IPAC2021 - List of Keywords (GUI)

Paper	Title	Other Keywords	Page
MOPAB003	Machine Learning Analysis of Electron Cooler Operation for RHIC	luminosity, electron, operation, scattering	45
	X. Gu, A.V. Fedotov, D. Kayran BNL, Upton, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. A regression machine learning algorithm was applied to analyze the operation data of RHIC with electron cooler LEReC during the 2020 physics run. After constructing a black-box surrogate model from the XGBoost algorithm and plotting their partial dependency plots for different operation parameters, we can find the effects of an individual parameter on the RHIC luminosity and optimize it accordingly offline.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB003
About •	paper received ※ 14 May 2021 paper accepted ※ 25 May 2021 issue date ※ 11 August 2021
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MOPAB041	Convergence Map with Action-Angle Variables Based on Square Matrix for Nonlinear Lattice Optimization	lattice, linear-dynamics, resonance, betatron	182
	L.H. Yu, Y. Hidaka, F. Plassard, V.V. Smaluk BNL, Upton, New York, USA Y. Hao FRIB, East Lansing, Michigan, USA
	We apply square matrix method to obtain in high speed a "convergence map", which is similar but different from frequency map. The convergence map is obtained from solving nonlinear dynamical equation by iteration of perturbation method and study the convergence. The map provides information about the stability border of dynamical aperture. We compare the map with frequency map from tracking. The result indicates the new method may be applied in nonlinear lattice optimization, taking the advantage of the high speed (about 10~50 times faster) to explore x, y and the off-momentum phase space.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB041
About •	paper received ※ 09 May 2021 paper accepted ※ 26 May 2021 issue date ※ 18 August 2021
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MOPAB047	A CAD Tool for Linear Optics Design: A Use Case Approach	controls, software, MMI, optics	205
	J. Bengtsson HZB, Berlin, Germany T.J.R. Nicholls, W.A.H. Rogers DLS, Oxfordshire, United Kingdom
	The formula relevant for linear optics design of synchrotrons are derived systematically from first principles, i.e., an exercise in Hamiltonian dynamics. Equipped with these, the relevant use cases are then captured; for a streamlined approach. To enable professionals, i.e., software engineers, to efficiently prototype & architect a CAD tool available to mechanical engineers since the mid-1960s. In other words, robust design of a modern synchrotron is an exercise in/pursuit of the art of Engineering-Science.
	Poster MOPAB047 [1.059 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB047
About •	paper received ※ 17 May 2021 paper accepted ※ 28 May 2021 issue date ※ 15 August 2021
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MOPAB077	Anomaly Detection in Accelerator Facilities Using Machine Learning	power-supply, operation, experiment, detector	304
	A. Das Stanford University, Stanford, California, USA M. Borland, L. Emery, X. Huang, H. Shang, G. Shen ANL, Lemont, Illinois, USA D.F. Ratner SLAC, Menlo Park, California, USA R.M. Smith, G.M. Wang BNL, Upton, New York, USA
	Synchrotron light sources are user facilities and usually run about 5000 hours per year to support many beamlines operations in parallel. Reliability is a key parameter to evaluate machine performance. Even many facilities have achieved >95% beam reliability, there are still many hours of unscheduled downtime and every hour lost is a waste of operation costs along with a big impact on individual scheduled user experiments. Preventive maintenance on subsystems and quick recovery from machine trips are the basic strategies to achieve high reliability, which heavily depends on experts’ dedication. Recently, SLAC, APS, and NSLS-II collaborated to develop machine-learning-based approaches aiming to solve both situations, hardware failure prediction and machine failure diagnosis to find the root sources. In this paper, we report our facility operation status, development progress, and plans.
	Poster MOPAB077 [1.240 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB077
About •	paper received ※ 16 May 2021 paper accepted ※ 14 June 2021 issue date ※ 01 September 2021
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MOPAB081	Feasibility Study of Using Multipole Injection Kicker (MIK) and Sextupole for TPS Injection	injection, sextupole, storage-ring, kicker	312
	C.-S. Fann, C.K. Chan, C.-C. Chang, H.-P. Chang, Y.-S. Cheng, M.-S. Chiu, Y.L. Chu, K.T. Hsu, S.Y. Hsu, K.H. Hu, J.C. Huang, C.-S. Hwang, S.H. Lee, K.-K. Lin, C.Y. Wu, C.S. Yang NSRRC, Hsinchu, Taiwan S.-Y. Lee Indiana University, Bloomington, Indiana, USA
	Feasibility of applying MIK/sextupole injection at TPS is evaluated in this study. This study adopts layout similar to MAX IV injection scheme and their collaboration project with SOLEIL for MIK. Although the light source service fulfills present user needs, yet the increasing demands for a transparent injection is inevitable in the foreseeable future. Notice that this preliminary study is constrained under routine user operation, the optional pinger ceramic chamber, located between existing injection kicker-3 and kicker-4, is chosen for the purpose. Kick strength requirement of the MIK is estimated with minor trajectory adjustment upstream at the booster to storage ring transfer line. Since the realization of MIK fabrication takes time, therefore a fast-built sextupole is prepared to examine the proposed injection scheme beforehand. The test result will be described in this report.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB081
About •	paper received ※ 17 May 2021 paper accepted ※ 20 May 2021 issue date ※ 21 August 2021
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MOPAB142	A Compact, Low-Field, Broadband Matching Section for Externally-Powered X-Band Dielectric-Loaded Accelerating Structures	vacuum, coupling, simulation, linac	495
	Y. Wei, C.P. Welsch The University of Liverpool, Liverpool, United Kingdom H. Bursali Sapienza University of Rome, Rome, Italy N. Catalán Lasheras, S. Gonzalez Anton, A. Grudiev, R. Wegner, Y. Wei CERN, Meyrin, Switzerland B.T. Freemire, C.-J. Jing Euclid TechLabs, Solon, Ohio, USA J. Sauza-Bedolla Lancaster University, Lancaster, United Kingdom Y. Wei, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom
	It has been technically challenging to efficiently couple external radiofrequency (RF) power to cylindrical dielectric-loaded accelerating (DLA) structures. This is especially true when the DLA structure has a high dielectric constant. This contribution presents a novel design of a matching section for coupling the RF power from a circular waveguide to an X-band DLA structure with a dielectric constant ε_r=16.66 and a loss tangent \tanθ = 3.43× 10^-5. It consists of a very compact dielectric disk with a width of 2.035 mm and a tilt angle of 60 degrees, resulting in a broadband coupling at a low RF field which has the potential to survive in the high-power environment. To prevent a sharp dielectric corner break, a 45-degree chamfer is added. Moreover, a microscale vacuum gap, caused by metallic clamping between the thin coating and the outer thick copper jacket, is studied in detail. Based on simulation studies, a prototype of the DLA structure with the matching sections was fabricated. Results from preliminary bench measurements and their comparison with design values will also be discussed.
	Poster MOPAB142 [2.617 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB142
About •	paper received ※ 11 May 2021 paper accepted ※ 21 May 2021 issue date ※ 19 August 2021
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MOPAB146	Status of the C-Band Engineering Research Facility (CERF-NM) Test Stand Development at LANL	cavity, klystron, controls, radiation	509
	D. Gorelov Private Address, Los Alamos, USA R.L. Fleming, S.K. Lawrence, J.W. Lewellen, D. Perez, M.E. Schneider, E.I. Simakov, T. Tajima LANL, Los Alamos, New Mexico, USA M.E. Middendorf ANL, Lemont, Illinois, USA
	Funding: LDRD-DR Project 20200057DR C-Band structures research is of increasing interest to the accelerator community. The RF frequency range of 4-6 GHz gives the opportunity to achieve significant increase in the accelerating gradient, and having the wakefields at the manageable levels, while keeping the geometric dimensions of the structure technologically convenient. Strong team of scientists, including theorists researching properties of metals under stressful thermal conditions and high electromagnetic fields, metallurgists working with copper as well as alloys of interest, and accelerator scientists developing new structure designs, is formed at LANL to develop a CERF-NM facility. A 50 MW, 5.712 GHz Canon klystron, was purchased in 2019, and laid the basis for this facility. As of Jan-21, the construction of the Test Stand has been finished and the high gradient processing of the waveguide components has been started. Future plans include high gradient testing of various accelerating structures, including benchmark C-band accelerating cavity, a proton ß=0.5 cavity, and cavities made from different alloys. An upgrade to the facility is planned to allow for testing accelerator cavities at cryogenic temperatures.
	Poster MOPAB146 [3.778 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB146
About •	paper received ※ 17 May 2021 paper accepted ※ 26 May 2021 issue date ※ 19 August 2021
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MOPAB147	Efficient, High Power Terahertz Radiation Outcoupling From a Beam Driven Dielectric Wakefield Accelerator	radiation, wakefield, acceleration, electron	513
	M. Yadav, G. Andonian, C.E. Hansel, W.J. Lynn, N. Majernik, B. Naranjo, J.B. Rosenzweig, O. Williams UCLA, Los Angeles, California, USA G. Andonian RadiaBeam, Santa Monica, California, USA C.P. Welsch The University of Liverpool, Liverpool, United Kingdom C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: This work was supported by DE-SC0009914 (UCLA) and the STFC Liverpool Centre for Doctoral Training on Data Intensive Science (LIV. DAT) under grant agreement ST/P006752/1. Wakefields in dielectric structures are a useful tool for beam diagnostics and manipulation with applications including acceleration, shaping, chirping, and THz radiation generation. It is possible to use the produced THz radiation to diagnose the fields produced during the DWA interaction but, to do so, it is necessary to effectively out-couple this radiation to free space for transport to diagnostics such as a bolometer or interferometer. To this end, simulations have been conducted using CST Studio for a 10 GeV beam with FACET-II parameters in a slab-symmetric, dielectric waveguide. Various termination geometries were studied including flat cuts, metal horns, and the "Vlasov antenna". Simulations indicate that the Vlasov antenna geometry is optimal and detailed studies were conducted on a variety of dielectrics including quartz, diamond, and silicon. Multiple modes were excited and coherent Cherenkov radiation (CCR) was computationally generated for both symmetric and asymmetric beams. Finally, we include witness beams to study transport and acceleration dynamics as well as the achievable field gradients.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB147
About •	paper received ※ 24 May 2021 paper accepted ※ 29 August 2021 issue date ※ 28 August 2021
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MOPAB152	High Power Tests of Brazeless Accelerating Structures	simulation, experiment, wakefield, target	532
	S.P. Antipov, P.V. Avrakhov, C.-J. Jing, S.V. Kuzikov Euclid TechLabs, Solon, Ohio, USA V.A. Dolgashev SLAC, Menlo Park, California, USA D.S. Doran, W. Liu, J.G. Power, J.H. Shao, E.E. Wisniewski ANL, Lemont, Illinois, USA
	Funding: DOE SBIR Grant #DE-SC0017749 A typical accelerating structure is a set of copper resonators brazed together. This multi step process is expensive and time consuming. In an effort to optimize production process for rapid prototyping and overall reduction of accelerator cost we developed a split block brazeless accelerating structure. In such structure the vacuum is sealed by the use of knife edges, similar to an industry standard conflat technology. In this paper we present high power tests of several different brazeless structures. First, an inexpensive 1 MeV accelerator powered by radar magnetron. Second, a high gradient power extractor tested at Argonne Wakefield Accelerator Facility. In this experiment a high charge electron beam generated a 180 MW peak power pulse. Finally, we report on high power testing of a brazeless x-band accelerating structure at SLAC.
	Poster MOPAB152 [0.783 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB152
About •	paper received ※ 20 May 2021 paper accepted ※ 24 June 2021 issue date ※ 31 August 2021
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MOPAB156	Wakefields and Transverse Bunch Dynamics Studies of a Plasma-Dielectric Accelerating Structure	plasma, wakefield, focusing, electron	542
	K. Galaydych, I.N. Onishchenko, G.V. Sotnikov NSC/KIPT, Kharkov, Ukraine
	Funding: The National Research Foundation of Ukraine, programme "Leading and Young Scientists Research Support" (grant agreement n. 2020.02/0299). A theoretical investigation of a wakefield excitation in a plasma-dielectric accelerating structure by a drive electron bunch in the case of an off-axis bunch injection is carried out. The structure under investigation is a round dielectric-loaded metal waveguide with channel for the charged particles, filled with homogeneous cold plasma. In this paper we focus on the spatial distribution of the bunch-excited wakefield components, which act on both the drive and test bunches, and on transverse bunch dynamics. Dependence of the drive bunch propagation distance on its offset is studied.
	Poster MOPAB156 [2.042 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB156
About •	paper received ※ 19 May 2021 paper accepted ※ 18 June 2021 issue date ※ 14 August 2021
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MOPAB215	Using ICA for Retrieving Teng Parameters	coupling, factory, optics, FEL	711
	A. Lauterbach IAP, Frankfurt am Main, Germany G. Franchetti GSI, Darmstadt, Germany
	The blind source separation (BSS) method of Independent Component Analysis (ICA) is explored as a new approach for the reconstruction of the transfer matrix of Linear Coupling Parameterization. ICA is a method to detangle independent signals out of several measurements of their mixtures. In BSS-calculations, it is usually not possible to retrieve the mixing matrix, for the source signals, as well as the matrix, are unknown. Combining the parameterization model of D.A. Edwards and L.C. Teng with the standard ICA approach, it is though possible to retrieve the mixing matrix, as the form of the original uncoupled motion is known. At the same time arises the possibility to recalculate the parameters of Edwards and Teng through a system of equations of the one turn map components. It can be shown as a proof of concept, that the parameters can be reconstructed up to high accuracy for a simulated, non-perturbed signal.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB215
About •	paper received ※ 10 May 2021 paper accepted ※ 31 May 2021 issue date ※ 23 August 2021
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MOPAB283	Simulations of Space-Charge and Guiding Fields Effects on the Performance of Gas Jet Profile Monitoring	electron, simulation, HOM, collimation	898
	O. Sedláček, N. Kumar, A. Salehilashkajani, C.P. Welsch, H.D. Zhang The University of Liverpool, Liverpool, United Kingdom P. Forck, S. Udrea GSI, Darmstadt, Germany N. Kumar, A. Salehilashkajani, O. Sedláček, C.P. Welsch, H.D. Zhang Cockcroft Institute, Warrington, Cheshire, United Kingdom S. Mazzoni, O. Sedláček CERN, Geneva, Switzerland
	Gas jet based profile monitors inject a usually curtain shaped gas jet across a charged particle beam and exploit the results of the minimally invasive beam-gas interaction to provide information about the beam’s transversal profile. Such monitor will be installed as part of the High Luminosity LHC upgrade at CERN in the Hollow Electron Lens (HEL). The HEL represents a new collimation stage increasing the diffusion rate of halo particles by placing a high intensity hollow electron beam concentrically around the LHC beam. The gas jet monitor will use the fluorescence radiation resulting due to the beam-gas interaction to create an image of the profiles of both hollow electron and LHC beams However, the high beam space-charge and strong guiding magnetic field of the electron beam cause significant displacements of the excited molecules, as they are also ionized, and thus image distortions. This work presents preliminary simulation results showing expected fluorescence images of the hollow electron profile as affected by space-charge and guiding fields using simulation tools such as IPMsim. The influence of the estimated electron beam and gas jet curtain parameters are investigated.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB283
About •	paper received ※ 18 May 2021 paper accepted ※ 28 July 2021 issue date ※ 19 August 2021
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MOPAB291	Design of Cavity BPM Pickup for EuPRAXIA@SPARC_LAB	cavity, coupling, pick-up, simulation	924
	Sh. Bilanishvili INFN/LNF, Frascati (Roma), Italy
	EuPRAXIA@SPARC_LAB will make available at LNF a unique combination offering three different options. A high-brightness electron beam with 1 GeV energy generated in a novel X-band RF linac; A PW-class laser system, and a compact light-source directly driven by a plasma accelerator. Plasma and conventional RF linac driven FEL provide beam with parameters of 30- 200pC charge range, 10-100Hz repetition rate, and 1 GeV electron energy. The control of the charge and the trajectory monitoring at a few pC and a few um is mandatory in this machine. Particularly in the plasma interaction region, where the pickup resolution under 1 um is required. As a possible solution, a cavity beam position monitor (cBPM) is proposed. A prototype in the C-band frequency range has been designed. The pickup was optimized for low charge and single-shot bunches. The poster presents the process to achieve the required specifications. The simulations were performed to study RF properties and the electromagnetic response of the device. Finally, the overall performance of the pickup is discussed, and theoretical resolution is approximated. https://www.researchgate.net/publication/335459394_From_SPARC_LAB_to_EuPRAXIASPARC_LAB **http://www.lnf.infn.it/sis/preprint/detail-new.php?id=5416
	Poster MOPAB291 [16.718 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB291
About •	paper received ※ 19 May 2021 paper accepted ※ 09 June 2021 issue date ※ 23 August 2021
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MOPAB319	Development of a Fast Betatron Tune and Chromaticity Measurement System for COSY	betatron, acceleration, controls, resonance	983
	P.J. Niedermayer, C. Böhme, B. Breitkreutz, V. Kamerdzhiev, A. Lehrach FZJ, Jülich, Germany A. Lehrach RWTH, Aachen, Germany
	A fast tune measurement is developed for the Cooler Synchrotron COSY at the Institut für Kernphysik of Forschungszentrum Jülich. Betatron oscillations of the beam are excited with a band-limited RF signal via a stripline kicker. Resonant transverse oscillations are then observed using capacitive beam position monitors. Based on the bunch-by-bunch beam position data the betatron tune is determined. The usage of bunch-by-bunch data is characteristic of the new system. It allows for a discrete tune measurement within a few milliseconds, as well as continuous tune monitoring during beam acceleration. The high precision tune measurement also enables determination of the beam chromaticity. Therefore, the beam momentum is varied by means of the RF frequency and the subsequent tune change is determined. For routine use during beam operation and experiments, the developed method is integrated into the control system.
	Poster MOPAB319 [1.209 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB319
About •	paper received ※ 19 May 2021 paper accepted ※ 16 June 2021 issue date ※ 12 August 2021
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MOPAB324	High Voltage Design and Evaluation of Wien Filters for the CEBAF 200 keV Injector Upgrade	electron, vacuum, high-voltage, simulation	1000
	G.G. Palacios Serrano, P.A. Adderley, J.F. Benesch, D.B. Bullard, J.M. Grames, C. Hernandez-Garcia, A.S. Hofler, D. Machie, M. Poelker, M.L. Stutzman, R. Suleiman JLab, Newport News, Virginia, USA H. Baumgart, G.G. Palacios Serrano ODU, Norfolk, Virginia, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177. High-energy nuclear physics experiments at the Jefferson Lab Continuous Electron Beam Accelerator Facility (CEBAF) require highly spin-polarization electron beams, produced from strained super-lattice GaAs photocathodes, activated to negative electron affinity in a photogun operating at 130 kV dc. A pair of Wien filter spin rotators in the injector defines the orientation of the electron beam polarization at the end station target. An upgrade of the CEBAF injector to better support the upcoming MOLLER experiment requires increasing the electron beam energy to 200 keV, to reduce unwanted helicity correlated intensity and position systematics and provide precise control of the polarization orientation. Our contribution describes design, fabrication and testing of the high voltage system to upgrade the Wien spin rotator to be compatible with the 200 keV beam. This required Solidworks modeling, CST and Opera electro- and magnetostatic simulations, upgrading HV vacuum feedthroughs, and assembly techniques for improving electrode alignment. The electric and magnetic fields required by the Wien condition and the successful HV characterization under vacuum conditions are also presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB324
About •	paper received ※ 19 May 2021 paper accepted ※ 24 May 2021 issue date ※ 29 August 2021
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MOPAB336	Multipacting Analysis of Warm Linac RF Vacuum Windows	simulation, multipactoring, vacuum, Windows	1044
	G.D. Toby, Y.W. Kang, S.-H. Kim, S.W. Lee, J.S. Moss ORNL, Oak Ridge, Tennessee, USA
	Funding: * This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under contract number DE-AC05-00OR22725. Multipacting in accelerating structures is a complex phenomenon with which there is much to be understood. While multipacting research efforts have primarily been focused on superconducting radio frequency (SRF) systems, normal conducting accelerating structures that have a higher thermal capacity and a greater vacuum pressure tolerance could benefit from additional investigation. This research details multipacting simulation methods and the results of 3-D electromagnetic simulations of RF vacuum windows used on normal conducting linac (NCL) cavities. Possible techniques for reducing and eliminating multipacting activities in these structures are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB336
About •	paper received ※ 17 May 2021 paper accepted ※ 28 May 2021 issue date ※ 29 August 2021
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MOPAB341	First C-Band High Gradient Cavity Testing Results at LANL	cavity, proton, operation, klystron	1057
	E.I. Simakov, R.L. Fleming, D. Gorelov, T.A. Jankowski, M.F. Kirshner, J.W. Lewellen, J.D. Pizzolatto, M.E. Schneider, T. Tajima LANL, Los Alamos, New Mexico, USA X. Lu, E.A. Nanni, S.G. Tantawi SLAC, Menlo Park, California, USA M.E. Middendorf ANL, Lemont, Illinois, USA
	Funding: Los Alamos National Laboratory LDRD Program. This poster will report the results of high gradient testing of the two proton β=0.5 C-band accelerating cavities. The cavities for proton acceleration were fabricated at SLAC and tested at high gradient C-band accelerator test stand at LANL. One cavity was made of copper, and the second was made of a copper-silver alloy. LANL test stand was constructed around a 50 MW, 5.712 GHz Canon klystron and is capable to provide power for conditioning single cell accelerating cavities for operation at surface electric fields up to 300 MV/m. These β=0.5 C-band cavities were the first two cavities tested on LANL C-band test stand. The presentation will report achieved gradients, breakdown probabilities, and other characteristics measured during the high power operation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB341
About •	paper received ※ 19 May 2021 paper accepted ※ 25 May 2021 issue date ※ 30 August 2021
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MOPAB342	Design, Fabrication, and Commissioning of the Mode Launchers for High Gradient C-Band Cavity Testing at LANL	cavity, klystron, simulation, MMI	1060
	E.I. Simakov, J.E. Acosta, D. Gorelov, M.F. Kirshner, J.W. Lewellen LANL, Los Alamos, New Mexico, USA P. Borchard Dymenso LLC, San Francisco, USA M.E. Schneider MSU, East Lansing, Michigan, USA
	Funding: Los Alamos National Laboratory LDRD Program. This poster will report on the design, fabrication, and operation status of the new high gradient C-band TM01 mode launchers for the high gradient C-band test stand at LANL. Modern applications require accelerators with optimized cost of construction and operation, naturally calling for high-gradient acceleration. At LANL we commissioned a test stand powered by a 50 MW, 5.712 GHz Canon klystron. The test is capable of conditioning single cell accelerating cavities for operation at surface electric fields up to 300 MV/m. The rf field is coupled into the cavity from a WR187 waveguide through a mode launcher that converts the fundamental mode of the rectangular waveguide into the TM01 mode of the circular waveguide. Several designs for mode launchers were considered and the final design was chosen based on a compromise between the field enhancements, bandwidth, and simplicity and cost of fabrication. Four mode launchers were fabricated and cold-tested. Two mode launchers with the best transmission characteristics were installed and conditioned to high power. The presentation will report achieved gradients, breakdown probabilities, and other characteristics measured during operation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB342
About •	paper received ※ 19 May 2021 paper accepted ※ 25 May 2021 issue date ※ 19 August 2021
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MOPAB346	Broadband Frequency Electromagnetic Characterisation of Coating Materials	experiment, electron, vacuum, site	1076
	A. Passarelli, C. Koral, M.R. Masullo INFN-Napoli, Napoli, Italy A. Andreone Naples University Federico II, Napoli, Italy M. De Stefano University of Naples, Naples, Italy V.G. Vaccaro Naples University Federico II and INFN, Napoli, Italy
	In the new generation of particle accelerators and storage rings, collective effects have to be carefully analyzed. In particular, the finite conductivity of the beam pipe walls is a major source of impedance and instabilities. A reliable electromagnetic (EM) characterisation of different coating materials is required up to hundreds of GHz due to very short bunches. We propose two different measurement techniques for an extended frequency characterization: (i) a THz time domain setup based on the signal transmission response of a tailored waveguide to infer the coating EM properties from 100 to 300 GHz or even further.. This technique has been tested both on NEG and amorphous Carbon films. (ii) a resonant method, based on dielectric cavities, to evaluate the surface resistance Rs of thin conducting samples at low (GHz) frequencies*. Due to its high sensitivity, Rs values can be obtained for very thin (nanometric) coatings or for copper samples with a laser treated surface, since they have an expected conductivity very close to bulk copper. A. Passarelli et al., Phys. Rev. Accel. Beams, v.21, p.103101, 2018 A. Passarelli et al., Cond. Matter, v.5, p.9, 2020 *A. Andreone et al., Applied Physics Letters, v.91, n.7, p.072512, 2007
	Poster MOPAB346 [2.613 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB346
About •	paper received ※ 18 May 2021 paper accepted ※ 09 June 2021 issue date ※ 26 August 2021
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MOPAB348	Portable 2.5 MeV X-Band Linear Accelerator Structure	linac, gun, radiation, target	1084
	A.V. Mishin, K. Brown, M. Denney, D. Fischer, N.P. Hanson, S. Proskin, J. Stammetti Varex Imaging, Salt Lake City, USA
	Two versions of 2.5 MeV X-Band linear accelerator structure have been designed and tested. The first is a traditional single input linac, and the other one is a dual input, two section linac with power input through a 3 dB coupler. The linac is designed for a portable linac system, which can be used for security screening, non-destructive testing, medical and industrial CT, and, perhaps, some other applications.
	Poster MOPAB348 [1.490 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB348
About •	paper received ※ 15 May 2021 paper accepted ※ 28 May 2021 issue date ※ 23 August 2021
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MOPAB349	New Accelerator Beam Centerline (ABC) Production Line at Varex Imaging Corporation	linac, gun, betatron, detector	1087
	A.V. Mishin Varex Imaging, Salt Lake City, USA
	In January 2017, a Salt Lake City Component Division of Varian Medical (Varian), producer of X-ray tubes, detectors, and imaging panels has been spun off, giving birth to a new public company Varex Imaging Corporation (Varex), which also includes the Security and Inspection Products (SIP) linac producer in Las Vegas. Based on Varian asset acquisition of two small LLCs** in May 2016, 8 months prior to the transition, a new business branch within Varex has been established, which included distribution of the betatrons and detector arrays as well as pilot production line for Accelerator Beam Centerlines (ABC). In 3 years, we moved ABC production from Fremont, CA to Salt Lake in Utah and improved it; several ABCs have been designed, produced, and qualified. A number of new products in energy range of 1-20 MeV are under development, based on the new ABCs used as components for SIP linear accelerator systems and ABCs sold to third parties for applications other than Security and NDT. The new products will brag broad energy and dose rate regulation, smooth and reliable operation, providing extended benefits to our customers. * - https://www.varian.com/ - https://www.vareximaging.com/ * - both Thought One LLC and Radmedex LLC have been dissolved in 2018 upon completion of the transition process
	Poster MOPAB349 [2.182 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB349
About •	paper received ※ 13 May 2021 paper accepted ※ 27 May 2021 issue date ※ 21 August 2021
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MOPAB358	Design and Measurement of the 1.4 GHz Cavity for LEReC Linac	cavity, electron, resonance, HOM	1113
	B.P. Xiao, J.C. Brutus, J.M. Fite, K. Hamdi, D. Holmes, K. Mernick, K.S. Smith, J.E. Tuozzolo, T. Xin, A. Zaltsman BNL, Upton, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. The Low Energy RHIC electron Cooler (LEReC) is the first electron cooler based on rf acceleration of electron bunches. To further improve RHIC luminosity for heavy ion beam energies below 10 GeV/nucleon, a normal conducting RF cavity at 1.4 GHz was designed and fabricated for the LINAC that will provide longer electron bunches for the LEReC. It is a single-cell cavity with an effective cavity length shorter than half of the 1.4 GHz wavelength. This cavity was fabricated and tested on-site at BNL to verify RF properties, i.e. the resonance frequency, FPC coupling strength, tuner system performance, and high power tests. In this paper, we report the RF test results for this cavity.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB358
About •	paper received ※ 17 May 2021 paper accepted ※ 25 June 2021 issue date ※ 24 August 2021
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MOPAB370	X-Band RF Spiral Load Optimization for Additive Manufacturing Mass Production	vacuum, simulation, ECR, linac	1143
	H. Bursali Sapienza University of Rome, Rome, Italy N. Catalán Lasheras, R.L. Gerard, A. Grudiev, O. Gumenyuk, P. Morales Sanchez, B. Riffaud CERN, Geneva, Switzerland J. Sauza-Bedolla Lancaster University, Lancaster, United Kingdom
	The CLIC main linac uses X-band traveling-wave normal conducting accelerating structures. The RF power not used for beam acceleration nor dissipated in the resistive wall is absorbed in two high power RF loads that should be as compact as possible to minimize the total footprint of the machine. In recent years, CERN has designed, fabricated and successfully tested several loads produced by additive manufacturing. With the current design, only one load can be produced in the 3D printing machine at a time. The aim of this study is optimizing the internal cross-section of loads in order to create a stackable design to increase the number of produced parts per manufacturing cycle and thus decrease the unit price. This paper presents the new design with an optimization of the internal vacuum part of the so-called RF spiral load. In this case, RF and mechanical designs were carried out in parallel. The new cross section has showed good RF reflection reaching less than -30 dB in simulations. The final load is now ready to be manufactured and high-power tested. This new load will not only provide cost saving but also faster manufacturing for mass production.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB370
About •	paper received ※ 18 May 2021 paper accepted ※ 26 May 2021 issue date ※ 23 August 2021
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TUXB01	A 3 MeV All Optical Terahertz-Driven Electron Source at Tsinghua University	electron, acceleration, laser, gun	1294
	H. Xu, Y.-C. Du, W.-H. Huang, R.K. Li, C.-X. Tang, L.X. Yan TUB, Beijing, People’s Republic of China
	Funding: Science Challenge Project No.TZ2018005 Efficient acceleration and manipulation of high-brightness electron beams using terahertz waves in a compact setup has been recently a hot research topic in acceleration community. Previous works have achieved multi-MV/m acceleration gradient and dozens of keV energy gain while leaving room for further improvements in the high-energy regime. Here, we experimentally demonstrate whole-bunch acceleration and cascaded terahertz-driven acceleration of a relativistic beam with a record energy gain of 204 keV. A terahertz-driven all-optical electron source is now under development, which hold great potential for terahertz-driven ultrafast electron diffraction and related scientific discoveries. * Xu, H., Yan, L., Du, Y. et al. Cascaded high-gradient terahertz-driven acceleration of relativistic electron beams. Nat. Photonics (2021). https://doi.org/10.1038/s41566-021-00779-x
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUXB01
About •	paper received ※ 19 May 2021 paper accepted ※ 01 June 2021 issue date ※ 10 August 2021
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TUXB04	Fabrication and Tuning of a THz-Driven Electron Gun	gun, electron, cavity, resonance	1297
	S.M. Lewis, A.A. Haase, J.W. Merrick, E.A. Nanni, M.A.K. Othman, S.G. Tantawi SLAC, Menlo Park, California, USA S.M. Lewis Fermilab, Batavia, Illinois, USA
	Funding: This work was supported by the Department of Energy Contract No. DE-AC02-76SF00515 (SLAC) and by NSF Grant No. PHY-1734015. We have developed a THz-driven field emission electron gun and beam characterization assembly. The two cell standing-wave gun operates in the pi mode at 110.08 GHz. It is designed to produce 360 keV electrons with 500 kW of input power supplied by a 110 GHz gyrotron. Multiple gun structures were electroformed in copper using a high precision diamond-turned mandrel. The field emission cathode is a rounded copper tip located in the first cell. The cavity resonances were mechanically tuned using azimuthal compression. This work will discuss details of the fabrication and tuning and present the results of low power measurements.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUXB04
About •	paper received ※ 18 May 2021 paper accepted ※ 22 June 2021 issue date ※ 14 August 2021
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TUPAB077	Novel Open Cavity for Rotating Mode SLED-Type RF Pulse Compressors	cavity, coupling, klystron, linear-collider	1547
	X.W. Wu, A. Grudiev CERN, Meyrin, Switzerland
	A new X-band high-power rotating mode SLAC Energy Doubler (SLED)-type rf pulse compressor is proposed. It is based on a novel cavity type, a single open bowl-shape energy storage cavity with high Q₀ and compact size, which is coupled to the waveguide using a compact rotating mode launcher. The novel cavity type is applied to the rf pulse compression system of the main linac rf module of the klystron-based option of the Compact Linear Collider (CLIC). Quasi-spherical rotating modes of \rm{TE}_1,2,4 and \rm{TE}_1,2,13 are proposed for the correction cavity and storage cavity of the rf pulse compression system respectively. The storage cavity working at \rm{TE}_1,2,13 has a Q₀ of 240000 and a diameter less than 33 cm. The design of the pulse compressor and in particular of the high-Q cavity will be presented in detail.
	Poster TUPAB077 [1.229 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB077
About •	paper received ※ 19 May 2021 paper accepted ※ 10 June 2021 issue date ※ 27 August 2021
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TUPAB126	Spectral Gap in the Middle Infrared FEL Oscillator of FELiCHEM	FEL, laser, electron, free-electron-laser	1685
	Y.P. Zhu, H.T. Li, Z. Zhao USTC/NSRL, Hefei, Anhui, People’s Republic of China
	A phenomenon of spectral gap is observed in the Middle Infrared FEL Oscillator of FELiCHEM: the laser power falls down at the particular wavelength. Starting with the experimental data, this paper focuses on the simulation calculation and analysis of the effect from using the partial waveguide. The relationship between waveguide and spectral gap is revealed.
	Poster TUPAB126 [1.063 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB126
About •	paper received ※ 17 May 2021 paper accepted ※ 14 June 2021 issue date ※ 21 August 2021
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TUPAB133	Brazing free RF Pulse Compressor for High Gradient Accelerators	cavity, coupling, simulation, vacuum	1700
	L. Kankadze, D. Alesini, F. Cardelli, G. Di Raddo, M. Diomede INFN/LNF, Frascati, Italy
	EURPRAXIA@SPARC\_LAB, is a proposal to upgrade the SPARC\_LAB test facility (at LNF, Frascati) to a soft X-ray user facility based on plasma acceleration and high-gradient X-band (11.9942 GHz) accelerating modules. Each module is made up of a group of 4 TW sections assembled on a single girder and fed by one klystron by means of one rf pulse compressor system and a low attenuation circular waveguide network that transports the rf power to the input hybrids of the sections. The pulse compressor is based on a single Barrel Open Cavity (BOC). The BOC use a ’whispering gallery’ mode which has an intrinsically high quality factor and operates in a resonant rotating wave regime. Compared to the conventional SLED scheme it requires a single cavity instead of two cavities and a 3-dB hybrid. A new brazeless mechanical design has been proposed and is described in the present paper together with the electro-magnetic and thermo-mechanical simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB133
About •	paper received ※ 21 May 2021 paper accepted ※ 15 June 2021 issue date ※ 10 August 2021
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TUPAB153	Modeling of Capillary Discharge Plasmas for Wakefield Accelerators and Beam Transport	plasma, simulation, laser, electron	1740
	N.M. Cook, J.A. Carlsson, S.J. Coleman, A. Diaw, J.P. Edelen RadiaSoft LLC, Boulder, Colorado, USA E.C. Hansen, P. Tzeferacos Flash Center for Computational Science, Chicago, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics under Award Number DE-SC0018719. Next generation accelerators demand sophisticated beam sources to reach ultra-low emittances at large accelerating gradients, along with improved optics to transport these beams without degradation. Capillary discharge plasmas can address each of these challenges. As sources, capillaries have been shown to increase the energy and quality of wakefield accelerators, and as active plasma lenses they provide orders-of-magnitude increases in peak magnetic field. Capillaries are sensitive to energy deposition, heat transfer, ionization dynamics, and magnetic field penetration; therefore, capillary design requires careful modeling. We present simulations of capillary discharge plasmas using FLASH, a publicly-available multi-physics code developed at the University of Chicago. We report on the implementation of 2D and 3D models of capillary plasma density and temperature evolution with realistic boundary and discharge conditions. We then demonstrate laser energy deposition to model channel formation for guiding intense laser pulses. Lastly, we examine active capillary plasmas with varying fill species and compare our simulations against experimental studies.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB153
About •	paper received ※ 24 May 2021 paper accepted ※ 29 July 2021 issue date ※ 30 August 2021
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TUPAB239	Radiation of a Charged Particle Bunch Moving Along a Deep Corrugated Surface with a Small Period	radiation, ECR, electromagnetic-fields, impedance	1999
	E.S. Simakov, A.V. Tyukhtin Saint Petersburg State University, Saint Petersburg, Russia
	Funding: This work was supported by the Russian Science Foundation (Grant No. 18-72-10137). We investigate the electromagnetic radiation of a bunch moving along a corrugated conductive surface. It is assumed that wavelengths under consideration are much more than the period of the corrugation. In this case, the corrugated structure can be replaced with a smooth surface on which so-called equivalent boundary conditions (EBC) are fulfilled. In fact, we deal with anisotropic surface characterized by certain matrix impedance. Here, we consider the case of deep corrugation, i.e. we assume that the depth of the structure is much more than its period (the case of shallow corrugation was studied earlier). Using the EBC we obtain electromagnetic field components which are presented in form of spectral integrals. It is shown that the bunch generates surface waves propagating in the plane of the structure, whereas volume radiation is absent at the frequencies under consideration. We also consider the energy losses of the bunch. Typical dependences of a spectral density of the energy losses on corrugation parameters are obtained and analyzed. It is demonstrated that the features of the surface waves can be used for the bunch diagnostics. E.I. Nefedov, A.N. Sivov. Electrodynamics of periodic structures. Moscow, Nauka, 1977, 208 p. (in Russian). ** E.S. Simakov, A.V. Tyukhtin, S.N. Galyamin, Phys. Rev. AB, 22, 061301 (2019).
	Poster TUPAB239 [0.637 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB239
About •	paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 23 August 2021
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TUPAB246	Numerical Simulation and Beam-Dynamics Study of a Hollow-Core Woodpile Coupler for Dielectric Laser Accelerators	photon, laser, acceleration, electron	2022
	G.S. Mauro, D. Mascali, G. Sorbello, G. Torrisi INFN/LNS, Catania, Italy A. Bacci INFN/LASA, Segrate (MI), Italy C. De Angelis, A. Locatelli University of Brescia, Brescia, Italy A.R. Rossi INFN-Milano, Milano, Italy G. Sorbello University of Catania, Catania, Italy
	Hollow core dielectric microstructures powered by lasers represent a new and promising area of accelerator research thanks to the higher damage threshold and accelerating gradients with respect to metals at optical wavelengths. In this paper we present the design of a dielectric Electromagnetic Band Gap (EBG) mode converter for high-power coupling of the accelerating mode in Dielectric Laser Accelerators (DLAs). The design is wavelength-independent, and here we propose an implementation operating at 90.505 GHz (wavelength 3.3 mm) based on a silicon woodpile structure. The coupler is composed by two perpendicularly coupled hollow-core waveguides: a TE-like mode waveguide (excited from RF/laser power) and a TM-like mode accelerating waveguide. The structure has been numerically designed and optimized, presenting Insertion Losses (IL) < 0.3 dB and an efficient mode conversion in the operating bandwidth. The properties and effectiveness of the confined accelerating mode have been optimized in order to derive the needed accelerating gradient. The simulated electric field has been used as input for Astra beam-dynamics simulations in order to compute the beam properties.
	Poster TUPAB246 [2.209 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB246
About •	paper received ※ 18 May 2021 paper accepted ※ 27 July 2021 issue date ※ 13 August 2021
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TUPAB249	Diffraction at the Open-Ended Dielectric-Loaded Circular Waveguide	radiation, wakefield, electron, acceleration	2033
	S.N. Galyamin, A.V. Tyukhtin, V.V. Vorobev Saint Petersburg State University, Saint Petersburg, Russia
	Funding: Work supported by Russian Science Foundation (Grant No. 18-72-10137). Contemporary beam and THz technologies are tightly interlaced during last years. Strong THz fields allow realization of THz driven electron guns, THz bunch compression, streaking* and THz driven wakefield acceleration. Inversely, dielectric capillaries similar to those used for THz bunch manipulation can be in turn utilized for development of high-power narrow-band THz sources. Mentioned cases involve interaction of THz waves and particle bunches with an open end of certain dielectric loaded waveguide structure, most frequently a circular capillary. For further development of the discussed prospective topics a rigorous approach allowing analytical investigation of both radiation from open-ended capillaries and their excitation by external source would be extremely useful. We present an elegant and efficient rigorous method for solving circular open-ended dielectric-loaded waveguide diffraction problems based on Wiener-Hopf technique. We deal with the case of uniform dielectric loading and internal excitation by a waveguide mode. S-parameters, near-field and far-field distributions are presented. The obtained results can be also applied to the narrow band wakefield. L. Zhao et al., Phys. Rev. Lett., 124, 054802 (2020). M.T. Hibberd et al., Nat. Photonics, 14, 755-759 (2020). * D. Wang et al., Rev. Sci. Instr., 89(9), 093301 (2018).
	Poster TUPAB249 [2.160 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB249
About •	paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 21 August 2021
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TUPAB269	Transverse Impedance of Lossy Circular Metal-Dielectric Waveguides	impedance, radiation, resonance, wakefield	2093
	M. Ivanyan, L.V. Aslyan CANDLE SRI, Yerevan, Armenia K. Flöttmann, F. Lemery DESY, Hamburg, Germany
	The properties of the transverse impedance of a dielectric-loaded metallic circular waveguide are investigated taking into account losses in the outer metallic pipe and in the inner dielectric layer. The dispersion relations, impedances, and wake functions for dipole modes are analyzed and compared for thin and thick dielectric layer cases. The correspondence of the resonant frequencies of the longitudinal monopole and transverse dipole impedances is established.
	Poster TUPAB269 [0.906 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB269
About •	paper received ※ 16 May 2021 paper accepted ※ 28 May 2021 issue date ※ 10 August 2021
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TUPAB308	Mechanical Consolidation of the LHC Inner Triplet Magnet Supporting System for Remote Alignment	alignment, vacuum, quadrupole, ECR	2207
	F. Micolon, N. Bourcey, J-B. Deschamps, A. Herty, S. Le Naour, T. Mikkola, V. Parma, D. Ramos, V. Rude, M. Sosin CERN, Meyrin, Switzerland
	Given the high radiation area and the tight alignment tolerances, the LHC inner triplet magnets were designed to be realigned remotely using motorized supporting jacks. However, during run 2 the LHC triplet realignment system started to show an unexpected behavior with erratic load variations on the magnet supporting jacks when operated. It was then decided to freeze any further realignment of the LHC triplet magnet for the remainder of the run. Subsequently, a project team was set up at CERN to understand better the conditions leading to such unexpected behavior and to study and propose a technical consolidation for the realignment system of the LHC triplet magnet. A fully instrumented magnet string using LHC triplet spare magnets was assembled and used at CERN to provide a realistic test bench for this study. This paper reports on the work undertaken to study the triplet magnet overall realignment kinematic, the findings on the readjustment system malfunction and details the consolidation solution implemented for the next LHC run
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB308
About •	paper received ※ 18 May 2021 paper accepted ※ 07 June 2021 issue date ※ 18 August 2021
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TUPAB346	Development of a 500-MHz 150-kW Solid-State Power Amplifier for High Energy Photon Source	cavity, controls, photon, booster	2312
	Y.L. Luo, T.M. Huang, J. Li, H.Y. Lin, Q. Ma, Q.Y. Wang, P. Zhang, F.C. Zhao IHEP, Beijing, People’s Republic of China
	A 500-MHz 150-kW solid-state power amplifier (SSA) has been developed to test the 500-MHz normal conducting cavities for High Energy Photon Source (HEPS) booster ring. It will also be used to power normal conducting cavities in the initial beam commissioning stage of the HEPS storage ring. A total number of 96 amplifier modules are combined initially by coaxial and later by waveguide combiners to deliver the 150-kW RF power. The final output is of EIA standard WR1800 rectangular waveguide. Each amplifier module consists four transistors equipped with individual circulator and load and outputs 2-kW RF power. Modularity, redundancy and satisfactory RF performance are demonstrated. In the final stage of HEPS project, this 150-kW amplifier will be modified to a 100-kW amplifier to join the other five 100-kW SSAs for normal operation of the booster cavities. The development and test results are presented in this paper.
	Poster TUPAB346 [1.870 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB346
About •	paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 15 August 2021
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TUPAB348	Magnetron R&D for High Efficiency CW RF Sources for Industrial Accelerators	injection, experiment, cavity, MMI	2318
	H. Wang, K. Jordan, R.M. Nelson, R.A. Rimmer, S.O. Solomon JLab, Newport News, Virginia, USA B.R.L. Coriton, C.P. Moeller, K.A. Thackston GA, San Diego, California, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177, and DOE OS/HEP Accelerator Stewardship award 2019-2021. The scheme of using high-efficiency magnetrons to drive radiofrequency accelerators has been demonstrated at 2450 MHz in CW mode . Magnetron test stands at JLab and GA have been set up to further test the noise figure and the locking speed of the injection phase-lock method. For higher power applications, power combining experiments using a TM010 cavity-type combiner and a magic tee for the binary combiner while using a single clean injection signal has been carried out at 2450 MHz. The frequency pulling effect between the magnetron and a low-Q cavity has been shown to enhance the frequency locking bandwidth compared to the injection phase-lock alone. The principle has been studied by the equivalent circuit simulation, analytical model, and finally confirmed experimentally on the magnetrons. Due to the pandemic delay in 2020, the equivalent high power tests using a 75kW, 915MHz industrial magnetron will be done in 2021 and will be reported in a future paper. H. Wang, et al, Magnetron R&Ds for High-Efficiency CW RF Sources of Particle Accelerators, WEXXPLS1, proceedings of IPAC 2019, Melbourne, Australia, May 19 -24, 2019.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB348
About •	paper received ※ 22 May 2021 paper accepted ※ 21 June 2021 issue date ※ 30 August 2021
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TUPAB354	352-MHz Solid State RF System Development at the Advanced Photon Source	cavity, controls, PLC, klystron	2335
	D. Horan, D.J. Bromberek, N.P. DiMonte, A. Goel, T.J. Madden, A. Nassiri, G. Trento, G.J. Waldschmidt ANL, Lemont, Illinois, USA
	Development effort is underway on a 352MHz, 200kW solid state rf system intended as the base design to replace the existing klystron-based rf systems presently in use at the Advanced Photon Source (APS). A sixteen-input, 200kW final combining cavity was designed, built, and successfully tested to 29kW CW in combiner mode, and to 200kW CW in back-feed mode, where an external klystron was used to transmit power into the combining cavity. A four-port waveguide combiner was also tested in both backfeed and combiner mode to 193kW and 26kW respectively. Slow and fast interlock systems were designed and implemented to support the testing process. An EPICS and Programmable Logic Controller (PLC)-based system was developed to control, communicate with, and monitor the rf amplifiers used in the combiner-mode test, and to monitor and log system performance parameters relating to the combining cavity. Low-level rf control of the cavity in 29kW combiner-mode operation was achieved using the existing APS analog low-level rf hardware. Test data and design details are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB354
About •	paper received ※ 18 May 2021 paper accepted ※ 31 May 2021 issue date ※ 19 August 2021
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WEXA05	Solving for Collider Beam Profiles from Luminosity Jitter with Ghost Imaging	luminosity, collider, operation, diagnostics	2524
	D.F. Ratner, A. Chao SLAC, Menlo Park, California, USA
	Large accelerator facilities must balance the need to achieve user performance requirements while also maximizing delivery time. At the same time, accelerators have advanced data-acquisition systems that acquire synchronous data at high-rate from a large variety of diagnostics. Here we discuss the application of ghost-imaging (GI) to measure beam parameters, switching the emphasis from beam control to data collection: rather than intentionally manipulating the accelerator, we instead passively monitor jitter gathered over thousands to millions of events to reconstruct the target of interest. Passive monitoring during routine operation builds large data sets that can even deliver higher resolution than brief periodic scans, and can provide experiments with event-by-event information. In this presentation we briefly present applications of GI to light-sources, and then discuss a potential new application for colliders: measuring the transverse beam shapes at a collider’s interaction point to determine both the integrated luminosity and the spatial distribution of collision vertices.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEXA05
About •	paper received ※ 19 May 2021 paper accepted ※ 27 July 2021 issue date ※ 10 August 2021
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WEPAB045	European XFEL High-Power RF System - the First 4 Years of Operation	klystron, operation, FEL, electron	2708
	M. Bousonville, S. Choroba, T. Grevsmühl, S. Göller, A. Hauberg, V.V. Katalev, K. Machau, V. Vogel, B. Yildirim DESY, Hamburg, Germany
	In 2016, the installation of the European XFEL was completed and its 26 RF stations started operation in 2017. Each RF station consists of a 10 MW-1.3 GHz-multibeam klystron, a HV pulse modulator and a waveguide system to supply the superconducting cavities and the normal-conducting electron gun with RF power. During commissioning and subsequent operation, the RF stations were closely monitored and causes of failures were investigated. For the optimisation of the RF systems, the various RF station failures were evaluated according to their impact on accelerator operation and the measures to eliminate them were prioritised accordingly. This report describes the operation experience and improvements of the high-power RF stations during the first 4 years of operation.
	Poster WEPAB045 [6.887 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB045
About •	paper received ※ 19 May 2021 paper accepted ※ 07 June 2021 issue date ※ 21 August 2021
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WEPAB077	High Power Terahertz Cherenkov Free Electron Laser from a Waveguide with a Thin Dielectric Layer by a Near-Relativistic Electron Beam	electron, radiation, wakefield, bunching	2769
	W.W. Li, T.L. He, Z.G. He, R. Huang, Q.K. Jia, S.M. Jiang, L. Wang USTC/NSRL, Hefei, Anhui, People’s Republic of China
	Funding: National Natural Science Foundation of China (11705198, 11775216, 11805200) Fundamental Research Funds for the Central Universities (No. WK2310000082 and No. WK2310000090) Corrugated and dielectric structures have been widely used for producing accelerator based terahertz radiation source. Recently, the novel schemes of the sub-terahertz free electron laser (FEL) from a metallic waveguide with corrugated walls and a normal dielectric loaded waveguide driven by a near-relativistic (beam energy of a few MeV) picosecond electron beam were studied respectively. Such a beam is used for driving resonant modes in the waveguide, and if the pipe is long enough, the interaction of these modes with the co-propagating electron beam will result in micro-bunching and the coherent enhancement of the wakefield radiation. It offers a promising candidate for compact accelerator-based high power terahertz source which can be realized with relatively low energy and low peak-current electron beams. However the choices of the waveguide above is less effective in order to obtain high power with frequency around 1THz. In this paper, we propose to use the waveguide with a thin dielectric layer instead, and high power radiation (>~10 MW) around 1 THz is expected to obtain in the proposed structure according to the simulation results.
	Poster WEPAB077 [1.332 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB077
About •	paper received ※ 12 May 2021 paper accepted ※ 23 June 2021 issue date ※ 22 August 2021
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WEPAB144	A New Flux Concentrator Made of Cu Alloy for the SuperKEKB Positron Source	positron, operation, vacuum, target	2954
	Y. Enomoto, K. Abe, N. Okada, T. Takatomi KEK, Ibaraki, Japan
	Flux concentrator (FC) is one of important device for positron source which translates position and momentum spread of the particles adiabatically to match them to the acceptance of the following section. To realize higher positron yield, higher magnetic field is desired. However, higher field by higher current generate stronger force on the coil. Since the gap between each turn of the coil is as narrow as 0.2 mm and the voltage across them is about as high as 1 kV at the design current, slight deformation of the coil cause discharge between the gap. To avoid such problem, a new FC made of Cu alloy which has 40 times higher yield strength than that of pure Cu was designed and tested. Finally, during summer shutdown in 2020, the old FC made of pure Cu was replaced by the new one made of Cu alloy in the KEK electron positron injector linac. The new one has been working stably at the design current, 12 kA, since Oct. 2020, and positron yield of 0.5 was realized. There were no discharge and other trouble till now.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB144
About •	paper received ※ 08 May 2021 paper accepted ※ 01 July 2021 issue date ※ 26 August 2021
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WEPAB165	Metamaterial Waveguide HOM Loads for SRF Accelerating Cavities	HOM, vacuum, cavity, SRF	2994
	S.V. Kuzikov Euclid TechLabs, Solon, Ohio, USA
	Suppression of beam induced HOMs is necessary for most SRF accelerating cavities driven with high currents. One of the problems in design of a HOM load is that vacuum compatible materials with high enough imaginary part of the dielectric permittivity, which provides absorption, have also a high real part of the permittivity. This does not allow absorbing RF radiation at short distance and in broad frequency band. We propose considering artificial metamaterials where besides lossy dielectric pieces, an absorber with high magnetic permeability is included. In our proposal, we suggest composing a waveguide HOM load of a metamaterial consisted of well-known ceramic and ferrite plates placed periodically in a stack. Such a design provides low return losses, compactness and broad frequency range of the operation.
	Poster WEPAB165 [1.844 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB165
About •	paper received ※ 19 May 2021 paper accepted ※ 02 June 2021 issue date ※ 24 August 2021
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WEPAB190	DC Break Design for a 2.45 GHz ECR Ion Source	site, ECR, high-voltage, simulation	3064
	M.S. Dmitriyev, M.V. Dyakonov, S.A. Tumanov, M.I. Zhigailova MEPhI, Moscow, Russia
	New 2.45 GHz Electron Cyclotron Resonance Ion Source (ECRIS) is under development at NRNU MEPhI. The transmission line is designed for transmitting the microwave power into the ECRIS. A DC break up to 80 kV was designed for the electrical insulation between the microwave supply system and the plasma chamber applied to high DC voltage. Current study considers the investigation results as well as the optimization of numerical simulations of the 2.45 GHz DC break with low losses and low emission into the surrounding space.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB190
About •	paper received ※ 20 May 2021 paper accepted ※ 08 June 2021 issue date ※ 30 August 2021
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WEPAB283	CERN SPS Sprinkler System: A Customized Industrial Solution for a Non-Conventional Site	radiation, controls, monitoring, operation	3313
	A. Suwalska, A. Arnalich, F. Deperraz, M. Munoz Codoceo, P. Ninin CERN, Meyrin, Switzerland
	Until 2018, the limited firefighting means in the SPS complex largely exposed it to the consequences of self-ignition or accidental fire. In 2015 the SPS Fire Safety project was launched with the objective of improving life safety and property protection by deploying a whole set of automatic actions to protect SPS in case of fire outbreak. If nothing was done, an unmanaged fire could be a threat to lives of those working underground and could mean losing a vast majority of the SPS machine and its equipment. In 2020, CERN has completed the consolidation of its SPS fire safety systems. Among these, a water based sprinkler system, following principles of standard industrial design but customized and tailor-made for SPS and its irradiated areas, is ready to operate. The system must take into account limitations related to the presence of fragile accelerator equipment, radioactive zones, integration constraints and comply with European norms, in particular EN12845. This paper presents the risk assessment, our experience from the planning and installation phase while discussing the custom-chosen and radiation tested equipment to end up with the lessons learned and outlook for the future.
	Poster WEPAB283 [2.224 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB283
About •	paper received ※ 13 May 2021 paper accepted ※ 14 June 2021 issue date ※ 16 August 2021
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WEPAB287	Upgrade of the ELBE Timing System	timing, operation, gun, hardware	3326
	M. Kuntzsch, M. Justus, A. Schwarz, K. Zenker HZDR, Dresden, Germany L. Krmpotic, U. Legat, U. Rojec Cosylab, Ljubljana, Slovenia Ž. Oven COSYLAB, Control System Laboratory, Ljubljana, Slovenia
	At the ELBE accelerator center a superconducting linac is operated to drive manifold secondary radiation sources like two infrared FELs, a positron source and a THz facility. The machine uses two injectors as electron sources that are accelerated in the main linac. The user experiments demand a large variety of bunch patterns from single shot to macro pulsed and cw beam at up to 26 MHz repetition rate. At ELBE a new timing system is being developed based on the MRF hardware platform and the MRF Timing System IOC. It uses two masters and a scalable number of connected receivers to generate the desired pulse patterns for operating the machine and to control user experiments. The contribution will show the architecture of the timing system, the control interfacing and performance measurements acquired on the test bench.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB287
About •	paper received ※ 21 May 2021 paper accepted ※ 01 July 2021 issue date ※ 13 August 2021
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WEPAB301	Design of an X-Band LLRF System for TEX Test Facility at LNF-INFN	LLRF, cavity, klystron, insertion	3371
	L. Piersanti, D. Alesini, M. Bellaveglia, S. Bini, B. Buonomo, F. Cardelli, C. Di Giulio, M. Diomede, A. Falone, G. Franzini, A. Gallo, A. Liedl, S. Pioli, S. Quaglia, L. Sabbatini, M. Scampati, G. Scarselletta, A. Stella INFN/LNF, Frascati, Italy
	Funding: Latino is a project co-funded by Regione Lazio within POR-FESR 2014-2020 program In the framework of LATINO project (Laboratory in Advanced Technologies for INnOvation) funded by Lazio regional government, a TEst stand for X-band (TEX) is being commissioned at Frascati National Laboratories (LNF) of INFN. TEX is born as a collaboration with CERN, aimed at carrying out high power tests of X-band accelerating structure prototypes and waveguide components, and it is of paramount importance in view of the construction of EuPRAXIA@SPARC_LAB facility at LNF. In order to generate, manipulate and measure the RF pulses needed to feed the RF power unit (solid state ScandiNova K400 modulator, CPI 50 MW 50 Hz klystron) an X-band low level RF system has been developed, making use of a commercial S-band (2.856 GHz) Libera digital LLRF (manufactured by Instrumentation Technologies) with a newly designed up/down conversion stage and a reference generation/distribution system, which is able to produce coherent reference frequencies for the American S-band (2.856 GHz) and European X-band (11.994 GHz). In this paper the main features of such systems will be reviewed together with preliminary laboratory measurement results.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB301
About •	paper received ※ 19 May 2021 paper accepted ※ 12 July 2021 issue date ※ 27 August 2021
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WEPAB305	Teeport: Break the Wall Between the Optimization Algorithms and Problems	experiment, controls, real-time, monitoring	3387
	Z. Zhang, X. Huang, M. Song SLAC, Menlo Park, California, USA
	Funding: DOE, Office of Science, Office of Basic Energy Sciences, DE-AC02-76SF00515 and FWP 2018-SLAC-100469 Computing Science, Office of Advanced Scientific Computing Research, FWP 2018-SLAC-100469ASCR. Optimization algorithms/techniques such as genetic algorithm (GA), particle swarm optimization (PSO) and Gaussian process (GP) have been widely used in the accelerator field to tackle complex design/online optimization problems. However, connecting the algorithm with the optimization problem can be difficult, sometimes even unrealistic, since the algorithms and problems could be implemented in different languages, might require specific resources, or have physical constraints. We introduce an optimization platform named Teeport that is developed to address the above issue. This real-time communication (RTC) based platform is particularly designed to minimize the effort of integrating the algorithms and problems. Once integrated, the users are granted a rich feature set, such as monitoring, controlling, and benchmarking. Some real-life applications of the platform are also discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB305
About •	paper received ※ 20 May 2021 paper accepted ※ 02 July 2021 issue date ※ 27 August 2021
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WEPAB314	TEX - an X-Band Test Facility at INFN-LNF	controls, klystron, LLRF, framework	3406
	S. Pioli, D. Alesini, F.A. Anelli, M. Bellaveglia, S. Bini, B. Buonomo, S. Cantarella, F. Cardelli, G. Catuscelli, R. Ceccarelli, A. Cecchinelli, F. Chiarelli, P. Ciuffetti, R. Clementi, C. Di Giulio, E. Di Pasquale, G. Di Raddo, M. Diomede, A. Esposito, L. Faillace, A. Falone, G. Franzini, A. Gallo, S. Incremona, A. Liedl, D. Pellegrini, G. Piermarini, L. Piersanti, S. Quaglia, R. Ricci, L. Sabbatini, M. Scampati, G. Scarselletta, A. Stella, R. Zarlenga INFN/LNF, Frascati, Italy
	Funding: The LATINO project is co-funded by the Regione Lazio within POR-FESR 2014-2020 European activities (public call "Open Research Infrastructures"). We report the status of the development of an High Power RF Laboratory in X-Band called TEX (TEst-stand for X-Band). TEX is part of the LATINO (Laboratory in Advanced Technologies for INnOvation) initiative that is ongoing at the Frascati National Laboratories (LNF) of the Italian Institute for Nuclear Physics (INFN) that covers many different areas focused on particle accelerator technologies. TEX is a RF test facility based on solid-state K400 modulator from ScandiNova with a 50MW class X-band (11.996 GHz) klystron tube model vkx 8311a operating at 50 Hz. This RF source will operate as resource for test and research programs such as the RF breakdown on RF waveguide components as well as high power testing of accelerating structures for future high gradient linear accelerator such as EuPRAXIA and CLIC. The high power testing will be performed in a dedicated brand-new bunker that has been recently built. RF system, vacuum controls and safety equipments are currently being installed. The first accelerating structure testing is scheduled by beginning 2022. In this document design and tests for all the sub-systems of the facility will be presented and discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB314
About •	paper received ※ 19 May 2021 paper accepted ※ 28 July 2021 issue date ※ 19 August 2021
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WEPAB349	Design of a Circular Waveguide TM₀₁ Mode Launcher with Wire Loop Feed	coupling, experiment, detector, simulation	3517
	A. Chittora BITS Pilani, Sancoale, India
	In Accelerator technology, RF power couplers are important component to couple RF signal to travelling wave structure. Circular waveguide TM₀₁ mode is one of the symmetric modes, that is suitable to use for RF coupling. TM₀₁ mode launcher is used as an RF coupler in Accelerator technology. Design of a compact circular waveguide TM₀₁ mode-launcher is presented in this paper. The design is based on the principle of magnetic field coupling between a wire loop and TM₀₁ mode of circular waveguide. The mode launcher exhibits high efficiency and 3.1% bandwidth at 3.2 GHz frequency with both circular and elliptical loop. Performance of the mode launcher is experimentally verified and simulated S-parameters agree with the measured results. The mode launcher is of compact size and is suitable for efficient excitation of TM₀₁ mode in circular waveguide and travelling wave structures. The launcher is also useful for cold testing of high power microwave antennas and Radars. M. Forno, "Design of a high power TM₀₁ mode launcher optimized for manufacturing by milling." 2016.
	Poster WEPAB349 [1.135 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB349
About •	paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 20 August 2021
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WEPAB371	Numerical Analysis on Nitrogen Injection Fire Extinguishing System in the LINAC Area at TPS	simulation, linac, injection, gun	3578
	J.-C. Chang, W.S. Chan, Y.F. Chiu NSRRC, Hsinchu, Taiwan
	The Linear accelerator (LINAC) of Taiwan Photon Source (TPS) could generate electrons to 150 MeV. The main subsystems including an electron gun, buncher, accelerating sections, vacuum system, and focusing and steering magnets are located in the LINAC area of 223.5 m2 and 3 m in height. We designed a nitrogen injection fire extinguishing system for the LINAC area and performed Computational Fluid Dynamic (CFD) simulation to analyse the fire extinguishing performance with and without fresh air supplied from the air conditioning system.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB371
About •	paper received ※ 16 May 2021 paper accepted ※ 21 June 2021 issue date ※ 20 August 2021
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WEPAB374	The Southern Hemisphere’s First X-Band Radio-Frequency Test Facility at the University of Melbourne	electron, klystron, gun, network	3588
	M. Volpi, R.P. Rassool, S.L. Sheehy, G. Taylor, S.D. Williams The University of Melbourne, Melbourne, Victoria, Australia M.J. Boland CLS, Saskatoon, Saskatchewan, Canada M.J. Boland University of Saskatchewan, Saskatoon, Canada N. Catalán Lasheras, S. Gonzalez Anton, G. McMonagle, S. Stapnes, W. Wuensch CERN, Meyrin, Switzerland R.T. Dowd, K. Zingre AS - ANSTO, Clayton, Australia
	The first Southern Hemisphere X-band Laboratory for Accelerators and Beams (X-LAB) is under construction at the University of Melbourne, and it will operate CERN X-band test stand containing two 12GHz 6MW klystron amplifiers. By power combination through hybrid couplers and the use of pulse compressors, up to 50 MW of peak power can be sent to any of 2 test slots at pulse repetition rates up to 400 Hz. The test stand is dedicated to RF conditioning and testing CLIC’s high gradient accelerating structures beyond 100 MV/m. It will also form the basis for developing a compact accelerator for medical applications, such as radiotherapy and compact light sources. Australian researchers working as part of a collaboration between the University of Melbourne, international universities, national industries, the Australian Synchrotron -ANSTO, Canadian Light Source and the CERN believe that creating a laboratory for novel accelerator research in Australia could drive technological and medical innovation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB374
About •	paper received ※ 18 May 2021 paper accepted ※ 06 July 2021 issue date ※ 30 August 2021
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WEPAB398	A C-Band RF Mode Launcher with Quadrupole Field Components Cancellation for High Brightness Applications	quadrupole, network, brightness, linac	3638
	G. Pedrocchi SBAI, Roma, Italy D. Alesini, F. Cardelli, A. Gallo, A. Giribono, B. Spataro INFN/LNF, Frascati, Italy G. Castorina AVO-ADAM, Meyrin, Switzerland L. Ficcadenti INFN-Roma, Roma, Italy M. Migliorati, A. Mostacci, L. Palumbo Sapienza University of Rome, Rome, Italy
	The R&D of high gradient radiofrequency devices is aimed to develop innovative and compact accelerating stuctures based on new manufactoring techniques and materials in order to produce devices operating with the highest accelerating gradient. Recent studies have shown a large increase in the maximum sustained RF surface electric fields in copper structure operating at cryogenic temperature. These novel approaches allow significant performance improvements of RF photoinjectors. Indeed the operation at high surface fields results in considerable increase of electron brilliance. This requires high field quality in the RF photoinjector and specifically in its poweer coupler. In this work we present a novel power coupler for the RF photoinjector. The coupler is a compact C-band TM01 mode launcher with a fourfold symmetry which minimized both the dipole and the quadrupole RF field components.
	Poster WEPAB398 [1.799 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB398
About •	paper received ※ 13 May 2021 paper accepted ※ 06 July 2021 issue date ※ 23 August 2021
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WEPAB402	Status and Progress of the High-Power RF System for High Energy Photon Source	cavity, booster, photon, storage-ring	3653
	T.M. Huang, J. Li, H.Y. Lin, Y.L. Luo, Q. Ma, W.M. Pan, P. Zhang, F.C. Zhao IHEP, Beijing, People’s Republic of China
	Funding: Work was supported in part by High Energy Photon Source, a major national science and technology infrastructure in China, and in part by the National Natural Science Foundation of China(12075263). High Energy Photon Source is a 6-GeV diffraction-limited synchrotron light source currently under construction in Beijing. Three types of high-power RF systems are used to drive the booster and the storage ring. For the booster ring, a total of 600-kW continuous-wave (CW) RF power is generated by six 500-MHz solid-state power amplifiers (SSA) and fed into six normal-conducting copper cavities. Concerning the storage ring, five CW 260-kW SSAs at 166 MHz and two CW 260-kW SSAs at 500-MHz are used to drive five fundamental and two third-harmonic superconducting cavities respectively. The RF power distributions are realized by 9-3/16" rigid coaxial line for the 166-MHz system and EIA standard WR1800 waveguide for the 500-MHz one. High-power circulators and loads are installed at the outputs of all SSAs to further protect the power transmitters from damages due to reflected power although each amplifier module is equipped with individual isolators. The overall system layout and the progress of the main components are presented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB402
About •	paper received ※ 18 May 2021 paper accepted ※ 02 July 2021 issue date ※ 14 August 2021
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THPAB077	Magnetic Shims Studies for APS-U Hybrid Permanent Magnet Undulators	undulator, multipole, simulation, quadrupole	3941
	Y. Piao, R.J. Dejus, M.F. Qian, I. Vasserman, J.Z. Xu ANL, Lemont, Illinois, USA
	Funding: Work supported by U.S. Department of Energy, Office of Science, under contract number DE-AC02-06CH11357 For the newly designed and fabricated APS Upgrade (APS-U) hybrid permanent magnet undulators (HPMUs), the development of magnetic shims has been critical to successfully tuning the undulators to meet the tight APS-U physics requirements. Different types of side and surface shims have been developed and applied for this purpose. The side shims are primarily used for trajectory tuning, and the surface shims are for phase and multipole tuning as well as trajectory tuning. Current design, applications, and measurement of the shims for the newly designed and fabricated APS28 (28 mm period) undulators are presented in this paper.
	Poster THPAB077 [0.531 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB077
About •	paper received ※ 20 May 2021 paper accepted ※ 18 June 2021 issue date ※ 27 August 2021
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THPAB081	High-Power Prototype Canon Coupler for APS-U Booster Cavities	cavity, booster, coupling, injection	3956
	G.J. Waldschmidt, D.J. Bromberek, D. Horan, G. Trento, U. Wienands ANL, Lemont, Illinois, USA T. Harada, H. Oikawa, H. Takahashi CETD, Tochigi, Japan
	The Advanced Photon Source Upgrade (APS-U) plans to achieve a beam capture efficiency above 90% at 17 nC bunch charge into the Booster. Due to large beam loading at injection, the 352-MHz Booster cavities will be significantly detuned necessitating effective-power handling much greater than the 100kW effective power rating of the present coupler. Canon Electron Tubes & Devices Co., Ltd. (CETD) has designed and built a compact coupler for the APS-U Booster using a high-power ceramic disk window design in addition to accommodating significant space restrictions and additional diagnostics and cooling requirements. The coupler design was modified from an existing 500MHz, 800kW coupler that has been in routine operation at KEKB. The APS-U coupler has been installed and tested in the high-power 352-MHz test stand at the APS. The details of the design and testing of the prototype coupler will be reported in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB081
About •	paper received ※ 18 May 2021 paper accepted ※ 28 July 2021 issue date ※ 15 August 2021
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THPAB147	Preliminary Study of 500 MHz HOM-Free RF Cavity	cavity, HOM, coupling, damping	4050
	Zh.X. Tang USTC/NSRL, Hefei, Anhui, People’s Republic of China
	Funding: Work supported by National Natural Science Foundation of China(Grant No. U1832135 and 11805199)} In this paper, we study the microwave characteristics of 500 MHz RF cavity, including the optimization of cavity structure, the simulation design of high-order mode (HOM) absorption structure and the design of coupler. The cavity structure is simulated by CST. The absorption waveguide is designed and optimized. The coupler is designed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB147
About •	paper received ※ 09 May 2021 paper accepted ※ 16 July 2021 issue date ※ 02 September 2021
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THPAB210	Extrapolated Range for Low Energy Electrons (< 1 keV)	electron, simulation, experiment, multipactoring	4201
	C. Inguimbert, M.B. Belhaj, Q. Gibaru ONERA, Toulouse, France Q. Gibaru, D. Lambert, M. Raine CEA, Arpajon, France Q. Gibaru CNES, PARIS, France
	Funding: ONERA- DPHY, 2 avenue E. Belin, 31055 Toulouse, France CEA, DAM, DIF, 91297 Arpajon, France CNES, 18 av. E. Belin, 31055 Toulouse, France The Secondary Electron Emission (SEE) process plays an important role in the performance of various devices. Mitigating the multipactor phenomenon that may occur in radio-frequency components is a concern in many fields such as space technologies or electron microscopy. SEE is also a concern in the accelerator physics community, where the beam lines stability can strongly be affected by this phenomenon,. In that scope, the escaped depth and thus the range of emitted electrons is of great interest. Our goal, by means of simulations is to provide a better knowledge of SEE. We have developed a Monte Carlo electron transport code for low energy electrons [~eV, ~10keV], that is part of the Dec. 2020 release of GEANT4*. It has been used to study the practical range of low energy electrons. Our goal is to formulate, below ~10 keV, an analytic range vs. energy expression, and to relate it to fundamental physcial parameters such as the mean free paths of electrons in matter. The goal is to provide simple practical extrapolated range formula that can help to understand SEE phenomenon. M. Mostajeran et al. J. of Instr. 5 (2010) C. Y. Vallgren et al. Phys. Rev. Accel. Beam 14 (2011) * Q. Gibaru et al. Nuc. Inst. And Met. 487 (2021)
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB210
About •	paper received ※ 10 May 2021 paper accepted ※ 23 June 2021 issue date ※ 27 August 2021
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THPAB211	Monte Carlo Simulation of 3D Surface Morphologies for Secondary Electron Emission Reduction	electron, simulation, multipactoring, experiment	4204
	Q. Gibaru, M.B. Belhaj, C. Inguimbert ONERA, Toulouse, France Q. Gibaru, D. Lambert, M. Raine CEA, Arpajon, France Q. Gibaru CNES, PARIS, France
	Low energy electrons of few tens of eV may cause Multipactor breakdowns in waveguides driven by the Secondary Electron Emission Yield (SEY) of the walls. This risk is lowered by using low emissive surfaces and this topic has been studied experimentally and with numerical simulations. The dependence of the SEY on surface properties is well known. Surface morphology has been widely used to reduce the SEY by forming roughness patterns on the surface. All patterns do not have the same efficiency so their analysis in terms of SEY is relevant. Monte-Carlo simulation codes can be used to study the processes behind the SEY. The MicroElec module of GEANT4 has recently been extended with more materials and processes and validated with experimental data for SEY calculations. In this work, simulation results are shown for a bulk sample capped with different roughness patterns. The effects of the shape parameters on the SEY are studied for typical dimensions between 20 µm and 100 µm. The results are checked with experimental SEY measurements on samples with similar roughness patterns. :T Gineste et al, Appl Surf Sci 359 (2015) 398-404 :J Pierron et al, J Appl Phys 124 (2018) 095101 *:Q. Gibaru, C. Inguimbert, P. Caron, M. Raine, D. Lambert, J. Puech, NIM B. 487 (2021) 66-77
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB211
About •	paper received ※ 12 May 2021 paper accepted ※ 23 June 2021 issue date ※ 17 August 2021
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THPAB223	Energy Compression System Radio Frequency Design at the Canadian Light Source	linac, impedance, simulation, RF-structure	4231
	E.J. Ericson, D. Bertwistle, M.J. Boland CLS, Saskatoon, Saskatchewan, Canada
	The Canadian Light Source (CLS), Canada’s only synchrotron light source, is considering a linear accelerator (LINAC) upgrade. As a result, the radio frequency (RF) structure in the downstream Energy Compression System (ECS) needs to be redesigned. In this paper, we describe the design process followed to determine the geometry of the RF structure cells and coupler.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB223
About •	paper received ※ 18 May 2021 paper accepted ※ 28 July 2021 issue date ※ 28 August 2021
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THPAB296	The Spallation Neutron Source Normal Conducting Linac RF System Design for the Proton Power Upgrade Project	DTL, cavity, klystron, linac	4383
	J.S. Moss, M.T. Crofford, S.W. Lee, G.D. Toby ORNL, Oak Ridge, Tennessee, USA M.E. Middendorf ORNL RAD, Oak Ridge, Tennessee, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under contract number DE-AC05-00OR22725. The Proton Power Upgrade (PPU) project at the Spallation Neutron Source will double the available proton beam power from 1.4 to 2.8 MW by increasing the beam energy from 1.0 to 1.3 GeV and the beam current from 26 to 38 mA. The increase in beam current resulted in the need to redesign the existing normal conducting linac (NCL) RF Systems. High-power testing of the existing NCL RF Systems configured to accelerate PPU-level beam provided the data used to make the final design decisions. This paper describes the development and execution of those in-situ tests and the subsequent results.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB296
About •	paper received ※ 17 May 2021 paper accepted ※ 22 July 2021 issue date ※ 20 August 2021
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THPAB300	Structure Design and Motion Analysis of 6-DOF Sample Positioning Platform	controls, radiation, synchrotron-radiation, synchrotron	4387
	G.Y. Wang, J.X. Chen, L. Liu, R.H. Liu, C.J. Ning, A.X. Wang, J.B. Yu, Y.J. Yu, J.S. Zhang IHEP CSNS, Guangdong Province, People’s Republic of China L. Kang IHEP, Beijing, People’s Republic of China
	with the development of synchrotron radiation (SR) light source technology, in order to meet the requirements of sample positioning platform of some beamline stations, such as adjusting resolution at the nanometer level and having larger sample scanning distance, a six degree of freedom positioning platform based on spacefab structure was developed. The key technologies such as coordinate parameter transformation, kinematics analysis, and adjustment decoupling algorithm of 6-DOF pose adjustment system of SpaceFAB positioning platform are mainly studied. A 6-DOF platform driven by a stepping motor is designed and manufactured. The control system of the 6-DOF Platform Based on bus control is developed, and the adjustment accuracy is tested. The repeated positioning accuracy of the platform in three directions is 0.019 mm, and that of rotation is 0.011 ° in three directions. The test results verify the correctness of the theoretical analysis of SpaceFAB structure and the rationality of mechanism design. The research on the platform motion algorithm and control system has important reference value for the follow-up research of large stroke nano-6-dof positioning platform.
	Poster THPAB300 [1.517 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB300
About •	paper received ※ 16 May 2021 paper accepted ※ 06 July 2021 issue date ※ 02 September 2021
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THPAB332	Development of a Pair of 182 GHz Two-Half Power Extractor and Accelerator for Short Pulse RF Breakdown Study	acceleration, electron, wakefield, alignment	4435
	J.H. Shao, J.G. Power ANL, Lemont, Illinois, USA R.B. Agustsson, S.V. Kutsaev, A.Yu. Smirnov RadiaBeam, Santa Monica, California, USA
	High-frequency structures are favorable in structure wakefield acceleration for their strong beam-structure interaction. Recent progress of advanced fabrication technologies, such as high-precision two-half milling and additive machining, has enabled experimental research of mm-wave/THz structures. In this work, we have designed a pair of 182 GHz two-half copper power extractor and accelerator for short pulse RF breakdown study. When driven by a 182 GHz 4-bunch train with 4 nC total charge and 0.3 mm rms bunch length, the power extractor will generate 0.4 ns ~8 MW RF pulses and the corresponding gradient in the single-cell accelerator will reach ~460 MV/m. RF and mechanical design of the proof-of-concept structures will be reported in this manuscript.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB332
About •	paper received ※ 26 May 2021 paper accepted ※ 19 July 2021 issue date ※ 26 August 2021
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THPAB335	Optical Phase Space Mapping Using a Digital Micro-Mirror Device	experiment, radiation, optics, controls	4439
	M. Vujanovic, R.B. Fiorito, C.P. Welsch, J. Wolfenden The University of Liverpool, Liverpool, United Kingdom A.L. Kippax Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: This project has received funding from European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 721559. Optical transition radiation (OTR) is routinely used to measure transverse beam size, divergence , and emittance of charged particle beams. Presented here is an experimental method, which uses micro-mirror device (DMD) to conduct optical phase space mapping (OPSM). OPSM will be a next step and significant enhancement of the measurements capabilities of an adaptive optics-based beam characterization system. For this measurements, a DMD will be used to generate a reflective mask that replicates the double slit. Since the DMD makes it possible to easily change the size, shape and position of the mask, the use of the DMD will greatly simplify OPSM and make it more flexible, faster and more useful for diagnostics applications. The process can be automated and integrated into a control system that can be used to optimize the beam transport.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB335
About •	paper received ※ 20 May 2021 paper accepted ※ 27 July 2021 issue date ※ 28 August 2021
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FRXC05	Gas Jet In-Vivo Dosimetry for Particle Beam Therapy	operation, diagnostics, proton, cyclotron	4548
	J. Wolfenden, N. Kumar, A. Salehilashkajani, C.P. Welsch, H.D. Zhang The University of Liverpool, Liverpool, United Kingdom N. Kumar, A. Salehilashkajani, C.P. Welsch, J. Wolfenden, H.D. Zhang Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: This work is supported by the HL-LHC-UK project funded by STFC and CERN and the STFC Cockcroft core grant No. ST/G008248/1. Medical applications of charged particle beams require a full online characterisation of the beam to ensure patient safety, treatment efficacy, and facility efficiency. In-vivo dosimetry, measurement of delivered dose during treatment, is a significant part of this characterisation. Current methods offer limited information or are invasive to the beam, meaning measurements must be done offline. This contribution presents the development of a non-invasive gas jet in-vivo dosimeter for treatment facilities. The technique is based on the interaction between a particle beam and a supersonic gas jet curtain, which was originally developed for the high luminosity upgrade of the large hadron collider (HL-LHC). To demonstrate the medical application of this technique, an existing HL-LHC test system with minor modifications will be installed at the University of Birmingham’s 35 MeV proton cyclotron, which has properties comparable to that of a treatment beam. This contribution presents the design and development of this test setup, plans for initial benchmarking measurements, and plans for a future optimised medical accelerator gas jet in-vivo dosimeter.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-FRXC05
About •	paper received ※ 18 May 2021 paper accepted ※ 23 July 2021 issue date ※ 11 August 2021
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Paper

Title

Other Keywords

Page

MOPAB003

Machine Learning Analysis of Electron Cooler Operation for RHIC

luminosity, electron, operation, scattering

45

X. Gu, A.V. Fedotov, D. Kayran
BNL, Upton, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
A regression machine learning algorithm was applied to analyze the operation data of RHIC with electron cooler LEReC during the 2020 physics run. After constructing a black-box surrogate model from the XGBoost algorithm and plotting their partial dependency plots for different operation parameters, we can find the effects of an individual parameter on the RHIC luminosity and optimize it accordingly offline.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB003

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paper received ※ 14 May 2021 paper accepted ※ 25 May 2021 issue date ※ 11 August 2021

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MOPAB041

Convergence Map with Action-Angle Variables Based on Square Matrix for Nonlinear Lattice Optimization

lattice, linear-dynamics, resonance, betatron

182

L.H. Yu, Y. Hidaka, F. Plassard, V.V. Smaluk
BNL, Upton, New York, USA
Y. Hao
FRIB, East Lansing, Michigan, USA

We apply square matrix method to obtain in high speed a "convergence map", which is similar but different from frequency map. The convergence map is obtained from solving nonlinear dynamical equation by iteration of perturbation method and study the convergence. The map provides information about the stability border of dynamical aperture. We compare the map with frequency map from tracking. The result indicates the new method may be applied in nonlinear lattice optimization, taking the advantage of the high speed (about 10~50 times faster) to explore x, y and the off-momentum phase space.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB041

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paper received ※ 09 May 2021 paper accepted ※ 26 May 2021 issue date ※ 18 August 2021

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MOPAB047

A CAD Tool for Linear Optics Design: A Use Case Approach

controls, software, MMI, optics

205

J. Bengtsson
HZB, Berlin, Germany
T.J.R. Nicholls, W.A.H. Rogers
DLS, Oxfordshire, United Kingdom

The formula relevant for linear optics design of synchrotrons are derived systematically from first principles, i.e., an exercise in Hamiltonian dynamics. Equipped with these, the relevant use cases are then captured; for a streamlined approach. To enable professionals, i.e., software engineers, to efficiently prototype & architect a CAD tool available to mechanical engineers since the mid-1960s. In other words, robust design of a modern synchrotron is an exercise in/pursuit of the art of Engineering-Science.

Poster MOPAB047 [1.059 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB047

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paper received ※ 17 May 2021 paper accepted ※ 28 May 2021 issue date ※ 15 August 2021

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MOPAB077

Anomaly Detection in Accelerator Facilities Using Machine Learning

power-supply, operation, experiment, detector

304

A. Das
Stanford University, Stanford, California, USA
M. Borland, L. Emery, X. Huang, H. Shang, G. Shen
ANL, Lemont, Illinois, USA
D.F. Ratner
SLAC, Menlo Park, California, USA
R.M. Smith, G.M. Wang
BNL, Upton, New York, USA

Synchrotron light sources are user facilities and usually run about 5000 hours per year to support many beamlines operations in parallel. Reliability is a key parameter to evaluate machine performance. Even many facilities have achieved >95% beam reliability, there are still many hours of unscheduled downtime and every hour lost is a waste of operation costs along with a big impact on individual scheduled user experiments. Preventive maintenance on subsystems and quick recovery from machine trips are the basic strategies to achieve high reliability, which heavily depends on experts’ dedication. Recently, SLAC, APS, and NSLS-II collaborated to develop machine-learning-based approaches aiming to solve both situations, hardware failure prediction and machine failure diagnosis to find the root sources. In this paper, we report our facility operation status, development progress, and plans.

Poster MOPAB077 [1.240 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB077

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paper received ※ 16 May 2021 paper accepted ※ 14 June 2021 issue date ※ 01 September 2021

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MOPAB081

Feasibility Study of Using Multipole Injection Kicker (MIK) and Sextupole for TPS Injection

injection, sextupole, storage-ring, kicker

312

C.-S. Fann, C.K. Chan, C.-C. Chang, H.-P. Chang, Y.-S. Cheng, M.-S. Chiu, Y.L. Chu, K.T. Hsu, S.Y. Hsu, K.H. Hu, J.C. Huang, C.-S. Hwang, S.H. Lee, K.-K. Lin, C.Y. Wu, C.S. Yang
NSRRC, Hsinchu, Taiwan
S.-Y. Lee
Indiana University, Bloomington, Indiana, USA

Feasibility of applying MIK/sextupole injection at TPS is evaluated in this study. This study adopts layout similar to MAX IV injection scheme and their collaboration project with SOLEIL for MIK. Although the light source service fulfills present user needs, yet the increasing demands for a transparent injection is inevitable in the foreseeable future. Notice that this preliminary study is constrained under routine user operation, the optional pinger ceramic chamber, located between existing injection kicker-3 and kicker-4, is chosen for the purpose. Kick strength requirement of the MIK is estimated with minor trajectory adjustment upstream at the booster to storage ring transfer line. Since the realization of MIK fabrication takes time, therefore a fast-built sextupole is prepared to examine the proposed injection scheme beforehand. The test result will be described in this report.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB081

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paper received ※ 17 May 2021 paper accepted ※ 20 May 2021 issue date ※ 21 August 2021

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MOPAB142

A Compact, Low-Field, Broadband Matching Section for Externally-Powered X-Band Dielectric-Loaded Accelerating Structures

vacuum, coupling, simulation, linac

495

Y. Wei, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
H. Bursali
Sapienza University of Rome, Rome, Italy
N. Catalán Lasheras, S. Gonzalez Anton, A. Grudiev, R. Wegner, Y. Wei
CERN, Meyrin, Switzerland
B.T. Freemire, C.-J. Jing
Euclid TechLabs, Solon, Ohio, USA
J. Sauza-Bedolla
Lancaster University, Lancaster, United Kingdom
Y. Wei, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

It has been technically challenging to efficiently couple external radiofrequency (RF) power to cylindrical dielectric-loaded accelerating (DLA) structures. This is especially true when the DLA structure has a high dielectric constant. This contribution presents a novel design of a matching section for coupling the RF power from a circular waveguide to an X-band DLA structure with a dielectric constant ε_r=16.66 and a loss tangent \tanθ = 3.43× 10^-5. It consists of a very compact dielectric disk with a width of 2.035 mm and a tilt angle of 60 degrees, resulting in a broadband coupling at a low RF field which has the potential to survive in the high-power environment. To prevent a sharp dielectric corner break, a 45-degree chamfer is added. Moreover, a microscale vacuum gap, caused by metallic clamping between the thin coating and the outer thick copper jacket, is studied in detail. Based on simulation studies, a prototype of the DLA structure with the matching sections was fabricated. Results from preliminary bench measurements and their comparison with design values will also be discussed.

Poster MOPAB142 [2.617 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB142

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paper received ※ 11 May 2021 paper accepted ※ 21 May 2021 issue date ※ 19 August 2021

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MOPAB146

Status of the C-Band Engineering Research Facility (CERF-NM) Test Stand Development at LANL

cavity, klystron, controls, radiation

509

D. Gorelov
Private Address, Los Alamos, USA
R.L. Fleming, S.K. Lawrence, J.W. Lewellen, D. Perez, M.E. Schneider, E.I. Simakov, T. Tajima
LANL, Los Alamos, New Mexico, USA
M.E. Middendorf
ANL, Lemont, Illinois, USA

Funding: LDRD-DR Project 20200057DR
C-Band structures research is of increasing interest to the accelerator community. The RF frequency range of 4-6 GHz gives the opportunity to achieve significant increase in the accelerating gradient, and having the wakefields at the manageable levels, while keeping the geometric dimensions of the structure technologically convenient. Strong team of scientists, including theorists researching properties of metals under stressful thermal conditions and high electromagnetic fields, metallurgists working with copper as well as alloys of interest, and accelerator scientists developing new structure designs, is formed at LANL to develop a CERF-NM facility. A 50 MW, 5.712 GHz Canon klystron, was purchased in 2019, and laid the basis for this facility. As of Jan-21, the construction of the Test Stand has been finished and the high gradient processing of the waveguide components has been started. Future plans include high gradient testing of various accelerating structures, including benchmark C-band accelerating cavity, a proton ß=0.5 cavity, and cavities made from different alloys. An upgrade to the facility is planned to allow for testing accelerator cavities at cryogenic temperatures.

Poster MOPAB146 [3.778 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB146

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paper received ※ 17 May 2021 paper accepted ※ 26 May 2021 issue date ※ 19 August 2021

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MOPAB147

Efficient, High Power Terahertz Radiation Outcoupling From a Beam Driven Dielectric Wakefield Accelerator

radiation, wakefield, acceleration, electron

513

M. Yadav, G. Andonian, C.E. Hansel, W.J. Lynn, N. Majernik, B. Naranjo, J.B. Rosenzweig, O. Williams
UCLA, Los Angeles, California, USA
G. Andonian
RadiaBeam, Santa Monica, California, USA
C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: This work was supported by DE-SC0009914 (UCLA) and the STFC Liverpool Centre for Doctoral Training on Data Intensive Science (LIV. DAT) under grant agreement ST/P006752/1.
Wakefields in dielectric structures are a useful tool for beam diagnostics and manipulation with applications including acceleration, shaping, chirping, and THz radiation generation. It is possible to use the produced THz radiation to diagnose the fields produced during the DWA interaction but, to do so, it is necessary to effectively out-couple this radiation to free space for transport to diagnostics such as a bolometer or interferometer. To this end, simulations have been conducted using CST Studio for a 10 GeV beam with FACET-II parameters in a slab-symmetric, dielectric waveguide. Various termination geometries were studied including flat cuts, metal horns, and the "Vlasov antenna". Simulations indicate that the Vlasov antenna geometry is optimal and detailed studies were conducted on a variety of dielectrics including quartz, diamond, and silicon. Multiple modes were excited and coherent Cherenkov radiation (CCR) was computationally generated for both symmetric and asymmetric beams. Finally, we include witness beams to study transport and acceleration dynamics as well as the achievable field gradients.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB147

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paper received ※ 24 May 2021 paper accepted ※ 29 August 2021 issue date ※ 28 August 2021

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MOPAB152

High Power Tests of Brazeless Accelerating Structures

simulation, experiment, wakefield, target

532

S.P. Antipov, P.V. Avrakhov, C.-J. Jing, S.V. Kuzikov
Euclid TechLabs, Solon, Ohio, USA
V.A. Dolgashev
SLAC, Menlo Park, California, USA
D.S. Doran, W. Liu, J.G. Power, J.H. Shao, E.E. Wisniewski
ANL, Lemont, Illinois, USA

Funding: DOE SBIR Grant #DE-SC0017749
A typical accelerating structure is a set of copper resonators brazed together. This multi step process is expensive and time consuming. In an effort to optimize production process for rapid prototyping and overall reduction of accelerator cost we developed a split block brazeless accelerating structure. In such structure the vacuum is sealed by the use of knife edges, similar to an industry standard conflat technology. In this paper we present high power tests of several different brazeless structures. First, an inexpensive 1 MeV accelerator powered by radar magnetron. Second, a high gradient power extractor tested at Argonne Wakefield Accelerator Facility. In this experiment a high charge electron beam generated a 180 MW peak power pulse. Finally, we report on high power testing of a brazeless x-band accelerating structure at SLAC.

Poster MOPAB152 [0.783 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB152

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paper received ※ 20 May 2021 paper accepted ※ 24 June 2021 issue date ※ 31 August 2021

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MOPAB156

Wakefields and Transverse Bunch Dynamics Studies of a Plasma-Dielectric Accelerating Structure

plasma, wakefield, focusing, electron

542

K. Galaydych, I.N. Onishchenko, G.V. Sotnikov
NSC/KIPT, Kharkov, Ukraine

Funding: The National Research Foundation of Ukraine, programme "Leading and Young Scientists Research Support" (grant agreement n. 2020.02/0299).
A theoretical investigation of a wakefield excitation in a plasma-dielectric accelerating structure by a drive electron bunch in the case of an off-axis bunch injection is carried out. The structure under investigation is a round dielectric-loaded metal waveguide with channel for the charged particles, filled with homogeneous cold plasma. In this paper we focus on the spatial distribution of the bunch-excited wakefield components, which act on both the drive and test bunches, and on transverse bunch dynamics. Dependence of the drive bunch propagation distance on its offset is studied.

Poster MOPAB156 [2.042 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB156

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paper received ※ 19 May 2021 paper accepted ※ 18 June 2021 issue date ※ 14 August 2021

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MOPAB215

Using ICA for Retrieving Teng Parameters

coupling, factory, optics, FEL

711

A. Lauterbach
IAP, Frankfurt am Main, Germany
G. Franchetti
GSI, Darmstadt, Germany

The blind source separation (BSS) method of Independent Component Analysis (ICA) is explored as a new approach for the reconstruction of the transfer matrix of Linear Coupling Parameterization. ICA is a method to detangle independent signals out of several measurements of their mixtures. In BSS-calculations, it is usually not possible to retrieve the mixing matrix, for the source signals, as well as the matrix, are unknown. Combining the parameterization model of D.A. Edwards and L.C. Teng with the standard ICA approach, it is though possible to retrieve the mixing matrix, as the form of the original uncoupled motion is known. At the same time arises the possibility to recalculate the parameters of Edwards and Teng through a system of equations of the one turn map components. It can be shown as a proof of concept, that the parameters can be reconstructed up to high accuracy for a simulated, non-perturbed signal.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB215

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paper received ※ 10 May 2021 paper accepted ※ 31 May 2021 issue date ※ 23 August 2021

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MOPAB283

Simulations of Space-Charge and Guiding Fields Effects on the Performance of Gas Jet Profile Monitoring

electron, simulation, HOM, collimation

898

O. Sedláček, N. Kumar, A. Salehilashkajani, C.P. Welsch, H.D. Zhang
The University of Liverpool, Liverpool, United Kingdom
P. Forck, S. Udrea
GSI, Darmstadt, Germany
N. Kumar, A. Salehilashkajani, O. Sedláček, C.P. Welsch, H.D. Zhang
Cockcroft Institute, Warrington, Cheshire, United Kingdom
S. Mazzoni, O. Sedláček
CERN, Geneva, Switzerland

Gas jet based profile monitors inject a usually curtain shaped gas jet across a charged particle beam and exploit the results of the minimally invasive beam-gas interaction to provide information about the beam’s transversal profile. Such monitor will be installed as part of the High Luminosity LHC upgrade at CERN in the Hollow Electron Lens (HEL). The HEL represents a new collimation stage increasing the diffusion rate of halo particles by placing a high intensity hollow electron beam concentrically around the LHC beam. The gas jet monitor will use the fluorescence radiation resulting due to the beam-gas interaction to create an image of the profiles of both hollow electron and LHC beams However, the high beam space-charge and strong guiding magnetic field of the electron beam cause significant displacements of the excited molecules, as they are also ionized, and thus image distortions. This work presents preliminary simulation results showing expected fluorescence images of the hollow electron profile as affected by space-charge and guiding fields using simulation tools such as IPMsim. The influence of the estimated electron beam and gas jet curtain parameters are investigated.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB283

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paper received ※ 18 May 2021 paper accepted ※ 28 July 2021 issue date ※ 19 August 2021

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MOPAB291

Design of Cavity BPM Pickup for EuPRAXIA@SPARC_LAB

cavity, coupling, pick-up, simulation

924

Sh. Bilanishvili
INFN/LNF, Frascati (Roma), Italy

EuPRAXIA@SPARC_LAB will make available at LNF a unique combination offering three different options. A high-brightness electron beam with 1 GeV energy generated in a novel X-band RF linac; A PW-class laser system, and a compact light-source directly driven by a plasma accelerator*. Plasma and conventional RF linac driven FEL provide beam with parameters of 30- 200pC charge range, 10-100Hz repetition rate, and 1 GeV electron energy**. The control of the charge and the trajectory monitoring at a few pC and a few um is mandatory in this machine. Particularly in the plasma interaction region, where the pickup resolution under 1 um is required. As a possible solution, a cavity beam position monitor (cBPM) is proposed. A prototype in the C-band frequency range has been designed. The pickup was optimized for low charge and single-shot bunches. The poster presents the process to achieve the required specifications. The simulations were performed to study RF properties and the electromagnetic response of the device. Finally, the overall performance of the pickup is discussed, and theoretical resolution is approximated.
* https://www.researchgate.net/publication/335459394_From_SPARC_LAB_to_EuPRAXIASPARC_LAB
**http://www.lnf.infn.it/sis/preprint/detail-new.php?id=5416

Poster MOPAB291 [16.718 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB291

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paper received ※ 19 May 2021 paper accepted ※ 09 June 2021 issue date ※ 23 August 2021

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MOPAB319

Development of a Fast Betatron Tune and Chromaticity Measurement System for COSY

betatron, acceleration, controls, resonance

983

P.J. Niedermayer, C. Böhme, B. Breitkreutz, V. Kamerdzhiev, A. Lehrach
FZJ, Jülich, Germany
A. Lehrach
RWTH, Aachen, Germany

A fast tune measurement is developed for the Cooler Synchrotron COSY at the Institut für Kernphysik of Forschungszentrum Jülich. Betatron oscillations of the beam are excited with a band-limited RF signal via a stripline kicker. Resonant transverse oscillations are then observed using capacitive beam position monitors. Based on the bunch-by-bunch beam position data the betatron tune is determined. The usage of bunch-by-bunch data is characteristic of the new system. It allows for a discrete tune measurement within a few milliseconds, as well as continuous tune monitoring during beam acceleration. The high precision tune measurement also enables determination of the beam chromaticity. Therefore, the beam momentum is varied by means of the RF frequency and the subsequent tune change is determined. For routine use during beam operation and experiments, the developed method is integrated into the control system.

Poster MOPAB319 [1.209 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB319

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paper received ※ 19 May 2021 paper accepted ※ 16 June 2021 issue date ※ 12 August 2021

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MOPAB324

High Voltage Design and Evaluation of Wien Filters for the CEBAF 200 keV Injector Upgrade

electron, vacuum, high-voltage, simulation

1000

G.G. Palacios Serrano, P.A. Adderley, J.F. Benesch, D.B. Bullard, J.M. Grames, C. Hernandez-Garcia, A.S. Hofler, D. Machie, M. Poelker, M.L. Stutzman, R. Suleiman
JLab, Newport News, Virginia, USA
H. Baumgart, G.G. Palacios Serrano
ODU, Norfolk, Virginia, USA

Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
High-energy nuclear physics experiments at the Jefferson Lab Continuous Electron Beam Accelerator Facility (CEBAF) require highly spin-polarization electron beams, produced from strained super-lattice GaAs photocathodes, activated to negative electron affinity in a photogun operating at 130 kV dc. A pair of Wien filter spin rotators in the injector defines the orientation of the electron beam polarization at the end station target. An upgrade of the CEBAF injector to better support the upcoming MOLLER experiment requires increasing the electron beam energy to 200 keV, to reduce unwanted helicity correlated intensity and position systematics and provide precise control of the polarization orientation. Our contribution describes design, fabrication and testing of the high voltage system to upgrade the Wien spin rotator to be compatible with the 200 keV beam. This required Solidworks modeling, CST and Opera electro- and magnetostatic simulations, upgrading HV vacuum feedthroughs, and assembly techniques for improving electrode alignment. The electric and magnetic fields required by the Wien condition and the successful HV characterization under vacuum conditions are also presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB324

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paper received ※ 19 May 2021 paper accepted ※ 24 May 2021 issue date ※ 29 August 2021

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MOPAB336

Multipacting Analysis of Warm Linac RF Vacuum Windows

simulation, multipactoring, vacuum, Windows

1044

G.D. Toby, Y.W. Kang, S.-H. Kim, S.W. Lee, J.S. Moss
ORNL, Oak Ridge, Tennessee, USA

Funding: * This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under contract number DE-AC05-00OR22725.
Multipacting in accelerating structures is a complex phenomenon with which there is much to be understood. While multipacting research efforts have primarily been focused on superconducting radio frequency (SRF) systems, normal conducting accelerating structures that have a higher thermal capacity and a greater vacuum pressure tolerance could benefit from additional investigation. This research details multipacting simulation methods and the results of 3-D electromagnetic simulations of RF vacuum windows used on normal conducting linac (NCL) cavities. Possible techniques for reducing and eliminating multipacting activities in these structures are discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB336

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paper received ※ 17 May 2021 paper accepted ※ 28 May 2021 issue date ※ 29 August 2021

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MOPAB341

First C-Band High Gradient Cavity Testing Results at LANL

cavity, proton, operation, klystron

1057

E.I. Simakov, R.L. Fleming, D. Gorelov, T.A. Jankowski, M.F. Kirshner, J.W. Lewellen, J.D. Pizzolatto, M.E. Schneider, T. Tajima
LANL, Los Alamos, New Mexico, USA
X. Lu, E.A. Nanni, S.G. Tantawi
SLAC, Menlo Park, California, USA
M.E. Middendorf
ANL, Lemont, Illinois, USA

Funding: Los Alamos National Laboratory LDRD Program.
This poster will report the results of high gradient testing of the two proton β=0.5 C-band accelerating cavities. The cavities for proton acceleration were fabricated at SLAC and tested at high gradient C-band accelerator test stand at LANL. One cavity was made of copper, and the second was made of a copper-silver alloy. LANL test stand was constructed around a 50 MW, 5.712 GHz Canon klystron and is capable to provide power for conditioning single cell accelerating cavities for operation at surface electric fields up to 300 MV/m. These β=0.5 C-band cavities were the first two cavities tested on LANL C-band test stand. The presentation will report achieved gradients, breakdown probabilities, and other characteristics measured during the high power operation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB341

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paper received ※ 19 May 2021 paper accepted ※ 25 May 2021 issue date ※ 30 August 2021

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MOPAB342

Design, Fabrication, and Commissioning of the Mode Launchers for High Gradient C-Band Cavity Testing at LANL

cavity, klystron, simulation, MMI

1060

E.I. Simakov, J.E. Acosta, D. Gorelov, M.F. Kirshner, J.W. Lewellen
LANL, Los Alamos, New Mexico, USA
P. Borchard
Dymenso LLC, San Francisco, USA
M.E. Schneider
MSU, East Lansing, Michigan, USA

Funding: Los Alamos National Laboratory LDRD Program.
This poster will report on the design, fabrication, and operation status of the new high gradient C-band TM01 mode launchers for the high gradient C-band test stand at LANL. Modern applications require accelerators with optimized cost of construction and operation, naturally calling for high-gradient acceleration. At LANL we commissioned a test stand powered by a 50 MW, 5.712 GHz Canon klystron. The test is capable of conditioning single cell accelerating cavities for operation at surface electric fields up to 300 MV/m. The rf field is coupled into the cavity from a WR187 waveguide through a mode launcher that converts the fundamental mode of the rectangular waveguide into the TM01 mode of the circular waveguide. Several designs for mode launchers were considered and the final design was chosen based on a compromise between the field enhancements, bandwidth, and simplicity and cost of fabrication. Four mode launchers were fabricated and cold-tested. Two mode launchers with the best transmission characteristics were installed and conditioned to high power. The presentation will report achieved gradients, breakdown probabilities, and other characteristics measured during operation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB342

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paper received ※ 19 May 2021 paper accepted ※ 25 May 2021 issue date ※ 19 August 2021

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MOPAB346

Broadband Frequency Electromagnetic Characterisation of Coating Materials

experiment, electron, vacuum, site

1076

A. Passarelli, C. Koral, M.R. Masullo
INFN-Napoli, Napoli, Italy
A. Andreone
Naples University Federico II, Napoli, Italy
M. De Stefano
University of Naples, Naples, Italy
V.G. Vaccaro
Naples University Federico II and INFN, Napoli, Italy

In the new generation of particle accelerators and storage rings, collective effects have to be carefully analyzed. In particular, the finite conductivity of the beam pipe walls is a major source of impedance and instabilities. A reliable electromagnetic (EM) characterisation of different coating materials is required up to hundreds of GHz due to very short bunches. We propose two different measurement techniques for an extended frequency characterization: (i) a THz time domain setup based on the signal transmission response of a tailored waveguide to infer the coating EM properties from 100 to 300 GHz or even further*.**. This technique has been tested both on NEG and amorphous Carbon films. (ii) a resonant method, based on dielectric cavities, to evaluate the surface resistance Rs of thin conducting samples at low (GHz) frequencies***. Due to its high sensitivity, Rs values can be obtained for very thin (nanometric) coatings or for copper samples with a laser treated surface, since they have an expected conductivity very close to bulk copper.
*A. Passarelli et al., Phys. Rev. Accel. Beams, v.21, p.103101, 2018
**A. Passarelli et al., Cond. Matter, v.5, p.9, 2020
***A. Andreone et al., Applied Physics Letters, v.91, n.7, p.072512, 2007

Poster MOPAB346 [2.613 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB346

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paper received ※ 18 May 2021 paper accepted ※ 09 June 2021 issue date ※ 26 August 2021

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MOPAB348

Portable 2.5 MeV X-Band Linear Accelerator Structure

linac, gun, radiation, target

1084

A.V. Mishin, K. Brown, M. Denney, D. Fischer, N.P. Hanson, S. Proskin, J. Stammetti
Varex Imaging, Salt Lake City, USA

Two versions of 2.5 MeV X-Band linear accelerator structure have been designed and tested. The first is a traditional single input linac, and the other one is a dual input, two section linac with power input through a 3 dB coupler. The linac is designed for a portable linac system, which can be used for security screening, non-destructive testing, medical and industrial CT, and, perhaps, some other applications.

Poster MOPAB348 [1.490 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB348

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paper received ※ 15 May 2021 paper accepted ※ 28 May 2021 issue date ※ 23 August 2021

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MOPAB349

New Accelerator Beam Centerline (ABC) Production Line at Varex Imaging Corporation

linac, gun, betatron, detector

1087

A.V. Mishin
Varex Imaging, Salt Lake City, USA

In January 2017, a Salt Lake City Component Division of Varian Medical (Varian)*, producer of X-ray tubes, detectors, and imaging panels has been spun off, giving birth to a new public company Varex Imaging Corporation (Varex)**, which also includes the Security and Inspection Products (SIP) linac producer in Las Vegas. Based on Varian asset acquisition of two small LLCs*** in May 2016, 8 months prior to the transition, a new business branch within Varex has been established, which included distribution of the betatrons and detector arrays as well as pilot production line for Accelerator Beam Centerlines (ABC). In 3 years, we moved ABC production from Fremont, CA to Salt Lake in Utah and improved it; several ABCs have been designed, produced, and qualified. A number of new products in energy range of 1-20 MeV are under development, based on the new ABCs used as components for SIP linear accelerator systems and ABCs sold to third parties for applications other than Security and NDT. The new products will brag broad energy and dose rate regulation, smooth and reliable operation, providing extended benefits to our customers.
* - https://www.varian.com/
** - https://www.vareximaging.com/
*** - both Thought One LLC and Radmedex LLC have been dissolved in 2018 upon completion of the transition process

Poster MOPAB349 [2.182 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB349

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paper received ※ 13 May 2021 paper accepted ※ 27 May 2021 issue date ※ 21 August 2021

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MOPAB358

Design and Measurement of the 1.4 GHz Cavity for LEReC Linac

cavity, electron, resonance, HOM

1113

B.P. Xiao, J.C. Brutus, J.M. Fite, K. Hamdi, D. Holmes, K. Mernick, K.S. Smith, J.E. Tuozzolo, T. Xin, A. Zaltsman
BNL, Upton, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
The Low Energy RHIC electron Cooler (LEReC) is the first electron cooler based on rf acceleration of electron bunches. To further improve RHIC luminosity for heavy ion beam energies below 10 GeV/nucleon, a normal conducting RF cavity at 1.4 GHz was designed and fabricated for the LINAC that will provide longer electron bunches for the LEReC. It is a single-cell cavity with an effective cavity length shorter than half of the 1.4 GHz wavelength. This cavity was fabricated and tested on-site at BNL to verify RF properties, i.e. the resonance frequency, FPC coupling strength, tuner system performance, and high power tests. In this paper, we report the RF test results for this cavity.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB358

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paper received ※ 17 May 2021 paper accepted ※ 25 June 2021 issue date ※ 24 August 2021

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MOPAB370

X-Band RF Spiral Load Optimization for Additive Manufacturing Mass Production

vacuum, simulation, ECR, linac

1143

H. Bursali
Sapienza University of Rome, Rome, Italy
N. Catalán Lasheras, R.L. Gerard, A. Grudiev, O. Gumenyuk, P. Morales Sanchez, B. Riffaud
CERN, Geneva, Switzerland
J. Sauza-Bedolla
Lancaster University, Lancaster, United Kingdom

The CLIC main linac uses X-band traveling-wave normal conducting accelerating structures. The RF power not used for beam acceleration nor dissipated in the resistive wall is absorbed in two high power RF loads that should be as compact as possible to minimize the total footprint of the machine. In recent years, CERN has designed, fabricated and successfully tested several loads produced by additive manufacturing. With the current design, only one load can be produced in the 3D printing machine at a time. The aim of this study is optimizing the internal cross-section of loads in order to create a stackable design to increase the number of produced parts per manufacturing cycle and thus decrease the unit price. This paper presents the new design with an optimization of the internal vacuum part of the so-called RF spiral load. In this case, RF and mechanical designs were carried out in parallel. The new cross section has showed good RF reflection reaching less than -30 dB in simulations. The final load is now ready to be manufactured and high-power tested. This new load will not only provide cost saving but also faster manufacturing for mass production.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB370

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paper received ※ 18 May 2021 paper accepted ※ 26 May 2021 issue date ※ 23 August 2021

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TUXB01

A 3 MeV All Optical Terahertz-Driven Electron Source at Tsinghua University

electron, acceleration, laser, gun

1294

H. Xu, Y.-C. Du, W.-H. Huang, R.K. Li, C.-X. Tang, L.X. Yan
TUB, Beijing, People’s Republic of China

Funding: Science Challenge Project No.TZ2018005
Efficient acceleration and manipulation of high-brightness electron beams using terahertz waves in a compact setup has been recently a hot research topic in acceleration community. Previous works have achieved multi-MV/m acceleration gradient and dozens of keV energy gain while leaving room for further improvements in the high-energy regime. Here, we experimentally demonstrate whole-bunch acceleration and cascaded terahertz-driven acceleration of a relativistic beam with a record energy gain of 204 keV. A terahertz-driven all-optical electron source is now under development, which hold great potential for terahertz-driven ultrafast electron diffraction and related scientific discoveries.
* Xu, H., Yan, L., Du, Y. et al. Cascaded high-gradient terahertz-driven acceleration of relativistic electron beams. Nat. Photonics (2021). https://doi.org/10.1038/s41566-021-00779-x

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUXB01

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paper received ※ 19 May 2021 paper accepted ※ 01 June 2021 issue date ※ 10 August 2021

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TUXB04

Fabrication and Tuning of a THz-Driven Electron Gun

gun, electron, cavity, resonance

1297

S.M. Lewis, A.A. Haase, J.W. Merrick, E.A. Nanni, M.A.K. Othman, S.G. Tantawi
SLAC, Menlo Park, California, USA
S.M. Lewis
Fermilab, Batavia, Illinois, USA

Funding: This work was supported by the Department of Energy Contract No. DE-AC02-76SF00515 (SLAC) and by NSF Grant No. PHY-1734015.
We have developed a THz-driven field emission electron gun and beam characterization assembly. The two cell standing-wave gun operates in the pi mode at 110.08 GHz. It is designed to produce 360 keV electrons with 500 kW of input power supplied by a 110 GHz gyrotron. Multiple gun structures were electroformed in copper using a high precision diamond-turned mandrel. The field emission cathode is a rounded copper tip located in the first cell. The cavity resonances were mechanically tuned using azimuthal compression. This work will discuss details of the fabrication and tuning and present the results of low power measurements.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUXB04

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paper received ※ 18 May 2021 paper accepted ※ 22 June 2021 issue date ※ 14 August 2021

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TUPAB077

Novel Open Cavity for Rotating Mode SLED-Type RF Pulse Compressors

cavity, coupling, klystron, linear-collider

1547

X.W. Wu, A. Grudiev
CERN, Meyrin, Switzerland

A new X-band high-power rotating mode SLAC Energy Doubler (SLED)-type rf pulse compressor is proposed. It is based on a novel cavity type, a single open bowl-shape energy storage cavity with high Q₀ and compact size, which is coupled to the waveguide using a compact rotating mode launcher. The novel cavity type is applied to the rf pulse compression system of the main linac rf module of the klystron-based option of the Compact Linear Collider (CLIC). Quasi-spherical rotating modes of \rm{TE}_1,2,4 and \rm{TE}_1,2,13 are proposed for the correction cavity and storage cavity of the rf pulse compression system respectively. The storage cavity working at \rm{TE}_1,2,13 has a Q₀ of 240000 and a diameter less than 33 cm. The design of the pulse compressor and in particular of the high-Q cavity will be presented in detail.

Poster TUPAB077 [1.229 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB077

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paper received ※ 19 May 2021 paper accepted ※ 10 June 2021 issue date ※ 27 August 2021

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TUPAB126

Spectral Gap in the Middle Infrared FEL Oscillator of FELiCHEM

FEL, laser, electron, free-electron-laser

1685

Y.P. Zhu, H.T. Li, Z. Zhao
USTC/NSRL, Hefei, Anhui, People’s Republic of China

A phenomenon of spectral gap is observed in the Middle Infrared FEL Oscillator of FELiCHEM: the laser power falls down at the particular wavelength. Starting with the experimental data, this paper focuses on the simulation calculation and analysis of the effect from using the partial waveguide. The relationship between waveguide and spectral gap is revealed.

Poster TUPAB126 [1.063 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB126

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paper received ※ 17 May 2021 paper accepted ※ 14 June 2021 issue date ※ 21 August 2021

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TUPAB133

Brazing free RF Pulse Compressor for High Gradient Accelerators

cavity, coupling, simulation, vacuum

1700

L. Kankadze, D. Alesini, F. Cardelli, G. Di Raddo, M. Diomede
INFN/LNF, Frascati, Italy

EURPRAXIA@SPARC\_LAB, is a proposal to upgrade the SPARC\_LAB test facility (at LNF, Frascati) to a soft X-ray user facility based on plasma acceleration and high-gradient X-band (11.9942 GHz) accelerating modules. Each module is made up of a group of 4 TW sections assembled on a single girder and fed by one klystron by means of one rf pulse compressor system and a low attenuation circular waveguide network that transports the rf power to the input hybrids of the sections. The pulse compressor is based on a single Barrel Open Cavity (BOC). The BOC use a ’whispering gallery’ mode which has an intrinsically high quality factor and operates in a resonant rotating wave regime. Compared to the conventional SLED scheme it requires a single cavity instead of two cavities and a 3-dB hybrid. A new brazeless mechanical design has been proposed and is described in the present paper together with the electro-magnetic and thermo-mechanical simulations.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB133

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paper received ※ 21 May 2021 paper accepted ※ 15 June 2021 issue date ※ 10 August 2021

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TUPAB153

Modeling of Capillary Discharge Plasmas for Wakefield Accelerators and Beam Transport

plasma, simulation, laser, electron

1740

N.M. Cook, J.A. Carlsson, S.J. Coleman, A. Diaw, J.P. Edelen
RadiaSoft LLC, Boulder, Colorado, USA
E.C. Hansen, P. Tzeferacos
Flash Center for Computational Science, Chicago, USA

Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics under Award Number DE-SC0018719.
Next generation accelerators demand sophisticated beam sources to reach ultra-low emittances at large accelerating gradients, along with improved optics to transport these beams without degradation. Capillary discharge plasmas can address each of these challenges. As sources, capillaries have been shown to increase the energy and quality of wakefield accelerators, and as active plasma lenses they provide orders-of-magnitude increases in peak magnetic field. Capillaries are sensitive to energy deposition, heat transfer, ionization dynamics, and magnetic field penetration; therefore, capillary design requires careful modeling. We present simulations of capillary discharge plasmas using FLASH, a publicly-available multi-physics code developed at the University of Chicago. We report on the implementation of 2D and 3D models of capillary plasma density and temperature evolution with realistic boundary and discharge conditions. We then demonstrate laser energy deposition to model channel formation for guiding intense laser pulses. Lastly, we examine active capillary plasmas with varying fill species and compare our simulations against experimental studies.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB153

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paper received ※ 24 May 2021 paper accepted ※ 29 July 2021 issue date ※ 30 August 2021

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TUPAB239

Radiation of a Charged Particle Bunch Moving Along a Deep Corrugated Surface with a Small Period

radiation, ECR, electromagnetic-fields, impedance

1999

E.S. Simakov, A.V. Tyukhtin
Saint Petersburg State University, Saint Petersburg, Russia

Funding: This work was supported by the Russian Science Foundation (Grant No. 18-72-10137).
We investigate the electromagnetic radiation of a bunch moving along a corrugated conductive surface. It is assumed that wavelengths under consideration are much more than the period of the corrugation. In this case, the corrugated structure can be replaced with a smooth surface on which so-called equivalent boundary conditions (EBC) are fulfilled*. In fact, we deal with anisotropic surface characterized by certain matrix impedance. Here, we consider the case of deep corrugation, i.e. we assume that the depth of the structure is much more than its period (the case of shallow corrugation was studied earlier**). Using the EBC we obtain electromagnetic field components which are presented in form of spectral integrals. It is shown that the bunch generates surface waves propagating in the plane of the structure, whereas volume radiation is absent at the frequencies under consideration. We also consider the energy losses of the bunch. Typical dependences of a spectral density of the energy losses on corrugation parameters are obtained and analyzed. It is demonstrated that the features of the surface waves can be used for the bunch diagnostics.
* E.I. Nefedov, A.N. Sivov. Electrodynamics of periodic structures. Moscow, Nauka, 1977, 208 p. (in Russian).
** E.S. Simakov, A.V. Tyukhtin, S.N. Galyamin, Phys. Rev. AB, 22, 061301 (2019).

Poster TUPAB239 [0.637 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB239

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paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 23 August 2021

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TUPAB246

Numerical Simulation and Beam-Dynamics Study of a Hollow-Core Woodpile Coupler for Dielectric Laser Accelerators

photon, laser, acceleration, electron

2022

G.S. Mauro, D. Mascali, G. Sorbello, G. Torrisi
INFN/LNS, Catania, Italy
A. Bacci
INFN/LASA, Segrate (MI), Italy
C. De Angelis, A. Locatelli
University of Brescia, Brescia, Italy
A.R. Rossi
INFN-Milano, Milano, Italy
G. Sorbello
University of Catania, Catania, Italy

Hollow core dielectric microstructures powered by lasers represent a new and promising area of accelerator research thanks to the higher damage threshold and accelerating gradients with respect to metals at optical wavelengths. In this paper we present the design of a dielectric Electromagnetic Band Gap (EBG) mode converter for high-power coupling of the accelerating mode in Dielectric Laser Accelerators (DLAs). The design is wavelength-independent, and here we propose an implementation operating at 90.505 GHz (wavelength 3.3 mm) based on a silicon woodpile structure. The coupler is composed by two perpendicularly coupled hollow-core waveguides: a TE-like mode waveguide (excited from RF/laser power) and a TM-like mode accelerating waveguide. The structure has been numerically designed and optimized, presenting Insertion Losses (IL) < 0.3 dB and an efficient mode conversion in the operating bandwidth. The properties and effectiveness of the confined accelerating mode have been optimized in order to derive the needed accelerating gradient. The simulated electric field has been used as input for Astra beam-dynamics simulations in order to compute the beam properties.

Poster TUPAB246 [2.209 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB246

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paper received ※ 18 May 2021 paper accepted ※ 27 July 2021 issue date ※ 13 August 2021

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TUPAB249

Diffraction at the Open-Ended Dielectric-Loaded Circular Waveguide

radiation, wakefield, electron, acceleration

2033

S.N. Galyamin, A.V. Tyukhtin, V.V. Vorobev
Saint Petersburg State University, Saint Petersburg, Russia

Funding: Work supported by Russian Science Foundation (Grant No. 18-72-10137).
Contemporary beam and THz technologies are tightly interlaced during last years. Strong THz fields allow realization of THz driven electron guns, THz bunch compression, streaking* and THz driven wakefield acceleration**. Inversely, dielectric capillaries similar to those used for THz bunch manipulation can be in turn utilized for development of high-power narrow-band THz sources***. Mentioned cases involve interaction of THz waves and particle bunches with an open end of certain dielectric loaded waveguide structure, most frequently a circular capillary. For further development of the discussed prospective topics a rigorous approach allowing analytical investigation of both radiation from open-ended capillaries and their excitation by external source would be extremely useful. We present an elegant and efficient rigorous method for solving circular open-ended dielectric-loaded waveguide diffraction problems based on Wiener-Hopf technique. We deal with the case of uniform dielectric loading and internal excitation by a waveguide mode. S-parameters, near-field and far-field distributions are presented. The obtained results can be also applied to the narrow band wakefield.
* L. Zhao et al., Phys. Rev. Lett., 124, 054802 (2020).
** M.T. Hibberd et al., Nat. Photonics, 14, 755-759 (2020).
*** D. Wang et al., Rev. Sci. Instr., 89(9), 093301 (2018).

Poster TUPAB249 [2.160 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB249

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paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 21 August 2021

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TUPAB269

Transverse Impedance of Lossy Circular Metal-Dielectric Waveguides

impedance, radiation, resonance, wakefield

2093

M. Ivanyan, L.V. Aslyan
CANDLE SRI, Yerevan, Armenia
K. Flöttmann, F. Lemery
DESY, Hamburg, Germany

The properties of the transverse impedance of a dielectric-loaded metallic circular waveguide are investigated taking into account losses in the outer metallic pipe and in the inner dielectric layer. The dispersion relations, impedances, and wake functions for dipole modes are analyzed and compared for thin and thick dielectric layer cases. The correspondence of the resonant frequencies of the longitudinal monopole and transverse dipole impedances is established.

Poster TUPAB269 [0.906 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB269

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paper received ※ 16 May 2021 paper accepted ※ 28 May 2021 issue date ※ 10 August 2021

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TUPAB308

Mechanical Consolidation of the LHC Inner Triplet Magnet Supporting System for Remote Alignment

alignment, vacuum, quadrupole, ECR

2207

F. Micolon, N. Bourcey, J-B. Deschamps, A. Herty, S. Le Naour, T. Mikkola, V. Parma, D. Ramos, V. Rude, M. Sosin
CERN, Meyrin, Switzerland

Given the high radiation area and the tight alignment tolerances, the LHC inner triplet magnets were designed to be realigned remotely using motorized supporting jacks. However, during run 2 the LHC triplet realignment system started to show an unexpected behavior with erratic load variations on the magnet supporting jacks when operated. It was then decided to freeze any further realignment of the LHC triplet magnet for the remainder of the run. Subsequently, a project team was set up at CERN to understand better the conditions leading to such unexpected behavior and to study and propose a technical consolidation for the realignment system of the LHC triplet magnet. A fully instrumented magnet string using LHC triplet spare magnets was assembled and used at CERN to provide a realistic test bench for this study. This paper reports on the work undertaken to study the triplet magnet overall realignment kinematic, the findings on the readjustment system malfunction and details the consolidation solution implemented for the next LHC run

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB308

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paper received ※ 18 May 2021 paper accepted ※ 07 June 2021 issue date ※ 18 August 2021

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TUPAB346

Development of a 500-MHz 150-kW Solid-State Power Amplifier for High Energy Photon Source

cavity, controls, photon, booster

2312

Y.L. Luo, T.M. Huang, J. Li, H.Y. Lin, Q. Ma, Q.Y. Wang, P. Zhang, F.C. Zhao
IHEP, Beijing, People’s Republic of China

A 500-MHz 150-kW solid-state power amplifier (SSA) has been developed to test the 500-MHz normal conducting cavities for High Energy Photon Source (HEPS) booster ring. It will also be used to power normal conducting cavities in the initial beam commissioning stage of the HEPS storage ring. A total number of 96 amplifier modules are combined initially by coaxial and later by waveguide combiners to deliver the 150-kW RF power. The final output is of EIA standard WR1800 rectangular waveguide. Each amplifier module consists four transistors equipped with individual circulator and load and outputs 2-kW RF power. Modularity, redundancy and satisfactory RF performance are demonstrated. In the final stage of HEPS project, this 150-kW amplifier will be modified to a 100-kW amplifier to join the other five 100-kW SSAs for normal operation of the booster cavities. The development and test results are presented in this paper.

Poster TUPAB346 [1.870 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB346

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paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 15 August 2021

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TUPAB348

Magnetron R&D for High Efficiency CW RF Sources for Industrial Accelerators

injection, experiment, cavity, MMI

2318

H. Wang, K. Jordan, R.M. Nelson, R.A. Rimmer, S.O. Solomon
JLab, Newport News, Virginia, USA
B.R.L. Coriton, C.P. Moeller, K.A. Thackston
GA, San Diego, California, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177, and DOE OS/HEP Accelerator Stewardship award 2019-2021.
The scheme of using high-efficiency magnetrons to drive radiofrequency accelerators has been demonstrated at 2450 MHz in CW mode *. Magnetron test stands at JLab and GA have been set up to further test the noise figure and the locking speed of the injection phase-lock method. For higher power applications, power combining experiments using a TM010 cavity-type combiner and a magic tee for the binary combiner while using a single clean injection signal has been carried out at 2450 MHz. The frequency pulling effect between the magnetron and a low-Q cavity has been shown to enhance the frequency locking bandwidth compared to the injection phase-lock alone. The principle has been studied by the equivalent circuit simulation, analytical model, and finally confirmed experimentally on the magnetrons. Due to the pandemic delay in 2020, the equivalent high power tests using a 75kW, 915MHz industrial magnetron will be done in 2021 and will be reported in a future paper.
* H. Wang, et al, Magnetron R&Ds for High-Efficiency CW RF Sources of Particle Accelerators, WEXXPLS1, proceedings of IPAC 2019, Melbourne, Australia, May 19 -24, 2019.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB348

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paper received ※ 22 May 2021 paper accepted ※ 21 June 2021 issue date ※ 30 August 2021

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TUPAB354

352-MHz Solid State RF System Development at the Advanced Photon Source

cavity, controls, PLC, klystron

2335

D. Horan, D.J. Bromberek, N.P. DiMonte, A. Goel, T.J. Madden, A. Nassiri, G. Trento, G.J. Waldschmidt
ANL, Lemont, Illinois, USA

Development effort is underway on a 352MHz, 200kW solid state rf system intended as the base design to replace the existing klystron-based rf systems presently in use at the Advanced Photon Source (APS). A sixteen-input, 200kW final combining cavity was designed, built, and successfully tested to 29kW CW in combiner mode, and to 200kW CW in back-feed mode, where an external klystron was used to transmit power into the combining cavity. A four-port waveguide combiner was also tested in both backfeed and combiner mode to 193kW and 26kW respectively. Slow and fast interlock systems were designed and implemented to support the testing process. An EPICS and Programmable Logic Controller (PLC)-based system was developed to control, communicate with, and monitor the rf amplifiers used in the combiner-mode test, and to monitor and log system performance parameters relating to the combining cavity. Low-level rf control of the cavity in 29kW combiner-mode operation was achieved using the existing APS analog low-level rf hardware. Test data and design details are presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB354

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paper received ※ 18 May 2021 paper accepted ※ 31 May 2021 issue date ※ 19 August 2021

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WEXA05

Solving for Collider Beam Profiles from Luminosity Jitter with Ghost Imaging

luminosity, collider, operation, diagnostics

2524

D.F. Ratner, A. Chao
SLAC, Menlo Park, California, USA

Large accelerator facilities must balance the need to achieve user performance requirements while also maximizing delivery time. At the same time, accelerators have advanced data-acquisition systems that acquire synchronous data at high-rate from a large variety of diagnostics. Here we discuss the application of ghost-imaging (GI) to measure beam parameters, switching the emphasis from beam control to data collection: rather than intentionally manipulating the accelerator, we instead passively monitor jitter gathered over thousands to millions of events to reconstruct the target of interest. Passive monitoring during routine operation builds large data sets that can even deliver higher resolution than brief periodic scans, and can provide experiments with event-by-event information. In this presentation we briefly present applications of GI to light-sources, and then discuss a potential new application for colliders: measuring the transverse beam shapes at a collider’s interaction point to determine both the integrated luminosity and the spatial distribution of collision vertices.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEXA05

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paper received ※ 19 May 2021 paper accepted ※ 27 July 2021 issue date ※ 10 August 2021

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WEPAB045

European XFEL High-Power RF System - the First 4 Years of Operation

klystron, operation, FEL, electron

2708

M. Bousonville, S. Choroba, T. Grevsmühl, S. Göller, A. Hauberg, V.V. Katalev, K. Machau, V. Vogel, B. Yildirim
DESY, Hamburg, Germany

In 2016, the installation of the European XFEL was completed and its 26 RF stations started operation in 2017. Each RF station consists of a 10 MW-1.3 GHz-multibeam klystron, a HV pulse modulator and a waveguide system to supply the superconducting cavities and the normal-conducting electron gun with RF power. During commissioning and subsequent operation, the RF stations were closely monitored and causes of failures were investigated. For the optimisation of the RF systems, the various RF station failures were evaluated according to their impact on accelerator operation and the measures to eliminate them were prioritised accordingly. This report describes the operation experience and improvements of the high-power RF stations during the first 4 years of operation.

Poster WEPAB045 [6.887 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB045

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paper received ※ 19 May 2021 paper accepted ※ 07 June 2021 issue date ※ 21 August 2021

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WEPAB077

High Power Terahertz Cherenkov Free Electron Laser from a Waveguide with a Thin Dielectric Layer by a Near-Relativistic Electron Beam

electron, radiation, wakefield, bunching

2769

W.W. Li, T.L. He, Z.G. He, R. Huang, Q.K. Jia, S.M. Jiang, L. Wang
USTC/NSRL, Hefei, Anhui, People’s Republic of China

Funding: National Natural Science Foundation of China (11705198, 11775216, 11805200) Fundamental Research Funds for the Central Universities (No. WK2310000082 and No. WK2310000090)
Corrugated and dielectric structures have been widely used for producing accelerator based terahertz radiation source. Recently, the novel schemes of the sub-terahertz free electron laser (FEL) from a metallic waveguide with corrugated walls and a normal dielectric loaded waveguide driven by a near-relativistic (beam energy of a few MeV) picosecond electron beam were studied respectively. Such a beam is used for driving resonant modes in the waveguide, and if the pipe is long enough, the interaction of these modes with the co-propagating electron beam will result in micro-bunching and the coherent enhancement of the wakefield radiation. It offers a promising candidate for compact accelerator-based high power terahertz source which can be realized with relatively low energy and low peak-current electron beams. However the choices of the waveguide above is less effective in order to obtain high power with frequency around 1THz. In this paper, we propose to use the waveguide with a thin dielectric layer instead, and high power radiation (>~10 MW) around 1 THz is expected to obtain in the proposed structure according to the simulation results.

Poster WEPAB077 [1.332 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB077

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paper received ※ 12 May 2021 paper accepted ※ 23 June 2021 issue date ※ 22 August 2021

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WEPAB144

A New Flux Concentrator Made of Cu Alloy for the SuperKEKB Positron Source

positron, operation, vacuum, target

2954

Y. Enomoto, K. Abe, N. Okada, T. Takatomi
KEK, Ibaraki, Japan

Flux concentrator (FC) is one of important device for positron source which translates position and momentum spread of the particles adiabatically to match them to the acceptance of the following section. To realize higher positron yield, higher magnetic field is desired. However, higher field by higher current generate stronger force on the coil. Since the gap between each turn of the coil is as narrow as 0.2 mm and the voltage across them is about as high as 1 kV at the design current, slight deformation of the coil cause discharge between the gap. To avoid such problem, a new FC made of Cu alloy which has 40 times higher yield strength than that of pure Cu was designed and tested. Finally, during summer shutdown in 2020, the old FC made of pure Cu was replaced by the new one made of Cu alloy in the KEK electron positron injector linac. The new one has been working stably at the design current, 12 kA, since Oct. 2020, and positron yield of 0.5 was realized. There were no discharge and other trouble till now.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB144

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paper received ※ 08 May 2021 paper accepted ※ 01 July 2021 issue date ※ 26 August 2021

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WEPAB165

Metamaterial Waveguide HOM Loads for SRF Accelerating Cavities

HOM, vacuum, cavity, SRF

2994

S.V. Kuzikov
Euclid TechLabs, Solon, Ohio, USA

Suppression of beam induced HOMs is necessary for most SRF accelerating cavities driven with high currents. One of the problems in design of a HOM load is that vacuum compatible materials with high enough imaginary part of the dielectric permittivity, which provides absorption, have also a high real part of the permittivity. This does not allow absorbing RF radiation at short distance and in broad frequency band. We propose considering artificial metamaterials where besides lossy dielectric pieces, an absorber with high magnetic permeability is included. In our proposal, we suggest composing a waveguide HOM load of a metamaterial consisted of well-known ceramic and ferrite plates placed periodically in a stack. Such a design provides low return losses, compactness and broad frequency range of the operation.

Poster WEPAB165 [1.844 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB165

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paper received ※ 19 May 2021 paper accepted ※ 02 June 2021 issue date ※ 24 August 2021

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WEPAB190

DC Break Design for a 2.45 GHz ECR Ion Source

site, ECR, high-voltage, simulation

3064

M.S. Dmitriyev, M.V. Dyakonov, S.A. Tumanov, M.I. Zhigailova
MEPhI, Moscow, Russia

New 2.45 GHz Electron Cyclotron Resonance Ion Source (ECRIS) is under development at NRNU MEPhI. The transmission line is designed for transmitting the microwave power into the ECRIS. A DC break up to 80 kV was designed for the electrical insulation between the microwave supply system and the plasma chamber applied to high DC voltage. Current study considers the investigation results as well as the optimization of numerical simulations of the 2.45 GHz DC break with low losses and low emission into the surrounding space.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB190

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paper received ※ 20 May 2021 paper accepted ※ 08 June 2021 issue date ※ 30 August 2021

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WEPAB283

CERN SPS Sprinkler System: A Customized Industrial Solution for a Non-Conventional Site

radiation, controls, monitoring, operation

3313

A. Suwalska, A. Arnalich, F. Deperraz, M. Munoz Codoceo, P. Ninin
CERN, Meyrin, Switzerland

Until 2018, the limited firefighting means in the SPS complex largely exposed it to the consequences of self-ignition or accidental fire. In 2015 the SPS Fire Safety project was launched with the objective of improving life safety and property protection by deploying a whole set of automatic actions to protect SPS in case of fire outbreak. If nothing was done, an unmanaged fire could be a threat to lives of those working underground and could mean losing a vast majority of the SPS machine and its equipment. In 2020, CERN has completed the consolidation of its SPS fire safety systems. Among these, a water based sprinkler system, following principles of standard industrial design but customized and tailor-made for SPS and its irradiated areas, is ready to operate. The system must take into account limitations related to the presence of fragile accelerator equipment, radioactive zones, integration constraints and comply with European norms, in particular EN12845. This paper presents the risk assessment, our experience from the planning and installation phase while discussing the custom-chosen and radiation tested equipment to end up with the lessons learned and outlook for the future.

Poster WEPAB283 [2.224 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB283

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paper received ※ 13 May 2021 paper accepted ※ 14 June 2021 issue date ※ 16 August 2021

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WEPAB287

Upgrade of the ELBE Timing System

timing, operation, gun, hardware

3326

M. Kuntzsch, M. Justus, A. Schwarz, K. Zenker
HZDR, Dresden, Germany
L. Krmpotic, U. Legat, U. Rojec
Cosylab, Ljubljana, Slovenia
Ž. Oven
COSYLAB, Control System Laboratory, Ljubljana, Slovenia

At the ELBE accelerator center a superconducting linac is operated to drive manifold secondary radiation sources like two infrared FELs, a positron source and a THz facility. The machine uses two injectors as electron sources that are accelerated in the main linac. The user experiments demand a large variety of bunch patterns from single shot to macro pulsed and cw beam at up to 26 MHz repetition rate. At ELBE a new timing system is being developed based on the MRF hardware platform and the MRF Timing System IOC. It uses two masters and a scalable number of connected receivers to generate the desired pulse patterns for operating the machine and to control user experiments. The contribution will show the architecture of the timing system, the control interfacing and performance measurements acquired on the test bench.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB287

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paper received ※ 21 May 2021 paper accepted ※ 01 July 2021 issue date ※ 13 August 2021

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WEPAB301

Design of an X-Band LLRF System for TEX Test Facility at LNF-INFN

LLRF, cavity, klystron, insertion

3371

L. Piersanti, D. Alesini, M. Bellaveglia, S. Bini, B. Buonomo, F. Cardelli, C. Di Giulio, M. Diomede, A. Falone, G. Franzini, A. Gallo, A. Liedl, S. Pioli, S. Quaglia, L. Sabbatini, M. Scampati, G. Scarselletta, A. Stella
INFN/LNF, Frascati, Italy

Funding: Latino is a project co-funded by Regione Lazio within POR-FESR 2014-2020 program
In the framework of LATINO project (Laboratory in Advanced Technologies for INnOvation) funded by Lazio regional government, a TEst stand for X-band (TEX) is being commissioned at Frascati National Laboratories (LNF) of INFN. TEX is born as a collaboration with CERN, aimed at carrying out high power tests of X-band accelerating structure prototypes and waveguide components, and it is of paramount importance in view of the construction of EuPRAXIA@SPARC_LAB facility at LNF. In order to generate, manipulate and measure the RF pulses needed to feed the RF power unit (solid state ScandiNova K400 modulator, CPI 50 MW 50 Hz klystron) an X-band low level RF system has been developed, making use of a commercial S-band (2.856 GHz) Libera digital LLRF (manufactured by Instrumentation Technologies) with a newly designed up/down conversion stage and a reference generation/distribution system, which is able to produce coherent reference frequencies for the American S-band (2.856 GHz) and European X-band (11.994 GHz). In this paper the main features of such systems will be reviewed together with preliminary laboratory measurement results.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB301

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paper received ※ 19 May 2021 paper accepted ※ 12 July 2021 issue date ※ 27 August 2021

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WEPAB305

Teeport: Break the Wall Between the Optimization Algorithms and Problems

experiment, controls, real-time, monitoring

3387

Z. Zhang, X. Huang, M. Song
SLAC, Menlo Park, California, USA

Funding: DOE, Office of Science, Office of Basic Energy Sciences, DE-AC02-76SF00515 and FWP 2018-SLAC-100469 Computing Science, Office of Advanced Scientific Computing Research, FWP 2018-SLAC-100469ASCR.
Optimization algorithms/techniques such as genetic algorithm (GA), particle swarm optimization (PSO) and Gaussian process (GP) have been widely used in the accelerator field to tackle complex design/online optimization problems. However, connecting the algorithm with the optimization problem can be difficult, sometimes even unrealistic, since the algorithms and problems could be implemented in different languages, might require specific resources, or have physical constraints. We introduce an optimization platform named Teeport that is developed to address the above issue. This real-time communication (RTC) based platform is particularly designed to minimize the effort of integrating the algorithms and problems. Once integrated, the users are granted a rich feature set, such as monitoring, controlling, and benchmarking. Some real-life applications of the platform are also discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB305

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paper received ※ 20 May 2021 paper accepted ※ 02 July 2021 issue date ※ 27 August 2021

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WEPAB314

TEX - an X-Band Test Facility at INFN-LNF

controls, klystron, LLRF, framework

3406

S. Pioli, D. Alesini, F.A. Anelli, M. Bellaveglia, S. Bini, B. Buonomo, S. Cantarella, F. Cardelli, G. Catuscelli, R. Ceccarelli, A. Cecchinelli, F. Chiarelli, P. Ciuffetti, R. Clementi, C. Di Giulio, E. Di Pasquale, G. Di Raddo, M. Diomede, A. Esposito, L. Faillace, A. Falone, G. Franzini, A. Gallo, S. Incremona, A. Liedl, D. Pellegrini, G. Piermarini, L. Piersanti, S. Quaglia, R. Ricci, L. Sabbatini, M. Scampati, G. Scarselletta, A. Stella, R. Zarlenga
INFN/LNF, Frascati, Italy

Funding: The LATINO project is co-funded by the Regione Lazio within POR-FESR 2014-2020 European activities (public call "Open Research Infrastructures").
We report the status of the development of an High Power RF Laboratory in X-Band called TEX (TEst-stand for X-Band). TEX is part of the LATINO (Laboratory in Advanced Technologies for INnOvation) initiative that is ongoing at the Frascati National Laboratories (LNF) of the Italian Institute for Nuclear Physics (INFN) that covers many different areas focused on particle accelerator technologies. TEX is a RF test facility based on solid-state K400 modulator from ScandiNova with a 50MW class X-band (11.996 GHz) klystron tube model vkx 8311a operating at 50 Hz. This RF source will operate as resource for test and research programs such as the RF breakdown on RF waveguide components as well as high power testing of accelerating structures for future high gradient linear accelerator such as EuPRAXIA and CLIC. The high power testing will be performed in a dedicated brand-new bunker that has been recently built. RF system, vacuum controls and safety equipments are currently being installed. The first accelerating structure testing is scheduled by beginning 2022. In this document design and tests for all the sub-systems of the facility will be presented and discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB314

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paper received ※ 19 May 2021 paper accepted ※ 28 July 2021 issue date ※ 19 August 2021

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WEPAB349

Design of a Circular Waveguide TM₀₁ Mode Launcher with Wire Loop Feed

coupling, experiment, detector, simulation

3517

A. Chittora
BITS Pilani, Sancoale, India

In Accelerator technology, RF power couplers are important component to couple RF signal to travelling wave structure. Circular waveguide TM₀₁ mode is one of the symmetric modes, that is suitable to use for RF coupling. TM₀₁ mode launcher is used as an RF coupler in Accelerator technology*. Design of a compact circular waveguide TM₀₁ mode-launcher is presented in this paper. The design is based on the principle of magnetic field coupling between a wire loop and TM₀₁ mode of circular waveguide. The mode launcher exhibits high efficiency and 3.1% bandwidth at 3.2 GHz frequency with both circular and elliptical loop. Performance of the mode launcher is experimentally verified and simulated S-parameters agree with the measured results. The mode launcher is of compact size and is suitable for efficient excitation of TM₀₁ mode in circular waveguide and travelling wave structures. The launcher is also useful for cold testing of high power microwave antennas and Radars.
* M. Forno, "Design of a high power TM₀₁ mode launcher optimized for manufacturing by milling." 2016.

Poster WEPAB349 [1.135 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB349

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paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 20 August 2021

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WEPAB371

Numerical Analysis on Nitrogen Injection Fire Extinguishing System in the LINAC Area at TPS

simulation, linac, injection, gun

3578

J.-C. Chang, W.S. Chan, Y.F. Chiu
NSRRC, Hsinchu, Taiwan

The Linear accelerator (LINAC) of Taiwan Photon Source (TPS) could generate electrons to 150 MeV. The main subsystems including an electron gun, buncher, accelerating sections, vacuum system, and focusing and steering magnets are located in the LINAC area of 223.5 m2 and 3 m in height. We designed a nitrogen injection fire extinguishing system for the LINAC area and performed Computational Fluid Dynamic (CFD) simulation to analyse the fire extinguishing performance with and without fresh air supplied from the air conditioning system.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB371

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paper received ※ 16 May 2021 paper accepted ※ 21 June 2021 issue date ※ 20 August 2021

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WEPAB374

The Southern Hemisphere’s First X-Band Radio-Frequency Test Facility at the University of Melbourne

electron, klystron, gun, network

3588

M. Volpi, R.P. Rassool, S.L. Sheehy, G. Taylor, S.D. Williams
The University of Melbourne, Melbourne, Victoria, Australia
M.J. Boland
CLS, Saskatoon, Saskatchewan, Canada
M.J. Boland
University of Saskatchewan, Saskatoon, Canada
N. Catalán Lasheras, S. Gonzalez Anton, G. McMonagle, S. Stapnes, W. Wuensch
CERN, Meyrin, Switzerland
R.T. Dowd, K. Zingre
AS - ANSTO, Clayton, Australia

The first Southern Hemisphere X-band Laboratory for Accelerators and Beams (X-LAB) is under construction at the University of Melbourne, and it will operate CERN X-band test stand containing two 12GHz 6MW klystron amplifiers. By power combination through hybrid couplers and the use of pulse compressors, up to 50 MW of peak power can be sent to any of 2 test slots at pulse repetition rates up to 400 Hz. The test stand is dedicated to RF conditioning and testing CLIC’s high gradient accelerating structures beyond 100 MV/m. It will also form the basis for developing a compact accelerator for medical applications, such as radiotherapy and compact light sources. Australian researchers working as part of a collaboration between the University of Melbourne, international universities, national industries, the Australian Synchrotron -ANSTO, Canadian Light Source and the CERN believe that creating a laboratory for novel accelerator research in Australia could drive technological and medical innovation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB374

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paper received ※ 18 May 2021 paper accepted ※ 06 July 2021 issue date ※ 30 August 2021

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WEPAB398

A C-Band RF Mode Launcher with Quadrupole Field Components Cancellation for High Brightness Applications

quadrupole, network, brightness, linac

3638

G. Pedrocchi
SBAI, Roma, Italy
D. Alesini, F. Cardelli, A. Gallo, A. Giribono, B. Spataro
INFN/LNF, Frascati, Italy
G. Castorina
AVO-ADAM, Meyrin, Switzerland
L. Ficcadenti
INFN-Roma, Roma, Italy
M. Migliorati, A. Mostacci, L. Palumbo
Sapienza University of Rome, Rome, Italy

The R&D of high gradient radiofrequency devices is aimed to develop innovative and compact accelerating stuctures based on new manufactoring techniques and materials in order to produce devices operating with the highest accelerating gradient. Recent studies have shown a large increase in the maximum sustained RF surface electric fields in copper structure operating at cryogenic temperature. These novel approaches allow significant performance improvements of RF photoinjectors. Indeed the operation at high surface fields results in considerable increase of electron brilliance. This requires high field quality in the RF photoinjector and specifically in its poweer coupler. In this work we present a novel power coupler for the RF photoinjector. The coupler is a compact C-band TM01 mode launcher with a fourfold symmetry which minimized both the dipole and the quadrupole RF field components.

Poster WEPAB398 [1.799 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB398

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paper received ※ 13 May 2021 paper accepted ※ 06 July 2021 issue date ※ 23 August 2021

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WEPAB402

Status and Progress of the High-Power RF System for High Energy Photon Source

cavity, booster, photon, storage-ring

3653

T.M. Huang, J. Li, H.Y. Lin, Y.L. Luo, Q. Ma, W.M. Pan, P. Zhang, F.C. Zhao
IHEP, Beijing, People’s Republic of China

Funding: Work was supported in part by High Energy Photon Source, a major national science and technology infrastructure in China, and in part by the National Natural Science Foundation of China(12075263).
High Energy Photon Source is a 6-GeV diffraction-limited synchrotron light source currently under construction in Beijing. Three types of high-power RF systems are used to drive the booster and the storage ring. For the booster ring, a total of 600-kW continuous-wave (CW) RF power is generated by six 500-MHz solid-state power amplifiers (SSA) and fed into six normal-conducting copper cavities. Concerning the storage ring, five CW 260-kW SSAs at 166 MHz and two CW 260-kW SSAs at 500-MHz are used to drive five fundamental and two third-harmonic superconducting cavities respectively. The RF power distributions are realized by 9-3/16" rigid coaxial line for the 166-MHz system and EIA standard WR1800 waveguide for the 500-MHz one. High-power circulators and loads are installed at the outputs of all SSAs to further protect the power transmitters from damages due to reflected power although each amplifier module is equipped with individual isolators. The overall system layout and the progress of the main components are presented in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB402

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paper received ※ 18 May 2021 paper accepted ※ 02 July 2021 issue date ※ 14 August 2021

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THPAB077

Magnetic Shims Studies for APS-U Hybrid Permanent Magnet Undulators

undulator, multipole, simulation, quadrupole

3941

Y. Piao, R.J. Dejus, M.F. Qian, I. Vasserman, J.Z. Xu
ANL, Lemont, Illinois, USA

Funding: Work supported by U.S. Department of Energy, Office of Science, under contract number DE-AC02-06CH11357
For the newly designed and fabricated APS Upgrade (APS-U) hybrid permanent magnet undulators (HPMUs), the development of magnetic shims has been critical to successfully tuning the undulators to meet the tight APS-U physics requirements. Different types of side and surface shims have been developed and applied for this purpose. The side shims are primarily used for trajectory tuning, and the surface shims are for phase and multipole tuning as well as trajectory tuning. Current design, applications, and measurement of the shims for the newly designed and fabricated APS28 (28 mm period) undulators are presented in this paper.

Poster THPAB077 [0.531 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB077

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paper received ※ 20 May 2021 paper accepted ※ 18 June 2021 issue date ※ 27 August 2021

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THPAB081

High-Power Prototype Canon Coupler for APS-U Booster Cavities

cavity, booster, coupling, injection

3956

G.J. Waldschmidt, D.J. Bromberek, D. Horan, G. Trento, U. Wienands
ANL, Lemont, Illinois, USA
T. Harada, H. Oikawa, H. Takahashi
CETD, Tochigi, Japan

The Advanced Photon Source Upgrade (APS-U) plans to achieve a beam capture efficiency above 90% at 17 nC bunch charge into the Booster. Due to large beam loading at injection, the 352-MHz Booster cavities will be significantly detuned necessitating effective-power handling much greater than the 100kW effective power rating of the present coupler. Canon Electron Tubes & Devices Co., Ltd. (CETD) has designed and built a compact coupler for the APS-U Booster using a high-power ceramic disk window design in addition to accommodating significant space restrictions and additional diagnostics and cooling requirements. The coupler design was modified from an existing 500MHz, 800kW coupler that has been in routine operation at KEKB. The APS-U coupler has been installed and tested in the high-power 352-MHz test stand at the APS. The details of the design and testing of the prototype coupler will be reported in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB081

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paper received ※ 18 May 2021 paper accepted ※ 28 July 2021 issue date ※ 15 August 2021

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THPAB147

Preliminary Study of 500 MHz HOM-Free RF Cavity

cavity, HOM, coupling, damping

4050

Zh.X. Tang
USTC/NSRL, Hefei, Anhui, People’s Republic of China

Funding: Work supported by National Natural Science Foundation of China(Grant No. U1832135 and 11805199)}
In this paper, we study the microwave characteristics of 500 MHz RF cavity, including the optimization of cavity structure, the simulation design of high-order mode (HOM) absorption structure and the design of coupler. The cavity structure is simulated by CST. The absorption waveguide is designed and optimized. The coupler is designed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB147

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paper received ※ 09 May 2021 paper accepted ※ 16 July 2021 issue date ※ 02 September 2021

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THPAB210

Extrapolated Range for Low Energy Electrons (< 1 keV)

electron, simulation, experiment, multipactoring

4201

C. Inguimbert, M.B. Belhaj, Q. Gibaru
ONERA, Toulouse, France
Q. Gibaru, D. Lambert, M. Raine
CEA, Arpajon, France
Q. Gibaru
CNES, PARIS, France

Funding: ONERA- DPHY, 2 avenue E. Belin, 31055 Toulouse, France CEA, DAM, DIF, 91297 Arpajon, France CNES, 18 av. E. Belin, 31055 Toulouse, France
The Secondary Electron Emission (SEE) process plays an important role in the performance of various devices. Mitigating the multipactor phenomenon that may occur in radio-frequency components is a concern in many fields such as space technologies or electron microscopy. SEE is also a concern in the accelerator physics community, where the beam lines stability can strongly be affected by this phenomenon*,**. In that scope, the escaped depth and thus the range of emitted electrons is of great interest. Our goal, by means of simulations is to provide a better knowledge of SEE. We have developed a Monte Carlo electron transport code for low energy electrons [~eV, ~10keV], that is part of the Dec. 2020 release of GEANT4***. It has been used to study the practical range of low energy electrons. Our goal is to formulate, below ~10 keV, an analytic range vs. energy expression, and to relate it to fundamental physcial parameters such as the mean free paths of electrons in matter. The goal is to provide simple practical extrapolated range formula that can help to understand SEE phenomenon.
* M. Mostajeran et al. J. of Instr. 5 (2010)
** C. Y. Vallgren et al. Phys. Rev. Accel. Beam 14 (2011)
*** Q. Gibaru et al. Nuc. Inst. And Met. 487 (2021)

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB210

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paper received ※ 10 May 2021 paper accepted ※ 23 June 2021 issue date ※ 27 August 2021

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THPAB211

Monte Carlo Simulation of 3D Surface Morphologies for Secondary Electron Emission Reduction

electron, simulation, multipactoring, experiment

4204

Q. Gibaru, M.B. Belhaj, C. Inguimbert
ONERA, Toulouse, France
Q. Gibaru, D. Lambert, M. Raine
CEA, Arpajon, France
Q. Gibaru
CNES, PARIS, France

Low energy electrons of few tens of eV may cause Multipactor breakdowns in waveguides driven by the Secondary Electron Emission Yield (SEY) of the walls. This risk is lowered by using low emissive surfaces and this topic has been studied experimentally and with numerical simulations. The dependence of the SEY on surface properties is well known*. Surface morphology has been widely used to reduce the SEY by forming roughness patterns on the surface**. All patterns do not have the same efficiency so their analysis in terms of SEY is relevant. Monte-Carlo simulation codes can be used to study the processes behind the SEY. The MicroElec module of GEANT4 has recently been extended with more materials and processes and validated with experimental data for SEY calculations**. In this work, simulation results are shown for a bulk sample capped with different roughness patterns. The effects of the shape parameters on the SEY are studied for typical dimensions between 20 µm and 100 µm. The results are checked with experimental SEY measurements on samples with similar roughness patterns.
*:T Gineste et al, Appl Surf Sci 359 (2015) 398-404
**:J Pierron et al, J Appl Phys 124 (2018) 095101
***:Q. Gibaru, C. Inguimbert, P. Caron, M. Raine, D. Lambert, J. Puech, NIM B. 487 (2021) 66-77

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB211

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paper received ※ 12 May 2021 paper accepted ※ 23 June 2021 issue date ※ 17 August 2021

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THPAB223

Energy Compression System Radio Frequency Design at the Canadian Light Source

linac, impedance, simulation, RF-structure

4231

E.J. Ericson, D. Bertwistle, M.J. Boland
CLS, Saskatoon, Saskatchewan, Canada

The Canadian Light Source (CLS), Canada’s only synchrotron light source, is considering a linear accelerator (LINAC) upgrade. As a result, the radio frequency (RF) structure in the downstream Energy Compression System (ECS) needs to be redesigned. In this paper, we describe the design process followed to determine the geometry of the RF structure cells and coupler.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB223

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paper received ※ 18 May 2021 paper accepted ※ 28 July 2021 issue date ※ 28 August 2021

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THPAB296

The Spallation Neutron Source Normal Conducting Linac RF System Design for the Proton Power Upgrade Project

DTL, cavity, klystron, linac

4383

J.S. Moss, M.T. Crofford, S.W. Lee, G.D. Toby
ORNL, Oak Ridge, Tennessee, USA
M.E. Middendorf
ORNL RAD, Oak Ridge, Tennessee, USA

Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under contract number DE-AC05-00OR22725.
The Proton Power Upgrade (PPU) project at the Spallation Neutron Source will double the available proton beam power from 1.4 to 2.8 MW by increasing the beam energy from 1.0 to 1.3 GeV and the beam current from 26 to 38 mA. The increase in beam current resulted in the need to redesign the existing normal conducting linac (NCL) RF Systems. High-power testing of the existing NCL RF Systems configured to accelerate PPU-level beam provided the data used to make the final design decisions. This paper describes the development and execution of those in-situ tests and the subsequent results.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB296

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paper received ※ 17 May 2021 paper accepted ※ 22 July 2021 issue date ※ 20 August 2021

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THPAB300

Structure Design and Motion Analysis of 6-DOF Sample Positioning Platform

controls, radiation, synchrotron-radiation, synchrotron

4387

G.Y. Wang, J.X. Chen, L. Liu, R.H. Liu, C.J. Ning, A.X. Wang, J.B. Yu, Y.J. Yu, J.S. Zhang
IHEP CSNS, Guangdong Province, People’s Republic of China
L. Kang
IHEP, Beijing, People’s Republic of China

with the development of synchrotron radiation (SR) light source technology, in order to meet the requirements of sample positioning platform of some beamline stations, such as adjusting resolution at the nanometer level and having larger sample scanning distance, a six degree of freedom positioning platform based on spacefab structure was developed. The key technologies such as coordinate parameter transformation, kinematics analysis, and adjustment decoupling algorithm of 6-DOF pose adjustment system of SpaceFAB positioning platform are mainly studied. A 6-DOF platform driven by a stepping motor is designed and manufactured. The control system of the 6-DOF Platform Based on bus control is developed, and the adjustment accuracy is tested. The repeated positioning accuracy of the platform in three directions is 0.019 mm, and that of rotation is 0.011 ° in three directions. The test results verify the correctness of the theoretical analysis of SpaceFAB structure and the rationality of mechanism design. The research on the platform motion algorithm and control system has important reference value for the follow-up research of large stroke nano-6-dof positioning platform.

Poster THPAB300 [1.517 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB300

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paper received ※ 16 May 2021 paper accepted ※ 06 July 2021 issue date ※ 02 September 2021

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THPAB332

Development of a Pair of 182 GHz Two-Half Power Extractor and Accelerator for Short Pulse RF Breakdown Study

acceleration, electron, wakefield, alignment

4435

J.H. Shao, J.G. Power
ANL, Lemont, Illinois, USA
R.B. Agustsson, S.V. Kutsaev, A.Yu. Smirnov
RadiaBeam, Santa Monica, California, USA

High-frequency structures are favorable in structure wakefield acceleration for their strong beam-structure interaction. Recent progress of advanced fabrication technologies, such as high-precision two-half milling and additive machining, has enabled experimental research of mm-wave/THz structures. In this work, we have designed a pair of 182 GHz two-half copper power extractor and accelerator for short pulse RF breakdown study. When driven by a 182 GHz 4-bunch train with 4 nC total charge and 0.3 mm rms bunch length, the power extractor will generate 0.4 ns ~8 MW RF pulses and the corresponding gradient in the single-cell accelerator will reach ~460 MV/m. RF and mechanical design of the proof-of-concept structures will be reported in this manuscript.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB332

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paper received ※ 26 May 2021 paper accepted ※ 19 July 2021 issue date ※ 26 August 2021

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THPAB335

Optical Phase Space Mapping Using a Digital Micro-Mirror Device

experiment, radiation, optics, controls

4439

M. Vujanovic, R.B. Fiorito, C.P. Welsch, J. Wolfenden
The University of Liverpool, Liverpool, United Kingdom
A.L. Kippax
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: This project has received funding from European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 721559.
Optical transition radiation (OTR) is routinely used to measure transverse beam size, divergence , and emittance of charged particle beams. Presented here is an experimental method, which uses micro-mirror device (DMD) to conduct optical phase space mapping (OPSM). OPSM will be a next step and significant enhancement of the measurements capabilities of an adaptive optics-based beam characterization system. For this measurements, a DMD will be used to generate a reflective mask that replicates the double slit. Since the DMD makes it possible to easily change the size, shape and position of the mask, the use of the DMD will greatly simplify OPSM and make it more flexible, faster and more useful for diagnostics applications. The process can be automated and integrated into a control system that can be used to optimize the beam transport.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB335

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paper received ※ 20 May 2021 paper accepted ※ 27 July 2021 issue date ※ 28 August 2021

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FRXC05

Gas Jet In-Vivo Dosimetry for Particle Beam Therapy

operation, diagnostics, proton, cyclotron

4548

J. Wolfenden, N. Kumar, A. Salehilashkajani, C.P. Welsch, H.D. Zhang
The University of Liverpool, Liverpool, United Kingdom
N. Kumar, A. Salehilashkajani, C.P. Welsch, J. Wolfenden, H.D. Zhang
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: This work is supported by the HL-LHC-UK project funded by STFC and CERN and the STFC Cockcroft core grant No. ST/G008248/1.
Medical applications of charged particle beams require a full online characterisation of the beam to ensure patient safety, treatment efficacy, and facility efficiency. In-vivo dosimetry, measurement of delivered dose during treatment, is a significant part of this characterisation. Current methods offer limited information or are invasive to the beam, meaning measurements must be done offline. This contribution presents the development of a non-invasive gas jet in-vivo dosimeter for treatment facilities. The technique is based on the interaction between a particle beam and a supersonic gas jet curtain, which was originally developed for the high luminosity upgrade of the large hadron collider (HL-LHC). To demonstrate the medical application of this technique, an existing HL-LHC test system with minor modifications will be installed at the University of Birmingham’s 35 MeV proton cyclotron, which has properties comparable to that of a treatment beam. This contribution presents the design and development of this test setup, plans for initial benchmarking measurements, and plans for a future optimised medical accelerator gas jet in-vivo dosimeter.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-FRXC05

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paper received ※ 18 May 2021 paper accepted ※ 23 July 2021 issue date ※ 11 August 2021

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