WG2: Optics, Beam Dynamics & Instrumentation
Paper Title Page
MOPSPP007 Beam Dynamics and Collimation Following MAGIX at MESA 17
 
  • B. Ledroit, K. Aulenbacher
    IKP, Mainz, Germany
 
  Funding: Supported by the DFG through GRK 2128
The Mainz Energy-recovering Superconducting Accelerator (MESA) will be an electron accelerator allowing operation in energy-recovery linac (ERL) mode. After the beam hits the target at the MESA Internal Gas Target Experiment (MAGIX), the beam is phase shifted and recirculated back into the linac sections. These will transfer the kinetic beam energy back to the RF-field by deceleration of the beam and allow for high beam power with low RF-power input. Since most of the beam does not interact with the target, the beam will mostly just pass the target untouched. However, a fraction of the scattered electrons may be in the range outside the accelerator and detector acceptances and therefore cause malicious beam dynamical behavior in the linac sections or even damage to the machine. The goal of this work is to determine the beam behavior upon target passage by simulation and experiment and to protect the machine with a suitable collimation system. The present status of the investigations is presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2017-MOPSPP007  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
MOPSPP009 Beam Break Up Simulations for the MESA Accelerator 26
 
  • C.P. Stoll, F. Hug, D. Simon
    IKP, Mainz, Germany
 
  Funding: Supported by DFG through GRK 2128
MESA is a recirculating superconducting accelerator under construction at Johannes Gutenberg-Universität Mainz. It will be operated in two different modes: the first is the external beam (EB) mode, where the beam is dumped after being used at the experiment. The required beam current in EB mode is 150 μA with polarized electrons at 155 MeV. In the second operation mode MESA will be run as an energy recovery linac (ERL) with an unpolarized beam of 1 mA at 105 MeV. In a later construction stage of MESA the achievable beam current in ERL-mode shall be upgraded to 10 mA. To understand the behavior of the superconducting cavities under recirculating operation with high beam currents simulations of beam breakup have to be performed. Current results for transverse beam break up calculations and simulations with Beam Instability (bi) code are presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2017-MOPSPP009  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
MOPSPP013
Proposal of Sharing 6-GeV Class CW Superconducting Linac With ILC and High Brilliance X-ray Light Source  
 
  • M. Shimada, M. Yamamoto, K. Yokoya
    KEK, Ibaraki, Japan
  • R. Hajima
    QST, Tokai, Japan
 
  We propose sharing of the 6-GeV class CW superconducting linac with ILC and X-ray light source. ILC utilizes it for the positron source and the two boosters for the 5-GeV damping ring. The conventional positron source, which is based on a collision of the multi-GeV electron with the target, was chosen to lengthen the macro-pulse duration for avoiding the heat loading. In this proposal, the CW linac realizes the long macro-pulse duration beam operation of the positron beam as well as the electron for collision with the target. Simultaneously, the CW linac can used as the 5-GeV booster of the polarized electron beam at the same bunch pattern. Because of the low average current of beams of ILC, the CW linac have enough ability to accelerate/decelerate the high quality electron beam for the high brilliant X-ray light source such as 6-GeV class ERL light source and XFELO. Each electron beam has different injection energy, injects at the different merger and accelerates at the different RF phase. Therefore, the electron energies are different at the end of the CW linac and it makes the simultaneous operation possible.  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUIDCC001 PERLE - Beam Optics Design 49
 
  • S.A. Bogacz
    JLab, Newport News, Virginia, USA
 
  Funding: Work has been authored by Jefferson Science Associates, LLC under Contract No. DE-AC05-06OR23177 with the U.S. Department of Energy.
PERLE (Powerful ERL for Experiments) is a novel ERL test facility, initially proposed to validate design choices for a 60 GeV ERL needed for a future extension of the LHC towards a hadron-electron collider, the LHeC. Its main goal is to test the limits of a high current, CW, multi-pass operation with superconducting cavities at 802 MHz (and perhaps exploring other frequencies of interest). PERLE optics features Flexible Momentum Compaction (FMC) lattice architecture for six vertically stacked return arcs and a high current, 5 MeV photo-injector. With only one pair of 4-cavity cryomodules, 400 MeV beam energy can be reached in three re-circulation passes, with beam currents in excess of 15 mA. This unique quality beam is intended to perform a number of experiments in different fields reaching from uncharted tests of accelerator components via elastic ep scattering to laser-Compton backscattering for photon physics. Following the experiment, the CW beam is decelerated in three consecutive passes back to the injection energy, transferring virtually stored energy back to the RF.
 
slides icon Slides TUIDCC001 [11.936 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2017-TUIDCC001  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUIDCC002
eRHIC Multi-Pass ERL  
 
  • V. Ptitsyn
    BNL, Upton, Long Island, New York, USA
 
  The talk concentrates on accelerator physics and accelerator technology issues related with the multi-pass ERL of ERL-Ring design option of future high luminosity electron-hadron collider eRHIC. Possible solutions for recirculating passes are described which include individual loops as well as FFAG-type re-circulations. Major beam dynamics effects dominating the ERL performance are described, which include electron beam disruption, multi-pass beam-break-up, preservation of transverse emittance and energy spread during acceleration and deceleration process. The recent design modifications of ERL-Ring eRHIC aim to balance technological risks and the project cost.  
slides icon Slides TUIDCC002 [10.494 MB]  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUIDCC003
CBETA Multipass Lattice Design  
 
  • C.E. Mayes
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Cornell University and Brookhaven National Laboratory are currently designing the Cornell-BNL ERL-FFAG Test Accelerator (CBETA), to be built at Cornell that utilizes the existing energy recovery linac (ERL) injector and main linac cryomodule (MLC). The bulk of the recirculation arcs will consist of fixed-field alternating-gradient (FFAG) magnets made from permanent magnet material. Four acceleration passes through the MLC will bring the beam to 150 MeV. We will review the overall lattice design for this machine.  
slides icon Slides TUIDCC003 [10.109 MB]  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUIDCC004 CBETA FFAG Beam Optics Design 52
 
  • J.S. Berg, S.J. Brooks, F. Méot, D. Trbojevic, N. Tsoupas
    BNL, Upton, Long Island, New York, USA
  • J.A. Crittenden, Y. Li, C.E. Mayes
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Funding: This manuscript has been authored by employees of Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
CBETA is an Energy Recovery Linac (ERL) accelerating an electron beam to 150 MeV in four linac passes. Instead of having four separate return loops to the linac, it instead has a single fixed field alternating gradient (FFAG) beamline with nearly a factor of 4 energy acceptance. While ideally the FFAG would be circular with identical cells all around, space and cost considerations dictate that small radius of curvature FFAGs should be used near the linac, connected by a straight beamline. To ensure good orbit matching over the entire energy range, adiabatic transitions are inserted between the arcs and the straight. After briefly introducing basic principles of FFAG optics, we describe how we choose the parameters of the arc cell, the basic building block of the lattice. We then describe how the straight cell is chosen to work well with the arc. Finally we describe the design process for the transition that ensures orbits over the entire energy range end up very close to the axis of the straight. We discuss how the realization of this lattice design with physical magnets impacts the design process.
 
slides icon Slides TUIDCC004 [1.868 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2017-TUIDCC004  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUIDCC005
ERL Recirculation Optics for MESA  
 
  • F. Hug
    IKP, Mainz, Germany
 
  Funding: Work supported by DFG through the PRISMA cluster of excellence EXC 1098/2014 and RTG 2128 and by the European Union's Horizon 2020 Research and Innovation programme under Grant Agreement No 730871.
MESA is a recirculating superconducting accelerator under construction at Johannes Gutenberg-Universität Mainz. It will be used for high precision particle physics experiments in two different operation modes: external beam (EB) mode and energy recovery (ERL) mode. The operating beam current and energy in EB mode is 0.15 mA with polarized electrons at 155 MeV. In ERL mode a beam of 1 mA at 105 MeV will be available. In a later construction stage of MESA the beam current in ERL-mode shall be upgraded to 10 mA. The recirculating main linac follows the concept of a double sided accelerator design with vertical stacking of return arcs. Acceleration is done by in total four TESLA/XFEL 9-cell SRF-cavities mounted in two modified ELBE cryomodules. Within this contribution the recirculation optics for MESA will be presented focussing on achieving best energy spread at the experimental setups in recirculation ERL and non-ERL operation.
 
slides icon Slides TUIDCC005 [29.931 MB]  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEIBCC001
Beam Dynamics Issues for Multi-Pass ERLs  
 
  • G.H. Hoffstaetter
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Several labs have proposed multi-turn ERLs as electron-drivers for major experiments. The beam dynamics of the 4-turn ERL CBETA will be studied in detail to understand the beam-dynamic issues for these electron drivers. These issues include: (a) current limits by the recirculative beam-breakup instability(BBU) and its control by HOM damping, optics adjustments, and optical coupling, (b) ions attracted to the electron beam and their control by clearing electrodes, current modulations, and beam shaking, (c) loss mechanism including Touschek scattering, gas scattering, field emission, ghost pules, and spurious emotions from the cathode, (d) high-chromaticity operation, orbit and optics controls of superimposed beams, coherent synchrotron radiation, micro-bunching, and longitudinal space charge, and (e) low energies space charge and emittance control  
slides icon Slides WEIBCC001 [21.645 MB]  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEIBCC002
LHeC ERL - Beam Dynamics Challenges  
 
  • D. Pellegrini
    CERN, Geneva, Switzerland
 
  The LHeC is envisioned as a natural upgrade of the LHC that aims at delivering an electron beam for collisions with the existing hadronic beams. The current baseline design for the electron facility consists of a multipass superconducting energy-recovery linac (ERL) operating in a continuous wave mode and delivering a beam current up to 25 mA at the energy of 60 GeV. This contribution aims at briefly reviewing the beam dynamics aspects motivating the existing design choices. Emphasis will be put in the open issues with their potential synergies with other projects.  
slides icon Slides WEIBCC002 [2.739 MB]  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEIBCC003
Beam Dynamics and Optics Challenges of BERLinPro  
 
  • M. Abo-Bakr
    HZB, Berlin, Germany
 
  Funding: Work supported by the German Bundesministerium für Bildung und Forschung, Land Berlin and grants of Helmholtz Association
The Helmholtz-Zentrum Berlin is constructing the Energy Recovery Linac Prototype BERLinPro, a demonstration facility for the science and technology of ERLs for future light source applications. BERLinPro is designed to accelerate a high current (100 mA, 50 MeV), high brilliance (norm. emittance below 1 mm mrad) cw electron beam. Various aspects and challenges of beam dynamics and optics in an ERL will be introduced and their relevance and influence on the beam optics layout of BERLinPro discussed. Beside storage ring known requirements emphasis is put to ERL specific problems. Especially collective effects due to space charge and high current are considered.
 
slides icon Slides WEIBCC003 [13.040 MB]  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEIBCC004 Studies of CSR and Microbunching at the Jefferson Laboratory ERLs 59
 
  • C. Tennant, S.V. Benson, D. Douglas, R. Li
    JLab, Newport News, Virginia, USA
  • C.-Y. Tsai
    SLAC, Menlo Park, California, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
One attractive feature of energy recovery linacs (ERLs) is they are source limited. However as beam brightness increases so too do the effects of coherent synchrotron radiation (CSR) and the microbunching instability. The Low Energy Recirculator Facility at Jefferson Laboratory provides a test bed to characterize aspects of CSR's effect on the beam by measuring the energy extraction via CSR as a function of bunch compression. Data was recorded with acceleration occuring on the rising part of the RF waveform while the full compression point was moved along the backleg of the machine and the response of the beam measured. Acceleration was moved to the falling part of the RF waveform and the experiment repeated. Initial start-to-end simulations using a 1D CSR model show good agreement with measurements. The experiment motivated the design of a modified Continuous Electron Beam Accelerator Facility style arc with control of CSR and the microbunching gain. Insights gained from that study informed designs for recirculation arcs in an ERL-driven electron cooler for Jefferson Laboratory's Electron Ion Collider. Progress on the design and outstanding challenges of the cooler are discussed.
 
slides icon Slides WEIBCC004 [14.419 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2017-WEIBCC004  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THIACC001
Higher Bunch Charge Operation in Compact ERL at KEK  
 
  • T. Miyajima
    KEK, Ibaraki, Japan
 
  Abstract not submitted at print time.  
slides icon Slides THIACC001 [5.164 MB]  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THIACC002
Dark Current and Halo Tracking in ERLs  
 
  • M. McAteer
    HZB, Berlin, Germany
 
  Funding: Work supported by the German Bundesministerium für Bildung und Forschung, Land Berlin and grants of Helmholtz Association
Particles that are far from the core of a bunch are often lost in an uncontrolled way within an accelerator, and in high-current machines beam loss can quickly damage accelerator components or cause significant residual activation. We give a brief overview of the common sources of unwanted beam, including halo generated by nonlinear dynamics, dark current from field emission in the cavities, out-of-time scattered laser light on the cathode, and incompletely blocked laser pulses. The results of tracking simulations to model these effects in BERLinPro are discussed.
 
slides icon Slides THIACC002 [3.935 MB]  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THIACC003
Low Emittance Optimization and Operation  
 
  • P.H. Williams
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
 
  Abstract not submitted at print time.  
slides icon Slides THIACC003 [3.837 MB]  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THICCC001
Beam Halo Study at the KEK Compact ERL  
 
  • O. Tanaka, T. Miyajima, N. Nakamura, M. Shimada
    KEK, Ibaraki, Japan
  • T. Hotei
    Sokendai, Ibaraki, Japan
  • K. Osaki
    Toshiba, Tokyo, Japan
 
  Funding: Work supported by the Grant-in-Aid for Creative Scientific Research of JSPS (KAKENHI 15K04747).
The beam halo control is of a great importance to attain high intensity beams. Thus, its detailed treatment is indispensable for the stable and safe operation. A systematic beam halo study was established at the KEK Compact ERL (cERL) since machine commissioning in spring 2015 in order to understand the beam halo formation and to have the stable and safe operation. The results of halo simulations have given a reasonable explanation of the low bunch charge (0.2-0.3 pC) beam profiles evaluated during the measurement. Thus, vertical beam halos observed at cERL are supposed to be due to the longitudinal bunch tails transferred into the transverse plane. Tails are mainly produced by the cathode response on the laser excitation. Further, when a beam passing the rf cavity off-center it experiences rf field kicks. The beam tilt could be a complex effect of the steering coils and cavities misalignments. During spring 2017 commissioning the bunch charge was increased up to 40 pC. In present study we are challenging to describe how the space charge effect acts on the beam halo profiles, and how the halo formation mechanisms change in this connection.
 
slides icon Slides THICCC001 [3.154 MB]  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THICCC002 Study of Microbunching Instability in MESA 74
MOPSPP001   use link to see paper's listing under its alternate paper code  
 
  • A. Khan, O. Boine-Frankenheim
    Institut Theorie Elektromagnetischer Felder, TU Darmstadt, Darmstadt, Germany
  • K. Aulenbacher
    IKP, Mainz, Germany
 
  Funding: Supported by the DFG through GRK 2128
The Institute for Nuclear Physics (KPH) at Mainz is building a multi-turn energy recovery linear accelerator, the Mainz Energy-recovering Superconducting Accelerator (MESA), to deliver a CW beam at 105 MeV with short pulses, high current and small emittance for physics experiments with an internal target. Space charge effects potentially cause beam quality degradation for medium energy beams in smaller machines like MESA. As beam quality preservation is a major concern in an ERL during recirculation. We present a study on Microbunching Instability (MBI) caused by Longitudinal Space Charge (LSC) in MESA. Our results demonstrate the impact of the MESA arc lattice design on the development of Microbunching Instability.
 
slides icon Slides THICCC002 [3.365 MB]  
poster icon Poster THICCC002 [1.232 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2017-THICCC002  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
FRIBCC002 ERL17 Workshop, WG2 Summary: Optics, Beam Dynamics and Instrumentation 79
 
  • S.A. Bogacz
    JLab, Newport News, Virginia, USA
  • D. Schulte
    CERN, Geneva, Switzerland
 
  During the workshop a number of interesting projects were discussed: ERL at KEK, ALICE, PERLE, LHeC, eRHIC, CBETA, ERL for MESA and BERLinPro; a nice mixture of future, existing and past facilities. A rather vigorous development of new ERLs is aggressively pushing the limits: maximizing number of passes, maximizing virtual beam power, opening longitudinal acceptance, mitigation of limiting factors: BBU, CSR/microbunching, diagnostics and Instrumentation for multiple beams, multiparticle tracking studies of dark current and halo formation. A bright future can be expected for the field.  
slides icon Slides FRIBCC002 [1.792 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2017-FRIBCC002  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)