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MOPML015 Simulations and Measurements of the CCL Modules of the LIGHT Accelerator coupling, linac, proton, cavity 429
 
  • V. F. Khan, G. De Michele, S. Fanella, S. H. Gibson, Ye. Ivanisenko, C. Mellace, J.L. Navarro Quirante, C. Zannini
    AVO-ADAM, Meyrin, Switzerland
  • M. Esposito, P. Gradassi
    CERN, Geneva, Switzerland
  
  A 230 MeV proton LINAC system for medical applications is being developed and commissioned for the LIGHT (Linac Image Guided Hadron Therapy) project by AVO-ADAM. The LINAC system consists of a 750 MHz RFQ (Radio frequency quadrupole) for the low energy proton acceleration, 2998 MHz SCDTL (Side Coupled Drift Tube Linacs) for the medium energy and 2998 MHz CCL (Coupled Cavity Linacs) for the high energy. In particular, the CCL accelerating modules are used in the energy range from 37.5 - 230 MeV. In this paper we discuss the 3D EM (electro-magnetic) simulation results and measurements of the CCL modules.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML015  
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TUPAF074 Preliminary Modelling of Radiation Levels at the Fermilab PIP-II Linac linac, proton, booster, radiation 898
 
  • L. Lari, C.M. Baffes, S.J. Dixon, N.V. Mokhov, I.L. Rakhno, I.S. Tropin
    Fermilab, Batavia, Illinois, USA
  • F. Cerutti, L.S. Esposito, L. Lari
    CERN, Geneva, Switzerland
  
  PIP-II is the Fermilab's flagship project for providing powerful, high-intensity proton beams to the laboratory's experiments. The heart of PIP-II is an 800-MeV superconducting linac accelerator. It will be located in a new tunnel with new service buildings and connected to the present Booster through a new transfer line. To support the design of civil engineering and mechanical integration, this paper provides preliminary estimation of radiation level in the gallery at an operational beam loss limit of 0.1 W/m, by means of Monte Carlo calculations with FLUKA and MARS15 codes.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF074  
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TUPMF010 A Conceptual Design of a Compact Wakefield Accelerator for a High Repetition Rate Multi User X-ray Free-Electron Laser Facility wakefield, electron, quadrupole, wiggler 1266
 
  • A. Zholents, D.S. Doran, W.G. Jansma, M. Kasa, R. Kustom, J.G. Power, N.O. Strelnikov, K.J. Suthar, E. Trakhtenberg, I. Vasserman, G.J. Waldschmidt, J.Z. Xu
    ANL, Argonne, Illinois, USA
  • S. Baturin
    Enrico Fermi Institute, University of Chicago, Chicago, Illinois, USA
  • H. Perez
    IIT, Chicago, Illinois, USA
  
  Funding: Supported by U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357
A preliminary design of a collinear wakefield accelerator is described. It is assumed that the array of such accelerators will play a central role in a free-electron laser-based x-ray user facility under consideration at Argonne National Laborator [1]. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF010  
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TUPMF032 RF Conceptual Design of Normal Conducting Cavity for an eRHIC Rapid Cycling Synchrotron cavity, electron, coupling, vacuum 1316
 
  • B. P. Xiao, M. Blaskiewicz, J.M. Brennan, D. Holmes, K.S. Smith, T. Xin, A. Zaltsman
    BNL, Upton, Long Island, New York, USA
  
  Funding: Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE.
The Rapid Cycling Synchrotron (RCS) for the eRHIC Ring-Ring design will provide on energy injection (up to 18 GeV) of high charge, polarized electron bunches to the eRHIC electron storage ring. The RF system comprises a large number of 563MHz fundamental cavities, providing up to 45MV per turn. The cavities will operate in pulsed mode with <20% duty factor, at a repetition rate of 1 Hz. In this paper we report the conceptual RF design of the cavity. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF032  
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TUPML009 Design and Test Plan for a Prototype Corrugated Waveguide wakefield, experiment, simulation, electron 1550
 
  • G.J. Waldschmidt, D.S. Doran, G. Ha, R. Kustom, A. Nassiri, J.G. Power, A. Zholents
    ANL, Argonne, Illinois, USA
  • A.E. Siy
    UW-Madison/PD, Madison, Wisconsin, USA
  
  A cylindrical, corrugated wakefield accelerating structure with a 1 mm radius bore is being designed to facilitate sub-terahertz Čerenkov radiation produced by an elec-tron bunch propagating along the waveguide. A 220 GHz axial mode for the wakefield is being considered. The waveguide is being optimized to maximize the trailing wakefield potential while maintaining a ratio of the trail-ing potential to the peak decelerating voltage in the bunch, or transformer ratio, of approximately 5 for the door step peak current distribution [1]. In order to evalu-ate the manufacturing tolerances and perform rf and electron beam testing of the waveguide, a 21 GHz proto-type waveguide structure will be built consisting of re-configurable parts allowing modelling of various fabrica-tion errors. Measurements with an electron beam will be performed at the Argonne Wakefield Accelerator (AWA) test facility. Analysis of the experimental layout has been performed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML009  
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TUPML074 Resonant Excitation of Accelerating Field in Dielectric Corrugated Waveguide simulation, wakefield, experiment, electron 1715
 
  • A. Lyapin, S.T. Boogert, K. Lekomtsev
    JAI, Egham, Surrey, United Kingdom
  • A. Aryshev
    KEK, Ibaraki, Japan
  • A.A. Tishchenko
    MEPhI, Moscow, Russia
  
  Funding: This project has received funding from the European Union Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 655179.
Beam driven dielectric wakefield accelerators (DWAs) [*] typically operate in the terahertz frequency range, which pushes the plasma breakdown threshold for surface electric fields into the multi GV/m range. DWA technique allows one to accommodate a significant amount of charge per bunch, and opens access to conventional fabrication techniques for the accelerating structures. Resonant excitation of coherent Cherenkov radiation in DWA by a multi-bunch beam was used for selective resonant mode excitation [**] and enhancement of accelerating wakefield [***]. We investigate the resonant excitation of Cherenkov Smith-Purcell radiation [****] in a corrugated cylindrical waveguide by a multi-bunch electron beam. The accelerating field is calculated using Particle in Cell simulations and some basic post-processing is done in order to estimate the possible enhancement of the accelerating field. The aim of this work is to investigate regimes of the resonant excitation that can potentially produce accelerating gradients above 1 GV/m.
* C. Jing, Rev. Acc. Phys. and Tech. 9, 127 (2016).
** G. Andonian, APL 98, 202901 (2011).
*** J.G. Power, PRSTAB 3, 101302 (2000).
**** A.A. Ponomarenko, A.A. Tishchenko, NIMB 309, 223 (2013).
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML074  
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WEPAF079 A Smart Framework for the Availability and Reliability Assessment and Management of Accelerators Technical Facilities operation, framework, controls, experiment 2024
 
  • L. Serio, A. Castellano, U. Gentile
    CERN, Geneva, Switzerland
  • F. Antonello, P. Baraldi, E. Zio
    Politecnico di Milano, Milan, Italy
  
  CERN operates and maintains a large and complex technical infrastructure serving the accelerator complex and experiments detectors. A performance assessment and enhancement framework based on data mining, artificial intelligence and machine-learning algorithms is under development with the objective of structuring, collecting and analyzing systems and equipment operation and failure data, to guide the identification and implementation of adequate corrective, preventive and consolidation interventions. The framework is designed to collect and structure the data, identify and analyze the associated driving events. It develops dynamically functional dependencies and logic trees, descriptive and predictive models to support operation and maintenance activities to improve the reliability and availability of the installations. To validate the performance of the framework and quality of the algorithms several case studies are being carried out. We report on the design, implementation and on the preliminary results inferred on historical and live stream data from CERN's technical infrastructure. Proposal for the full deployment and expected long-term capabilities will also be discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF079  
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WEPAK008 Reconstructing Space-Charge Distorted IPM Profiles with Machine Learning Algorithms electron, simulation, space-charge, network 2099
 
  • D.M. Vilsmeier, M. Sapinski, R. Singh
    GSI, Darmstadt, Germany
  • J.W. Storey
    CERN, Geneva, Switzerland
  
  Measurements of undistorted transverse profiles via Ionization Profile Monitors (IPMs) may pose a great challenge for high brightness or high energy beams due to interaction of ionized electrons or ions with the electromagnetic field of the beam. This contribution presents application of various machine learning algorithms to the problem of reconstructing the actual beam profile from measured profiles that are distorted by beam space-charge interaction. (Generalized) linear regression, artificial neural network and support vector machine algorithms are trained with simulation data, obtained from the Virtual-IPM simulation tool, in order to learn the relation between distorted profiles and original beam dimension. The performance of different algorithms is assessed and the obtained results are very promising for testing with simulation data.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAK008  
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WEPAL048 Control Command Strategy for the ThomX Accelerator controls, HOM, TANGO, network 2284
 
  • H. Guler, N. ElKamchi, P. Gauron, H. Monard
    LAL, Orsay, France
  
  ThomX is an accelerator project designed to create a compact X Compton Backscattering Source for medical and cultural heritage applications. Control-Command (CC) system is a central part for the commissionning. ThomX CC is designed with TANGO SCADA system. This framework allows to control several devices from several places with the same SCADA System. TANGO Device Servers are software programs allowing to control devices and to implement data processing and presentation layers. For commissionning, experts need to access values of each device in a convenient way to allow them to modify parameters and check effect of a configuration on hardware. CC is a key part for this stage. Several GUI have been designed and gathered into several panels in collaboration with each expert group to gather their needs.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL048  
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WEPAL049 Simulating Non-Relativistic Beams Using Helical Pulse Lines impedance, simulation, site, ECR 2288
 
  • C.J. Richard
    NSCL, East Lansing, Michigan, USA
  • S.M. Lidia
    FRIB, East Lansing, USA
  
  Funding: Work supported by the US Department of Energy, Office of Science, High Energy Physics under Cooperative Agreement award number DE-SC0018362.
Benchtop calibration of capacitive beam position monitors (BPMs) in low energy beamlines is challenging due to non-relativistic effects. Typical benchtop calibrations cannot account for these effects because they rely on speed of light fields transmitted along a straight wire. However, it is possible to replicate the electromagnetic fields generated by non-relativistic beams using a helical line pulse instead of a straight wire. In order to properly replicate the fields from a beam, a method must be developed for tailoring input pulses into the helical line to match bunch shape and a model of the impedance of the helix should be developed to assist with matching. This paper uses the sheath helix model to analyze signal propagation along a helical line in the time domain, with attention to dispersive effects and impedance matching. The results from this model are then compared to Microwave Studio simulations. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL049  
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WEPAL063 A Method to Tune Pulse Magnets' Waveforms injection, kicker, power-supply, septum 2320
 
  • T.Y. Lee, B.Y. Chen, S. Fann, C.S. Huang, C.H. Kuo, C.C. Liang, W.Y. Lin, Y.-C. Liu, Y.C. Yang
    NSRRC, Hsinchu, Taiwan
  
  Pulse magnets are used in storage ring injection kickers. The waveform of the the four kickers have strong relation with injection efficiency. A slightly offset of waveform may cause the four kickers mismatched, which would lead to storaged beam loss and decrease injection efficiency. In order to define the peak value and timing of the half-sine waveform which has noises interfering diagnosis, a curve-fitting method was introduced to monitor and fine-tuning the waveform. The waveforms' data are also archived for reference in case of replacing power supplies. By using this method, it helps to retain a consistent injection efficiency after the power supplies maintenance or replacement.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL063  
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WEPMF005 Design and Testing of a 12 kW, 352 MHz Solid State rf System at the Advanced Photon Source cavity, controls, operation, simulation 2378
 
  • D. Horan, D.J. Bromberek, A. Goel, T.J. Madden, A. Nassiri, G.J. Waldschmidt
    ANL, Argonne, Illinois, USA
  
  A 12 kW, 352 MHz rf power amplifier system was designed and constructed at the Advanced Photon Source as a research and development test bed for eventual development of a 200 kW cw rf system capable of supporting accelerator beam operation. The system utilizes six 2 kW laterally diffused metal oxide field effect transistor (MOSFET) rf amplifiers, an output cavity combiner terminated with a WR2300 waveguide output flange, and a monitoring system based on programmable logic controller technology. The combining cavity has a total capacity of 108 two-kilowatt inputs to support eventual operation up to 216kW maximum output power. Design details and operational performance of the 12 kW system will be discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF005  
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WEPMF031 Development of a High-Power High-Directivity Directional Coupler and Four Power Dividers for S-Band coupling, vacuum, MMI, simulation 2422
 
  • X. He, J. Lei, J.R. Zhang
    IHEP, Beijing, People's Republic of China
  
  A novel Bethe-hole S band directional coupler has been designed based on some structural optimizations, the prototype has been tested with a Directivity of more than 30 dB. The new directional coupler can also hold higher power compared to the old type, which is more useful for the future accelerator applications. Four power dividers using different structures are studied and the best one is chosen for fabrication. The prototype with matching rod in the middle has got qualified microwave cold test results and has been used during the whole microwave commissioning of an accelerating structure, the performance is quite stable.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF031  
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WEPMF062 Simulation of Cavity Conditioning for the Diamond SCRF Cavity cavity, coupling, simulation, operation 2509
 
  • S.A. Pande, C. Christou, P. Gu
    DLS, Oxfordshire, United Kingdom
  
  Diamond SCRF cavities are pulse conditioned every week in order to keep them operating reliably. During conditioning, the cavities are detuned in order to sweep the standing wave through the waveguide. To match these cavities at lower voltage (typically < 1.4 MV) and at higher power, 3 stub tuners are used in the waveguide feed. Simulations with CST studio show that a strong SW field exists between the RF window and the matching posts. As the cavity is detuned the electric field maximum passes through the window causing heating of the ceramic. Temperature measurements with thermal camera reveal that the temperature of the window increases to maximum when the cavity is detuned towards higher frequency. Based on the simulation results and the measurements, it was decided to reduce the conditioning voltage. These results are summarised.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF062  
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WEPMF069 High Shunt Impedance Accelerating Structure with Distributed Microwave Coupling cavity, coupling, distributed, impedance 2531
 
  • S.P. Antipov, R.A. Kostin, S.V. Kuzikov
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • V.A. Dolgashev
    SLAC, Menlo Park, California, USA
  
  Funding: DOE SBIR
Conventional traveling wave or pi-phase advance standing wave structures use coupling of the microwave power through the beam pipe. This feature constrains the cavity shunt impedance (efficiency) to relatively small values. As microwave power flows through the accelerating cells in such structures, the probability of breakdown in high gradient operation is greatly increased. In this paper we present results from an accelerating structure prototype with distributed microwave coupling, an approach invented at SLAC. These structures include one or more parallel waveguides which are loaded by accelerating cavities. In this configuration accelerating cavities are fed independently and completely isolated at the beam pipe. Thus there is no microwave power flow through the accelerating cavity, making this geometry favorable for high gradient operation and maximizing the shunt impedance. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF069  
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WEPMF074 High Power Conditioning of X-Band RF Components operation, vacuum, cavity, hardware 2545
 
  • N. Catalán Lasheras, H. Damerau, R.L. Gerard, A. Grudiev, G. McMonagle, J. Paszkiewicz, A. Solodko, I. Syratchev, B.J. Woolley, W. Wuensch, V. del Pozo Romano
    CERN, Geneva, Switzerland
  • T.G. Lucas, M. Volpi
    The University of Melbourne, Melbourne, Victoria, Australia
  • S. Pitman
    Lancaster University, Lancaster, United Kingdom
  • A. Vnuchenko
    IFIC, Valencia, Spain
  
  As part of the effort to qualify CLIC accelerating struc-tures prototypes, new X-band test facilities have been built and commissioned at CERN in the last years. In this context, a number of RF components have been designed and manufactured aiming at stable operation above 50 MW peak power and several kW of average power. All of them have been tested now in the X-band facility at CERN either as part of the facility or in dedicated tests. Here, we describe shortly the main design and manufac-turing steps for each component, the testing and eventual conditioning as well as the final performance they achieved.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF074  
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WEPMF079 Experimental Modal Analysis of Lightweight Structures used in Particle Detectors: Optical non-contact Method laser, experiment, detector, operation 2565
 
  • M. Guinchard, M. Angeletti, F.B. Boyer, A. Catinaccio, C.G. Gargiulo, L.L. Lacny, E.L. Laudi, L.S. Scislo
    CERN, Geneva, Switzerland
  
  CERN's specialized structures such as particle detectors are built to have high rigidity and low weight, which comes at a cost of their high fragility. Shock and vibration issues are a key element for their successful transport, handling operations around the CERN infra-structure, as well as for their operation underground. The experimental modal analysis measurement technique is performed to validate the Finite Element Analysis in the case of complex structures (with cables and substructure coupling). In the case of lightweight structures, standard contact measurements based on accelerometers are not possible due to the high mass ratio between the accelerometers and the structure itself. In such a case, the vibration of the structure can be calculated based on the Doppler shift of the laser beam reflected off the vibrating surface. This paper details the functioning and application of an advanced laser-scanning vibrometry system, which utilizes the fore-mentioned non-contact method. The results of the Experimental Modal Analysis of selected lightweight structure using this instrument is also presented and discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF079  
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WEPMF081 Mechanical Strain Measurements Based on Fiber Bragg Grating Down to Cryogenic Temperature - R&D Study and Applications radiation, cryogenics, superconducting-magnet, experiment 2572
 
  • M. Guinchard, A. Bertarelli, L. Bianchi, F.B. Boyer, M. Cabon, M. Calviani, O. Capatina, A. Catinaccio, P. Ferracin, P. Grosclaude
    CERN, Geneva, Switzerland
  
  In recent years, optical fiber sensors have been increasingly used due to their outstanding performances. Their application is preferable in case of special requirements that exclude the application of conventional electrical sensors. The scientific background of optical fiber sensors is well developed. However, the characteristic of sensors employed in rather harsh environments is often different from the one determined in laboratory conditions or prior to their installation. In order to achieve long-term stable functioning and reliable measurement under severe working environments, such as those occurring at CERN (radiation, cryogenics, high magnetic and electrical field), a statistical measurement campaign was carried out following the international standard ISO 5725. The paper describes the ongoing study to define the accuracy of optical fiber sensors based on Fiber Bragg Grating (FBG) for strain measurements, from room temperature down to 4.2 K. It also describes some of the demanding applications for which optical fiber sensors have been deployed to perform experimental strain measurements (e.g. detectors components, high-energy beam targets and dumps, superconducting magnets).  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF081  
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WEPMK014 A New Design for the Hilumi Radio-Frequency Dipole Bare Cavity cavity, niobium, resonance, SRF 2659
 
  • M. Parise, P. Berrutti, L. Ristori
    Fermilab, Batavia, Illinois, USA
  
  Crabbing cavities are one of the technological landmark that will allow the LHC to optimize its per-formance and maximize its integrated luminosity by allowing a head-on collision between the bunches despite the non-zero crossing angle. A total of 8 crab cavities will be installed in the interaction region of each of the two experiments, ATLAS and CMS. In the last years, the two types of crab cavities were de-signed, built and tested under the US-LARP R&D pro-gram. Horizontal crabbing is obtained with a radio-frequency dipole cavity (RFD) designed by Old Do-minion University (ODU), SLAC and Fermilab (FNAL). In this paper a new mechanical design, that uses passive stiffeners, is presented. This design leads to a decrease of the Lorentz Force Detuning frequency shift, satisfy the requirements on pressure sensitivity, validate the structural integrity and increase the tuner sensitivity and the maximum elastic tuning range. Furthermore, it will be possible to greatly simplify the shape of the magnetic shield and Helium vessel with respect to the current design.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMK014  
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WEPML003 Precision Q0 Measurement of an SRF Cavity with a Digital RF Techniques cavity, coupling, SRF, impedance 2674
 
  • J.P. Holzbauer, B.M. Hanna, Y.M. Pischalnikov, W. Schappert, D.A. Sergatskov, A.I. Sukhanov
    Fermilab, Batavia, Illinois, USA
  
  Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
Direct measurement of the quality factor of SRF cavity using traditional RF techniques is essential for cavity production and development. Systematic effects of the measurement can contribute significant amounts of error to these measurements if not accounted for. This paper will present measurements taken at Fermilab using a digital RF system to characterize and correct for these systematic effects and directly measure the quality factor versus gradient curve for a single spoke resonator in the Spoke Test Cryostat at Fermilab. These measurements will be compared to traditional calorimetric measurements, and a discussion of improving/extending these techniques to other testing situations will be included. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML003  
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WEPML047 Study on RF Coupler Kicks of SRF Cavities in the BESSY VSR Module cavity, SRF, storage-ring, HOM 2804
 
  • A.V. Tsakanian, T. Mertens
    Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), Berlin, Germany
  • H.-W. Glock, J. Knobloch, M. Ries, A.V. Vélez
    HZB, Berlin, Germany
  
  The BESSY VSR upgrade of the BESSY II light source represents a novel approach to simultaneously store long (ca. 15ps) and short (ca. 1.7ps) bunches in the storage ring with the standard user optics. This challenging goal requires installation of four new SRF multi-cell cavities (2x1.5GHz and 2x1.75GHz) equipped with strong waveguide HOM dampers ensuring tolerable beam coupling impedance, necessary for stable operation. These cavities will operate at high 20MV/m in CW mode and at the zero-crossing phase according to the accelerating voltage. Consequently the transverse voltages will be maximum and can impact the transverse beam dynamics. The asymmetric character of those transverse kicks are caused by cavity fundamental power couplers (FPC) with strong monopole terms, introducing transverse kick to on-axis particles. Different FPC orientations were analyzed to optimize the net coupler kick from the four cavity chain. The coupler kick strength of each cavity is estimated taking into account accelerating mode amplitudes and phases required for operation in VSR mode.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML047  
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WEPML048 HOM Power Levels in the BESSY VSR Cold String HOM, cavity, SRF, simulation 2808
 
  • A.V. Tsakanian, T. Flisgen
    Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), Berlin, Germany
  • H.-W. Glock, J. Knobloch, A.V. Vélez
    HZB, Berlin, Germany
  
  The BESSY VSR upgrade of the BESSY II light source represents a novel approach to simultaneously store long (ca. 15ps) and short (ca. 1.7ps) bunches in the storage ring. This challenging goal requires installation of four new SRF cavities (2x1.5 GHz and 2x1.75 GHz) in one module for installation in a single straight. These cavities are equipped with strong waveguide HOM dampers necessary for stable operation. The expected HOM power and spectrum has been analyzed for the complete cold string. The cold string is a combination of various elements such as SRF cavities, bellows with and without shielding, warm HOM beampipe absorbers and UHV pumping domes. The presented study is performed for various BESSY VSR bunch filling patterns with 300 mA beam current. The contribution of each component to the total HOM power is presented. In addition the optimization of different cavity arrangements in the module is performed in order to reach the optimal operation conditions with equally distributed power levels along the string and tolerable beam coupling impedance.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML048  
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WEPML053 Availability of the TiN Coating-Free Ceramic in the STF-type Power Coupler for ILC electron, SRF, vacuum, cryomodule 2819
 
  • Y. Yamamoto, E. Kako, T. Matsumoto, S. Michizono, A. Yamamoto
    KEK, Ibaraki, Japan
  • M. Irikura, M. Ishibashi, H. Yasutake
    Toshiba Electron Tubes & Devices Co., Ltd (TETD), Tochigi, Japan
  • C. Julie, E. Montesinos
    CERN, Geneva, Switzerland
  
  In the Superconducting RF Test Facility (STF) in KEK, the research and development for the power coupler with the TiN coating-free ceramic has been done from 2014. In 2016, the high power test at the test bench was stopped due to the worse vacuum level by the unusual heating around the RF window with the TiN coating-free ceramic and the coaxial tapered section, which was caused by the enormous emission of the secondary electrons from the ceramic. And, the situation was never also changed by the ultrapure water rinsing for the power couplers several times. However, in 2017, the ultrasonic rinsing was done for the power couplers for the first time by the collaboration between KEK and TETD. After that, the situation was drastically improved, and the secondary electron emission almost disappeared even in the higher RF duty. This shows that the TiN coating-free ceramic is the prospective item for the cost reduction in ILC. In this report, the recent result for the power coupler with the TiN coating-free ceramic will be presented in detailed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML053  
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THPAF083 LINAC-Multitool - an Open Source Java-Toolkit linac, cavity, MMI, simulation 3179
 
  • M. Schwarz, D. Bade, J. Corbet, H. Podlech
    IAP, Frankfurt am Main, Germany
  
  Funding: Work supported by BMBF contr. No. 05P15RFRBA and HIC for FAIR.
Dedicating more precious time to advanced research instead of spending it towards time-consuming routine tasks is a desirable goal in particle accelerator simulation and development. Requirements engineering was started at IAP in order to identify routine processes at our institute's R&D that can be automated or simplified. Results indicated that there were several areas to consider: Bead pull measurements, data processing and visualization for the beam dynamics code LORASR, CST field map processing for the use with TraceWin, conversion between different particle distribution data formats and more. Subsequently development of the LINAC-Multitool started to rationalize these processes and replace preexisting scripts also to ensure consistency of results and increase transparency and reliability of computation. In order to guarantee maintainability, expandability and platform independence, LINAC-Multitool is programmed using Java and will be open source. This contribution presents the current state of development. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF083  
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THPAF085 Estimation of Dielectric Losses in the Bessy VSR Warm Beam Pipe Absorbers cavity, HOM, storage-ring, wakefield 3185
 
  • T. Flisgen
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
  • H.-W. Glock
    HZB, Berlin, Germany
  • A.V. Tsakanian
    Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), Berlin, Germany
  
  Funding: Work supported by the German Bundesministerium für Bildung und Forschung, Land Berlin and grants of Helmholtz Association.
Currently Helmholtz Zentrum Berlin prepares the update of the BESSY II ring to BESSY VSR. The updated ring will be capable to simultaneously store short and long bunches to satisfy the various user demands. For this sake, a cryomodule accommodating two 1.5 GHz and two 1.75 GHz superconducting cavities will be installed into the storage ring. The cavity string will be equipped with warm dielectric absorber rings at both ends. Together with the waveguide dampers of the cavities, these rings damp electromagnetic fields excited by the beam. This contribution presents the estimation of the dielectric losses in the beam pipe absorber rings of the BESSY VSR module. The presented approach is based on determining a broad band impedance of the dielectric ring by exciting the numerical model with a single broad band Gaussian bunch. Subsequently, the power deposited into the ring is estimated in frequency domain by multiplying the impedance with the square of the beam current for all considered harmonics of the beam. Finally, these power contributions are added up. In addition to details of the scheme, the contribution presents results for the recent absorber layout of the BESSY VSR string. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF085  
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THPAK010 Optimization on the Optical Resonator of CTFEL FEL, radiation, coupling, electron 3228
 
  • X.J. Shu, Y.H. Dou
    Institute of Applied Physics and Computational Mathematics, People's Republic of China
  • M. Li, Z. Xu, Y. Xu, X. Yang
    CAEP/IAE, Mianyang, Sichuan, People's Republic of China
  
  Funding: Program for the National Science Foundation of China (Grant No. 11105019) and the National Science Device Exploitation Foundation of China (Grant No. 2011YQ130018).
A high power THz free electron laser (FEL) facility is under construction at China Academy of Engineering Physics (CTFEL) since October, 2011. The radiation frequency of the FEL facility will be tuned in range of 1~3 THz and the average output power is about 10 W. The system mainly consists of a GaAs photoemission DC gun, superconductor accelerator, the hybrid wiggler, optical cavity. The first lasing is obtained on Aug. 29, 2017. The optical resonator of CTFEL is optimized to ensure wavelength tunable in a wide range and high power operation. The FEL power strongly depends on the performance of the optical resonator including output efficiency, gain and round-trip loss. The optical resonator consists of metal-coated reflect mirror, the center-hole output mirror, waveguide. The influence of waveguide and Rayleigh length on the quality of optical cavity is evaluated by the 3D-OSIFEL code. The waveguide size, mirror curvature radius, output hole radius is optimized to different frequencies between 1 THz to 3 THz. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK010  
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THPAK069 Open XAL Status Report 2018 cavity, linac, MMI, diagnostics 3388
 
  • A.P. Zhukov, C.K. Allen, A.P. Shishlo
    ORNL, Oak Ridge, Tennessee, USA
  • C.P. Chu, Y. Li
    IHEP, Beijing, People's Republic of China
  • J.F. Esteban Müller, E. Laface, Y. Levinsen, N. Milas, C. Rosati
    ESS, Lund, Sweden
  • P. Gillette, G. Normand, A. Savalle
    GANIL, Caen, France
  • X.H. Lu
    CSNS, Guangdong Province, People's Republic of China
  
  The Open XAL accelerator physics software platform is being developed through an international collaboration among several facilities since 2010. The goal of the collaboration is to establish Open XAL as a multi-purpose software platform supporting a broad range of tool and application development in accelerator physics and high-level control (Open XAL also ships with a suite of general purpose accelerator applications). This paper discusses progress in beam dynamics simulation, new RF models, and updated application framework along with new generic accelerator physics applications. We present the current status of the project, a roadmap for continued development and an overview of the project status at each participating facility.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK069  
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THPAL005 Construction and Commissioning of the S-Band High-Gradient RF Laboratory at IFIC klystron, network, linac, cathode 3619
 
  • D. Esperante Pereira, C. Blanch Gutiérrez, M. Boronat, J. Fuster, D. Gonzalez Iglesias, A. Vnuchenko
    IFIC, Valencia, Spain
  • N. Catalán Lasheras, G. McMonagle, I. Syratchev, W. Wuensch
    CERN, Geneva, Switzerland
  • A. Faus-Golfe
    LAL, Orsay, France
  • B. Gimeno
    UVEG, Burjasot (Valencia), Spain
  
  An S-Band High-Gradient (HG) Radio Frequency (RF) laboratory is under construction and commissioning at IFIC. The purpose of the laboratory is to perform investigations of high-gradient phenomena and to develop normal-conducting RF technology, with special focus on RF systems for hadron-therapy. The layout of the facility is derived from the scheme of the Xbox-3 test facility at CERN* and uses medium peak-power (7.5 MW) and high repetition rate (400 Hz) klystrons, whose RF output is combined to drive two testing slots to the required power. The design and construction of the various components of the system started in 2016 and has been completed. The installation and commissioning of the laboratory is progressing, with first results expected before mid 2018. The technical characteristics of the different elements of the system and the commissioning status together with preliminary results are described.
* N. Catalan Lasheras, et al., 'Commissioning of Xbox3: a very high capacity X-band RF test stand', Proc. LINAC2016, East Lansing, USA, September 2016.
 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL005  
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THPAL009 A TM01 Mode Launcher With Quadrupole Field Components Cancellation for High Brightness Applications network, quadrupole, gun, brightness 3631
 
  • G. Castorina
    INFN-Roma1, Rome, Italy
  • A.D. Cahill, J.B. Rosenzweig
    UCLA, Los Angeles, California, USA
  • F. Cardelli, G. Franzini, A. Marcelli, B. Spataro
    INFN/LNF, Frascati (Roma), Italy
  • L. Celona, S. Gammino, G. Torrisi
    INFN/LNS, Catania, Italy
  • V.A. Dolgashev
    SLAC, Menlo Park, California, USA
  • L. Ficcadenti
    Rome University La Sapienza, Roma, Italy
  • M. Migliorati, A. Mostacci, L. Palumbo
    Sapienza University of Rome, Rome, Italy
  • G. Sorbello
    University of Catania, Catania, Italy
  
  The R&D of high gradient radiofrequency (RF) devices is aimed to develop innovative accelerating structures based on new manufacturing techniques and materials in order to construct devices operating with the highest accelerating gradient. Recent studies have shown a large increase in the maximum sustained RF surface electric fields in copper structures operating at cryogenic temperatures. These novel approaches allow significant performance improvements of RF photoinjectors. Indeed the operation at high surface fields results in considerable increase of electron beam brilliance. This increased brilliance requires high field quality in the RF photoinjector and specifically in its power coupler. In this work we present a novel power coupler for the RF photoinjector. The coupler is a compact X-band TM01 mode launcher with a fourfold symmetry which minimized both the dipole and the quadrupole RF components.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL009  
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THPAL018 DQW HOM Coupler Design for the HL-LHC HOM, impedance, cavity, simulation 3663
 
  • J.A. Mitchell
    Lancaster University, Lancaster, United Kingdom
  • G. Burt
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • R. Calaga
    CERN, Geneva, Switzerland
  • S. Verdú-Andrés, B. P. Xiao
    BNL, Upton, Long Island, New York, USA
  
  HOMs in the DQW crab cavity can produce large heat loads and beam instabilities as a result of the high current HL-LHC beams. The DQW crab cavity has on-cavity, coaxial HOM couplers to damp the HOMs whilst providing a stop-band response to the fundamental mode. Manufacturing experience and further simulations give rise to a set of desirable coupler improvements. This paper will assess the performance of the current HOM coupler design, present operational improvements and propose an evolved design for HL-LHC.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL018  
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THPAL027 Transverse RF Deflecting Structures for the MAX IV LINAC linac, polarization, klystron, emittance 3684
 
  • D. Olsson, F. Curbis, E. Mansten, S. Thorin, S. Werin
    MAX IV Laboratory, Lund University, Lund, Sweden
  
  The MAX IV LINAC operates both as a full-energy injector for two electron storage rings, and as a driver for a Short Pulse Facility (SPF). A soft X-ray Laser (SXL) beamline will also be installed in the end of the existing LINAC. For SPF and SXL operation, it is important to characterize beam parameters such as bunch profile, slice energy spread and slice emittance. For these measurements, two 3 m long transverse deflecting RF structures with a matching section are being developed. The structures are operating at S-band and have variable polarizations. When fed via a SLED pulse compressor, the two structures can generate a total integrated deflecting voltage higher than 100 MV which is sufficient for measurements with temporal resolutions down to 1 fs. This paper describes the initial RF design of the deflecting structures.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL027  
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THPAL063 RF and Thermo-Mechanical Considerations in Designing the Waveguide Iris Coupler for the Drift Tube Linac in the ORNL Spallation Neutron Source cavity, DTL, simulation, vacuum 3796
 
  • S.W. Lee, Y.W. Kang
    ORNL, Oak Ridge, Tennessee, USA
  
  Funding: This work was supported by SNS through UT Battelle, LLC, under contract DE AC05 00OR22725 for the U.S.DOE
The Spallation Neutron Source (SNS) employs tapered ridge waveguide iris couplers to power six drift tube linac (DTL) cavity structures with pulsed RF systems using 2.5MW klystrons at 402.5MHz. All DTL iris couplers have been operating continuously for more than a decade without replacement. Transferring high RF energy to the cavities requires robust RF and mechanical performances with respect to power dissipation, electrical breakdown, and vacuum pressure. Considering the upcoming full 1.4MW operation and the future proton power upgrade (PPU) project, the structural design and the material selection needed to be reviewed for potential spare manufacturing. The existing design and the modified design with improvements to the coupler have been numerically studied. For the study, 3D models were used for RF and structural characterizations of the waveguide iris couplers on the DTL cavity. RF and thermo-mechanical co-simulations were performed to assess the effects of using the different materials and the structural modification. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL063  
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THPAL104 The Magnetic Field Measurement Systems for a Cryogenic Undulator and a Superconducting Undulator at SSRF cryogenics, SRF, undulator, vacuum 3878
 
  • H.F. Wang
    SSRF, Shanghai, People's Republic of China
  • M.F. Qian, W. Zhang, Q.G. Zhou
    SINAP, Shanghai, People's Republic of China
  
  Two cryogenic permanent magnet undulators (CPMU) have been developed and assembled into storage ring at SSRF，in order to reach larger magnetic field and to produce higher brilliance in the hard X rays domain. Lowering the temperature of permanent magnets increases the magnetic produced field about by 15%. A set of magnetic measurement system and a suitable magnetic field optimization method have been developed. The design of a magnetic measurement bench based on a Hall probe to perform low temperature measurement has been finished. In addition, a 50-period superconducting undulator prototype with 16mm period length is also being developed for more photons with some specific photon characteristic. And a special hall probe system has been built in order to characterize the magnetic field distribution of the SCU prototype.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL104  
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THPAL150 Development of Tsinghua X-Band High Power Test Facility klystron, controls, vacuum, software 3999
 
  • M.M. Peng, D.Z. Cao, W. Gai, Y.L. Jiang, J. Liu, J. Shi, P. Wang
    TUB, Beijing, People's Republic of China
  
  The X band high power test facility consists of a 11.424 GHz, 50 MW CPI klystron and a ScandiNova pulse modulator at Tsinghua University has been built since Sept 2017 and the output RF power has reached 60 MW with 200 ns pulse width at a repetition frequency of 10. The klystron output RF pulse will eventually be 50 MW at a 1.5 μs. A group of cylinder pulse compressor will be installed. High gradient accelerating structures for research and TTX will be tested on this facility.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL150  
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THPAL152 Study of X-Band Phase Shifter Using Ferrite Material cavity, simulation, coupling, insertion 4005
 
  • Y.L. Jiang, D.Z. Cao, H.B. Chen, J. Shi, P. Wang, H. Zha
    TUB, Beijing, People's Republic of China
  
  Ferrite has the feature of the permeability depended on the external static magnetic field, thus could be used to shift the phase of the propagating radio frequency (RF) signal. In this paper, we introduce a novel design of ferrite-based RF phase shifter. The design changes the resonant frequency of a ferrite-filled pill-box cavity to implement the phase changing. This design has a lower local RF field and a higher sensitivity on the phase changing than those of waveguide phase shifter, which may bring advantages such as higher power capacity, fast changing speed and lower insertion loss. Theory and simulation results are also presented in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL152  
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THPAL154 High-Gradient Performance of X-Band Choke-Mode Structures ECR, experiment, HOM, damping 4011
 
  • X.W. Wu, D.Z. Cao, H.B. Chen, J. Shi, H. Zha
    TUB, Beijing, People's Republic of China
  • T. Abe, T. Higo, S. Matsumoto
    KEK, Ibaraki, Japan
  
  Funding: National Natural Science Foundation of China (Grant No. 11135004)
The choke-mode accelerating structure is one of the higher-order-mode (HOM) damping structures. It has the advantage of relatively simple fabrication and low surface magnetic field. C-band choke-mode accelerating structures have been successfully applied in multibunch XFEL. However, the X-band choke-mode study remains in the theoretical design stage. The high-gradient performance of the choke is still unknown. Five different single-cell choke-mode accelerating structures were designed, fabricated and high-gradient tested to study the related RF breakdown characteristics. It was observed that high electric field and small choke dimension caused serious breakdowns in the choke which was the main limitation of the high-gradient performance. The Choke-mode accelerating structures reached 130 MV/m by decreasing the electric field and increasing the choke gap. A new quantity was proposed to give the high-gradient performance limit of choke-mode accelerating structures due to RF breakdown. The new quantity was obtained from the summary of the high-gradient experiments and could be used to guide high-gradient choke-mode accelerating structure design. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL154  
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THPAL156 High-Power Test of a Compact X-Band RF Rotary Joint linac, network, cathode, electromagnetic-fields 4017
 
  • J. Liu, H.B. Chen, J.Q. Qiu, J. Shi, Z.H. Wang, X.W. Wu, H. Zha
    TUB, Beijing, People's Republic of China
  
  A compact X-band (9.3 GHz) RF rotary joint has been developed in the accelerator laboratory of Tsinghua University. Cold measurements on the rotary joint using Vector-Network showed good results. In recent high-power tests, the RF rotary joint was operated under a 1.6 MW X-band magnetron. The incident power, the transmitted power and the pulse width of this rotary joint have been measured. The transmitted power kept stable in different rotation angle. In this paper, the setup and results of the high-power tests of this RF rotary joint are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL156  
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THPAL158 Development of an Half-Cell Accelerating Structure in Tsinghua cavity, simulation, alignment, radiation 4023
 
  • M.M. Peng, W. Gai, J. Shi, Z.H. Wang, H. Zha
    TUB, Beijing, People's Republic of China
  
  The half-cell high gradient accelerating structure is attractive for its easy manufacturing and good alignment. A structure with 12 cells has been designed for the frequency of 11.424 GHz and a cold test will be conducted. Two different mechanical factory manufacture with same machining drawing and the results will be compared.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL158  
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THPMK058 RF Design of the X-band Linac for the EuPRAXIA@SPARC_LAB Project klystron, linac, booster, electron 4422
 
  • M. Diomede
    Sapienza University of Rome, Rome, Italy
  • D. Alesini, M. Bellaveglia, B. Buonomo, F. Cardelli, E. Chiadroni, G. Di Raddo, R.D. Di Raddo, M. Diomede, M. Ferrario, A. Gallo, A. Ghigo, A. Giribono, V.L. Lollo, L. Piersanti, B. Spataro, C. Vaccarezza
    INFN/LNF, Frascati (Roma), Italy
  • N. Catalán Lasheras, A. Grudiev, W. Wuensch
    CERN, Geneva, Switzerland
  
  We illustrate the RF design of the X-band linac for the upgrade of the SPARC_LAB facility at INFN-LNF (EuPRAXIA@SPARC_LAB). The structures are travelling wave (TW) cavities, working on the 2π/3 mode, fed by klystrons with pulse compressor systems. The tapering of the cells along the structure and the cell profiles have been optimized to maximize the effective shunt impedance keeping under control the maximum value of the modified Poynting vector, while the couplers have been designed to have a symmetric feeding and a reduced pulsed heating. In the paper we also present the RF power distribution layout of the accelerating module and a preliminary mechanical design.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK058  
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THPMK095 Design of an RF Modulated Thermionic Electron Source at TRIUMF electron, impedance, cathode, gun 4524
 
  • K. Fong, D.W. Storey
    TRIUMF, Vancouver, Canada
  
  The electron source in the TRIUMF ARIEL project is a gridded dispenser cathode. The cathode is biased at -300kV, and the grid requires a RF control signal of up to 150V at 650 MHz. The required RF power is approximately 20 W and is provided by an RF amplifier located outside the gun vessel. This RF power is coupled into the gun circuit through a ceramic transmission line. The design of this ceramic transmission line, as well as the impedance transformation circuit which provides both the impedance matching and the dc powers to the gun assembly are described.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK095  
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THPMK104 High Power and High Repetition Rate X-band Power Source Using Multiple Klystrons klystron, controls, MMI, network 4552
 
  • M. Volpi, M.J. Boland, P.J. Giansiracusa, T.G. Lucas, R.P. Rassool
    The University of Melbourne, Melbourne, Victoria, Australia
  • N. Catalán Lasheras, A. Grudiev, G. McMonagle, I. Syratchev, B.J. Woolley, W. Wuensch, V. del Pozo Romano
    CERN, Geneva, Switzerland
  • J. Paszkiewicz
    University of Oxford, Oxford, United Kingdom
  • C. Serpico
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  • A. Vnuchenko
    IFIC, Valencia, Spain
  
  In July 2016, the first X-band test facility operating with two interwoven, 6 MW klystron pulses was commissioned at CERN. Outputting up to 46 MW after pulse compression, the new test stand allows testing of two structures concurrently with repetition rates up to 400 Hz in each line. RF commissioning of all four lines has been completed and testing of high gradient accelerating structures for the Compact Linear Collider has commenced. Operations have been ongoing for more than a year, where dedicated control algorithms have been developed to conditioning the structure and to keep the pulse compressors tuned. Significant progress has been made in understanding the conditioning of two structures that are sharing an interlock and vacuum system. The high repetition rate is already showing the significantly reduced time needed to condition accelerating structures.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK104  
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THPMK126 Numerical Method for Longitudinal Dynamics of a Terahertz Cherenkov Free Electron Laser Driven by a Mev Picosecond Electron Beam electron, radiation, FEL, wakefield 4614
 
  • W.W. Li, Z.G. He, Q.K. Jia, S.M. Jiang, L. Wang
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  • D. He
    Anhui Electrical Engineering Professional Technique College, Hefei, People's Republic of China
  
  Funding: Natural Science Foundation of China (11705198, 11775216) China Postdoctoral Science Foundation (2017M622023) Fundamental Research Funds for the Central Universities (WK2310000061)
Corrugated or dielectric structures have been widely used for producing electron bunch train or THz radiation source. Recently, a novel scheme of sub-terahertz free electron laser (FEL) from a metallic pipe with corrugated walls driven by a non-ultra-relativistic (<10 MeV) picosecond electron beam was proposed and analyzed using the Vlasov-Maxwell equations. In this paper, we use the dielectric loaded waveguide instead, and a numerical method for the longitudinal beam dynamics and electromagnetics of the FEL interaction is presented. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK126  
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THPML015 Dielectric Multipactor Discharges at 110 GHz multipactoring, cavity, experiment, vacuum 4684
 
  • S. C. Schaub
    MIT, Cambridge, Massachusetts, USA
  • M.A. Shapiro, R.J. Temkin
    MIT/PSFC, Cambridge, Massachusetts, USA
  
  A 1.5 MW, 110 GHz gyrotron has been used to experimentally measure the maximum sustainable fields on dielectric materials in vacuum. The purpose of this work is to evaluate the suitability of these materials for future applications in high frequency linear accelerators and high power terahertz components. To our knowledge, these are the first measurements of multipactor phenomena in the millimeter wave or terahertz frequency range. Materials tested include alumina, sapphire, fused quartz, crystal quartz, and high resistivity silicon. Dielectric samples were tested both as windows, with electric fields parallel to the surface, and sub-wavelength dielectric rod waveguides, with electric fields perpendicular to the surface. Surface electric fields in excess of 52 MV/m were achieved in 3 microsecond pulses. Visible light emission, absorbed/scattered microwave power, and emitted electrons were measured to characterize the discharges on the dielectric surfaces. The results of these experiments have been compared to theoretical calculations of multipactor discharges, testing these theories at significantly higher frequencies than has been done before.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML015  
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THPML027 Longitudinal and Transverse Wakefields Simulations and Studies in Dielectric-Coated Circular Waveguides electron, wakefield, simulation, radiation 4708
 
  • L. Ficcadenti
    Rome University La Sapienza, Roma, Italy
  • A. Biagioni
    INFN/LNF, Frascati (Roma), Italy
  • G. Castorina, D. Francescone, M. Marongiu, M. Migliorati, A. Mostacci, L. Palumbo
    Sapienza University of Rome, Rome, Italy
  
  In recent years, there has been a growing interest and rapid experimental progress on the use of e.m. fields produced by electron beams passing through dielectric-lined structures and on the effects they might have on the drive and witness bunches. Short ultra-relativistic electron bunches can excite very intense wakefields, which provide an efficient acceleration through the dielectric wakefield accelerators (DWA) scheme with higher gradient than that in the conventional RF LINAC. These beams can also generate high power narrow band THz coherent Cherenkov radiation. These high gradient fields may create strong instabilities on the beam itself causing issues in plasma acceleration experiments (PWFA), plasma lensing experiments and in recent beam diagnostic applications. In this work we report the results of the simulations and studies of the wakefields generated by electron beams at different lengths and charges passing on and off axis in dielectric-coated circular waveguides. We also propose a semi-analytical method to calculate these high gradient fields without resorting to time consuming simulations.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML027  
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THPML047 Design and Measurement of the X-Band Pulse Compressor for TTX cavity, coupling, vacuum, ISOL 4745
 
  • Y.L. Jiang, H.B. Chen, C. Cheng, W. Gai, J. Shi, P. Wang, Z.H. Wang, X.W. Wu, H. Zha
    TUB, Beijing, People's Republic of China
  
  A radio frequency (RF) pulse compressor had been designed for the X-band (11.424 GHz) high power test stands at the Accelerator Laboratory of Tsinghua University. It is the SLED-I type pulse compressor, which uses a high quality factor corrugated circular cavity to store the RF power. An RF polarizer couples two quadrature modes into the cavity so that the pulse compressor needs only one cavity. The cavity implements HE1-1-14 mode, with the Q0 of 115, 000 and the coupling factor (β) of 3.23. The design and the microwave measurement before brazing of this pulse compressor are presented in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML047  
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THPML061 X-Band Low Q Cavity Beam Position Monitor Study cavity, FEL, simulation, electron 4777
 
  • S.S. Cao
    SINAP, Shanghai, People's Republic of China
  • Y.B. Leng, R.X. Yuan
    SSRF, Shanghai, People's Republic of China
  
  The high repetition-rate and high peak brilliance of X-ray free-electron laser (XFEL) allow studying many scientific experiments that have not been feasible. To realize such high performance, a sub-micron beam transverse position measurement is required. The cavity-type beam position monitor (CBPM), as a non-destructive diagnostics tool with high potential in resolution performance, has been applied in different free electron laser facilities (FELs). In this research, an X-band high bandwidth CBPM has been studied and used for pre-research on bunch-by-bunch diagnostic for the pulsed FEL with high repetition-rate. Its bandwidth reaches 300 MHz. Design considerations and simulation results of the CBPM have been discussed and presented in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML061  
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THPML075 MYRRHA Control System Development controls, interface, software, framework 4823
 
  • R. Modic, M. Pavleski, T. Zagar
    Cosylab, Ljubljana, Slovenia
  • J. Belmans, P. Della Faille, D. Vandeplassche
    Studiecentrum voor Kernenergie - Centre d'Étude de l'énergie Nucléaire (SCK•CEN), Mol, Belgium
  
  MYRRHA ADS (Accelerator Driven System), the prototype of a nuclear reactor driven by a particle accelerator, is being realized through a staged approach. This paper will explore the Control System (CS) strategy for the current stage of the accelerator R&D, where the goal is injector for the energies up to 5.9 MeV. Accelerator components are being delivered within international semi-industrial partnerships. Currently the RFQ, MYRRHA's first RF structure, is being introduced. It will be followed by the first Medium Energy Beam Transport (MEBT1) and several normal-conducting CH cavities. As the portfolio and number of devices and systems grows there is increased push towards standardization of integration procedures, interfaces to system-wide services, configuration management. Several partners provide components with varying level of vertical integration. The responsibility of the Control System integrator is therefore shifting towards provision of integration guidelines, configuration and deployment of central services and management tools, training to the contributing developers, help with specifications and requirements, quality insurance and acceptance criteria.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML075  
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THPML096 A Non-Invasive Magnetic Momentum Monitor Using a TE011 Cavity cavity, impedance, electron, coupling 4889
 
  • J. Guo, J. Henry, M. Poelker, R.A. Rimmer, R. Suleiman, H. Wang
    JLab, Newport News, Virginia, USA
  
  Funding: Authored by Jefferson Science Associates, LLC with Laboratory Directed Research and Development funding, under U.S. DOE Contract No. DE-AC05-06OR23177.
The Jefferson Lab Electron-Ion Collider (JLEIC) design relies on cooling of the ion beam with bunched electron beam. The bunched beam cooler complex consists of a high current magnetized electron source, an energy recovery linac, a circulating ring, and a pair of long solenoids where the cooling takes place. A non-invasive real time monitoring system is highly desired to quantify electron beam magnetization. The authors propose to use a passive copper RF cavity in TE011 mode as such a monitor. In this paper, we will show the mechanism and scaling law of this device, as well as the design and testing results of the prototype cavity. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML096  
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THPML113 Design and Simulation of the Waveguide Coupler for the Cavity Beam Monitor cavity, simulation, coupling, electromagnetic-fields 4932
 
  • Q. Wang, Q. Luo, B.G. Sun, F.F. Wu, Y.L. Yang, Z.R. Zhou
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  • Y.W. Wu
    USTC, Hefei, Anhui, People's Republic of China
  
  Funding: Supported by The National Key Research and Development Program of China (2016YFA0401900), NSFC (11375178, 11575181) and the Fundamental Research Funds for the Central Universities (WK2310000046)
The waveguide coupling is an important way to extract the signals of the specific eigenmodes required. The design of the waveguide coupler, including the waveguide-to-coaxial adapter behind it for the cavity bunch length monitor is presented. The influence of the dimension parameters is analyzed, which offers the theoretical support for the design and application of cavity bunch length monitor or cavity beam position monitor (CBPM). A series simulation based on CST is performed to verify the feasibility, and the simulation results show good performance. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML113  
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THPML116 AutoTuner: A General Graphical User Interface for Automated Tuning interface, controls, target, kicker 4939
 
  • X. Huang
    SLAC, Menlo Park, California, USA
  • T. Zhang
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  
  AutoTuner is a general graphical user interface (GUI) that we developed for automated tuning or online optimization. The GUI provides a convenient interface to select tuning knobs, objectives, and optimization algorithms and to change the tuning control parameters. Tuning setup can be created and saved for reuse. The progress of the tuning processing is plotted in real time. The tuning process can be paused, aborted, or resumed. We have tested the program for real-life accelerator tuning problems.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML116  
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