Keyword: multipole
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MOPAB069 Measurement of Transverse Multipole Moments of the Proton Beam in the J-PARC MR quadrupole, proton, simulation, vacuum 274
 
  • T. Toyama
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  • A. Ichikawa, A. Minamino, K.G. Nakamura, Y. Nakanishi, T. Nakaya, W. Uno
    Kyoto University, Kyoto, Japan
  • T. Koseki, H. Kuboki, M. Okada
    KEK, Tokai, Ibaraki, Japan
  
  Funding: This work was partially supported by MEXT/JSPS KAKENHI Grant Numbers 25105002 and 16H06288.
Transverse multipole moments (quadrupole and more) of the beam may give important informations of the beam such as beam sizes, nonlinear resonances and so on. However higher moments are difficult to measure because signal-to-noise-ratio becomes smaller proportional to the n-th order of the beam-radius-to-vacuum-duct-radius ratio. In order to increase the SNR and to extend the multipole order, we developed and installed a 16 electrode beam monitor in the J-PARC MR, which consists of guard-potential-separated 16 striplines. The calibration method, beam test results will be presented. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB069  
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MOPIK046 Phase Space Folding Studies for Beam Loss Reduction During Resonant Slow Extraction at the CERN SPS extraction, sextupole, simulation, proton 615
 
  • L.S. Stoel, M. Benedikt, K. Cornelis, M.A. Fraser, B. Goddard, V. Kain, F.M. Velotti
    CERN, Geneva, Switzerland
  
  The requested number of protons slow-extracted from the CERN Super Proton Synchrotron (SPS) for Fixed Target (FT) physics is expected to continue increasing in the coming years, especially if the proposed SPS Beam Dump Facility is realised. Limits on the extracted intensity are already being considered to mitigate the dose to personnel during interventions required to maintain the extraction equipment, especially the electrostatic extraction septum. In addition to other on-going studies and technical developments, a reduction of the beam loss per extracted proton will play a crucial role in the future performance reach of the FT experimental programme at the SPS. In this paper a concept is investigated to reduce the fraction of beam impacting the extraction septum by folding the arm of the phase space separatrix. Beam dynamics simulations for the concept are presented and compared to the phase space acceptance of the extraction channel. The performance potential of the concept at SPS is evaluated and discussed alongside the necessary changes to the non-linear optical elements in the machine.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK046  
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MOPIK079 The Off-Axis Injection Lattice Design of HEPS Storage Ring injection, lattice, dynamic-aperture, storage-ring 716
 
  • Y.M. Peng, D. Ji, Y. Jiao, S.K. Tian, J.Q. Wang, G. Xu
    IHEP, Beijing, People's Republic of China
  
  The dynamic aperture size determines the injection scheme to a large extent. The aim of storage ring design of HEPS is to achieve ultralow emittances on both transverse planes. This will bring very strong lattice nonlinearities. The present nominal design is a hybrid 7BA design with effective dynamic aperture of about 3 mm both in horizontal and vertical plane. Due to the restriction of dynamic aperture of this lattice, on-axis injection is the only choice . But, on-axis injection will bring a very big challenge for injector or injection kicker, if it is feasible to obtain a large dynamic aperture, off-axis injection is a favoured choice. In this paper, we will show the preliminary study of the lattice design with a sufficient dynamic aperture for pulsed multipole injection..  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK079  
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MOPIK123 Beam Dynamics Numerical Studies Regarding CBETA Cornell-BNL ERL lattice, quadrupole, simulation, optics 824
 
  • F. Méot, S.J. Brooks, D. Trbojevic, N. Tsoupas
    BNL, Upton, Long Island, New York, USA
  • S.C. Tygier
    UMAN, Manchester, United Kingdom
  
  Funding: Work supported by New York State Energy Research and Development Authority (NYSERDA)
The Cornell-BNL Electron Test Accelerator CBETA is based on a 36 MeV superconducting linac and on a single 4-pass up/4-pass down linear FFAG return loop, for beam acceleration from 6 to 150 MeV and energy recovery. Numerical beam dynamics simulations have accompanied and eventually validated the quadrupole-doublet FFAG cell technology and parameters, and following that the complete return loop, all along the ERL lattice design process. They are key to assessing and validating the ERL optics and beam behavior over the whole acceleration/ER cycle, and in preparing future machine operation. This paper presents various of these beam dynamics studies, including start-to-end simulations. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK123  
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MOPVA136 Higher Order Multipole Analysis for 952.6 Mhz Superconducting Crabbing Cavities for Jefferson Lab Electron-Ion Collider cavity, dipole, electron, proton 1177
 
  • S.U. De Silva, J.R. Delayen
    ODU, Norfolk, Virginia, USA
  • H. Park
    JLab, Newport News, Virginia, USA
  
  The proposed electron ion collider at Jefferson Lab requires a crabbing cavity system to increase the luminosity in the colliding beams. Currently several superconducting crabbing cavity designs are being reviewed as the design option for the crabbing cavity. Knowledge of higher order mode multipole field effects is important for accurate beam dynamics study for the crabbing system, in selecting the design that meets the design specifications. The multipole components can be accurately determined numerically using the electromagnetic field data in the rf structure. This paper discusses the detailed analysis of higher order multipole components for the operating crabbing mode and design modifications in reducing those components.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA136  
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TUPAB035 Field Quality of 1.5 m Long Conduction Cooled Superconducting Undulator Coils with 20 mm Period Length undulator, photon, synchrotron, emittance 1395
 
  • S. Casalbuoni, N. Glamann, A.W. Grau, T. Holubek, D. Saez de Jauregui
    KIT, Eggenstein-Leopoldshafen, Germany
  • C. Boffo, T.A. Gerhard, M. Turenne, W. Walter
    Babcock Noell GmbH, Wuerzburg, Germany
  
  The Institute for Beam Physics and Technology (IBPT) at the Karlsruhe Institute of Technology (KIT) and the industrial partner Babcock Noell GmbH (BNG) are col-laborating since 2007 on the development of superconducting undulators both for ANKA and low emittance light sources. The first full length device with 15 mm period length has been successfully tested in the ANKA storage ring for one year*. The next superconducting undulator has 20 mm period length (SCU20) and is also planned to be installed in the accelerator test facility and synchrotron light source ANKA. The SCU20 1.5 m long coils have been characterized in a conduction cooled horizontal test facility developed at KIT IBPT. Here we present the local magnetic field and field integral measurements, as well as their analysis including the expected photon spectrum.
*S. Casalbuoni et al., Characterization and long term operation of a novel superconducting undulator with 15 mm period length in a synchrotron light source, Phys. Rev. ST Accel. Beams, vol. 19, p.110702, Nov. 2016. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB035  
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TUPAB080 Considerations of the HALS Injection System and a New Non-linear Kicker Design injection, kicker, accumulation, lattice 1503
 
  • L. Shang, W. Liu, Y. Lu, F.L. Shang, Z.B. Sun
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  
  Funding: Work supported by The National Key Research and Development Program of China No. 2016YFA0402000(2016YFA0402002)
Hefei Advanced Light Source (HALS) is a newly designed diffraction-limited synchrotron radiation source with an energy of 2GeV and a natural emittance of 18.4 pm. A project to build test facility of this new light source has been approved and funded in 2017. Among many key subsystems, the injection system of HALS is a very important one. Both on-axis swap out, on-axis longitudinal accumulation and off-axis single multipole kicker injection are considered. For on-axis fast kicker injection, basic parameters of the system are given. Layout of kickers and septums are presented. For off-axis multipole injection, non-linear kickers (NLK) draw much attention in recent years, various studies have been carried out in many laboratories. But it suffered from low injection efficiency and has not been used in routine operation. In this paper, we propose a new ferrite-loaded non-linear kicker (FNLK) and a prototype FNLK has been developed and tested. Compared to the air bus design of NLK, the FNLK not only improves the flat region of magnetic field but also reduce the error sensitivity of bars' position. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB080  
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TUPAB105 Field Measurement System for a Cryogenic Permanent Magnet Undulator in TPS undulator, cryogenics, vacuum, permanent-magnet 1559
 
  • C.K. Yang, C.H. Chang, T.Y. Chung, W.H. Hsieh, J.C. Huang, C.-S. Hwang
    NSRRC, Hsinchu, Taiwan
  
  Short period in-vacuum, permanent magnet undulators operating at cryogenic temperatures are being developed worldwide to serve as brilliant and coherent light sources for medium energy storage rings. A hybrid cryogenic permanent magnet undulator (CU) with PrFeB magnets has now been designed and constructed at NSRRC [1]. To characterize the performance and to determine magnetic field errors after cool down poses some technical chal-lenges compared to room temperature undulators. A new system combining a Hall probe and a stretched wire has been designed to measure the field integrals, trajectory, phase errors, and K value under low temperature and vacuum conditions. Field measurements in this cryogenic undulator will be performed around 77 K as well as at room temperature, making temperature dependent calibra-tion of the Hall probes necessary. The main features and improvement of the measurement and calibration system are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB105  
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TUPAB109 Study on Injection with Pulsed Multipole Magnet for SPS Storage Ring injection, kicker, operation, storage-ring 1573
 
  • T. Pulampong, P. Klysubun, P. Sudmuang, P. Sunwong
    SLRI, Nakhon Ratchasima, Thailand
  
  Pulsed multipole magnet (PM) has zero magnetic field at the centre, therefore it introduces no perturbation to the stored beam. It has been demonstrated that this injection scheme is able to minimise the oscillation of the stored beam, and thus make it suitable for top-up operation. To investigate the suitability of employing this injection method at Siam Photon Source, PM was modelled and optimised for best performance using particle tracking based method. This work presents injection optimisation process with PM considering various constraints such as position of injected beam, injection conditions, and effects of installed IDs.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB109  
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TUPAB147 The Final RF-Design of the 36 MHz-HSI-RFQ-Upgrade at GSI rfq, simulation, alignment, resonance 1678
 
  • M. Baschke, H. Podlech
    IAP, Frankfurt am Main, Germany
  • L. Groening, S. Mickat, C. Zhang
    GSI, Darmstadt, Germany
  
  In Darmstadt/Germany the existing accelerator cite GSI is expanding to one of the biggest joint research projects worldwide: FAIR, a new antiproton and ion research facility with so far unmatched intensities and quality. The existing accelerators will be used as pre-accelerators and therefor need to be upgraded to fulfill the requirements with respect for intensity and beam quality. In a first step the 9.2 m long 36 MHz-HSI-RFQ for high current beams will obtain new electrodes to reach the specific frequency and to allow a higher electric strength. Therefor several simulations with CST MWS have been done. The final RF-design will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB147  
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TUPIK014 Detailed Analysis of a Linear Beam Transport Line from a Laser Wakefield Accelerator to a Transverse-Gradient Undulator quadrupole, beam-transport, alignment, simulation 1711
 
  • A. Will, A. Bernhard, A.-S. Müller, C. Widmann
    KIT, Karlsruhe, Germany
  • M. Kaluza
    HIJ, Jena, Germany
  • M. Kaluza
    IOQ, Jena, Germany
  
  A linear beam transport system, experimentally tested at the Laser Wakefield Accelerator in Jena, Germany, has been carefully analyzed in order to gain a deeper understanding of the experimental results and to develop experimental strategies for the future. This analysis encompassed a detailed characterization of the focusing magnets and an investigation of the effects of source parameters as well as magnet and alignment errors on the observables accessible in the experiment. A dedicated tracking tool was developed for these investigations. In this contribution we review the main results of these studies.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK014  
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TUPVA051 Magnets and Wien Filters for SECAR dipole, quadrupole, target, high-voltage 2191
 
  • F. Bødker, N. Hauge, J. Kristensen
    Danfysik A/S, Taastrup, Denmark
  • G.P.A. Berg, M. Couder
    University of Notre Dame, Indiana, USA
  • H. Schatz
    NSCL, East Lansing, Michigan, USA
  
  The Separator for Capture Reactions, SECAR, is being built at Michigan State University for the study of low-energy capture reactions. The high performance magnets and two large Wien filters required to reach the very high recoil mass separation factor are being designed and produced at Danfysik to the SECAR specifications. The 2.4 m long Wien filters with a weight of 35 ton each including a large vacuum tank have high electrode voltages of ±300 kV combined with a magnetic field of 0.12 T. Challenging design requirements for integrated magnetic and electrostatic field homogeneity combined with tight tolerance on the effective lengths have been meet. The dipole magnets for this facility are special in having stringent ±0.5 mm effective magnetic length specifications in a wide excitation range and the transverse field boundary variation is described by a 4th order polynomial. Most of the dipoles are made with variable segmented field clamps in order to keep the deviation of the magnetic fringe field boundary within the required ±0.1 mm. The wide range of different quadrupole, sextupole and octupole magnets are required to meet the specified magnetic length with a tight tolerance.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA051  
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WEPAB026 BRho-Dependent Taylor Transfer Maps for Super-FRS Dipole Magnets dipole, ion, simulation, radiation 2631
 
  • E.S. Kazantseva, O. Boine-Frankenheim
    TEMF, TU Darmstadt, Darmstadt, Germany
  • M. Berz, R. Jagasia, K. Makino
    MSU, East Lansing, Michigan, USA
  • H. Weick, J.S. Winfield
    GSI, Darmstadt, Germany
  
  The Super-FRS is an in-flight projectile fragment separator being built at GSI for FAIR. Due to the required high design momentum resolution and large acceptance (Ah= ±40mrad, Av= ±20mrad) the dipole magnets of the Super-FRS have large apertures (38×14cm²). The wide design magnetic rigidity (BRho) range 2-20 Tm requires the variation of the main dipole magnetic field B0 in the range 0.16-1.6 T. Since the upper third of the B0 range is situated in a non-linear saturation region of the magnetization curve B(H) and the spatial distribution of magnetic permeability in the steel yoke is non-uniform, the field distribution in the useful aperture of the magnet is a non-linear and non-uniform function of the excitation current I. One consequence is the shortening of the effective length and the change of the field distribution with increasing I. In this study we analyze these effects for the Super-FRS dipole magnets. We use 3D field distribution from FEM simulations for different I values and a resulting BRho(I). From the fields the Taylor transfer maps for the particles are obtained using DA techniques (COSY-infinity) and the convergence of the resulting transfer maps is discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB026  
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WEPAB109 Multipole Field Effects in a Transverse Gradient Undulator undulator, FEL, electron, simulation 2833
 
  • P. Baxevanis, Z. Huang
    SLAC, Menlo Park, California, USA
  
  Using a transverse gradient undulator (TGU) is one of the methods proposed in order to enable the utilization of electron beams with large energy spread (such as those from plasma-based accelerators) in a free-electron laser (FEL). Most of the analytical treatments of this scheme assume a linear variation of the undulator field with one of the transverse coordinates. While this assumption leads to a simplified and more tractable model, including higher-order multipoles allows us to offer a more complete and rigorous description of the system. In this paper, we investigate the magnetic field components of a TGU using both theory and simulation and explore the impact of higher-order multipoles on the FEL performance.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB109  
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WEPIK044 Effects of Crab Cavitiy Multipoles on JLEIC Ion Ring Dynamic Aperture cavity, ion, dynamic-aperture, dipole 3025
 
  • S.I. Sosa Guitron, S.U. De Silva, J.R. Delayen
    ODU, Norfolk, Virginia, USA
  • V.S. Morozov
    JLab, Newport News, Virginia, USA
  
  We study the effects of crab cavity multipole fields on the beam dynamic aperture of the Jefferson Lab Electron-Ion Collider (JLEIC) ion ring. Crab cavities are needed to compensate for luminosity loss due to a 50 mrad crossing angle at the interaction point. New compact crab cavity designs are interesting as they do not require considerable space in the ring but their non-linear field needs to be well understood. In this contribution, we study the impact of field multipoles on the beam dynamic aperture and report tolerance values for crab cavity multipoles.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK044  
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WEPIK061 Lattice Tuning and Error Setting in Accelerator Toolbox lattice, dipole, quadrupole, closed-orbit 3067
 
  • S.M. Liuzzo, N. Carmignani, L. Farvacque, B. Nash
    ESRF, Grenoble, France
  
  New lattice designs need to be studied in the presence of magnetic and alignment errors and appropriate lattice tuning procedures. For this reason a set of tools to perform a commissioning-like sequence has been developed for the ESRF-EBS* ** upgrade in Accelerator Toolbox (AT)*** and is now generalized to be used for other accelerators lattice design. The functions presented here allow to correct first turn trajectory, orbit, tune, chromaticity, optics and coupling, in any order. A set of functions to define errors is introduced to address, among others, the issues of: misalignment of magnets modeled by several slices, multiple errors setting on the same magnet and spatially recursive errors along the lattice.
* J.C. Biasci et al. ,A low emittance lattice for the ESRF, Synchrotron Radiation News, vol. 27, Iss.6, 2014.
** ESRF upgrade programme phase II, ESRF, December 2014.
*** Nash, B. et al.. New functionality for beam dynamics in Accelerator Toolbox (AT) IPAC'15. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK061  
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WEPIK067 Beam-Dynamics Simulation Studies for the HESR dynamic-aperture, simulation, dipole, coupling 3084
 
  • J.H. Hetzel, U. Bechstedt, J. Böker, A. Lehrach, B. Lorentz, S. Quilitzsch, H. Soltner, R. Tölle
    FZJ, Jülich, Germany
  • A. Lehrach
    RWTH, Aachen, Germany
  
  The High Energy Storage Ring (HESR) is part of the future Facility for Antiproton and Ion Research (FAIR) placed in Darmstadt (Germany). The HESR is designed for antiprotons with a momentum range from 1.5 GeV/c to 15 GeV/c, but will as well be suitable to provide heavy ion beams with a momentum range from approximately 0.6 GeV/c to 5.8 GeV/c. To guarantee smooth operation it is crucial to verify and to optimize the design with beam-dynamics simulations. Within recent studies* calculations based on a variant of the Lyapunov exponent were carried out to estimate the dynamic aperture. The studies could reproduce expected influences as reduced aperture due to tune resonances and tune shifts due to coupling. Thus they can be extended to investigate the dynamic behaviour of the beam and identify the main restrictions to the dynamic aperture near the chosen betatron tune. Furthermore ongoing measurements of the magnetic fields of the already produced bending dipoles and quadrupoles deliver a more precise insight to the harmonic content of these elements. Thus the existing simulations could now be updated by including the new measurement results.
*J. Hetzel, A. Lehrach, U. Bechstedt, J. Böker, B. Lorentz, R. Tölle: Towards Beam-Dynamics Simulations Including More Realistic Field Descriptions for the HESR, IPAC'16 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK067  
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WEPIK085 Beam Shaping with 4N-order Multipole Magnets octupole, focusing, electron, quadrupole 3124
 
  • B.T. Folsom, E. Laface
    ESS, Lund, Sweden
  
  A uniformly irradiating beam is beneficial in spallation for preventing irregular wear on the target. For octupoles (n = 4) and higher-order (n = 4N) magnets, passing charged-particle bunches undergo symmetric shaping effects along the x and y axes. Using a Lie-mapping formalism, we illustrate how well Gaussian distributions can be flattened symmetrically in 2D with single, dual-pulse, and RF magnets of 4N order. Incidental shaping effects are also discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK085  
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WEPIK101 Novel Implementation of Quadrupole and Higher Order Fringe Fields to Accelerator Design quadrupole, sextupole, dipole, space-charge 3184
 
  • B.D. Muratori
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  
  Until recently, in the initial design phase of any accelerator project, it was not possible to have an adequate description of quadrupole and higher order multipole fringe fields. We report on the latest developments in analytical fringe fields for multipoles, particularly for quadrupoles and sextupoles. We show how they can be used to improve accelerator codes and make them both faster and more precise. We also show how the analytical formulae for the fringe fields yield expressions for both the scalar and vector potentials in electromagnetism. We conclude by discussing the application of both potentials to the design of multipole magnets as well as the implementation of symplectic kick approximations for fringe fields in thin lens models that could be used in accelerator codes.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK101  
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WEPIK116 Aberration Compensation in a Skew Parametric-Resonance Ionization Cooling Channel resonance, damping, simulation, sextupole 3221
 
  • A.V. Sy, Y.S. Derbenev, V.S. Morozov
    JLab, Newport News, Virginia, USA
  • A. Afanasev
    GWU, Washington, USA
  • Y. Bao
    UCR, Riverside, California, USA
  • R.P. Johnson
    Muons, Inc, Illinois, USA
  
  Funding: This work was supported in part by U.S. DOE STTR Grant DE-SC0005589. Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Skew Parametric-resonance Ionization Cooling (Skew PIC) represents a novel method for focusing of highly divergent particle beams, as in the final 6D cooling stage of a high-luminosity muon collider. In the muon collider concept, the resultant equilibrium transverse emittances from cooling with Skew PIC are an order of magnitude smaller than in conventional ionization cooling. The concept makes use of coupling of the transverse dynamic behavior, and the linear dynamics are well-behaved with good agreement between analytic solutions and simulation results. Compared to the uncoupled system, coupling of the transverse dynamic behavior purports to reduce the number of multipoles required for aberration compensation while also avoiding unwanted resonances. Aberration compensation is more complicated in the coupled case, especially in the high-luminosity muon collider application where equilibrium angular spreads in the cooling channel are on the order of 200 mrad. We present recent progress on aberration compensation for control of highly divergent muon beams in the coupled correlated optics channel, and a simple cooling model to test the transverse acceptance of the channel. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK116  
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WEPVA142 Active Compensation Coils in the Fermilab g-2 Experiment dipole, experiment, simulation, storage-ring 3602
 
  • K.E. Badgley
    Texas A&M University, College Station, USA
  • B. Kiburg
    Fermilab, Batavia, Illinois, USA
  • M.W. Smith
    University of Washington, CENPA, Seattle, USA
  
  The recently commissioned Fermilab muon g-2 experiment is aiming to determine the anomalous magnetic moment of the muon to 140 ppb. To achieve this level of precision, the magnetic field seen by the muon must be know at fraction of a ppm level, which puts limits on the required magnetic field uniformity. In addition to the mechanical adjustments made to magnet pole tips, a set of 200 trim coils were added to the ring. These coils form concentric rings with 100 on the top pole and 100 on the bottom. Measurements of the remaining integrated filed errors were made using NMR probes. The use of these trim coils to reduce the remaining higher order field errors will be discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA142  
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THPAB011 Optimization of Multicell Microwave Cavities Using YACS cavity, controls, dipole, software 3708
 
  • B.D. Isbarn, B. Riemann, M. Sommer, T. Weis
    DELTA, Dortmund, Germany
  
  Funding: Work supported by the BMBF under contract no. 05K13PEB.
YACS is a 2.5D finite element method solver capable of solving for the full 3D eigenfrequency spectra of resonant axisymmetric structures while reducing the computational problem to a 2D rotation plane. The most recent revision of the code introduced arbitrary order basis functions and curved meshes, for both triangular and quadrilateral unstructured meshes. This led to significant increases in convergence rates. However, due to the utilization of curved meshes and the complex coordinate transformations that are involved, spurious modes were introduced when solving the axisymmetric problem. Although workarounds do exist that circumvent these issues by lowering the likelihood and frequency of spurious modes, linear triangular meshes with higher order basis functions were chosen due to their simplicity and spurious free solutions. In order to support the usage of spline cavities as an alternative parameterization to the well known elliptical cavities, parameter space scans were carried out for non-reentrant spline cavities. In addition a new optimization strategy is presented that exploits the arbitrary polynomial order of Bézier curves by utilizing the degree elevation technique. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB011  
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THPAB052 Recent Developments in DEMIRCI, the RFQ Design Software rfq, simulation, software, ion 3830
 
  • E. Celebi
    Bogazici University, Bebek / Istanbul, Turkey
  • O. Cakir, G. Turemen, B. Yasatekin
    Ankara University, Faculty of Sciences, Ankara, Turkey
  • G. Turemen, B. Yasatekin
    TAEK - SANAEM, Ankara, Turkey
  • G. Unel
    UCI, Irvine, California, USA
  
  Funding: This project has been supported by TUBITAK with project number 114F106.
The RFQ design tool DEMIRCI aims to provide fast and accurate simulation of a light ion accelerating cavity and of the ion beam in it. It is a modern tool with a graphical user interface leading to a point and click method to help the designer. This article summarizes the recent developments of DEMIRCI software such as the addition of beam dynamics and 8-term potential coefficient calculations. Its results are compared to other software available on the market, to show the attained compatibility level. Finally the future prospects are discussed. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB052  
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THPAB055 Modelling of Curvilinear Electrostatic Multipoles in the Fermilab Muon g-2 Storage Ring quadrupole, emittance, storage-ring, lattice 3837
 
  • A.T. Herrod, S. Jones, A. Wolski
    The University of Liverpool, Liverpool, United Kingdom
  • I.R. Bailey, A.T. Herrod, S. Jones, M. Korostelev, A. Wolski
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • I.R. Bailey, M. Korostelev
    Lancaster University, Lancaster, United Kingdom
  
  Funding: This research was funded by the STFC Cockcroft Institute Core grants no. ST/G008248/1 and ST/P002056/1.
The Fermilab Muon g-2 Experiment (E989) contains flat-plate electrostatic quadrupoles, curved with the reference trajectory as defined by the constant, uniform magnetic dipole field. To understand the beam behaviour at a sufficient level, we require fast, high-accuracy particle tracking methods for this layout. Standard multipole fits to numerically calculated 2D transverse electric field maps have provided a first approximation to the electric field within the main part of the quadrupole, but cannot model the longitudinal curvature or extended fringe fields of the electrostatic plates. Expressions for curvilinear multipoles can be fit to a 2D transverse slice taken from the central point of a numerically calculated 3D electric field map of the quadrupole, providing a curved-multipole description. Generalised gradients can be used to model the fringe field regions. We present the results of curvilinear multipole and generalised gradient fits to the curved quadrupole fields, and the differences in tracking using these fields over 200 turns of a model of the storage ring in BMAD. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB055  
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THPIK007 Production of Low Cost, High Field Quality Halbach Magnets quadrupole, dipole, simulation, controls 4118
 
  • S.J. Brooks, J. Cintorino, A.K. Jain, G.J. Mahler
    BNL, Upton, Long Island, New York, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
A shimming method has been developed at BNL that can improve the integrated field linearity of Halbach magnets to roughly 1 unit (1 part in 104) at r=10mm. Two sets of magnets have been produced: six quadrupoles of strength 23.62T/m and six combined-function (asymmetrical) Halbach magnets of 19.12T/m with a central field of 0.377T. These were assembled using a 3D printed plastic mould inside an aluminium tube for strength. A shim holder, which is also 3D printed, is fitted within the magnet bore and holds iron wires of particular masses that cancel the multipole errors measured using a rotating coil on the unshimmed magnet. A single iteration of shimming reduces error multipoles by a factor of 4 on average. This assembly and shimming method results in a high field quality magnet at low cost, without stringent tolerance requirements or machining work. Applications of these magnets include compact FFAG beamlines such as FFAG proton therapy gantries, or any bending channel requiring a ~4x momentum acceptance. The design and shimming method can also be generalised to produce custom nonlinear fields, such as those for scaling FFAGs. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK007  
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THPIK012 The Magnets of BERLinPro: Specification, Design, Measurement and Quality Analysis dipole, quadrupole, sextupole, operation 4124
 
  • A.N. Matveenko, M. Abo-Bakr, K.B. Bürkmann-Gehrlein
    HZB, Berlin, Germany
  • I.V. Davidyuk, O.A. Shevchenko, A.V. Utkin, N.A. Vinokurov
    BINP SB RAS, Novosibirsk, Russia
  
  Funding: Work supported by grants of Helmholtz Association VH-NG-636 and HRJRG-214
A total of 77 magnets form the magnetic lattice of the BERLinPro energy recovery linac prototype: 1+8+8 dipole magnets of three different types, 12+40 quadrupole magnets of two different types and 8 sextupole magnets have been produced by BINP. After the design phase, magnets production started in 2015, measurements and delivery took place in 2016, first assembly stage was finished in 03/2017. The motivation for the magnet specification and a summary of the basic design is given in this paper. Select-ed measurement data from the final acceptance tests are presented and analysed to ensure the magnet quality. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK012  
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THPIK092 Considerations on the Effect of Magnet Yoke Dilution on Remanent Field at ELENA quadrupole, antiproton, simulation, dipole 4299
 
  • C. Carli, L. Fiscarelli, D. Schoerling
    CERN, Geneva, Switzerland
  
  The Extra Low Energy Antiproton ring (ELENA) is a small synchrotron constructed at CERN to decelerate antiprotons down to 100 keV and, thus, operated at very low magnetic fields. The CERN magnet group has carried out extensive investigations on accelerator magnets for very low fields, comprising theoretical studies and the construction of several prototype magnets, to ensure that the required field quality can be reached at these very low fields. In the course of this work, experimental investigations [1] led to the initially unexpected observation that dilution of the yoke, i.e. alternating laminations made of electric steel with thicker non-magnetic stainless steel laminations, increases the remnant field. An explanation for this behaviour has already been anticipated in a previous paper [2]. Here, we treat this specific topic in analytical detail. We come to the conclusion that magnet yoke thinning in most practical situations does not improve the field quality at very low field levels, but rather enhances the impact from hysteresis and remanence effects.
[1] L.Fiscarelli, Magnetic measurements on the quadrupoles prototypes for ELENA (PXMQNLGNAP), CERN internal report.
[2] D. Schoerling, Case Study of a Magnetic System for low-Energy Machines, PRAB 19, 082401 (2016). 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK092  
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THPIK107 Design and Characterisation of the Focusing Solenoidal System for the CLARA High Repetition Rate Electron Source solenoid, simulation, alignment, cathode 4346
 
  • D.J. Scott, A.R. Bainbridge, K.B. Marinov, B.L. Militsyn, B.J.A. Shepherd
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • R.J. Cash, T.J. Jones
    STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
  • C.S. Edmonds
    The University of Liverpool, Liverpool, United Kingdom
  
  One of the critical components of electron injectors based on RF photoelectron sources is the focusing system. The system typically consists of a Main Focusing Solenoid and a Bucking Coil. Combination of these two solenoids should provide proper focusing of the beam at the exit of the RF cavity and zero longitudinal magnetic field in the photocathode plane to minimise the beam emittance. Imperfection of the solenoid design, manufacturing and alignment frequently leads to asymmetry of the focusing field which has to be compensated with additional coils. In order to eliminate mechanical and magnetic misalignment the CLARA photoinjector solenoids are mounted on one integrated bench and before installation into the beamline have been aligned in the magnet laboratory with simultaneous measurement of the magnetic field. In order to define multipole field components, dedicated measurements of the transverse magnetic field have been done. The amplitudes of the multipoles have been obtained from analysis of the transverse field map. We present here the results of field characterisation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK107  
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THPVA015 Application of Modified KV-Distributions to Study the Phase Portrait Transformation of Intense Bunches in Magnetic Fields emittance, cyclotron, optics, electronics 4448
 
  • H.Y. Barminova
    MEPhI, Moscow, Russia
  
  Modified KV-distribution functions are applied to study the intense bunch behavior in transverse magnetic fields. The functions used allow to consider both the emittance-dominated and charge-dominated bunches in 2D and 3D approximations. Peculiarities of the bunch phase portrait transformation in magnetic fields of achromatic structures are discussed. Particular case is proved to exist characterized by the absence of the emittance transfer.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA015  
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