determination in numerical simulations is an essential aspect of nonlinear beam dynamics studies. In particular, because it allows probing whether an initial condition is close to resonance, and it enables assessment of the stability of the orbit, i.e. whether the motion is regular or chaotic. In this paper, results of recently developed techniques to obtain accurate tune computation from numerical simulation data are presented and discussed in detail. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB189 | ||
About • | paper received ※ 18 May 2021 paper accepted ※ 26 July 2021 issue date ※ 19 August 2021 | ||
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THPAB190 | Optimising and Extending a Single-Particle Tracking Library for High Parallel Performance | GPU, lattice, interface, hardware | 4146 |
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SixTrackLib is a library for performing beam-dynamics simulations on highly parallel computing devices such as shared memory multi-core processors or graphical processing units (GPUs). Its single-particle approach fits very well with parallel implementations with reasonable baseline performance, making such a library an interesting building block for various use cases, including simulations covering collective effects. We describe optimizations to improve their performance on SixTrackLib’s main target platforms and the associated performance gains. Finally, we outline the implemented technical interfaces and extensions that allow SixTrackLib to be used in a wider range of applications and studies. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB190 | ||
About • | paper received ※ 18 May 2021 paper accepted ※ 14 July 2021 issue date ※ 16 August 2021 | ||
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THPAB191 | Physics-Enhanced Reinforcement Learning for Optimal Control | network, lattice, controls, alignment | 4150 |
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We propose an approach for incorporating accelerator physics models into reinforcement learning agents. The proposed approach is based on the Taylor mapping technique for simulation of the particle dynamics. The resulting computational graph is represented as a polynomial neural network and embedded into the traditional reinforcement learning agents. The application of the model is demonstrated in a nonlinear simulation model of beam transmission. The comparison of the approach with the traditional numerical optimization as well as neural networks based agents demonstrates better convergence of the proposed technique. | |||
Poster THPAB191 [0.846 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB191 | ||
About • | paper received ※ 11 May 2021 paper accepted ※ 29 July 2021 issue date ※ 24 August 2021 | ||
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THPAB192 | Continuous Beam Dynamics Simulation in COMSOL Multiphysics | cyclotron, solenoid, beam-losses, ion-source | 4153 |
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The classic way of beam dynamics simulation in a cyclotron is to separate it into many different stages from the ion source to the extraction (or even further), this was absolutely necessary to fit the calculations into any reasonable time in a cost of influence of some operation devices from one stage, on beam dynamics of another (next or previous mostly) stage. We’ve managed to perform beam dynamics from ion source through a solenoid to the center region in a single model in COMSOL, using several fields simultaneously: external magnetic (the magnet), calculated magnetic (the solenoid) and alternating and stationary electric fields in the center region. | |||
Poster THPAB192 [1.233 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB192 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 23 June 2021 issue date ※ 17 August 2021 | ||
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THPAB197 | Enhancing Efficiency of Multi-Objective Neural-Network-Assisted Nonlinear Dynamics Lattice Optimization via 1-D Aperture Objectives & Objective Focusing | lattice, focusing, network, storage-ring | 4156 |
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Funding: This work is supported by U.S. DOE under Contract No. DE-SC0012704. Mutli-objective optimizers such as multi-objective genetic algorithm (MOGA) have been quite popular in discovering desirable lattice solutions for accelerators. However, even these successful algorithms can become ineffective as the dimension and range of the search space increase due to exponential growth in the amount of exploration required to find global optima. This difficulty is even more exacerbated by the resource-intensive and time-consuming tendency for the evaluations of nonlinear beam dynamics. Lately the use of surrogate models based on neural network has been drawing attention to alleviate this problem. Following this trend, to further enhance the efficiency of nonlinear lattice optimization for storage rings, we propose to replace typically used objectives with those that are less time-consuming and to focus on a single objective constructed from multiple objectives, which can maximize utilization of the trained models through local optimization and objective gradient extraction. We demonstrate these enhancements using a NSLS-II upgrade lattice candidate as an example. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB197 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 23 June 2021 issue date ※ 10 August 2021 | ||
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THPAB199 | Studies of Longitudinal Beam Losses at LHC Injection | injection, impedance, beam-losses, extraction | 4164 |
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Funding: Research supported by the HL-LHC project. Due to higher beam intensities, the required rf power in the High-Luminosity LHC (HL-LHC) era is expected to be at the limit of the available rf power. To mitigate potential limitations of the rf system, the injection voltage can be reduced at the expense of beam losses. In this paper, the average and bunch-by-bunch losses are estimated from Run 2 beam intensity measurements in the SPS before extraction and in the LHC after injection. Macro-particle simulations are performed with CERN’s Beam Longitudinal Dynamics code to reproduce the observed SPS-to-LHC capture and LHC flat-bottom losses. First estimates of injection losses for the HL-LHC at different injection voltages and injection energy errors are discussed. |
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Poster THPAB199 [2.428 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB199 | ||
About • | paper received ※ 18 May 2021 paper accepted ※ 28 July 2021 issue date ※ 14 August 2021 | ||
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THPAB200 | Cavity Control Modelling for SPS-to-LHC Beam Transfer Studies | cavity, controls, beam-loading, injection | 4168 |
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Funding: Research supported by the HL-LHC project. To accurately simulate injection losses in the LHC and the High-Luminosity LHC era, a realistic beam distribution model at SPS extraction is needed. To achieve this, the beam-loading compensation by the SPS cavity controller has to be included, as it modulates the bunch positions with respect to the rf buckets. This dynamic cavity control model also allows generating a more realistic beam halo, from which the LHC injection losses will mainly originate. In this paper, the implementation of the present SPS cavity controller in CERN’s Beam Longitudinal Dynamics particle tracking code is described. Just like in the machine, the feedback and feedforward controls are included in the simulation model, as well as the generator-beam-cavity interaction. Benchmarking against measurements of the generated beam distributions at SPS extraction are presented. |
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Poster THPAB200 [4.164 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB200 | ||
About • | paper received ※ 18 May 2021 paper accepted ※ 27 July 2021 issue date ※ 26 August 2021 | ||
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THPAB201 | A Machine Learning Technique for Dynamic Aperture Computation | network, dynamic-aperture, hadron, distributed | 4172 |
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Currently, dynamic aperture calculations of high-energy hadron colliders are performed through computer simulations, which are both a resource-heavy and time-costly processes. The aim of this study is to use a reservoir computing machine learning model in order to achieve a faster extrapolation of dynamic aperture values. A recurrent echo-state network (ESN) architecture is used as a basis for this work. Recurrent networks are better fitted to extrapolation tasks while the reservoir echo-state structure is computationally effective. Model training and validation is conducted on a set of "seeds" corresponding to the simulation results of different machine configurations. Adjustments in the model architecture, manual metric and data selection, hyper-parameters tuning and the introduction of new parameters enabled the model to reliably achieve good performance on examining testing sets. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB201 | ||
About • | paper received ※ 14 May 2021 paper accepted ※ 22 July 2021 issue date ※ 02 September 2021 | ||
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THPAB202 | Problem and Solution with the Longitudinal Tracking of the ORBIT Code | acceleration, emittance, synchrotron, space-charge | 4176 |
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The ORBIT code has been widely used for beam dynamics simulations including injection and acceleration in high-intensity hadron synchrotrons. When the ORBIT’s 1D longitudinal tracking was employed for the acceleration process in CSNS/RCS, the longitudinal emittance in eV-s was found decreasing substantially during acceleration, though the adiabatic condition is still met during this process. This is against the Liouville theorem that predicts the preservation of the emittance during acceleration. The recent machine study in the accelerator and the simulations with a self-made code demonstrate that the longitudinal emittance is almost invariant, which further indicates that the ORBIT longitudinal tracking might be incorrect. A detailed check-over in the ORBIT code source finds that the longitudinal finite difference equation used in the code is erroneous when applied to an acceleration process. The new code format PyORBIT has the same problem. After the small secondary factor is included in the code, ORBIT can produce results keeping the longitudinal emittance invariant. This paper presents some details about the study. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB202 | ||
About • | paper received ※ 14 May 2021 paper accepted ※ 01 July 2021 issue date ※ 21 August 2021 | ||
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THPAB203 | Update of the Tracking Code RF-Track | laser, wakefield, scattering, space-charge | 4180 |
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During the last couple of years, the RF-Track particle tracking code has seen a tremendous increase in the number of its applications: medical linacs, compact injector electron guns, and positron sources are among the main ones. Following a work of consolidation of its internal structure, new simulation capabilities have been introduced, together with several new effects: arbitrary orientation of elements in space, full element overlap, short- and long-range wakefields, and laser-beam interaction through Compton scattering are the most significant ones. In this paper, some of these new features are presented and discussed. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB203 | ||
About • | paper received ※ 14 May 2021 paper accepted ※ 02 August 2021 issue date ※ 01 September 2021 | ||
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THPAB204 | End-to-End RMS Envelope Model of the ISAC-I Linac | ISAC, rfq, linac, DTL | 4183 |
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A full end-to-end simulation of the ISAC-I linear accelerator has been built in the first order envelope code TRANSOPTR. This enables the fast tracking of rms sizes and correlations for a 6-dimensional hyperellipsoidal beam distribution defined around a Frenet-Serret reference particle frame, for which the equations guiding envelope evolution are numerically solved through a model of the machine’s electromagnetic potentials. Further, the adopted formalism enables the direct integration of energy gain via time-dependent accelerating potentials, without resorting to transit-time factors. | |||
Poster THPAB204 [0.627 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB204 | ||
About • | paper received ※ 18 May 2021 paper accepted ※ 08 July 2021 issue date ※ 31 August 2021 | ||
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THPAB207 | Beam Dynamics Simulation about the Dual Harmonic System by PyORBIT | bunching, synchrotron, acceleration, space-charge | 4194 |
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The space charge effect is a strong limitation in high-intensity accelerators, especially for low- and medium-energy proton synchrotrons. And for CSNS-II, the number of particles in the RCS is 3.9·1013 ppp, which is five times of CSNS. To mitigate the effects of the strong space charge effect, CSNS-II/RCS (Rapid Cycling Synchrotron) will use a dual harmonic system to increase the bunching factor during the injection and the initial acceleration phase. For studying the beam dynamics involved in a dual harmonic RF system, PyORBIT is used as the major simulation code, which is developed at SNS to simulate beam dynamics in accumulation rings and synchrotrons. We modified parts of the code to make it applicable to the beam dynamic in RCS. This paper includes the major code modification of the Dual Harmonic RF system and some benchmark results. The preliminary simulation results of the dual-harmonic system in CSNS-II/RCS simulated by the particle tracking code PyORBIT will also be discussed. | |||
Poster THPAB207 [0.354 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB207 | ||
About • | paper received ※ 16 May 2021 paper accepted ※ 05 July 2021 issue date ※ 11 August 2021 | ||
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THPAB210 | Extrapolated Range for Low Energy Electrons (< 1 keV) | electron, experiment, multipactoring, GUI | 4201 |
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Funding: ONERA- DPHY, 2 avenue E. Belin, 31055 Toulouse, France CEA, DAM, DIF, 91297 Arpajon, France CNES, 18 av. E. Belin, 31055 Toulouse, France The Secondary Electron Emission (SEE) process plays an important role in the performance of various devices. Mitigating the multipactor phenomenon that may occur in radio-frequency components is a concern in many fields such as space technologies or electron microscopy. SEE is also a concern in the accelerator physics community, where the beam lines stability can strongly be affected by this phenomenon*,**. In that scope, the escaped depth and thus the range of emitted electrons is of great interest. Our goal, by means of simulations is to provide a better knowledge of SEE. We have developed a Monte Carlo electron transport code for low energy electrons [~eV, ~10keV], that is part of the Dec. 2020 release of GEANT4***. It has been used to study the practical range of low energy electrons. Our goal is to formulate, below ~10 keV, an analytic range vs. energy expression, and to relate it to fundamental physcial parameters such as the mean free paths of electrons in matter. The goal is to provide simple practical extrapolated range formula that can help to understand SEE phenomenon. * M. Mostajeran et al. J. of Instr. 5 (2010) ** C. Y. Vallgren et al. Phys. Rev. Accel. Beam 14 (2011) *** Q. Gibaru et al. Nuc. Inst. And Met. 487 (2021) |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB210 | ||
About • | paper received ※ 10 May 2021 paper accepted ※ 23 June 2021 issue date ※ 27 August 2021 | ||
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THPAB211 | Monte Carlo Simulation of 3D Surface Morphologies for Secondary Electron Emission Reduction | electron, multipactoring, GUI, experiment | 4204 |
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Low energy electrons of few tens of eV may cause Multipactor breakdowns in waveguides driven by the Secondary Electron Emission Yield (SEY) of the walls. This risk is lowered by using low emissive surfaces and this topic has been studied experimentally and with numerical simulations. The dependence of the SEY on surface properties is well known*. Surface morphology has been widely used to reduce the SEY by forming roughness patterns on the surface**. All patterns do not have the same efficiency so their analysis in terms of SEY is relevant. Monte-Carlo simulation codes can be used to study the processes behind the SEY. The MicroElec module of GEANT4 has recently been extended with more materials and processes and validated with experimental data for SEY calculations**. In this work, simulation results are shown for a bulk sample capped with different roughness patterns. The effects of the shape parameters on the SEY are studied for typical dimensions between 20 µm and 100 µm. The results are checked with experimental SEY measurements on samples with similar roughness patterns.
*:T Gineste et al, Appl Surf Sci 359 (2015) 398-404 **:J Pierron et al, J Appl Phys 124 (2018) 095101 ***:Q. Gibaru, C. Inguimbert, P. Caron, M. Raine, D. Lambert, J. Puech, NIM B. 487 (2021) 66-77 |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB211 | ||
About • | paper received ※ 12 May 2021 paper accepted ※ 23 June 2021 issue date ※ 17 August 2021 | ||
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THPAB214 | Recent BDSIM Related Developments and Modeling of Accelerators | laser, experiment, radiation, shielding | 4208 |
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Funding: This work is supported by the STFC (UK) grants: JAI ST/P00203X/1, HL-LHC-UK1 ST/N001583/1, HL-LHC-UK2 ST/T001925/1, and ST/P003028/1. Beam Delivery Simulation (BDSIM) is a program based on Geant4 that creates 3D radiation transport models of accelerators from a simple optical description in a vastly reduced time frame with great flexibility. It also uses ROOT and CLHEP to create a single simulation model that can accurately track all particle species in an accelerator to predict and understand beam losses, secondary radiation, dosimetric quantities and their origin. BDSIM provides a library of scalable generic geometry for a variety of applications. Our Python package, Pyg4ometry, allows rapid preparation and conversion of geometries for BDSIM and other radiation transport simulations including FLUKA. We present a broad overview of BDSIM developments related to a variety of experiments at several facilities. We present a model of the forward experiment FASER at the LHC, CERN where the geometry is composited from multiple sources using Pyg4ometry. The analysis of particle history is presented as well as production mechanisms. We also present the application of recently introduced laser interactions in Geant4 to Compton photons from a laserwire diagnostic at the ATF2. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB214 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 19 July 2021 issue date ※ 22 August 2021 | ||
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THPAB217 | Lightsource Unified Modeling Environment (LUME), a Start-to-End Simulation Ecosystem | interface, FEL, software, electron | 4212 |
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SLAC is developing the Lightsource Unified Modeling Environment (LUME) for efficient modeling of X-ray free electron laser (XFEL) performance. This project takes a holistic approach starting with the simulation of the electron beams, to the production of the photon pulses, to their transport through the optical components of the beamline, to their interaction with the samples and the simulation of the detectors, and finally followed by the analysis of simulated data. LUME leverages existing, well-established simulation codes, and provides standard interfaces to these codes via open-source Python packages. Data are exchanged in standard formats based on openPMD and its extensions. The platform is built with an open, well-documented architecture so that science groups around the world can contribute specific experimental designs and software modules, advancing both their scientific interests and a broader knowledge of the opportunities provided by the exceptional capabilities of X-ray FELs. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB217 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 20 July 2021 issue date ※ 19 August 2021 | ||
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THPAB219 | Beam Dynamics in Coherent Electron Cooling Accelerator | electron, linac, cavity, emittance | 4216 |
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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. Coherent electron Cooling (CeC) has the potential to substantially reduce the cooling time of the high-energy hadrons and hence to boost luminosity in high-intensity hadron-hadron and electron-hadron colliders. Recent development in CeC cooling theory requires the accelerator to deliver high-quality electron bunches with low beam noise. In this paper, we present our design of the CeC accelerator to achieve the electron beam requirements and compare our findings with the experimental observations. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB219 | ||
About • | paper received ※ 27 May 2021 paper accepted ※ 27 July 2021 issue date ※ 11 August 2021 | ||
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THPAB221 | Multi-Objective Optimization with ACE3P and IMPACT | cathode, cavity, lattice, interface | 4223 |
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Funding: This work is supported by the Director of the Office of Science of the US Department of Energy under contracts DE-AC02-05-CH11231 and DE-AC02-76-SF00515. Photo injector design is an important consideration in the construction of next-generation accelerators. In current injector optimization, components (e.g. RF cavities) are individually shape-optimized for performance subject to requirements such as peak surface field, shunt impedance, and resonant frequency. Once these component shapes are determined, beam dynamics simulations optimize the injector lattice by adjusting parameters such as the amplitude and phase of the driving fields. However, this form of beam dynamics optimization is restricted by the fixed geometry and field profile of the components. To optimize accelerator design more generally, a coupled optimization of the cavity shape and beam parameters is required. For this coupled optimization problem, we have created an integrated ACE3P-IMPACT workflow. Within this workflow, component geometries are adjusted, field modes are computed with Omega3P (a module in the ACE3P suite), and beam dynamics are simulated with IMPACT-T. This workflow is encapsulated into a multi-objective optimization algorithm using the DEAP* and libEnsemble** Python libraries to yield a Pareto-optimal set of solutions for a simple injector model. * F.-A. Fortin et al, DEAP: Evolutionary Algorithms Made Easy, J Mach Learn Res, 13, 2171-2175, July 2012 ** S. Hudson et al, libEnsemble User Manual, Argonne National Laboratory, Rev 0.7.1, 2020 |
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Poster THPAB221 [1.842 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB221 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 02 August 2021 issue date ※ 14 August 2021 | ||
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THPAB222 | Transverse Impedance Coaxial Wire Measurement in an Extended Frequency Range | impedance, HOM, storage-ring, collective-effects | 4227 |
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The low energy accelerators are tend to have some instabilities especially the beam coupling impedances which comes from the interaction between the beam and accelerator components. As long as the longitudinal impedance are important, transverse impedance determination is crucial for determine the instabilities which will affect the working efficiency of the accelerators. However due to their small amplitudes and measurement setup configuration they are hardly measurable especially in wide frequency ranges. We developed a specific setup for small diameter pieces (28-40mm) for moving and two wire transverse impedance measurements. The dipolar and quadrupolar impedance measurement even with a few Ω level up to 6 GHz for the bellows of ThomX will be presented. Also the comparison with electromagnetic simulations have been performed and can be seen for dipolar impedance measurements. | |||
Poster THPAB222 [1.578 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB222 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 27 July 2021 issue date ※ 23 August 2021 | ||
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THPAB223 | Energy Compression System Radio Frequency Design at the Canadian Light Source | linac, impedance, GUI, RF-structure | 4231 |
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The Canadian Light Source (CLS), Canada’s only synchrotron light source, is considering a linear accelerator (LINAC) upgrade. As a result, the radio frequency (RF) structure in the downstream Energy Compression System (ECS) needs to be redesigned. In this paper, we describe the design process followed to determine the geometry of the RF structure cells and coupler. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB223 | ||
About • | paper received ※ 18 May 2021 paper accepted ※ 28 July 2021 issue date ※ 28 August 2021 | ||
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THPAB224 | The Correction of Time-Dependent Tune Shift by Harmonic Injection | focusing, injection, quadrupole, neutron | 4234 |
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In the Rapid Cycling Synchrotron(RCS) of China Spallation Neutron Source(CSNS), transverse painting injection is employed to suppress the space-charge effects. The beta-beating caused by edge focusing of the injection bump magnets leads to tune shift. A new method based on the harmonic injection is firstly introduced to correct the time-dependent tune shift caused by the edge focusing effect of the chicane bump magnets in RCS. The simulation study was done on the application of the new method to the CSNS/RCS, and the results show the validity and effectiveness of the method. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB224 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 16 July 2021 issue date ※ 10 August 2021 | ||
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THPAB227 | MACH-B: Fast Multipole Method Approaches in Particle Accelerator Simulations for the Computational and Intensity Frontiers | multipole, framework, embedded, space-charge | 4237 |
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Funding: U.S. Department of Energy DOE SBIR Phase I Project DE-SC0020934 The MACH-B (Multipole Accelerator Codes for Hadron Beams) project is developing a Fast Multipole Method (FMM**)-based tool for higher fidelity modeling of particle accelerators for high-energy physics within the next generation of Fermilab’s Synergia* simulation package. MACH-B incorporates (1) highly-scalable, high-performance and generally-applicable FMM-based algorithms to accurately model space-charge effects in high-intensity hadron beams and (2) boundary integral approaches to handle singular effects near the beam pipe using advanced quadratures. MACH-B will allow for more complex beam dynamics simulations that more accurately capture bunch effects and predict beam loss. Further, by introducing an abstraction layer to hide FMM implementation and parallelization complexities, MACH-B removes one of the key impediments to the adoption of FMMs by the accelerator physics community. * J. Amundson et al. "Synergia: An accelerator modeling tool with 3-D space charge". J.C.P. 211.1 (2006) 229-248. ** L. Greengard. "Fast algorithms for classical physics". Science (Aug 1994) 909-914. |
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Poster THPAB227 [0.984 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB227 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 14 July 2021 issue date ※ 27 August 2021 | ||
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THPAB228 | Study on Laser Modulator for Electron Beam Density Modulation | laser, electron, undulator, bunching | 4241 |
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Ultrashort electron beams are essential for light sources and time-resolved measurements. Laser modulation using an undulator and pulsed near infrared light is expected for attosecond density modulation of electron beam. In this study, simulation of laser modulation using undulator with period length of 6.6 mm and optical pulse with a wavelength of 800 nm was performed by ELEGANT* code. Simulation results of laser modulation for electron beam with an energy of 32.5 MeV will be presented from a view point of the density modulation.
* M. Borland, elegant: A Flexible SDDS-Compliant Code for Accelerator Simulation, Advanced Photon Source LS-287, September 2000. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB228 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 28 July 2021 issue date ※ 16 August 2021 | ||
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THPAB229 | Energy-Binning Fast Multipole Method for Electron Injector Simulations | space-charge, electron, multipole, cathode | 4244 |
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In a high brilliance electron injector, small beam energy and large charge density give rise to strong space charge effects. Furthermore, a large relative energy spread during the beam generation modifies the space charge interaction between different regions of the particle bunch. Therefore, modeling the phase space evolution in an electron injector requires a numerically efficient particle tracking code that can handle space charge interactions of spatially and energetically strongly inhomogeneous particle distributions. We implemented an energy-binning scheme for a meshless fast multipole method (FMM). The energy-binning approximates the momentum distribution of the beam by assigning particles to adaptive tree structures defined at different Lorentz frames. Based on the tree structures, the FMM computes a hierarchical approximation for the space charge interaction of the particle bunch. We use the energy-binning FMM to simulate the beam generation in the photoinjector of the European XFEL developed at DESY-PITZ. Furthermore, we present numerical convergence and performance studies and compare the simulation results to direct particle-particle methods. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB229 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 12 July 2021 issue date ※ 25 August 2021 | ||
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THPAB230 | Design of Split Permanent Magnet Quadrupoles for Small Aperture Implementation | quadrupole, permanent-magnet, electron, focusing | 4247 |
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Permanent magnet quadrupoles are ideal for strong focusing in compact footprints. Recent research in the use of permanent magnet based quadrupole magnets has enabled very high-gradient uses approaching 800T/m in final focus systems. However, in order to achieve high quality field profiles with strong fields, small diameter bore magnets must be used necessitating in vacuum operation, or very small beampipes. For small beampipe geometry, we have developed a hybrid-permanent magnet quadrupole, with steel and permanent magnet wedges, that is able to maintain high quality fields but also readily machinable in a separable design. The split design allows for accurate and reproducible reconfiguration on a beam pipe. In this paper, we will discuss the design, engineering, fabrication and first measurements of the split permanent magnet quadrupole. | |||
Poster THPAB230 [1.605 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB230 | ||
About • | paper received ※ 15 May 2021 paper accepted ※ 08 July 2021 issue date ※ 30 August 2021 | ||
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THPAB235 | Detailed Electromagnetic Characterisation of HL-LHC Low Impedance Collimators | impedance, operation, collimation, factory | 4258 |
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The High Luminosity Large Hadron Collider (HL-LHC) project will upgrade the LHC machine to allow operation with increased luminosity for the experiments. In order to achieve this goal, different operational parameters of the machine need to be pushed beyond the present design values, including the stored beam energy. One of the main challenges related to the achievement of the upgraded performance is the beam collimation system and its contribution to the overall machine impedance budget. In this perspective, new low impedance collimators have been designed, fabricated, and installed in the LHC. In this study, we will present their detailed electromagnetic (EM) characterization by means of radio frequency (RF) measurements and EM simulations. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB235 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 19 July 2021 issue date ※ 10 August 2021 | ||
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THPAB236 | First Order Analytic Approaches to Modelling the Vertical Excursion Fixed Field Alternating Gradient Accelerator | lattice, focusing, closed-orbit, optics | 4262 |
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Whilst the Vertical Excursion Fixed Field Alternating Gradient Accelerator (VFFA) remains a promising solution to a number of problems at the frontiers of accelerator physics, the optics of this type of machine are still poorly understood. Current designers are forced to rely on brute-force numerical tracking codes, with optimisation dependent on time-consuming parameter scans. With an aim to both improve understanding of this machine, as well as to develop tools for rapid design and optimisation of VFFA lattices, first steps towards an analytic approach based on a linearised Hamiltonian formalism have been developed. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB236 | ||
About • | paper received ※ 13 May 2021 paper accepted ※ 14 July 2021 issue date ※ 10 August 2021 | ||
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THPAB238 | An Overview of the Collective Effects and Impedance Calculation for the EIC | electron, vacuum, wakefield, dipole | 4266 |
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Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. A new high-luminosity Electron-Ion Collider (EIC) is being designed at Brookhaven National Laboratory (BNL). Stable operation of the electron beam at an average current of 2.5A within 1100 bunches with a 7mm bunch length is one of the challenging tasks in achieving an electron-proton luminosity of 1033-1034 cm-2 ses−1 range. Beam induced heating, short-range and long-range wakefield analysis is discussed for some of the vacuum components of the electron storage ring (ESR), the hadron storage ring (HSR), and the rapid cycling synchrotron (RCS) and as well as the impact of the collective effects on the beam stability. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB238 | ||
About • | paper received ※ 15 May 2021 paper accepted ※ 24 June 2021 issue date ※ 29 August 2021 | ||
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THPAB240 | Combined Effect of IBS and Impedance on the Longitudinal Beam Dynamics | emittance, experiment, lattice, wakefield | 4274 |
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Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. The horizontal/vertical emittances, the bunch length, and the energy spread increase have been studied in the NSLS-II as a function of a single bunch current. The monotonic growth of the horizontal emittance dependence and the energy spread dependence on the single bunch current below the microwave instability threshold can be explained by the Intrabeam Scattering Effect (IBS). The IBS effect results in an increase in the bunch length and the microwave instability thresholds. It was observed experimentally by varying the vertical emittance. To compare with experimental data, particle tracking simulations have been performed with the ELEGANT code including both IBS and the total longitudinal wakefield calculated from the 3D electromagnetic code GdfidL. The same particle tracking simulations have also been applied for the APS-U project, where IBS is predicted to produce only a marginal effect. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB240 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 05 July 2021 issue date ※ 14 August 2021 | ||
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THPAB241 | Examination of Semi-Analytic Model for Mode Coupling Instabilities | space-charge, coupling, transverse-dynamics, damping | 4278 |
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Funding: Work supported by by Brookhaven Science Associates, LLC under contract number 364776. A semianalytic model for studying beams at high SC tune shift is shown. It is a generalization of SWM ** /ABS ** for an arbitrary number of longitudinal phase space cycles, yielding more realistic longitudinal physics. The consequences of this generalization are explored; model is benchmarked against TRANFT *** and analytical methods. * Blaskiewicz, Michael. Phys. Rev. ST Accel. Beams, vol. 1, p. 044201, 1998. ** Burov, Alexey. Phys. Rev. Accel. Beams, vol. 22, p. 034202, 2019. *** M. Blaskiewicz, in Proc. PAC07, Albuquerque, |
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Poster THPAB241 [0.894 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB241 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 14 July 2021 issue date ※ 14 August 2021 | ||
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THPAB243 | Optimizing Mu2e Spill Regulation System Algorithms | extraction, controls, network, resonance | 4281 |
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Funding: The work has been performed at Fermilab. Fermilab is managed by Fermi Research Alliance, LLC (FRA), acting under Contract No. DE-AC02-07CH11359. A slow extraction system is being developed for the Fermilab’s Delivery Ring to deliver protons to the Mu2e experiment. During the extraction, the beam on target experiences small intensity variations owing to many factors. Various adaptive learning algorithms will be employed for beam regulation to achieve the required spill quality. We discuss here preliminary results of the slow and fast regulation algorithms validation through the computer simulations before their implementation in the FPGA. Particle tracking with sextupole resonance was used to determine the fine shape of the spill profile. Fast semi-analytical simulation schemes and Machine Learning models were used to optimize the fast regulation loop. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB243 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 28 July 2021 issue date ※ 20 August 2021 | ||
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THPAB244 | Design of Interdigital H-Mode Re-Buncher at KoBRA Beamline | cavity, bunching, heavy-ion, impedance | 4285 |
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KOrea Broad acceptance Recoil spectrometer & Apparatus (KOBRA) is an experimental facility for low energy nuclear physics in the heavy ion accelerator complex RAON. Two re-buncher systems at KOBRA beamline are required to longitudinally focus the 40Ar9+ with 27MeV/u. The normal conducting IH resonator with seven-gap as the re-buncher structure was chosen because of the reduction in the risk of particulate contamination and total power consumption. In this paper, the detailed design results of the 162.5 MHz IH re-buncher cavity will be presented. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB244 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 27 July 2021 issue date ※ 24 August 2021 | ||
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THPAB245 | A Simulation Study of Beam Pipe Eddy Current Effects on Beam Optics | quadrupole, operation, vacuum, power-supply | 4288 |
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In synchrotrons, fast changes of magnetic field induce eddy currents at the wall of beam pipes. The eddy currents cause a phase delay between excitation currents of the magnets and the magnetic field. The undesired magnetic field affected by eddy currents might be a serious obstacle in controlling beam optics precisely. In fact, in the operation of a high-intensity proton synchrotron J-PARC MR, the largest beam loss is observed at the beginning of acceleration when the magnetic field starts to vary in time. Therefore, it is important to estimate and understand the effects of eddy currents on beam optics. In this study, we have calculated the effect of eddy currents on magnetic field for some magnets in J-PARC MR, using electromagnetic simulation software. In this paper, we would like to report the details and results of the simulation. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB245 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 26 July 2021 issue date ※ 17 August 2021 | ||
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THPAB258 | Status of Time-Domain Simulation for the Fast Orbit Feedback System at the HEPS | feedback, vacuum, power-supply, emittance | 4311 |
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High Energy Photon Source (HEPS) is a complex designed at ultra-low emittance. A fast orbit feedback system is proposed to meet the requirement of beam orbit stability at the sub-micron level. In this paper, we present our work on setting up an orbit feedback process combined with noise model, system modeling, and particle tracking in the time domain. RF phase parameter is adjusted together with fast correctors to mitigate the orbit fluctuation due to energy vibration. The preliminary results are shown here. By the following optimization, we hope to provide an effective tool to specify and configure the FOFB system with the simulation. | |||
Poster THPAB258 [1.334 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB258 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 27 July 2021 issue date ※ 31 August 2021 | ||
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THPAB268 | Hierarchical Intelligent Real-Time Optimal Control for LLRF Using Time Series Machine Learning Methods and Transfer Learning | controls, LLRF, cavity, network | 4329 |
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Funding: supported by DOE, Office of Science, Office of High Energy Physics, under award number DE-SC0019468, Contract No. DE-AC02-76SF00515, also supported Office of Basic Energy Sciences. ALCF, Element Aero Machine learning (ML) has recently been applied to Low-level RF (LLRF) control systems to keep the voltage and phase of Superconducting Radiofrequency (SRF) cavities stable within 0.01 degree in phase and 0.01% amplitude as constraints. Model predictive control (MPC) uses an optimization algorithm offline to minimize a cost function with constraints on the states and control input. The surrogate model optimally controls the cavities online. Time series deep ML structures including recurrent neural network (RNN) and long short-term memory (LSTM) can model the control input of MPC and dynamics of LLRF as a surrogate model. When the predicted states diverge from the measured states more than a threshold at each time step, the states’ measurements from the cavity fine-tune the surrogate model with transfer learning. MPC does the optimization offline again with the updated surrogate model, and, next, transfer learning fine-tunes the surrogate model with the new data from the optimal control inputs. The surrogate model provides us with a computationally faster and accurate modeling of MPC and LLRF, which in turn results in a more stable control system. Machine learning, Surrogate model, control, LLRF, MPC, Transfer learning |
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Poster THPAB268 [0.377 MB] | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB268 | ||
About • | paper received ※ 16 May 2021 paper accepted ※ 13 July 2021 issue date ※ 18 August 2021 | ||
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THPAB269 | Compton Spectrometer for FACET-II | electron, detector, plasma, wakefield | 4332 |
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Funding: DARPA GRIT Contract 20204571, DOE HEP Grant DE-SC0009914 We present the design of a Compton spectrometer for use at FACET-II. A sextupole is used for magnetic spectral analysis, giving a broad dynamic range (180 keV through 28 MeV) and the capability to capture an energy-angular double-differential spectrum in a single shot. At low gamma energies, below 1 MeV, Compton spectroscopy becomes increasingly challenging as the scattering cross-section becomes more isotropic. To extend the range of the spectrometer down to around 180 keV, we use a 3D-printed tungsten collimator at the detector plane to preferentially select forward-scattered electrons at the Compton edge. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB269 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 22 July 2021 issue date ※ 19 August 2021 | ||
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THPAB276 | X-Ray Double Slit Interferometer Progress at CLS | synchrotron, storage-ring, emittance, photon | 4349 |
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The Canadian Light Source (CLS) is a 3rd generation synchrotron that is used to produce extremely bright synchrotron light that can be used for research. The light at the CLS is produced by an electron storage ring that has an emittance of 20 nm. A 4th generation synchrotron (CLS2) is planned which will reduce the emittance to less than 1 nm and thus reduce the transverse beam size significantly, making it very challenging to measure. A double slit interferometer can be used to measure small transverse beam sizes, as first described by Mitsuhashi. An x-ray double slit interferometer will be designed and tested at the current CLS with the goal of using this setup at CLS2. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB276 | ||
About • | paper received ※ 20 May 2021 paper accepted ※ 23 July 2021 issue date ※ 01 September 2021 | ||
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THPAB307 | Behaviour of Ironless Inductive Position Sensors in Close Proximity to Each Other | ECR, FEM, collimation, site | 4390 |
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Funding: CERN - The European Organisation for Nuclear Research UM - The University of Malta Safety critical systems like the collimators of the Large Hadron Collider require transducers which are immune to interference from their surroundings. The ironless inductive position sensor is used to measure the position of collimator jaws with respect to the beam and is designed to be immune to external DC or slowly changing magnetic fields. In this paper we investigate whether frequency separation is required when multiple ironless inductive position sensors are used and whether two or more sensors at the same frequency results in cross-talk. Numerical simulations and experiments are conducted to study the magnetic field behaviour of the sensors, their interference with each other and the impact of this interference on the position reading. Finally, this paper defines guidelines on safe operation of the ironless inductive position sensor in the aforementioned conditions. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB307 | ||
About • | paper received ※ 17 May 2021 paper accepted ※ 02 July 2021 issue date ※ 22 August 2021 | ||
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THPAB328 | Tapered Modular Quadrupole Magnet to Reduce Higher-Order Optical Aberrations | quadrupole, focusing, operation, optics | 4429 |
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Funding: US Department of Energy under the contract Nos. DE-SC0017648, DE-SC0009914 and National Science Foundation Grant No. PHY-1549132m At UCLA’s SAMURAI Laboratory, there will be a need for beam optics to accommodate operation over a range of beam energies. We present a modular quadrupole design that, in addition to satisfying this requirement, incorporates interchangeable tapered end-pieces for mitigation of higher-order aberrations *. The design progresses in an iterative fashion, whereby the tapered shapes, generated algorithmically, are fed into a field solver, and then the aberrations of the resulting particle trajectories are calculated and minimized. * R. Baartman, Quadrupole shapes, Phys. Rev. ST Accel. Beams 15, 074002 (2012). |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB328 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 27 July 2021 issue date ※ 20 August 2021 | ||
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THPAB359 | Simulations of the Stage 2 FFA Injection Line of LhARA for Evaluating Beam Transport Performance | space-charge, injection, laser, target | 4495 |
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A new, novel facility for radiobiological research, the Laser-hybrid Accelerator for Radiobiological Applications (LhARA), has recently been proposed. LhARA will be a two-stage facility with the first stage employing laser-target acceleration to produce intense proton bunches of energies up to 15 MeV. The second stage will accelerate the beam in an FFA ring up to 127 MeV. Optimal performance of stage 2, however, will require an emittance reduction of the stage 1 beam due to the FFA’s nominal dynamical acceptance. Here, we demonstrate a new optical configuration of LhARA’s stage 1 lattice that will provide this reduced emittance. The profile of the laser-target generated beam is far from an ideal Gaussian, therefore two start-to-end Monte Carlo particle tracking codes have been used to model beam transport performance from the laser-target source through to the end of the stage 2 FFA injection line. The Geant4-based Beam Delivery Simulation (BDSIM) was used to model beam losses and the collimation that is crucial to LhARA’s energy selection system, and General Particle Tracer (GPT) was used to model the space-charge effects that may impact performance given the emittance reduction. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB359 | ||
About • | paper received ※ 19 May 2021 paper accepted ※ 07 July 2021 issue date ※ 18 August 2021 | ||
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