LINAC2016 - Table of Session: MOPRC (Poster Session)

Paper	Title	Page
MOPRC001	Development of Ultracold Neutron Accelerator for Time Focusing of Pulsed Neutrons
MOOP07	use link to access more material from this paper's primary paper code
SPWR015	use link to access more material from this paper's primary paper code
	S. Imajo Kyoto University, Kyoto, Japan T. Ino, K. Mishima KEK, Ibaraki, Japan Y. Iwashita Kyoto ICR, Uji, Kyoto, Japan M. Kitaguchi, H.M. Shimizu Nagoya University, Nagoya, Japan S. Yamashita ICEPP, Tokyo, Japan
	Low energy neutron accelerator can be realized by the combination of an adiabatic fast passage spin flipper and a gradient magnetic field. Neutrons have magnetic moments, so that the accumulated potential energies are not cancelled before and after passage of a magnetic field and their kinetic energies change in case their spins are flipped in the field. This accelerator handles lower kinetic energy neutrons than approximately 300 neV. Currently we have developed the advanced version which makes it possible to handle broader kinetic energy range. The design and measured characteristics are described.
	Slides MOPRC001 [1.313 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOOP07
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MOPRC002	Latest News on High Average RF Power Operation at PITZ
MOOP08	use link to access more material from this paper's primary paper code
	Y. Renier, G. Asova, P. Boonpornprasert, J.D. Good, M. Groß, H. Huck, I.I. Isaev, D.K. Kalantaryan, M. Krasilnikov, O. Lishilin, G. Loisch, D. Melkumyan, A. Oppelt, T. Rublack, F. Stephan DESY Zeuthen, Zeuthen, Germany G. Asova INRNE, Sofia, Bulgaria M. Bousonville, S. Choroba, S. Lederer DESY, Hamburg, Germany C. Saisa-ard Chiang Mai University, Chiang Mai, Thailand Q.T. Zhao IMP/CAS, Lanzhou, People's Republic of China
	The Photo Injector Test Facility at DESY in Zeuthen (PITZ) develops, tests and characterizes high brightness electron sources for FLASH and European XFEL. Since these FELs work with superconducting accelerators in pulsed mode, also the corresponding normal-conducting RF gun has to operate with long RF pulses. Generating high beam quality from the photocathode RF gun in addition requires a high accelerating gradient at the cathode. Therefore, the RF gun has to ensure stable and reliable operation at high average RF power, e.g. 6.5 MW peak power in the gun for 650 μs RF pulse length at 10 Hz repetition rate for the European XFEL. Several RF gun setups have been operated towards these goals over the last years. The latest gun setup was brought into the PITZ tunnel on February 10th 2016 and its RF operation started on March 7th. This setup includes RF gun prototype 4.6 with a new cathode contact spring design and an RF input distribution which consists of an in-vacuum coaxial coupler, an in-vacuum T-combiner and 2 RF windows from DESY production. In this contribution we will summarize the experience from the RF conditioning of this setup towards high average RF power and first experience from the operation with photoelectrons.
	Slides MOPRC002 [0.563 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOOP08
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MOPRC003	Dielectric and THz Acceleration (Data) Programme at the Cockcroft Institute
MOOP09	use link to access more material from this paper's primary paper code
	S.P. Jamison, Y.M. Saveliev STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom R.B. Appleby, H.L. Owen, T.H. Pacey, T.H. Pacey, G.X. Xia UMAN, Manchester, United Kingdom G. Burtpresenter, R. Letizia, C. Paoloni Cockcroft Institute, Lancaster University, Lancaster, United Kingdom A.W. Cross USTRAT/SUPA, Glasgow, United Kingdom D.M. Graham The University of Manchester, The Photon Science Institute, Manchester, United Kingdom C.P. Welsch The University of Liverpool, Liverpool, United Kingdom C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: This work has been funded by STFC Normal conducting RF systems are currently able to pro-vide gradients of around 100 MV/m, limited by break-down on the metallic structures. The breakdown rate is known to scale with pulse length and, in conventional RF systems, this is limited by the filling time of the RF struc-ture. Progressing to higher frequencies, from RF to THz and optical, can utilise higher gradient structures due to the fast filling times. Further increases in gradient may be possible by replacing metallic structures with dielectric structures. The DATA programme at the Cockcroft Insti-tute is investigating concepts for particle acceleration with laser driven THz sources and dielectric structures, beam driven dielectric and metallic structures, and optical and infrared laser acceleration using grating and photonic structures. A cornerstone of the programme is the VELA and CLARA electron accelerator test facility at Daresbury Laboratory which will be used for proof-of-principle experiments demonstrating particle acceleration.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOOP09
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MOPRC004	Beam Orbit Analysis and Correction of the FRIB Superconducting Linac	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	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	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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MOPRC007	Status of and Plans for the Beam Dynamics Program DYNAC	80
	E. Tanke, M. Eshraqi, Y.I. Levinsen, A. Ponton ESS, Lund, Sweden S. Valero CEA, Gif-sur-Yvette, France
	A short introduction to the linac beam dynamics code DYNAC will be given. Recently implemented features, such as a Graphical User Interface (GUI), will be presented and benchmarking of the Radio Frequency Quadrupole (RFQ) model will be discussed. Additional planned features to DYNAC and the GUI will be touched upon.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPRC007
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MOPRC008	Dispersion Free and Dispersion Target Steering Experience at CTF3	83
	D. Gamba, R. Corsini, T. Persson, P.K. Skowroński, F. Tecker CERN, Geneva, Switzerland P. Burrows Oxford University, Physics Department, Oxford, Oxon, United Kingdom P. Burrows JAI, Oxford, United Kingdom
	One of the goals of the CLIC Test Facility (CTF3) at CERN is to demonstrate the feasibility of the CLIC Drive Beam recombination, which takes place in the Drive Beam Recombination Complex (DBRC). The tight geometry of the DBRC together with its strong optics and the high energy-spread of the beam require a careful control of the beam size along the different sections of the DBRC. One of the main contribution to beam size is the dispersion. If uncontrolled, dispersion leads to fast increase of the beam size, hence it may affect the beam current stability of the combined beam. A tool has been implemented at CTF3 to measure and correct dispersion during and after the setup of the machine. Dispersion Free Steering (DFS) has been applied in the upstream drive beam LINAC, while Dispersion Target Steering (DTS) has been used in the rings of the DBRC. In the LINAC the weak optics and the wide dynamic aperture of the beamline allow a straightforward correction. In the DBRC the aperture is tighter, and the strong optics produce non-linear dispersion which one needs to take into account. A general overview of current status and future plans in controlling dispersion at CTF3 will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPRC008
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MOPRC009	Simulating Apertures in the Uniform Equivalent Beam Model	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	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 MOPRC011 [1.295 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPRC011
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MOPRC013	Tracking Based Courant-Snyder Parameter Matching in a Linac with a Strong Space-Charge Force	93
	R. Miyamoto ESS, Lund, Sweden
	During the design of a hadron linac, matching at the interfaces of different structures or lattice periods is often performed with the linear approximation of the space-charge force. When space-charge is extremely strong, like in the low energy part of the proton linac of the European Spallation Source, such a matching method is not always good enough and could lead to a residual mismatch at the design level. To avoid this, a matching scheme based on iterations of tracking, thus including the full effect of the space-charge force, is developed. This paper presents the scheme itself as well as its application to the ESS linac.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPRC013
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MOPRC014	Beam Dynamics Simulations of a High Charge S-Band Photoinjector for Electron Beam Imaging Experiments	97
SPWR004	use link to see paper's listing under its alternate paper code
	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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MOPRC015	Development Status of FRIB On-line Model Based Beam Commissioning Application	100
	Z.Q. He, M.A. Davidsaver, K. Fukushima, D.G. Maxwell, G. Shen, Y. Zhang, Q. Zhao FRIB, East Lansing, USA
	Funding: The work is supported by the U.S. National Science Foundation under Grant No. PHY-11-02511, and the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661. The new software FLAME has been developed to serve as physics model used for on-line beam commissioning applications. FLAME is specially designed to cover FRIB modeling challenges to balance between speed and precision. Several on-line beam commissioning applications have been prototyped based on FLAME and tested on the physics application prototyping environment. In this paper, components of the physics application prototyping environment are firstly described. Then, the design strategy and result of the four major applications: baseline generator, cavity tuning, orbit correction, transverse matching, are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPRC015
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MOPRC016	RF-Track: Beam Tracking in Field Maps Including Space-Charge Effects, Features and Benchmarks	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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MOPRC017	CIADS HEBT Lattice Design	108
SPWR029	use link to see paper's listing under its alternate paper code
	Y.S. Qin IMP/CAS, Lanzhou, People's Republic of China
	Funding: I want to apply for financial support. CIADS (China Initiative Accelerator Driven System) 600MeV HEBT (High-Energy Beam Transport) will deliver 6 MW beam to the target, with CW (continuous wave) 10 mA beam. The most serious challenges are vacuum differential section and beam uniformization on the target. A novel collimation plus vacuum differential section is proposed in the lattice design. A scanning method is designed for the round beam uniformization on the target.
	Poster MOPRC017 [1.273 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPRC017
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MOPRC018	Improved Beam Dynamics and Cavity RF Design for the FAIR Proton Injector	111
MOOP06	use link to see paper's listing under its alternate paper code
	R. Tiede, A. Almomani, M. Busch, F.D. Dziuba, U. Ratzinger IAP, Frankfurt am Main, Germany
	The FAIR facility at GSI requires a dedicated 70 MeV, 70 mA proton injector for the research program with intense antiproton beams. The main accelerator part consists of six 'Crossbar H-type' (CH) cavities operated at 325 MHz. Based on a linac layout carefully developed over several years, recently the beam dynamics has been revised with the scope of finalising the design and thus being able to start the construction of the main linac components. As compared to previous designs the MEBT behind the RFQ was slightly extended, the gap numbers per CH cavity and the voltage distributions were optimised and the layout of the intermediate diagnostics section including a rebuncher cavity at 33 MeV was redesigned. Finally, detailed machine error studies were performed in order to check the error response of the new design and the steering concept in particular. In the consequence, the final parameters obtained from the beam dynamics update are used for finalizing the CH-DTL cavity design by CST-MWS calculations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPRC018
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MOPRC019	Beam Dynamic of Transport Line 1+ with New HRMS for the SPES Project	114
	E. Khabibullina MEPhI, Moscow, Russia L. Bellan, M. Comunianpresenter, 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	117
	A.V. Ziiatdinova MEPhI, Moscow, Russia L. Bellan, M. Comunianpresenter, 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	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	123
	G. Ferrand CEA/DSM/IRFU, France L. Boudjaoui, P. Hardy, F. Leseigneur, C. Madec, N. Misiarapresenter, 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	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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MOPRC027	Surface Roughness Effect on the Performance of Nb3Sn Cavities	129
SPWR032	use link to see paper's listing under its alternate paper code
	R.D. Porter, D.L. Hall, M. Liepe, J.T. Maniscalco Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: DOE award DE-SC0008431 Surface roughness of current Niobium-3 Tin (Nb3Sn) superconducting radio-frequency (SRF) accelerator cavities can cause enhancement of the surface magnetic field. This enhancement can push the surface magnetic field beyond the critical field, which, if it occurs over a large enough area, can cause the cavity to quench. This paper presents simulations of the surface magnetic field enhancements in SRF cavities caused by the surface roughness of current Cornell Nb3Sn cavities, which have achieved record efficiency. Simple, smooth cavity geometry is defined and surface magnetic fields calculated using SLANS2. The cavity geometry is modified with a small rough region for which the geometry is determined from AFM scans of a Nb3Sn coated sample and the surface fields are calculated again. The calculated surface fields of the smooth and rough cavities are compared to determine the extent of the field enhancement, the area over which the enhancement is significant, and which surface features cause large field enhancement. We find that 1% of the surface analyzed has fields enhance by more than 45%. On average the Q-factor is increased by (3.8 ± 1.0) \%.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPRC027
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MOPRC029	Experiment of Plasma Discharge on HWR Cavity for In-Situ Surface Cleaning Study	133
SPWR008	use link to see paper's listing under its alternate paper code
	A.D. Wu, Y. He, T.C. Jiang, C.L. Li, Y.M. Li, W.M. Yue, S.H. Zhang, H.W. Zhao IMP/CAS, Lanzhou, People's Republic of China L.M. Chen Institute of Physics, Chinese Academy of Sciences, Beijing, People's Republic of China L. Yang IHEP, Beijing, People's Republic of China
	Hydrocarbons, which migrate from the vacuum bumps system, will absorb on the cavity surface after periods of operation. The contaminants can reduce the surface electron work function to enhance the field emission effect and restrict the cavity accelerating gradient. The room temperature in-situ plasma surface processing to clean the hydrocarbon contaminants can act as a convenient and efficient technology for the accelerator on line performance recovery. For better control of the discharge inside the cavity, the experiment works on a single HWR cavity aims to research the ignition between the swarm parameters (gas flow, pressure, forward power).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPRC029
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MOPRC030	Traveling Wave Linear Accelerator With RF Power Flow Outside of Accelerating Cavities
MOOP04	use link to access more material from this paper's primary paper code
	V.A. Dolgashev SLAC, Menlo Park, California, USA
	Funding: Work supported by the U.S. DOE under Contract No. DE-AC02-76-SF00515. An accelerating structure is a critical component of particle accelerators for medical, security, industrial and scientific applications. Standing-wave side-coupled accelerating structures are used where available RF power is at a premium, while average current and average RF power lost in the structure are high. These structures are expensive to manufacture and typically require a circulator to divert structure-reflected power away from RF source, klystron or magnetron. In this report a traveling wave accelerating structure is presented which combines high shunt impedance of the side-coupled standing wave structure with such advantages as simpler tuning and manufacturing. In addition, the structure is matched to the RF source so no circulator is needed. This paper presents the motivation for this structure and shows a practical example.
	Slides MOPRC030 [5.459 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOOP04
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MOPRC032	Dry-Ice Cleaning of RF-Structures at DESY
MOOP05	use link to access more material from this paper's primary paper code
	A. Brinkmann, J. Ziegler DESY, Hamburg, Germany
	Dry-Ice cleaning is today a well established cleaning method in matters of reducing harmful dark current and field emission in copper RF-structures like RF-Guns such as for the European XFEL, FLASH and REGAE. This led to the idea to clean longer RF-structures, in particular 3GHz transverse deflecting structures for the European XFEL. We developed a cleaning device with the possibility to clean up to 2 m long structures in horizontal position with an inner diameter of not more than 40 mm. Furthermore this device also allows to clean 9-cell TESLA-type Nb-cavities as well. A report of the technical layout and results of RF-tests will be given.
	Slides MOPRC032 [0.969 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOOP05
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Paper

Title

Page

MOPRC001

Development of Ultracold Neutron Accelerator for Time Focusing of Pulsed Neutrons

MOOP07

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SPWR015

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S. Imajo
Kyoto University, Kyoto, Japan
T. Ino, K. Mishima
KEK, Ibaraki, Japan
Y. Iwashita
Kyoto ICR, Uji, Kyoto, Japan
M. Kitaguchi, H.M. Shimizu
Nagoya University, Nagoya, Japan
S. Yamashita
ICEPP, Tokyo, Japan

Low energy neutron accelerator can be realized by the combination of an adiabatic fast passage spin flipper and a gradient magnetic field. Neutrons have magnetic moments, so that the accumulated potential energies are not cancelled before and after passage of a magnetic field and their kinetic energies change in case their spins are flipped in the field. This accelerator handles lower kinetic energy neutrons than approximately 300 neV. Currently we have developed the advanced version which makes it possible to handle broader kinetic energy range. The design and measured characteristics are described.

Slides MOPRC001 [1.313 MB]

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MOPRC002

Latest News on High Average RF Power Operation at PITZ

MOOP08

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Y. Renier, G. Asova, P. Boonpornprasert, J.D. Good, M. Groß, H. Huck, I.I. Isaev, D.K. Kalantaryan, M. Krasilnikov, O. Lishilin, G. Loisch, D. Melkumyan, A. Oppelt, T. Rublack, F. Stephan
DESY Zeuthen, Zeuthen, Germany
G. Asova
INRNE, Sofia, Bulgaria
M. Bousonville, S. Choroba, S. Lederer
DESY, Hamburg, Germany
C. Saisa-ard
Chiang Mai University, Chiang Mai, Thailand
Q.T. Zhao
IMP/CAS, Lanzhou, People's Republic of China

The Photo Injector Test Facility at DESY in Zeuthen (PITZ) develops, tests and characterizes high brightness electron sources for FLASH and European XFEL. Since these FELs work with superconducting accelerators in pulsed mode, also the corresponding normal-conducting RF gun has to operate with long RF pulses. Generating high beam quality from the photocathode RF gun in addition requires a high accelerating gradient at the cathode. Therefore, the RF gun has to ensure stable and reliable operation at high average RF power, e.g. 6.5 MW peak power in the gun for 650 μs RF pulse length at 10 Hz repetition rate for the European XFEL. Several RF gun setups have been operated towards these goals over the last years. The latest gun setup was brought into the PITZ tunnel on February 10th 2016 and its RF operation started on March 7th. This setup includes RF gun prototype 4.6 with a new cathode contact spring design and an RF input distribution which consists of an in-vacuum coaxial coupler, an in-vacuum T-combiner and 2 RF windows from DESY production. In this contribution we will summarize the experience from the RF conditioning of this setup towards high average RF power and first experience from the operation with photoelectrons.

Slides MOPRC002 [0.563 MB]

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MOPRC003

Dielectric and THz Acceleration (Data) Programme at the Cockcroft Institute

MOOP09

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S.P. Jamison, Y.M. Saveliev
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
R.B. Appleby, H.L. Owen, T.H. Pacey, T.H. Pacey, G.X. Xia
UMAN, Manchester, United Kingdom
G. Burtpresenter, R. Letizia, C. Paoloni
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
A.W. Cross
USTRAT/SUPA, Glasgow, United Kingdom
D.M. Graham
The University of Manchester, The Photon Science Institute, Manchester, United Kingdom
C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: This work has been funded by STFC
Normal conducting RF systems are currently able to pro-vide gradients of around 100 MV/m, limited by break-down on the metallic structures. The breakdown rate is known to scale with pulse length and, in conventional RF systems, this is limited by the filling time of the RF struc-ture. Progressing to higher frequencies, from RF to THz and optical, can utilise higher gradient structures due to the fast filling times. Further increases in gradient may be possible by replacing metallic structures with dielectric structures. The DATA programme at the Cockcroft Insti-tute is investigating concepts for particle acceleration with laser driven THz sources and dielectric structures, beam driven dielectric and metallic structures, and optical and infrared laser acceleration using grating and photonic structures. A cornerstone of the programme is the VELA and CLARA electron accelerator test facility at Daresbury Laboratory which will be used for proof-of-principle experiments demonstrating particle acceleration.

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MOPRC004

Beam Orbit Analysis and Correction of the FRIB Superconducting Linac

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.

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MOPRC005

Beam Tuning of Achromatic Bending Areas of the FRIB Superconducting Linac

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.

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MOPRC006

Beam Tuning and Error Analysis of a Superconducting Linac

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.

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MOPRC007

Status of and Plans for the Beam Dynamics Program DYNAC

80

E. Tanke, M. Eshraqi, Y.I. Levinsen, A. Ponton
ESS, Lund, Sweden
S. Valero
CEA, Gif-sur-Yvette, France

A short introduction to the linac beam dynamics code DYNAC will be given. Recently implemented features, such as a Graphical User Interface (GUI), will be presented and benchmarking of the Radio Frequency Quadrupole (RFQ) model will be discussed. Additional planned features to DYNAC and the GUI will be touched upon.

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MOPRC008

Dispersion Free and Dispersion Target Steering Experience at CTF3

83

D. Gamba, R. Corsini, T. Persson, P.K. Skowroński, F. Tecker
CERN, Geneva, Switzerland
P. Burrows
Oxford University, Physics Department, Oxford, Oxon, United Kingdom
P. Burrows
JAI, Oxford, United Kingdom

One of the goals of the CLIC Test Facility (CTF3) at CERN is to demonstrate the feasibility of the CLIC Drive Beam recombination, which takes place in the Drive Beam Recombination Complex (DBRC). The tight geometry of the DBRC together with its strong optics and the high energy-spread of the beam require a careful control of the beam size along the different sections of the DBRC. One of the main contribution to beam size is the dispersion. If uncontrolled, dispersion leads to fast increase of the beam size, hence it may affect the beam current stability of the combined beam. A tool has been implemented at CTF3 to measure and correct dispersion during and after the setup of the machine. Dispersion Free Steering (DFS) has been applied in the upstream drive beam LINAC, while Dispersion Target Steering (DTS) has been used in the rings of the DBRC. In the LINAC the weak optics and the wide dynamic aperture of the beamline allow a straightforward correction. In the DBRC the aperture is tighter, and the strong optics produce non-linear dispersion which one needs to take into account. A general overview of current status and future plans in controlling dispersion at CTF3 will be presented.

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MOPRC009

Simulating Apertures in the Uniform Equivalent Beam Model

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.

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MOPRC011

FRIB Lattice-Model Service for Commissioning and Operation

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 MOPRC011 [1.295 MB]

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MOPRC013

Tracking Based Courant-Snyder Parameter Matching in a Linac with a Strong Space-Charge Force

93

R. Miyamoto
ESS, Lund, Sweden

During the design of a hadron linac, matching at the interfaces of different structures or lattice periods is often performed with the linear approximation of the space-charge force. When space-charge is extremely strong, like in the low energy part of the proton linac of the European Spallation Source, such a matching method is not always good enough and could lead to a residual mismatch at the design level. To avoid this, a matching scheme based on iterations of tracking, thus including the full effect of the space-charge force, is developed. This paper presents the scheme itself as well as its application to the ESS linac.

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MOPRC014

Beam Dynamics Simulations of a High Charge S-Band Photoinjector for Electron Beam Imaging Experiments

97

SPWR004

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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.

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MOPRC015

Development Status of FRIB On-line Model Based Beam Commissioning Application

100

Z.Q. He, M.A. Davidsaver, K. Fukushima, D.G. Maxwell, G. Shen, Y. Zhang, Q. Zhao
FRIB, East Lansing, USA

Funding: The work is supported by the U.S. National Science Foundation under Grant No. PHY-11-02511, and the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661.
The new software FLAME has been developed to serve as physics model used for on-line beam commissioning applications. FLAME is specially designed to cover FRIB modeling challenges to balance between speed and precision. Several on-line beam commissioning applications have been prototyped based on FLAME and tested on the physics application prototyping environment. In this paper, components of the physics application prototyping environment are firstly described. Then, the design strategy and result of the four major applications: baseline generator, cavity tuning, orbit correction, transverse matching, are discussed.

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MOPRC016

RF-Track: Beam Tracking in Field Maps Including Space-Charge Effects, Features and Benchmarks

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.

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MOPRC017

CIADS HEBT Lattice Design

108

SPWR029

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Y.S. Qin
IMP/CAS, Lanzhou, People's Republic of China

Funding: I want to apply for financial support.
CIADS (China Initiative Accelerator Driven System) 600MeV HEBT (High-Energy Beam Transport) will deliver 6 MW beam to the target, with CW (continuous wave) 10 mA beam. The most serious challenges are vacuum differential section and beam uniformization on the target. A novel collimation plus vacuum differential section is proposed in the lattice design. A scanning method is designed for the round beam uniformization on the target.

Poster MOPRC017 [1.273 MB]

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MOPRC018

Improved Beam Dynamics and Cavity RF Design for the FAIR Proton Injector

111

MOOP06

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R. Tiede, A. Almomani, M. Busch, F.D. Dziuba, U. Ratzinger
IAP, Frankfurt am Main, Germany

The FAIR facility at GSI requires a dedicated 70 MeV, 70 mA proton injector for the research program with intense antiproton beams. The main accelerator part consists of six 'Crossbar H-type' (CH) cavities operated at 325 MHz. Based on a linac layout carefully developed over several years, recently the beam dynamics has been revised with the scope of finalising the design and thus being able to start the construction of the main linac components. As compared to previous designs the MEBT behind the RFQ was slightly extended, the gap numbers per CH cavity and the voltage distributions were optimised and the layout of the intermediate diagnostics section including a rebuncher cavity at 33 MeV was redesigned. Finally, detailed machine error studies were performed in order to check the error response of the new design and the steering concept in particular. In the consequence, the final parameters obtained from the beam dynamics update are used for finalizing the CH-DTL cavity design by CST-MWS calculations.

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MOPRC019

Beam Dynamic of Transport Line 1+ with New HRMS for the SPES Project

114

E. Khabibullina
MEPhI, Moscow, Russia
L. Bellan, M. Comunianpresenter, 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.

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MOPRC020

Primary Beam Dynamic Simulation of Double Drift Double Buncher System for SPES Project

117

A.V. Ziiatdinova
MEPhI, Moscow, Russia
L. Bellan, M. Comunianpresenter, 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.

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MOPRC023

Semi-3D Beam-Tracking Code for Electron Injectors Using Bulk-to-Point Calculation Technique for Space Charge Fields

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.

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MOPRC025

Final Design of the Fully Equipped HWR Cavities for SARAF

123

G. Ferrand
CEA/DSM/IRFU, France
L. Boudjaoui, P. Hardy, F. Leseigneur, C. Madec, N. Misiarapresenter, 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.

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MOPRC026

Mechanical Design of the HWR Cavities for the SARAF SRF LINAC

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.

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MOPRC027

Surface Roughness Effect on the Performance of Nb3Sn Cavities

129

SPWR032

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R.D. Porter, D.L. Hall, M. Liepe, J.T. Maniscalco
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: DOE award DE-SC0008431
Surface roughness of current Niobium-3 Tin (Nb3Sn) superconducting radio-frequency (SRF) accelerator cavities can cause enhancement of the surface magnetic field. This enhancement can push the surface magnetic field beyond the critical field, which, if it occurs over a large enough area, can cause the cavity to quench. This paper presents simulations of the surface magnetic field enhancements in SRF cavities caused by the surface roughness of current Cornell Nb3Sn cavities, which have achieved record efficiency. Simple, smooth cavity geometry is defined and surface magnetic fields calculated using SLANS2. The cavity geometry is modified with a small rough region for which the geometry is determined from AFM scans of a Nb3Sn coated sample and the surface fields are calculated again. The calculated surface fields of the smooth and rough cavities are compared to determine the extent of the field enhancement, the area over which the enhancement is significant, and which surface features cause large field enhancement. We find that 1% of the surface analyzed has fields enhance by more than 45%. On average the Q-factor is increased by (3.8 ± 1.0) \%.

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MOPRC029

Experiment of Plasma Discharge on HWR Cavity for In-Situ Surface Cleaning Study

133

SPWR008

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A.D. Wu, Y. He, T.C. Jiang, C.L. Li, Y.M. Li, W.M. Yue, S.H. Zhang, H.W. Zhao
IMP/CAS, Lanzhou, People's Republic of China
L.M. Chen
Institute of Physics, Chinese Academy of Sciences, Beijing, People's Republic of China
L. Yang
IHEP, Beijing, People's Republic of China

Hydrocarbons, which migrate from the vacuum bumps system, will absorb on the cavity surface after periods of operation. The contaminants can reduce the surface electron work function to enhance the field emission effect and restrict the cavity accelerating gradient. The room temperature in-situ plasma surface processing to clean the hydrocarbon contaminants can act as a convenient and efficient technology for the accelerator on line performance recovery. For better control of the discharge inside the cavity, the experiment works on a single HWR cavity aims to research the ignition between the swarm parameters (gas flow, pressure, forward power).

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPRC029

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MOPRC030

Traveling Wave Linear Accelerator With RF Power Flow Outside of Accelerating Cavities

MOOP04

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V.A. Dolgashev
SLAC, Menlo Park, California, USA

Funding: Work supported by the U.S. DOE under Contract No. DE-AC02-76-SF00515.
An accelerating structure is a critical component of particle accelerators for medical, security, industrial and scientific applications. Standing-wave side-coupled accelerating structures are used where available RF power is at a premium, while average current and average RF power lost in the structure are high. These structures are expensive to manufacture and typically require a circulator to divert structure-reflected power away from RF source, klystron or magnetron. In this report a traveling wave accelerating structure is presented which combines high shunt impedance of the side-coupled standing wave structure with such advantages as simpler tuning and manufacturing. In addition, the structure is matched to the RF source so no circulator is needed. This paper presents the motivation for this structure and shows a practical example.

Slides MOPRC030 [5.459 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOOP04

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MOPRC032

Dry-Ice Cleaning of RF-Structures at DESY

MOOP05

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A. Brinkmann, J. Ziegler
DESY, Hamburg, Germany

Dry-Ice cleaning is today a well established cleaning method in matters of reducing harmful dark current and field emission in copper RF-structures like RF-Guns such as for the European XFEL, FLASH and REGAE. This led to the idea to clean longer RF-structures, in particular 3GHz transverse deflecting structures for the European XFEL. We developed a cleaning device with the possibility to clean up to 2 m long structures in horizontal position with an inner diameter of not more than 40 mm. Furthermore this device also allows to clean 9-cell TESLA-type Nb-cavities as well. A report of the technical layout and results of RF-tests will be given.

Slides MOPRC032 [0.969 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOOP05

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