Keyword: simulation
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MO3A02 Achievement of Small Beam Size at ATF2 Beamline optics, sextupole, wakefield, laser 27
 
  • T. Okugi
    KEK, Ibaraki, Japan
  
  The beam commissioning of the ATF2 facility at KEK - a 1.3 GeV prototype of the compact local chromaticity correction final focus system for the linear collider - achieved 44nm beam size, very close to ideal expected size of 37nm, by developing various knobs and improving the performances of the interferometric Shintake monitor at the same time. These results have opened the way to reliable and predictable operation of the linear collider.  
slides icon Slides MO3A02 [3.495 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MO3A02  
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MOOP12 Klynac Design Simulations and Experimental Setup cavity, linac, electron, klystron 68
 
  • K.E. Nichols, B.E. Carlsten, A. Malyzhenkov
    LANL, Los Alamos, New Mexico, USA
  
  Funding: The authors gratefully acknowledge the support of the US Department of Energy through the LANL/LDRD Program for this work.
We present results of a proof-of-principle demonstration of the first ever klynac, a compact 1 MeV linear accelerator with integrated klystron source using one electron beam. This device is bi-resonant, utilizing one resonant circuit for the klystron input and gain cavities, and one for the klystron output and linac cavities. The purpose of a klynac-type device is to provide a compact and inexpensive alternative for a conventional 1 to 6 MeV accelerator. A conventional accelerator requires a separate RF source and linac and all the associated hardware needed for that architecture. The klynac configuration eliminates many of the components to reduce the weight of the entire system by 60%. We have built an 8-cavity, 2.84-GHz RF structure for a 1-MeV bi-resonant klynac. A 50-kV, 10-A electron gun provides the single beam needed. Numerical modeling was used to optimize the design. The separation between the klynac ouput cavity and the first accelerator cavity was adjusted to optimize the bunch capture and a pin-hole aperture between the two cavities reduces the beam current in the linac section to about 0.1 A. Standard high-shunt impedance linac cavities designs are used. We have fabricated the first test structure. The structure will be tested with beam in early Summer 2016. Results will be presented at LINAC 2016. 		 
slides icon Slides MOOP12 [1.136 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOOP12  
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MOPRC004 Beam Orbit Analysis and Correction of the FRIB Superconducting Linac linac, quadrupole, operation, injection 71
 
  • Y. Zhang, Z.Q. He
    FRIB, East Lansing, USA
  
  Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661
Beam based alignment (BBA) techniques are important tools for precise beam orbit correction of a high power linac, and supplement to the model based or orbit response matrix (ORM) based correction methods. BBA will be applied to beam orbit analysis and correction of the FRIB linac arcs where a beam orbit offset within 0.1 mm is required to the second order achromatic beam tuning. In this paper, we first introduce the study of model based beam orbit correction of the arc, and then a more precise orbit correction with BBA. Realistic misalignment of beam elements and beam position monitors (BPMs) are included in the simulation studies. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPRC004  
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MOPRC005 Beam Tuning of Achromatic Bending Areas of the FRIB Superconducting Linac linac, sextupole, quadrupole, lattice 74
 
  • Y. Zhang, C.P. Chu
    FRIB, East Lansing, USA
  
  Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661
To achieve the design beam power for heaviest ion species, acceleration and transport of multi charge state beams simultaneously in the FRIB superconducting linac becomes necessary, which poses a technical challenge especially to the FRIB folded lattice design. Achromatic and isochronous beam optics up to the second order must be established precisely in the linac bending areas, and as none-perfection beam elements and system errors exist in the real machine, beam tuning and beam optics corrections of the bending area are important to high power operation. In this paper, we introduce the beam tuning algorithms of the FRIB linac achromatic arcs and also discuss the simulation studies. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPRC005  
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MOPRC006 Beam Tuning and Error Analysis of a Superconducting Linac linac, cavity, quadrupole, lattice 77
 
  • Y. Zhang
    FRIB, East Lansing, USA
  
  Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661
Beam tuning and error analysis of a superconducting linac for heavy ion beams are introduced in this paper. In simulation studies with accelerator codes, system errors to the beam tuning are analyzed numerically, which include random cavity and magnet errors and measurement errors of absolute beam phase, beam bunch length, and beam transverse profiles. Simple statistical equations are developed from the tedious and time-consuming numerical simulations, and they may provide advantage tools not only to analyze a linac beam tuning, such as phase and amplitude tuning of superconducting cavity, longitudinal and transverse beam matching, but also will be very helpful to linac design with practical beam diagnostics system and authentic accelerator lattice. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPRC006  
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MOPRC009 Simulating Apertures in the Uniform Equivalent Beam Model quadrupole, optics, space-charge, software 87
 
  • G.H. Gillespie
    G.H. Gillespie Associates, Inc., Del Mar, California, USA
  
  The uniform equivalent beam model is useful for simulating particle beam envelopes. Beam root-mean-square (rms) sizes, divergences, and emittances of an equivalent uniform beam approximate well the rms properties of more realistic beam distributions, even in the presence of space charge. Envelope simulation codes for high current beams using the model, such as TRACE 3-D, are central to particle optics design. However, the modeling of apertures has required multi-particle simulation codes. Multi-particle codes do not typically have the fitting and optimization capabilities common to envelope codes, so the evaluation of aperture effects is often a secondary study that may result in further design iteration. To incorporate aperture effects into the optics design at the start, a method has been developed for simulating apertures in the context of a uniform equivalent beam. The method is described and its TRACE 3-D implementation is outlined. Comparisons with multi-particle simulations are used to validate the method and examine regions of applicability.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPRC009  
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MOPRC011 FRIB Lattice-Model Service for Commissioning and Operation lattice, operation, database, software 90
 
  • D.G. Maxwell, Z.Q. He, G. Shen
    FRIB, East Lansing, USA
  
  Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DESC0000661, the State of Michigan and Michigan State University.
Accelerator beam simulation is crucial for the successful commissioning and operation of the FRIB linear accelerator. A primary requirement of the FRIB linear accelerator is to support a broad range of particle species and change states. Beam simulations must be performed for these various accelerator configurations and it is important the results be managed to ensure consistency and reproducibility. The FRIB Lattice-Model Service has been developed to manage simulation data using a convenient web-based interface, as well as, a RESTful API to allow integration with other services. This service provides a central location to store and organize simulation data. Additional features include search, comparison and visualization. The system architecture, data model and key features are discussed. 		 
poster icon Poster MOPRC011 [1.295 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPRC011  
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MOPRC014 Beam Dynamics Simulations of a High Charge S-Band Photoinjector for Electron Beam Imaging Experiments gun, solenoid, electron, booster 97
 
  • Y.R. Wang
    AAI/ANL, Argonne, Illinois, USA
  • S. Cao, Z.M. Zhang
    IMP/CAS, Lanzhou, People's Republic of China
  • W. Gai
    ANL, Argonne, Illinois, USA
  • J.Q. Qiu
    Euclid TechLabs, LLC, Solon, Ohio, USA
  
  A major challenge for high energy density physics is to measure properties of matter under extreme states of temperature and pressure that only occur in a time scale of 10 ns to 1 μs. Here we propose to use a single shot electron beam from an S-band photoinjector with enough energy to penetrate the material as a diagnostic capable of time resolution (< ns). In this paper, we report on the primary beam dynamics simulation of a S-band photocathode electron gun and accelerator that capable of producing up to 10 nC charge with high enough energy. Optimizations of the system parameters, including gun, focusing solenoid and acceleration field are performed using particle tracking code. The beam-line is designed to be installed in the Institute of Modern Physics(IMP) electron accelerator centre for high precision electron imaging experimental studies.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPRC014  
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MOPRC016 RF-Track: Beam Tracking in Field Maps Including Space-Charge Effects, Features and Benchmarks space-charge, linac, ion, rfq 104
 
  • A. Latina
    CERN, Geneva, Switzerland
  
  RF-Track is a novel tracking code developed at CERN for the optimization of low-energy ion linacs in presence of space-charge effects. RF-Track features great flexibility and rapid simulation speed. It can transport beams of particles with arbitrary mass and charge even mixed together, solving fully relativistic equations of motion. It implements direct space-charge effects in a physically consistent manner, using parallel algorithms. It can simulate bunched beams as well as continuous ones, and transport through conventional elements as well as through maps of oscillating radio-frequency fields. RF-Track is written in optimized and parallel C++, and it uses the scripting languages Octave and Python as user interfaces. RF-Track has been tested successfully in several cases. The main features of the code and the results of its benchmark studies are presented in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPRC016  
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MOPRC019 Beam Dynamic of Transport Line 1+ with New HRMS for the SPES Project dipole, ion, beam-transport, beam-losses 114
 
  • E. Khabibullina
    MEPhI, Moscow, Russia
  • L. Bellan, M. Comunian, A. Pisent
    INFN/LNL, Legnaro (PD), Italy
  • E. Khabibullina
    ITEP, Moscow, Russia
  • A.D. Russo
    INFN/LNS, Catania, Italy
  
  SPES (Selective Production of Exotic Species) is integrated Italian facility in LNL (Laboratori Nazionali di Legnaro, Legnaro, Italy) for production of high-intensity and highly charged beams of neutron-rich nuclei for Advanced Studies. The facility is based on 35-70MeV proton cyclotron, an ISOL fission target station and the existing ALPI superconducting accelerator as the post accelerator. In this paper the results of beam dynamic simulation of 132Sn ion beam transport line from Beam Cooler to the Charge Breeder, including HRMS (High Resolution Mass Separator) with mass resolution 1/20000 and electrostatic dipoles are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPRC019  
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MOPRC020 Primary Beam Dynamic Simulation of Double Drift Double Buncher System for SPES Project rfq, solenoid, ion, focusing 117
 
  • A.V. Ziiatdinova
    MEPhI, Moscow, Russia
  • L. Bellan, M. Comunian, A. Pisent
    INFN/LNL, Legnaro (PD), Italy
  • A.V. Ziiatdinova
    ITEP, Moscow, Russia
  
  SPES (Selective Production of Exotic Species) is a facility intended for production of neutron-rich Radioactive Ion Beams (RIBs) at the National Institute of Nuclear Physics (INFN-LNL, Legnaro, Italy). Exotic nuclei production based on the ISOL (Isotope Separation On-Line) technology using UCx target. Neutron-rich nuclei will be generated by uranium fission under the influence of proton beam from cyclotron. After that, RIBs will be reaccelerated by the ALPI (Acceleratore Lineare Per Ioni). RFQ (Radio Frequency Quadrupole) will be used as a front-end part of the ALPI. Double drift double buncher system is planned to install before RFQ for increasing transmission. This article is dedicated to beam dynamic simulation and laying-out of transport line at section before ALPI.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPRC020  
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MOPRC023 Semi-3D Beam-Tracking Code for Electron Injectors Using Bulk-to-Point Calculation Technique for Space Charge Fields emittance, space-charge, electron, gun 120
 
  • A. Mizuno, H. Hanaki
    JASRI/SPring-8, Hyogo-ken, Japan
  
  A new semi-three-dimensional beam-tracking simulation code for electron injectors using bulk-to-point calculation technique for space charge fields is developed. The calculated space charge fields are not produced by a point charge but a doughnut which has the volume and whose cross-section is ellipsoid. Since the calculation noise which is usually caused by distributions of positions of point charge can be minimized, high accuracy calculation on emittance is realized with small number of electrons. Simultaneously, the calculation time becomes markedly shortened. In this paper, calculation examples for asymmetrical beams are demonstrated by the new code. The accuracy of emittance is also discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPRC023  
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MOPRC025 Final Design of the Fully Equipped HWR Cavities for SARAF cavity, cryomodule, linac, multipactoring 123
 
  • G. Ferrand
    CEA/DSM/IRFU, France
  • L. Boudjaoui, P. Hardy, F. Leseigneur, C. Madec, N. Misiara, N. Pichoff
    CEA/IRFU, Gif-sur-Yvette, France
  
  SNRC and CEA collaborate to the upgrade of the SARAF accelerator to 5 mA CW 40 MeV deuteron and proton beams (Phase 2). CEA is in charge of the design, construction and commissioning of the superconducting linac (SARAF-LINAC Project). The SCL is made up of 4 cryomodules: the first two will host each 6 half-wave resonator (HWR) low beta cavities (β = 0.09) at 176 MHz; the last two will host each 7 HWR high-beta cavities (β = 0.18) at 176 MHz. The fully equipped cavity includes the niobium cavity with a helium tank, an input power couplers and a frequency tuning system. The final RF design of the low and high beta cavities will be presented in this poster, as well as the RF design of the couplers, the expected tuning range of the cavities and the multipactor analysis.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPRC025  
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MOPRC026 Mechanical Design of the HWR Cavities for the SARAF SRF LINAC cavity, linac, cryomodule, SRF 126
 
  • N. Misiara, L. Boudjaoui, G. Ferrand, P. Hardy, F. Leseigneur, C. Madec, N. Pichoff
    CEA/IRFU, Gif-sur-Yvette, France
  
  SNRC and CEA collaborate to the upgrade of the SARAF accelerator to 5 mA CW 40 MeV deuteron and proton beams (Phase 2). CEA is in charge of the design, construction and commissioning of the superconducting linac (SARAF-LINAC Project). The SCL consists in 4 cryomodules. The first two identical cryomodules host 6 half-wave resonator (HWR) low beta cavities (β = 0.09) at 176 MHz. The last two identical cryomodules will host 7 HWR high-beta cavities (β = 0.18) at 176 MHz. The fully equipped cavity includes the niobium cavity with its helium tank, the couplers and the frequency tuning system. In this paper, the mechanical design and the foreseen qualification procedures for both cavities and tuning systems are presented with compliance, to the best extent, to the rules of Unfired Pressure Vessels NF-EN 13445 (1-5) standards.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPRC026  
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MOPLR013 Investigations on Electron Beam Imperfections at PITZ electron, laser, solenoid, gun 165
 
  • M. Krasilnikov, P. Boonpornprasert, J.D. Good, M. Groß, H. Huck, I.I. Isaev, D.K. Kalantaryan, O. Lishilin, G. Loisch, D. Melkumyan, A. Oppelt, G. Pathak, Y. Renier, T. Rublack, F. Stephan, G. Vashchenko, Q.T. Zhao
    DESY Zeuthen, Zeuthen, Germany
  • G. Asova
    INRNE, Sofia, Bulgaria
  • C. Hernandez-Garcia
    JLab, Newport News, Virginia, USA
  
  Since more than a decade, the photo injector test facility at DESY, Zeuthen site (PITZ), has developed and optimized high brightness electron sources for modern Free Electros Lasers like FLASH and the European XFEL. Despite a very high performance of the photo injector was experimentally demonstrated, several discrepancies between measurements and beam dynamics simulations have been revealed. Although the optimized measured values of the projected transverse emittance are close to those obtained from the beam dynamics simulations, the corresponding experimental machine parameters show certain systematic deviations from the simulated optimized setup. As a source for these deviations, electron beam imperfections were experimentally investigated. This includes studies on bunch charge production, electron beam imaging using the RF gun with its solenoid, and investigations on the transverse asymmetry of the electron beam generated in a rotationally symmetric gun cavity. Experimental studies were supplied with corresponding beam dynamics simulations. The paper reports on results of these studies.  
poster icon Poster MOPLR013 [2.140 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR013  
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MOPLR014 Construction of a Third Recirculation for the S-DALINAC* dipole, linac, recirculation, operation 168
 
  • M. Arnold, T. Kürzeder, J. Pforr, N. Pietralla, M. Steinhorst
    TU Darmstadt, Darmstadt, Germany
  • F. Hug
    IKP, Mainz, Germany
  
  Funding: * Work supported by DFG through CRC 634 and RTG 2128
Since 1991 the superconducting recirculating electron accelerator S-DALINAC is running at TU Darmstadt. Its designated design energy of 130 MeV wasn't reached yet due to a lower quality factor of the 3 GHz cavities and thus a higher dissipated power to the helium bath. To increase the maximum achievable energy in cw operation from approx. 85 MeV to the design value of 130 MeV the main accelerator will be passed a fourth time. In this configuration the accelerating gradients of the cavities can be lowered, so that the resulting dissipated power will match the available cooling power of the cryo plant. To realize an additional main linac pass a new recirculation beam line is needed. The most crucial points are the design of the separation dipole and its mirrored version as well as a properly calculated lattice. For the implementation of a new recirculation beam line the existing sections must be adapted to fit the new boundary conditions. This contribution will present some aspects of the design and will report on the actual status of this project. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR014  
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MOPLR015 Thermal-Mechanical Study of 3.9 GHz CW Coupler and Cavity for LCLS-II Project cavity, resonance, cryomodule, linac 171
 
  • I.V. Gonin, E.R. Harms, T.N. Khabiboulline, N. Solyak, V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
  
  Third harmonic system was originally developed by Fermilab for FLASH facility at DESY and then was adopted and modified by INFN for the XFEL project [1-3]. In contrast to XFEL project, all cryomodules in LCLS-II project will operate in CW regime with higher RF average power for 1.3 GHz and 3.9 GHz cavities and couplers. Design of the cavity and fundamental power coupler has been modified to satisfy LCLS-II requirements. In this paper we discuss the results of COMSOL thermal and mechanical analysis of the 3.9 GHz coupler and cavity to verify proposed modifica-tion of the design. For the dressed cavity we present simulations of Lorentz force detuning, helium pressure sensitivity df/dP and major mechanical resonances.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR015  
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MOPLR032 Preparation for Cavity Material Studies at the Vertical High-Temperature UHV-Furnace of the S-DALINAC vacuum, niobium, SRF, superconductivity 209
 
  • R. Grewe, L. Alff, J. Conrad, T. Kürzeder, M. Major, N. Pietralla
    TU Darmstadt, Darmstadt, Germany
  • F. Hug
    IKP, Mainz, Germany
  
  Funding: Work supported by the Federal Ministry of Education and Research through grant No. 05H15RDRBA.
Since 2005 the Institute for Nuclear Physics at the Technische Universität Darmstadt operates a high temperature vacuum furnace. It is designed to reach temperatures of up to 1800°C. It has been used for baking out several niobium superconducting RF cavities at 850°C with proven success*. Current research for improving the performance of SRF cavities is focused on nitrogen treatment of such cavities. Nitrogen doping of SRF cavtities results in an up to four times higher quality-factor as compared to untreated cavities**. At higher temperatures between 1300°C and 1700°C the so-called delta-phase of NbN forms, which is highly interesting for applications to superconducting accelerator technology***. The UHV-furnace at the S-DALINAC offers the possibility to treat niobium samples at considerably higher temperatures than what has been done up to now in order to study the effect of delta-phase NbN and N-doping on superconducting properties. The furnace has been refurbished and recommissioned to realize research on nitrogen treatment of niobium samples. We will report on our first experiences with operating the upgraded furnace.
*Araz et al., Proceedings of SRF05, 2015
**Grasselino et al., Superconducting Science and Technology, 2013
***Pham Tu et al., Proceedings of SRF87, 1987 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR032  
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MOPLR069 Implication of Manufacturing Errors on the Layout of Stabilization System and on the Field Quality in a Drift Tube Linac - RF DTL Error Study DTL, linac, emittance, drift-tube-linac 290
 
  • R. De Prisco, A.R. Karlsson
    Lund University, Lund, Sweden
  • M. Eshraqi, Y.I. Levinsen, R. Miyamoto
    ESS, Lund, Sweden
  
  The field flatness and the layout of the stabilization system in a drift tube linac are strongly dependent on the manufacturing errors that affect the local resonant frequency. In this paper a methodology is presented to study, firstly, the sensitivity of the resonant frequency and of the field flatness to each geometrical parameter of the drift tubes; then a set of tolerances for each parameter is found and a stabilization system layout is defined in order to keep the field flatness within an acceptable limit.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR069  
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MOPLR070 Integration of Interfaces and Stabilization System in the Design of a Drift Tube Linac DTL, vacuum, interface, linac 294
 
  • R. De Prisco, A.R. Karlsson
    Lund University, Lund, Sweden
  • M. Eshraqi, Y.I. Levinsen, R. Miyamoto
    ESS, Lund, Sweden
  
  Making an accurate RF design of any accelerating structure is fundamental to ensure that electromagnetic and beam dynamics requirements will be achieved. This is essential for the most complicated accelerating structures like the drift tube linac: in this case a meticulous design facilitates the RF commissioning too. In this paper the influence of the interfaces and of the field stabilization system on the RF design is analyzed and an advanced design methodology to mitigate field degradation is presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR070  
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MOP106001 Energy Stability of ERLs and Recirculating Linacs linac, recirculation, cavity, operation 304
 
  • R.G. Eichhorn, J. Hoke, Z. Mayle
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Energy recovery linacs can be seen as a hybrid between a linear and a circular accelerator. It has been shown in the past that an appropriate choice of the longitudinal working point can significantly improve the energy stability of a recirculating linac. In this contribution we will expand the concept of energy recovery linacs and investigate the energy spread of the beam as well as the recovery efficiency stability which can be a more demanding quantity in a high current ERL.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOP106001  
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MOP106006 Electro-Mechanical Modeling of the LCLS-II Superconducting Cavities cavity, damping, vacuum, linac 310
 
  • O. Kononenko, C. Adolphsen, Z. Li, T.O. Raubenheimer, C.H. Rivetta
    SLAC, Menlo Park, California, USA
  
  Funding: Work supported by the Department of Energy, Office of Science, Office of Basic Energy Science, under Contract No. DEAC0276SF00515
The 4 GeV LCLS-II superconducting linac will contain 280, 1.3 GHz TESLA-style cavities operated CW at 16 MV/m. Because of the low beam current, the cavity bandwidth will be fairly small, about 32 Hz, which makes the field stability sensitive to detuning from external vibrations and He pressure fluctuations. Piezo-electric actuators will be used to compensate for the detuning, which historically has been difficult at frequencies above a few Hz due to excitation of cavity mechanical resonances. To understand this interaction better, we have been doing extensive modeling of the cavities including mapping out the mechanical modes and computing their coupling to pressure changes, Lorentz forces and piezo actuator motion. One goal is to reproduce the measured detuning response of the piezo actuators up to 1 kHz, which is sensitive to how the cavities are constrained within a cryomodule. In this paper, we summarize these results and their implications for suppressing higher frequency detuning. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOP106006  
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MOP106018 Measurement of the Transverse Beam Dynamics in a TESLA-type Superconducting Cavity cavity, HOM, experiment, alignment 323
 
  • A. Halavanau, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  • N. Eddy, D.R. Edstrom, A. Lunin, P. Piot, J. Ruan, N. Solyak
    Fermilab, Batavia, Illinois, USA
  
  Funding: US Department of Energy (DOE) under contract DE-SC0011831 with Northern Illinois University. Fermilab is operated by the Fermi Research Alliance LLC under US DOE contract DE-AC02-07CH11359.
Superconducting linacs are capable of producing intense, ultra-stable, high-quality electron beams that have widespread applications in Science and Industry. Many project are based on the 1.3-GHz TESLA-type superconducting cavity. In this paper we provide an update on a recent experiment aimed at measuring the transfer matrix of a TESLA cavity at the Fermilab Accelerator Science and Technology (FAST) facility. The results are discussed and compared with analytical and numerical simulations. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOP106018  
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TUOP01 Applying Transverse Gradient Undulators to Suppression of Microbunching Instability electron, linac, laser, FEL 380
 
  • D. Huang, H.X. Deng, C. Feng, D. Gu, Q. Gu, Z.T. Zhao
    SINAP, Shanghai, People's Republic of China
  
  Funding: Major State Basic Research Development Program of China (2011CB808300). National Natural Science Foundation of China (NSFC), grant No. 11275253.
The microbunching instability developed during the beam compression process in the linear accelerator (LIN-AC) of a free-electron laser (FEL) facility has always been a problem that degrades the lasing performance, and even no FEL is able to be produced if the beam quality is destroyed too much by the instability. A common way to suppress the microbunching instability is to introduce extra uncorrelated energy spread by the laser heater that heats the beam through the interaction between the electron and laser beam, as what has been successfully implemented in the Linac Coherent Light Source and Fermi@Elettra. In this paper, a simple and effective scheme is proposed to suppress the microbunching instability by adding two transverse gradient undulators (TGU) before and after the magnetic bunch compressor. The additional uncorrelated energy spread and the density mixing from the transverse spread brought up by the first TGU results in significant suppression of the instability. Meanwhile, the extra slice energy spread and the transverse emittance can also be effectively recovered by the second TGU. The magnitude of the suppression can be easily controlled by varying the strength of the magnetic fields of the TGUs. Theoretical analysis and numerical simulations demonstrate the capability of the proposed technique in the LINAC of an x-ray free-electron laser facility. 		 
slides icon Slides TUOP01 [1.148 MB]  
poster icon Poster TUOP01 [0.447 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUOP01  
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TUPRC002 ESS DTL Beam Dynamics Comparison Between S-Code and T-Code DTL, emittance, software, linac 411
 
  • M. Comunian, L. Bellan, F. Grespan, A. Pisent
    INFN/LNL, Legnaro (PD), Italy
  • L. Bellan
    Univ. degli Studi di Padova, Padova, Italy
  
  The Drift Tube Linac (DTL) of the European Spallation Source (ESS) is designed to operate at 352.2 MHz with a duty cycle of 4% (3 ms pulse length, 14 Hz repetition period) and will accelerate a proton beam of 62.5 mA pulse peak current from 3.62 to 90 MeV. In this paper the DTL beam dynamics comparison between the s-code TraceWin and the t-code Parmela is presented. Full field map of the permanent magnet quadrupoles (with COMSOL) and RF fields of each of the 5 tanks (with MDTFish) were used for the two programs.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPRC002  
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TUPRC003 Effect of Number of Macro Particles on Time Evolution of Phase Space Distribution electron, emittance, linac, operation 414
 
  • T. Miyajima
    KEK, Ibaraki, Japan
  
  Funding: This work was supported by JSPS KAKENHI Grant Number 26600147.
In particle tracking simulation with space charge effect, the macro-particle model, which has same mass-to-charge ratio, is widely used, since it does not require any symmetry of beam shape. However, selection of proper number of macro-particles is important, because the accuracy depends on it. Emittance, which is calculated by phase-space distribution, is especially affected by the number of macro-particles. In order to study the relation between the number of macro-particles and the resolution in the phase space, we defined a transformation, which describes reduction process of macro-particle number, and analyzed static phase space distribution. As a next step, we studied the effect of the macro-particle number on the dynamics of the phase space distribution for 1D charged particle distribution in the rest frame. The numerical result shows that the number of macro-particles affected the phase space distribution around the head and the tail of the bunch.
* T. Miyajima, "Effect of number of macro particles in phase space distribution", in Proc. of IPAC2015, Richmond, VA, USA, pp.242-244 (2015). 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPRC003  
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TUPRC005 Source and LEBT Beam Preparation for IFMIF-EVEDA RFQ rfq, emittance, solenoid, injection 420
 
  • L. Bellan, M. Comunian, E. Fagotti, F. Grespan, A. Pisent
    INFN/LNL, Legnaro (PD), Italy
  • P.-Y. Beauvais, B. Bolzon, N. Chauvin
    CEA/DSM/IRFU, France
  • L. Bellan
    Univ. degli Studi di Padova, Padova, Italy
  • P. Cara
    Fusion for Energy, Garching, Germany
  • H. Dzitko
    F4E, Germany
  • R. Gobin, F. Senée
    CEA/DRF/IRFU, Gif-sur-Yvette, France
  • R. Ichimiya, A. Kasugai, M. Sugimoto
    JAEA, Aomori, Japan
  • A. Marqueta, F. Scantamburlo
    IFMIF/EVEDA, Rokkasho, Japan
  
  The commissioning phase of the IFMIF-EVEDA RFQ requires a complete beam characterization with simula-tions and measurements of the beam input from the IFMIF-EVEDA ion source and LEBT, in order to reach the RFQ input beam parameters. In this article, the simula-tions results of the complex source-LEBT with the corre-sponding set of measurements and their impact on the commissioning plan will be reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPRC005  
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TUPRC006 Phase-Space Transformation for a Uniform Target Irradiation at DONES target, octupole, space-charge, neutron 424
 
  • C. Oliver, A. Ibarra
    CIEMAT, Madrid, Spain
  • P. Cara
    Fusion for Energy, Garching, Germany
  • N. Chauvin
    CEA/DSM/IRFU, France
  • A. Gallego
    Universidad Complutense Madrid, Madrid, Spain
  
  Funding: "This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-2018 under grant agreement No 633053."
In the framework of the EU Roadmap, a DEMO Oriented Neutron Source (DONES) [*] has been proposed to provide a high neutron intense neutron source with a suitable neutron spectrum to understand the degradation of advanced materials under DEMO and future fusion plants irradiation conditions. DONES will be based on the International Fusion Materials Irradiation Facility IFMIF [**], being only one accelerator considered. The HEBT will be devoted to the transport, bending and shaping of the 40 MeV, 125 mA CW deuteron beam to the free surface of the rapidly flowing lithium target. To produce a forward peaked source of fusion-like neutrons, which stream through the target into the test cell, a rectangular uniform distribution across the flat top of the beam profile is required, being the footprint tailored in both the vertical and horizontal directions according to the target design. Different methods for beam uniformization in IFMIF accelerator has been proposed in the past [***]. Two main concerns in DONES will be the minimization of particle losses over the whole HEBT and the effect of the different shaping techniques on such strong space charge regime, specially on the beam halo modulation. A review of the different methods for the beam shaping of the high power, high space charge DONES HEBT beam will be depicted. A final solution will be proposed.
[*] DONES Conceptual Design Report, April 2014
[**] IFMIF Comprehensive Design Report, CDR, IFMIF International Team, January 2004
[***] IFMIF Intermediate Engineering Design Report
 		 
poster icon Poster TUPRC006 [2.546 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPRC006  
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TUPRC007 An RFQ Based Neutron Source for BNCT rfq, operation, cavity, neutron 427
 
  • X.W. Zhu, Z.Y. Guo, Y.R. Lu, H. Wang, Z. Wang, K. Zhu, B.Y. Zou
    PKU, Beijing, People's Republic of China
  
  Boron Neutron Capture Therapy (BNCT), promises a bright prospect for future cancer treatment, in terms of effectiveness, safety and less expanse. The PKU RFQ group proposes an RFQ based neutron source for BNCT. A unique beam dynamics design of 162.5 MHz BNCT-RFQ, which accelerates 20 mA of H+ from 30 keV to 2.5 MeV in CW operation, has been performed in this study. The Proton current will be about 20 mA. The source will deliver a neutron yield of 1.76×1013 n/sec/cm2 in the Li(p, n)Be reaction. Detailed 3D electromagnetic (EM) simulations of all components, including cross-section, tuners, pi-rods, and undercuts, of the resonant structure are performed. The design of a coaxial type coupler is developed. Two identical RF couplers will deliver approximately 153 kW CW RF power to the RFQ cavity. RF property optimizations of the RF structures are performed with the utilization of the CST MICROWAVE STUDIO.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPRC007  
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TUPRC008 Electron Driven ILC Positron Source with a Low Gradient Capture Linac positron, electron, linac, beam-loading 430
 
  • M. Kuriki
    HU/AdSM, Higashi-Hiroshima, Japan
  • T. Kakita
    Hiroshima University, Graduate School of Advanced Sciences of Matter, Higashi-Hiroshima, Japan
  • S. Kashiwagi
    Tohoku University, School of Science, Sendai, Japan
  • K. Negishi
    Iwate University, Morioka, Iwate, Japan
  • T. Okugi, T. Omori, M. Satoh, Y. Seimiya, J. Urakawa, K. Yokoya
    KEK, Ibaraki, Japan
  • T. Takahashi
    Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan
  
  ILC (International Linear Collider) is e+ e− linear collider in the next high energy program promoted by ICFA. In ILC, an intense positron pulse in a multi-bunch format is generated with gamma ray from Undulator radiation. As a technical backup, the electron driven positron source has been studied. By employing a standing wave L-band accelerator for the capture linac, an enough amount of positron can be captured due to the large aperture, even with a limited accelerator gradient. However, the heavy beam loading up to 2 A perturbs the field gradient and profile along the longitudinal position. We present the capture performance of the ILC positron source including the heavy beam loading effect.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPRC008  
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TUPRC010 Multispecies Simulation of the FRIB Frontend Near the ECR Sources with the Warp Code dipole, ECR, space-charge, solenoid 434
 
  • K. Fukushima, S.M. Lund
    FRIB, East Lansing, USA
  • C.Y. Wong
    NSCL, East Lansing, Michigan, USA
  
  Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661 and the National Science Foundation under Grant No. PHY-1102511.
The linear accelerator in the Facility for Rare Isotope Beams (FRIB) will use Electron Cyclotron Resonance (ECR) sources. ECR sources can generate a high-brightness DC beam with high charge states. However, the ECR sources produce numerous species that must be collimated to one or two target species with minimal degradation to beam quality. The first stage of this collimation is accomplished in a tight 90 degree dipole bend with a wide aperture and slanted pole faces to provide additional focusing. We report on simulations for the high-rigidity U ion operation using linked 2D xy-slice runs in the straight section upstream of the bend and steady-state 3D simulations in the dipole bend comparing simulations with both ideal (sector) and full 3D field maps of the dipole magnet. Issues associated with placing a 3D dipole field with fringe on a bent simulation coordinate system are addressed. Placement of the dipole bend is optimized consistent with the 3D field and is found to closely correspond to the ideal field center. Minimal problems are found (small centroid shift and distribution distortions) due to 3D space-charge effects in the species separation within the bend when using simple fractional neutralization factors. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPRC010  
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TUPRC014 Self-Consistent PIC Modeling of Near Source Transport of FRIB lattice, space-charge, ion, ECR 441
 
  • C.Y. Wong
    NSCL, East Lansing, Michigan, USA
  • K. Fukushima, S.M. Lund
    FRIB, East Lansing, USA
  
  Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661 and the National Science Foundation under Grant No. PHY-1102511.
Self-consistent simulation studies of the FRIB low energy beam transport (LEBT) system are conducted with the PIC code Warp. Transport of the many-species DC ion beam emerging from an Electron Cyclotron Resonance (ECR) ion source is examined in a realistic lattice through the Charge Selection System (CSS) which employs two 90-degree bends, two quadrupole triplets, and slits to collimate non-target species. Simulation tools developed will support commissioning activities on the FRIB front end which begins early operations in 2017. Efficient transverse (xy) slice simulation models using 3D lattice fields are employed within a scripted framework that is readily adaptable to analyze many ion cases and levels of model detail. Effects from large canonical angular momentum (magnetized beam emerging from ECR), thermal spread, nonlinear focusing, and electron neutralization are examined for impact on collimated beam quality. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPRC014  
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TUPLR012 HOM Measurements for Cornell's ERL Main Linac Cryomodule HOM, cavity, linac, cryomodule 496
 
  • F. Furuta, R.G. Eichhorn, M. Ge, D. Gonnella, G.H. Hoffstaetter, M. Liepe, P. Quigley, V. Veshcherevich
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  The main linac cryomodule (MLC) for a future energy-recovery linac (ERL) based X-ray source at Cornell has been designed, fabricated, and tested. It houses six 7-cell SRF cavities with individual higher order-modes (HOMs) absorbers, cavity frequency tuners, and one magnet/BPM section. All HOMs in MLC have been scanned in 1.8K. The results show effective damping of HOMs, and also agree well with simulation results and the previous HOM scan results on one 7-cell cavity prototype test cryomodule. Here we present detailed results from these HOM studies.  
poster icon Poster TUPLR012 [2.773 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR012  
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TUPLR028 Alternative Design for the RISP Pre-Stripper Linac linac, cryomodule, solenoid, cavity 531
 
  • B. Mustapha, Z.A. Conway, M.P. Kelly, P.N. Ostroumov, A.S. Plastun
    ANL, Argonne, USA
  • J.-H. Jang, H. Jin, H.J. Kim, J.-W. Kim
    IBS, Daejeon, Republic of Korea
  
  Funding: This work was supported by the work-for-other grant WFO8550H titled "Pre-conceptual design, cost and schedule estimate of the 18.5 MeV/u Pre-stripper linac for the RISP/IBS"
In a collaborative effort between Argonne's Linac Development Group and the RISP project team at the Korean Institute for Basic Science, we have developed an alternative design for the pre-stripper section of the RISP driver linac. The proposed linac design takes advantage of the recent accelerator developments at Argonne, namely the ATLAS upgrades and the Fermilab PIP-II HWR Cryomodule. In particular, the state-of-the-art performance of QWRs and HWRs, the integrated steering correctors and clean BPMs for a compact cryomodule design. To simplify the design and avoid frequency transitions, we used two types of QWRs at 81.25 MHz. The QWRs were optimized for β ~ 0.05 and ~ 0.11 respectively. Nine cryomodules are required to reach the stripping energy of 18.5 MeV/u. Following the lattice design optimization, end-to-end beam dynamics simulations including all sources of machine errors were performed. The results showed that the design is tolerant to errors with no beam losses observed for nominal errors. However, the robustness of the design could be further improved by a modified RFQ design, better optimized with the multi-harmonic buncher located upstream. This could lead to a significant reduction in the longitudinal beam emittance, offering much easier beam tuning and more tolerance to errors. The proposed design and the simulation results will be presented and discussed. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR028  
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TUPLR057 Advanced Design Optimizations of a Prototype for a Newly Revised 4-Rod CW RFQ for the HLI at GSI rfq, dipole, resonance, impedance 586
 
  • D. Koser, H. Podlech
    IAP, Frankfurt am Main, Germany
  • P. Gerhard, L. Groening
    GSI, Darmstadt, Germany
  • O.K. Kester
    TRIUMF, Vancouver, Canada
  
  Within the scope of the FAIR project (Facility for Antiproton and Ion Research) at GSI Helmholtz Centre for Heavy Ion Research in Darmstadt, Germany, the front end of the existing High Charge State Injector (HLI) is upgraded for cw operation. The dedicated new 4-Rod RFQ structure is currently being designed at the Institute for Applied Physics (IAP) of the Goethe University of Frankfurt. The overall design is based on the RFQ structures that were originally developed for FRANZ* and MYRRHA**. Regarding the HLI-RFQ the comparatively low operating frequency of 108 MHz causes a general susceptibility towards mechanical vibrations especially concerning the electrodes because of the necessarily larger distance between the stems. Besides RF simulations and basic thermal simulations with CST Studio Suite, the key issues like mechanical electrode oscillations as well as temperature distribution from heat loss in cw operation are investigated with simulations using ANSYS Workbench. At first instance a dedicated 6-stem prototype is currently being manufactured in order to validate the simulated RF performance, thermal behavior and structural mechanical characteristics.
*M. Heilmann et al., A Coupled RFQ-IH Cavity for the Neutron Source FRANZ, IPAC13
**C. Zhang, H. Podlech, New Reference Design of the European ADS RFQ Accelerator For MYRRHA, IPAC14
 		 
poster icon Poster TUPLR057 [1.484 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR057  
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TUPLR058 Progress of a 162.5 MHz High-Current RFQ With Coupling Windows rfq, Windows, cavity, coupling 589
 
  • Q. Fu, P.P. Gan, S.L. Gao, F.J. Jia, H.P. Li, Y.R. Lu, Z. Wang, K. Zhu
    PKU, Beijing, People's Republic of China
  
  Funding: Supported by National Basic Research Program of China(2014CB845503)
A 162.5 MHz, four-vane RFQ with magnetic coupling windows has been designed by the RFQ group of Peking University. Clear frequency separation of the resonant modes and smaller transverse dimension are the advantages of the window-type RFQ. The electromagnetic simulations have shown that the average power loss of this 1.809 m long RFQ is about 50 kW in continuous wave mode. Consequently, a water cooling system was designed via the multi-physics analysis. The mechanical design and assembling technology were also presented in this paper. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR058  
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TUPLR059 Asymmetric Four-Vane RFQ dipole, quadrupole, impedance, rfq 592
 
  • A.S. Plastun
    ANL, Argonne, Illinois, USA
  • A. Kolomiets, D.A. Liakin
    ITEP, Moscow, Russia
  
  Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.
A four-vane resonator is widely used in Radio Frequency Quadrupole (RFQ) accelerators. The field distribution in a long four-vane resonator can be easily perturbed by nearest dipole modes which are excited due to the local geometry errors. This paper describes the electromagnetic properties of a four-vane resonator with an introduced asymmetry between neighboring chambers. The asymmetry provides necessary separation of dipole modes keeping losses and field uniformity of quadrupole mode similar to those in a conventional four-vane resonator. This feature of an asymmetric resonator is confirmed by analytical results from transmission line model as well as by CST Studio simulations. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR059  
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TUPLR060 RF Design of the Nuclotron-NICA 145.2 MHz RFQ rfq, Windows, coupling, dipole 595
 
  • A.S. Plastun, V. Andreev, V.A. Koshelev, T. Kulevoy, V.G. Kuzmichev, D.A. Liakin, A. Sitnikov
    ITEP, Moscow, Russia
  • A.V. Butenko
    JINR, Dubna, Moscow Region, Russia
  
  ITEP has designed the Radio-Frequency Quadrupole (RFQ) linac for the JINR NICA Complex (Dubna, Russia) to provide ion beams (q/A ≥ 0.3) with energy of 156 keV/u for further acceleration by existing Alvarez-type linac. The RFQ is based on a 4-vane structure with magnetic coupling windows in order to avoid a risk of excitation of dipole field components inherent in a conventional 4-vane resonator. The paper presents results of the radio-frequency (RF) design and capabilities used for coarse and fine tuning of the field distribution and resonant frequency during manufacturing and finalizing of the RFQ.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR060  
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TUPLR063 IMPACT Model for ReA and its Benchmark with DYNAC ion, cavity, rfq, lattice 601
 
  • T. Yoshimoto, M. Ikegami
    FRIB, East Lansing, USA
  
  Funding: * Work supported by the U.S. National Science Foundation under Grant No. PHY-11-02511 ** Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661
Abstract New online model for ReAccelerator 3 (ReA3) has been developed for actual beam tunings using IMPACT, which is one of famous particle tracking codes in accelerator field. DYNAC model was used for ReA3 optics calculation. However it basically can calculate symmetric cavity, not axisymmetric ones such as super-conductive Quarter-Wave Resonators (QWRs), which are installed in ReA3. This means that it is difficult to effectively tune beams at present situation. In order to handle beams at ReA3, a new alternative and more precise model of IMPACT is under development, which would be acceptable to actual beam operation. This paper reports benchmarked results of IMPACT and DYNAC model for ReA3 acceleration line just after RFQ exit to a transport line with symmetric cavity as a first step before more precise simulation including non-axisymmetric cavity and RFQ calculation. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR063  
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TUPLR069 Simulation Study on the Beam Loss Mitigation in the 1st Arc Section of FRIB Driver Linac ion, electron, linac, heavy-ion 613
 
  • T. Maruta
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  • M. Ikegami, F. Marti
    FRIB, East Lansing, USA
  
  Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661.
The Facility of Rare Isotope Beams (FRIB) at Michigan State University is now under construction toward user operation in year 2020. Charge-state transition of accelerating ions occurs in the beam line due to interaction with the residual gas. Since this exchange changes charge to mass ratio of the ions, the ion orbit is distorted especially in an arc section with the ion potentially hitting the vacuum pipe. This will generate outgassing from the beamline pipe. Moreover, they become a seed of further charge-state exchanges. Therefore, a collimation of charge exchanged ions is necessary to prevent this feedback cycle. In this presentation, the results of a simulation study on charge exchange reaction in the 1st arc section of FRIB and optimization of collimator position are presented. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR069  
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TUPLR070 Efficient Heavy Ion Acceleration with IH-Type Cavities for High Current Machines in the Energy Range up to 11.4 MeV/u linac, emittance, DTL, cavity 616
 
  • H. Hähnel, U. Ratzinger, R. Tiede
    IAP, Frankfurt am Main, Germany
  
  Funding: BMBF 05P15RFRBA
We propose an efficient design for heavy ion acceleration from 1.4 to 11.4 MeV/u with a design current of 15 emA for a Uranium 28+ beam. The proposed linac is based on IH-DTL cavities and quadrupole triplet focusing. The KONUS beam dynamics concept is used to achieve high acceleration efficiency. By optimization of the transversal focusing scheme and the longitudinal bunch center motion, low emittance growth for the entire linac is achieved. Beam dynamics simulations were performed along with 3D rf-simulations of all cavities. The cavities are designed for 108.408 MHz, reaching an effective shunt impedance of 100-200 MOhm/m. The overall length of the linac is below 25 m. A mechanical realization concept employing a modular tank design is presented. The proposed design is a viable option for the GSI UNILAC poststripper linac replacement, leaving free space in the UNILAC tunnel for future energy upgrades. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR070  
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THOP03 Cold Bead-Pull Test Stand for SRF Cavities cavity, HOM, niobium, SRF 748
 
  • A.V. Vélez, A. Frahm, J. Knobloch, A. Neumann
    HZB, Berlin, Germany
  
  Bead-pull measurements represent a final step in the fabrication process of an SRF cavity. These tests allow to characterize the flatness of the field profile in order to perform mechanical tuning if needed. These test has been always performed at room temperature, where material properties differ from the superconducting state properties. Still questions like mechanical deformation due to assymetrical thermal shrincage have not yet been answered experimentaly. In this paper, an upgrade of the former Cold-Bead pull system developed by HZB [1] is presented. This test stand is capable of holding a 9-cell Tesla cavity at LHe temperature providing a realistic insight to cavity parameters under realistic conditions. A copper test pill-box is placed in series with the multi-cell cavity in order to perform 1.8K calibration of the bead. Results will be presented on this paper and compared to electromagnetic simulations.  
slides icon Slides THOP03 [2.731 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THOP03  
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THPRC006 Development of 704.4 MHz Power Coupler Window for Myrrha Project linac, cavity, Windows, electron 776
 
  • F. Geslin, P. Blache, M. Chabot, J. Lesrel
    IPN, Orsay, France
  • Ch.L. Lievin, S. Sierra
    TED, Velizy, France
  
  Myrrha is an accelerator driven system (ADS) hybrid research reactor designed for spent nuclear fuel burning. The linac controlling the reactor has to be highly reliable (low failure rate). In order to fulfill requirements of ADS projects like Myrrha, IPNO and Thales are involved in a power couplers research and development program. We develop a power coupler window, with MAX RF design, for 80 kW CW input power. During the study, we take account of fabrication and cost issues. We present in this paper the result of simulations needed to design this coupler window. The electromagnetic, thermal and thermo-mechanical simulations were performed with Ansys. The multipacting simulations were performed with Musicc3D, software developed by IPNO. The conditioning and test bench is also described as two prototypes have to be tested this autumn.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPRC006  
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THPRC007 Development of 352.2 Mhz Power Coupler Window for R&D Purposes cavity, klystron, electron, vacuum 779
 
  • F. Geslin, M. Chabot, J. Lesrel, D. Reynet
    IPN, Orsay, France
  • Ch.L. Lievin, S. Sierra
    TED, Velizy, France
  
  IPNO and Thales are conducting power couplers research and development. This paper present a new window design that fulfills European Spallation Source (ESS) requirements (400 kW RF peak power). The results of electromagnetic, thermal, thermo-mechanical, multipacting simulations and the consequences of the new ceramic window of power coupler will be reported. The multipacting simulations were performed with Musicc3D, software developed by IPNO. The new design overcome ceramic's weakness in tension and allows stronger constraints in the power coupler window.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPRC007  
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THPRC023 Cost Reduction for FRIB Magnetic Shielding shielding, cavity, cryomodule, cryogenics 818
 
  • Z. Zheng, J.T. Popielarski, K. Saito, T. Xu
    FRIB, East Lansing, USA
  
  Funding: *Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661
Cryogenic magnetic shielding (A4K) is generally used in SRF cryomodules which is much more expensive than mu-metal used in room temperature. In order to reduce the cost, FRIB QWR and HWR magnetic shieldings were redesign to improve the shielding performance so that mu-metal can be implemented as an alternative shielding material. The magnetic shielding of first FRIB β=0.085 cryomodule was made up of 50% by A4K and 50% by mu-metal. Cavities were tested in 4K and 2K, the results showed that the Q0 of cavities were similar for both shielding materials, which is a success as a validation test for mu-metal magnetic shielding. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPRC023  
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THPRC028 Deflector Design for Spin Rotator in Muon Linear Accelerator dipole, solenoid, experiment, vacuum 830
 
  • S. Artikova
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  • Y. Kondo
    JAEA, Ibaraki-ken, Japan
  • T. Mibe, M. Otani
    KEK, Tsukuba, Japan
  
  A muon g-2/EDM experiment based on muon linear accelerator was proposed for the J-PARC muon facility. In this experiment, the ultra-slow muons created in muonium target region will be accelerated to 210 MeV kinetic energy then will be injected into the muon storage ring to measure the decay products depending on the muon spin. Therefore, a spin rotator (device) is a key component of the muon linac. Spin rotator consists of a pair of combined electrostatic and magnetic deflectors and a pair of solenoids which will be placed in between these two deflectors. In this paper, we report the design of these two dispersion-free deflectors and the simulation results of the device performance will be discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPRC028  
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THPLR009 A Compact Muon Accelerator for Tomography and Active Interrogation linac, electron, target, cavity 861
 
  • R.W. Garnett, S.S. Kurennoy, L. Rybarcyk
    LANL, Los Alamos, New Mexico, USA
  • K. Hasegawa
    JAEA, Ibaraki-ken, Japan
  • S. Portillo, E. Schamiloglu
    University of New Mexico, Albuquerque, USA
  • N. Saito
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  
  Funding: This work is supported by the United States Department of Energy, National Nuclear Security Agency, under contract DE-AC52-06NA25396.
Muons have been demonstrated to be great probes for imaging large and dense objects due to their excellent penetrating ability. At present there are no muon accelerators. Development of a compact system that can produce an intense beam of accelerated muons would provide unique imaging options for stockpile stewardship while delivering minimal radiation dose, as well as various homeland-security and industrial applications. Our novel compact accelerator approach allows a single linac to be used to first accelerate an electron beam to 800 MeV to generate muons by interacting with a production target in a high-field solenoid magnet and then to collect and accelerate these low-energy muons to 1 GeV to be used for imaging or active interrogation. The key enabling technology is a high-gradient accelerator with large energy and angular acceptances. Our proposed solution for efficient acceleration of low-energy muons is a 0-mode linac coupled with conventional electron RF accelerating structures to provide a compact system that could deliver a controllable high-flux beam of muons with well-defined energy to allow precise radiographic inspections of complicated objects. The details of the conceptual design will be discussed. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR009  
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THPLR013 LEETCHI: The High Current Electron Source for the CLIC Drive Beam Injector electron, cathode, gun, high-voltage 870
 
  • K. Pepitone, S. Döbert
    CERN, Geneva, Switzerland
  • B. Cadilhon, B. Cassany, J. Gardelle
    CEA, LE BARP cedex, France
  
  LEETCHI is a source which will produce 140 keV, 5 A, 140 μs electron beams at a repetition rate of 50 Hz. The shot to shot and flat top current stability of this drive beam injector for CLIC has to be better than 0.1% and a geometrical emittance of 14 mm mrad is expected. The development of a high voltage modulator, to achieve those requirements, is ongoing. A small test stand has been built which allows to diagnose and dump the beam produced by the thermionic cathode. The thermionic cathode is equipped with a grid which will allow us to control the current and eventually to have a feedback on the flattop shape. The beam dump, made of graphite, has been designed using two different codes, the Monte Carlo code GEANT4 to simulate the energy deposition and ANSYS used to simulate the thermal resistance of the graphite due to the long pulse duration. The geometry has been optimized with the ray tracing code EGUN and the 2D PIC-code MAGIC. All these simulations allowed us to optimize the geometry of the gun and to develop diagnostics which must survive to the heat deposition. Finally, the first electrical measurements of the beam will be presented.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR013  
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THPLR014 Laser-Driven Dielectric Nano-Beam Accelerator for Radiation Biology Researches electron, acceleration, laser, ion 873
 
  • K. Koyama, M. Yoshida
    KEK, Ibaraki, Japan
  • Z. Chen, H. Okamoto
    The University of Tokyo, Tokyo, Japan
  • M. Uesaka
    The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan
  
  Funding: This work was partly supported by JSPS KAKENHI (B)(Grant-in-Aid for Scientific Research) Grant Number 15H03595.
Since a laser-driven dielectric accelerator (LDA) is most likely to deliver a nano-beam with a small scale device, a combination of the LDA and a biological cell observation device such as a fluorescence microscope seems to be a powerful tool for radiation biology researches. The LDA consists of single or a pair of binary-blazed transmission grating. In case of normal incidence, a grating constant must be the same with a laser wavelength to synchronize with the electron and an acceleration field. Although demonstration experiments have been published from SLAC and MPQ, there are many problems to be solved, especially in the non-relativistic energy region. A crucial problem is to make it clear whether electrons are accelerated with negligibly small wiggling or lateral shift. We are simulating at various conditions with the aid of CST-code. We also analyze an oblique incidence (OI) scheme for the efficient acceleration of slow electron. The OI-scheme enables to use the grating of larger grating constant. Adoption of the large grating constant makes it easy to fabricate the grating. Besides analytical works, we are making gratings and developing an Yb-doped fiber laser for the acceleration experiment. Gratings of two different materials, a glass silica and crystal silica, were fabricated by the e-beam lithography technique. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR014  
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THPLR015 Fifth-Order Moment Correction for Beam Position and Second-Order Moment Measurement linac, experiment, factory, quadrupole 876
 
  • K. Yanagida, H. Hanaki, S. Suzuki
    JASRI/SPring-8, Hyogo-ken, Japan
  
  For precise beam position measurement using a beam position monitor (BPM), a recursive correction which is expressed by the higher-order polynomials of beam positions are usually adopted. We recognized that the higher-order polynomials came from the higher-order moments and that beam position measurement is consequently influenced by a transverse beam shape. To investigate what order was required for adequate correction, we performed a successive iteration for the six-electrode BPM holding an inner radius of 16mm (circular cross-section). The successive iteration is a method to obtain a self-consistent solution for the higher-order correction. An amplitude of static electric field due to a beam charge was calculated by two-dimensional mirror charge method. As a result of the successive iteration, the convergence region was large enough for ordinary measurements (from lower than -5mm to higher than 5mm horizontally and vertically). In the convergence region the root mean square of the differences between the set and calculated vertical position were obtained as 0.487mm (without correction), 0.030mm (with third-order correction) and 0.003mm (with fifth-order correction).  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR015  
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THPLR028 Simulation of Mechanical Oscillations in PIP-II Cryomodule Using ACE3P cavity, SRF, linac, proton 910
 
  • L. Xiao, O. Kononenko, C.-K. Ng
    SLAC, Menlo Park, California, USA
  
  Funding: Work supported by the US DOE under contract DE-AC02-76SF00515.
The linac in the PIP-II project at Fermilab consists of different sections of superconducting rf (SRF) cavities that can accelerate the proton beams to 800 MeV. At the end of the linac is a section containing a number of HB (β = 0.92) cryomodules operating at 650 MHz, with each cryomodule consisting of six SRF cavities. Previous calculations have been carried out to determine the mechanical modes of a single cavity in the 650 MHz cryomodule. In this paper, the parallel code suite ACE3P is used to evaluate the mechanical modes for a string of SRF cavities in the 650 MHz cryomodule. The effects of multi cavities on the mechanical mode frequencies and any possible coupling between cavities will be investigated. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR028  
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THPLR030 Performances of the Two First Single Spoke Prototypes for the MYRRHA Project cavity, cryomodule, superconductivity, linac 916
 
  • D. Longuevergne, J.-L. Biarrotte, S. Blivet, P. Duchesne, G. Olry, H. Saugnac
    IPN, Orsay, France
  • Y. Gómez Martínez
    LPSC, Grenoble Cedex, France
  
  Funding: This work is being supported by the Euratom research and training program 2014-2018 under grant agreement N°662186 (MYRTE project)
The MYRRHA project aims at the construction of an accelerator driven system (ADS) at MOL (Belgium) for irradiation and transmutation experiment purposes. The facility will feature a superconducting LINAC able to produce a proton flux of 2.4 MW (600 MeV - 4 mA). The first section of the superconducting LINAC will be composed of 352 MHz (β = 0.37) Single Spoke Resonators (SSR) housed in short cryomodules operating at 2K. After a brief presentation of the cryomodule design, this paper will aim at presenting the RF performances of the SSR tested in vertical cryostat in the framework of European MYRTE project (MYRRHA Research and Transmutation Endeavour) and at comparing experimental results (Lorentz forces, pressure sensitivity, multipacting barriers…) to simulated values. 		 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR030  
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THPLR032 Update on SSR2 Cavity EM Design for PIP-II cavity, linac, quadrupole, acceleration 920
 
  • P. Berrutti, T.N. Khabiboulline, V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
  
  Proton Improvement Plan II (PIP-II) is the future plan for upgrading the Fermilab proton accelerator complex to a beam power capability of at least 1 MW delivered to the neutrino production target. A room temperature section accelerates H− ions to 2.1 MeV and creates the desired bunch structure for injection into the superconducting (SC) linac. SC linac using five cavity types. One 162.5 MHz half wave resonator, two 325 MHz spoke resonators and two 650 MHz elliptical 5-cell cavities, provide acceleration to 800 MeV. The EM design of the second family of spoke resonator is presented in this paper. The work reported is a thorough electromagnetic study including: the RF parameters, multipacting mitigation and transverse field asymmetry. The cavity is now ready for structural design analysis.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR032  
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THPLR035 FZJ SRF TSR with Integrated LHe Vessel cavity, SRF, operation, electromagnetic-fields 926
 
  • E.N. Zaplatin
    FZJ, Jülich, Germany
  
  Single- or Multi-Spoke SRF cavities are one of the basic accelerating structures for the low and intermediate energy part of many accelerators. Different types of external loads on the resonator walls predetermine the main working conditions of the SC cavities. The most important of them are very high electromagnetic fields that result in strong Lorentz forces acting on cavity walls and the pressure on cavity walls from the helium tank that also deforms the cavity shape. For the accelerators operating in pulsed regime the Lorentz forces are the dominant factor. The liquid helium vessel pressure instability even for 2K operations is the source of large microphonics and dominates for cw operation. Here we propose an innovative integrated helium vessel-cavity and stiffener design that will provide an effective passive damping minimizing df/dp ratio. Minimizing df/dp may be accomplished without an enhancement of the structure rigidity, which in turn minimizes the load on the cavity tuner. A separate stiffening scheme reducing Lorentz force cavity detuning to be added without violation of df/dp optimization. The developed at the Research Center in Jülich, Germany (FZJ) the 352 MHz, β=v/c=0.48 Triple-Spoke Resonator was used as an example to demonstrate the proposed conceptual integrated helium vessel-cavity design.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR035  
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THPLR036 SRF Low-Beta Elliptical Resonator Two-Ring Stiffening cavity, SRF, resonance, vacuum 929
 
  • E.N. Zaplatin
    FZJ, Jülich, Germany
  • I.V. Gonin, T.N. Khabiboulline, V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
  
  Elliptical SRF cavities are the basic accelerating structures for the high energy part of many accelerators. Since a series of external loads on the resonator walls predetermine the main working conditions of the SC cavities the detailed investigation of their mechanical properties should be conducted in parallel with the main RF design. The effects of very high electromagnetic fields that result in strong Lorentz forces and the pressure on cavity walls from the helium tank that also deforms the cavity shape, the tuning scheme resulting in the change of accelerating field profile and mechanical eigen resonances of cavities which are the main source of the microphonics must be taken into account during integrated design of the resonator and its liquid helium vessel. SRF elliptical cavities for the medium energies (β=v/c is around 0.6) inherently have more flexible shape and their ultimate stiffening with a "standard" stiffening rings installed between resonator cells becomes problematic. The second row of the rings should enhance the overall cavity rigidity. In the paper we report the basic investigations of the cavity two-row ring stiffening using FNAL 650 MHz β=0.61 as an example. The single-cell investigation results were used as the reference to develop the ultimate scheme of the helium vessel structure to ensure the best resonator stability.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR036  
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THPLR054 Recent RF and Mechanical Developments for the ESS RFQ rfq, cavity, operation, vacuum 978
 
  • N. Misiara, A. Albéri, G. Bourdelle, A.C. Chauveau, D. Chirpaz-Cerbat, M. Desmons, A.C. France, M. Lacroix, P.-A. Leroy, J. Neyret, G. Perreu, O. Piquet, B. Pottin, H. Przybilski, N. Sellami
    CEA/IRFU, Gif-sur-Yvette, France
  
  The ESS Radio-Frequency Quadrupole (RFQ) is a 4-vane resonant cavity designed at the frequency of 352.21 MHz frequency. It must accelerate and bunch a 70 mA proton beams from 75 keV to 3.62 Mev of energy with a 4% duty cycle. The current 3D design evolved and is currently divided in 5 segments for a total length of 4.54 m. This paper presents a complete radiofrequency (RF) analysis using the ANSYS Multiphysics 3D RF simulating code HFSS and a RFQ 4-wire transmission line model (TLM). It describes the integrated cooling strategy based on a coupling between the RF power losses and the thermo-mechanical physics in order to allow a proper RFQ tuning once under operation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR054  
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THPLR063 RF Design of a Deuteron Beam RFQ rfq, cavity, dipole, operation 996
 
  • C.X. Li, W.P. Dou, Y. He, F.F. Wang, Z.J. Wang, X.B. Xu, Z.L. Zhang
    IMP/CAS, Lanzhou, People's Republic of China
  
  In a material irradiation facility in IMP, a RFQ is required for accelerating deuteron beam from 20 keV/u to 1.52 MeV/u. The structure design of the RFQ is drawing on the experience of the RFQ of Injector II of China ADS LINAC. Four-vane structure is adopted and the operation frequency is 162.5 MHz. Inter vane voltage is 65 kV and the Kilpatrick factor is 1.4. Π-mode stabilizing loops are used to move the dipole modes away from the working mode. Slug tuners are used to compensate for capacitance errors induced by machining. Cutbacks and end plate are modified to reach a reasonable field flatness. After the structure design and optimization, the simulation results of the cavity frequency is 162.459 MHz, the power loss is 109 kW. The multiphysics simulations are also performed to determine the frequency shift caused by the shift of the cooling water temperature.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR063  
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THPLR064 Design and Simulation of a High Intensity Heavy Ion RFQ Accelerator Injector rfq, dipole, ion, heavy-ion 999
 
  • W. Ma, Y. He, C.X. Li, L. Lu, L.B. Shi, L.P. Sun, X.B. Xu, Z.L. Zhang, H.W. Zhao
    IMP/CAS, Lanzhou, People's Republic of China
  
  An 81.25 MHz continuous wave (CW) radio frequency quadrupole (RFQ) accelerator has been developed for Low Energy Accelerator Facility (LEAF) at the Institute of Modern Physics (IMP), the Chinese Academy of Science (CAS). In the CW operating mode, the proposed RFQ design adopted the conventional four-vane structure. The main design goals are providing the high shunt impendence with low power losses. In the electromagnetic (EM) design, the π-mode stabilizing loops (PISLs) were optimized to produce a good mode separation. The tuners were also designed and optimized to tune frequency and field flatness of the operating mode. The vane undercuts were optimized to provide a flat field along the RFQ cavity. Additionally, a full length model with modulations was set up for the final EM simulations. In this paper, detailed EM design of the LEAF-RFQ will be presented and discussed. Meanwhile, structure error analysis is also studied.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR064  
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