Electron Accelerators and Applications
Energy recovery linacs
Paper Title Page
PERLE, a Powerful ERL for Experiments at Orsay  
  • W. Kaabi, I. Chaikovska, A. Stocchi, C. Vallerand
    LAL, Orsay, France
  • D. Angal-Kalinin, J.W. McKenzie, B.L. Militsyn, P.H. Williams
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • G. Arduini, O.S. Brüning, R. Calaga, L. Dassa, F. Gerigk, B.J. Holzer, E. Jensen, A. Milanese, E. Montesinos, D. Pellegrini, D. Schulte, P.A. Thonet, A. Valloni
    CERN, Geneva, Switzerland
  • S.A. Bogacz, D. Douglas, F.E. Hannon, A. Hutton, F. Marhauser, R.A. Rimmer, Y. Roblin, C. Tennant
    JLab, Newport News, Virginia, USA
  • S. Bousson, D. Longuevergne, G. Olivier, G. Olry
    IPN, Orsay, France
  • B. Hounsell, M. Klein, U.K. Klein, P. Kostka, C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  • E.B. Levichev, Yu.A. Pupkov
    BINP SB RAS, Novosibirsk, Russia
  PERLE is a proposed multi-pass Energy Recovery Linac, based on SRF technology, to be built at Orsay, France, in a collaborative effort between local laboratories LAL/IN2P3, IPNO/IN2P3 and international partners such as JLAB, STFC, Liverpool University, BINP and CERN. A part from experimental program, PERLE will serve as testbed to study a broad range of accelerator phenomena and to validate technical choices for the LHeC, which aims at electron proton collisions using the existing LHC machine together with an added electron ERL. In its final configuration, PERLE provides a 500 MeV electron beam using high current (20 mA) acceleration during three passes through 801.6 MHz cavities. This talk outlines the technological choices, the lattice design and describes the potential contributions of the interested partners.  
slides icon Slides WE1A01 [3.525 MB]  
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CBETA, a 4-turn ERL Based on SRF Linacs and Permanent Magnet Beam Transport  
  • G.H. Hoffstaetter, N. Banerjee, J. Barley, A.C. Bartnik, I.V. Bazarov, D.C. Burke, J.A. Crittenden, L. Cultrera, J. Dobbins, F. Furuta, R.E. Gallagher, M. Ge, C.M. Gulliford, B.K. Heltsley, R.P.K. Kaplan, V.O. Kostroun, Y. Li, M. Liepe, W. Lou, J.R. Patterson, P. Quigley, D.M. Sabol, D. Sagan, J. Sears, C.H. Shore, E.N. Smith, K.W. Smolenski, V. Veshcherevich, D. Widger
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • J.S. Berg, S.J. Brooks, C. Liu, G.J. Mahler, F. Méot, R.J. Michnoff, M.G. Minty, S. Peggs, V. Ptitsyn, T. Roser, P. Thieberger, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, F.J. Willeke, H. Witte
    BNL, Upton, Long Island, New York, USA
  • D. Jusic
    Cornell University, Ithaca, New York, USA
  A collaboration between Cornell University and Brookhaven National Laboratory has designed a novel accelerator and is constructing it at Cornell: CBETA, the Cornell-BNL ERL Test Accelerator. The ERL technology that has been prototyped at Cornell for many years is being used, including a DC electron source and an SRF injector Linac with world-record current and normalized brightness in a bunch train, a high-current linac cryomodule optimized for ERLs, a high-power beam stop, and several diagnostics tools for high-current and high-brightness beams. BNL has designed a multi-turn ERL and a recirculating linac for eRHIC; in both designs the beam is transported many times around the 4 km long RHIC tunnel. The number of transport lines is minimized by using two arcs with Fixed Field Alternating Gradient design. This technique will be tested in CBETA, which has a single return for the 4-beam energies with strongly-focusing permanent magnets of Halbach type. The high-brightness beam with 150 MeV and up to 40 mA will have applications for Electron Ion Colliders (EICs), e.g. for their electron cooling, and for applications in industry, in nuclear physics, and in X-ray science.  
slides icon Slides WE1A02 [6.367 MB]  
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THPO006 Status of 650 MHz SRF Cavity for eRHIC SRF Linac 688
  • W. Xu, I. Ben-Zvi, Y. Gao, D. Holmes, P. Kolb, G.T. McIntyre, R. Porqueddu, K.S. Smith, F.J. Willeke, Q. Wu, A. Zaltsman
    BNL, Upton, Long Island, New York, USA
  Funding: This work is supported by LDRD program of Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE.
A 5-cell 650 MHz SRF cavity was designed for eRHIC SRF linac. One Cu cavity was fabricated for HOM damping study, and one Nb cavity was fabricated for SRF studies. Through various post-processing recipes and vertical tests, the SRF study includes high Q-value study for ERL SRF linac and high gradient study for recirculating linac. This paper reports the HOM damping measurement on the Cu cavity and preliminary vertical test results.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO006  
About • paper received ※ 22 August 2018      issue date ※ 18 January 2019  
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THPO007 MESA - Status of the Implementation of the MicroTCA.4-based LLRF Control System 691
  • J.N. Bai, K. Aulenbacher, J. Diefenbach, F. Fichtner
    IKP, Mainz, Germany
  • P. Echevarria
    HZB, Berlin, Germany
  • R.G. Heine
    KPH, Mainz, Germany
  MESA at the Institut für Kernphysik (KPH) at Johannes Gutenberg-Universität Mainz is a multi-turn energy recovery linac (ERL), aiming to serve as user facility for particle physics experiments. The RF-accelerating systems of MESA consist of four 9-cell TESLA superconducting cavities, four normal conducting (NC) pre-accelerator cavities, two NC buncher cavities and two NC chopper cavities. They operate in continuous wave (CW) mode. In order to control the radio frequency (RF) amplitude and phase within the 12 cavities with the required accuracy and stability in the range of better than 0.01% and 0.01°, the MicroTCA.4 based digital low-level RF (LLRF) control system based on the development at DESY, Hamburg will be well adapted for the MESA cavities. In this paper, we describe the theoretical modelling of superconducting cavity and PID controller in SIMULINK which is useful to find the suitable control parameter for the PID controller and to predict the system performance. The progress to date of the implementation and tests of the LLRF system at MESA will also be presented.  
poster icon Poster THPO007 [1.274 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO007  
About • paper received ※ 11 September 2018      issue date ※ 18 January 2019  
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THPO008 Long-term 0peration with Beam and Cavity Performance Degradation in Compact-ERL Main Linac at KEK 695
  • H. Sakai, T. Furuya, E. Kako, T. Konomi, T. Miura, F. Qiu, K. Umemori
    KEK, Ibaraki, Japan
  We developed ERL main linac cryomodule for Compact ERL (cERL) in KEK. The module consists of two 9-cell 1.3 GHz superconducting cavities. After construction of cERL recirculation loop, beam operation was started in 2013 Dec. First electron beam of 20 MeV successfully passed the main linac cavities. Beam current increased step by step and currently reached to 1mA (CW). Energy recovery has successfully achieved. However, field emission was one of the problems for long term operation. Therefore, the performance of the SRF cavities through long term beam operation has been investigated. In this paper, we express the measurement of the cavity performances and its degradation during long term beam operation. We also described the details of the cavity performance degradation and some trial for the cavity performance recovery.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO008  
About • paper received ※ 11 September 2018      issue date ※ 18 January 2019  
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THPO009 Evaluation of 60pC Beam Performance at cERL Injector for ERL Based EUV-FEL 699
SPWR001   use link to see paper's listing under its alternate paper code  
  • T. Hotei
    Sokendai, Ibaraki, Japan
  • R. Kato, T. Miyajima
    KEK, Ibaraki, Japan
  In order to compensate for the emittance which is increased by space charge in the low energy region, it is important to transport the beam as designed. Until now, we did not consider couplers in injector superdonducting cavities in optics design. But in this study, to improve optics matching and emittance compensation conditions for space charge dominated beam in cERL at KEK, we introduced a new 3D cavity model. We first investigated the influence of the couplers on electromagnetic field distribution. As a result, it was found that an asymmetric focusing force is generated by the influence of the couplers. It also became clear that the influence of the coupler kick on the optics significantly devastated the emittance compensation condition from the calculating including space charge. Furthermore, it was found that by optimizing the optics in consideration of the coupler kick, it is possible to improve the beam control accuracy and reduce the emittance in beam commissioning.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO009  
About • paper received ※ 12 September 2018      issue date ※ 18 January 2019  
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THPO010 Novel Straight Merger for Energy Recovery Linacs 702
  • K.E. Deitrick, A. Hutton
    JLab, Newport News, Virginia, USA
  • A.C. Bartnik, C.M. Gulliford
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • S.A. Overstreet
    ODU, Norfolk, Virginia, USA
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
One of the most critical design considerations for an energy recovery linac (ERL) is how to merge the injected bunch onto the linac axis with minimal beam degradation. All merger designs in established and upcoming machines involve significant bending of the injected beam ’ even using a so-called straight merger bends the injected beam several degrees. We propose a merger which reduces the bending of the injected beam by an order of magnitude. By passing both beams through a septum magnet followed by an rf separator cavity with a superimposed dipole magnetic field, the injected beam bends minimally within the cavity, while the recirculated beam bends to align with the linac axis. Here we describe the concept in detail and present simulation results to demonstrate the advantages of such a design, particularly for magnetized beams or minimal energy separation between the injected and recirculated beams. Measurements from an experiment at CBETA evaluating the beam dynamics of the rf separator are presented and compared with simulation results.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO010  
About • paper received ※ 12 September 2018      issue date ※ 18 January 2019  
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THPO011 First Energy Recovery Operation at the S-DALINAC: RF Control Stability Measurements 706
  • M. Steinhorst, M. Arnold, N. Pietralla
    TU Darmstadt, Darmstadt, Germany
  • C. Burandt
    HIM, Mainz, Germany
  Funding: *Supported by the DFG through GRK 2128.
One of the main research instruments at the institute for nuclear physics at the TU Darmstadt is the recirculating superconducting linear accelerator S‑DALINAC. Many improvements were implemented since the first recirculated beam in 1991. One of the major enhancement is the upgrade from a twice to a thrice recirculating scheme in 2015/2016. With this upgrade the operation mode can be changed between a conventional accelerating operation and energy recovery linac (ERL) mode by an 180° rf phaseshift of the beam done via a path length variation of the arcs in the second recirculation. ERL operation was not possible when the rf control system for the superconducting structures was set up in 2010. Therefore the current rf control system is not optimized for this kind of operation and so it had to be tested during ERL operation in order to also demonstrate its capability of this operation mode. In August 2017 a first once recirculating ERL operation was achieved. During this operation measurements regarding the rf control stability and the demand of rf power were done. This contribution is discussing this measurements and possible improvements for future energy recovery beam times.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO011  
About • paper received ※ 12 September 2018      issue date ※ 18 January 2019  
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THPO012 Once Recirculating Energy Recovery Linac Operation of S-DALINAC* 710
  • M. Arnold, J. Birkhan, J. Pforr, N. Pietralla, F. Schließmann, M. Steinhorst
    TU Darmstadt, Darmstadt, Germany
  • F. Hug
    KPH, Mainz, Germany
  Funding: *Work supported by DFG through GRK 2128 and INST163/383-1/FUGG
Since 1991 the superconducting S-DALINAC is running in recirculating operation. It was built in a twice recirculating layout. A third recirculation beam line was added in 2015/2016 as an upgrade. The new recirculation beam line is installed in-between the two existing beam lines. It houses a path length adjustment system capable of changing the length of the orbit for recirculation by up to 10 cm corresponding to the RF wave length at the operation frequency of 3 GHz and consequently to a freedom of RF phase adjustment by 360°. The new beam line can, thus, be utilized for an accelerating operation or, if the change in phase is set to 180°, for an energy recovery linac (ERL) operation. In August 2017 the S-DALINAC was first operated in once recirculating ERL mode and became the first running ERL in Germany. Different aspects of this ERL run have been observed and were evaluated. The layout of the S-DALINAC allows a once or twice recirculating ERL mode. Beam dynamics simulations for both modes have been conducted or are currently under investigation. This contribution will discuss the once recirculating ERL operation, its results, and future plans concerning ERL measurements.
poster icon Poster THPO012 [0.708 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO012  
About • paper received ※ 12 September 2018      issue date ※ 18 January 2019  
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