IPAC2022 - List of Keywords (GUI)

Paper	Title	Other Keywords	Page
MOPOTK065	Minimising Transverse Multipoles in Accelerating RF Cavities via Azimuthally Modulated Designs	cavity, multipole, simulation, coupling	610
	L.M. Wroe JAI, Oxford, United Kingdom R. Apsimon Cockcroft Institute, Lancaster University, Lancaster, United Kingdom M. Dosanjh CERN, Meyrin, Switzerland S.L. Sheehy The University of Melbourne, Melbourne, Victoria, Australia
	In this paper, we build upon previous work of designing RF structures that support modes with tailored multipolar fields by applying the concept to negate the transverse multipoles in accelerating RF cavities caused by the incorporation of waveguide slots and tuning deformations. We outline a systematic method for designing structures that minimise these transverse multipoles and present analysis of simulations of two different minimisation designs.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOTK065
About •	Received ※ 08 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 06 July 2022
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MOPOMS007	Optimized Dielectric Loaded Waveguide Terahertz LINACs	electron, acceleration, linac, vacuum	634
	M. Vahdani University of Hamburg, Hamburg, Germany M. Fakhari DESY, Hamburg, Germany F.X. Kärtner The Hamburg Center for Ultrafast Imaging, University of Hamburg, Hamburg, Germany F.X. Kärtner Deutsches Elektronen Synchrotron (DESY) and Center for Free Electron Science (CFEL), Hamburg, Germany M. Vahdani CFEL, Hamburg, Germany
	Dielectric loaded waveguides (DLW) powered by multicycle terahertz (THz) pulses have shown promising performance as compact linear accelerators due to higher breakdown fields at THz frequencies compared to conventional RF components. By changing the dielectric dimensions one can control phase and group velocities of the THz pulse inside the DLW. Since optimum waveguide dimensions are dependent on initial electron energy, THz pulse energy, and etc., it is worthwhile to determine optimum values for different conditions to maximize final kinetic energy. In this work, we present a combined analytical/numerical guide to determine the optimum DLW parameters for single on-axis electron acceleration. We also introduce normalized graphic representations to visualize optimum designs for different initial electron and THz pulse energies.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOMS007
About •	Received ※ 09 June 2022 — Revised ※ 09 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 21 June 2022
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MOPOMS012	Simulation Studies of Drive Beam Instability in a Dielectric Wakefield Accelerator	wakefield, simulation, focusing, quadrupole	645
	W.H. Tan, P. Piot Northern Illinois University, DeKalb, Illinois, USA A. Huebl, R. Jambunathan, R. Lehé, A. Myers, T. Rheaume, J.-L. Vay, W. Zhang LBNL, Berkeley, USA P. Piot ANL, Lemont, Illinois, USA
	Funding: This work is supported by the US DOE award DE-SC0018656 with NIU and DE-AC02-06CH11357 with ANL. This work used resources from NERSC, supported by DOE contract DE-AC02-05CH11231. This research used WarpX, which is supported by the US DOE Exascale Computing Project. Primary WarpX contributors are with LBNL, LLNL, CEA-LIDYL, SLAC, DESY, CERN, and Modern Electron. Beam-driven collinear wakefield acceleration using structure wakefield accelerators promises a high gradient acceleration within a smaller physical footprint. Sustainable extraction of energy from the drive beam relies on precise understanding of its long term dynamics and the possible onset or mitigation of the beam instability. The advance of computational power and tools makes it possible to model the full physics of beam-driven wakefield acceleration. Here we report on the long-term beam dynamics studies of a drive beam considering the example of a dielectric waveguide using high fidelity particle-in-cell simulations performed with WarpX.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOMS012
About •	Received ※ 08 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 16 June 2022
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MOPOMS013	Toward Emittance Measurements at 11.7 GHz Short-Pulse High-Gradient RF Gun	gun, linac, emittance, experiment	649
	S.V. Kuzikov, C.-J. Jing, E.W. Knight Euclid TechLabs, Solon, Ohio, USA G. Chen, C.-J. Jing, P. Piot, E.E. Wisniewski ANL, Lemont, Illinois, USA C.-J. Jing Euclid Beamlabs, Bolingbrook, USA P. Piot Fermilab, Batavia, Illinois, USA P. Piot, W.H. Tan Northern Illinois University, DeKalb, Illinois, USA
	Funding: This project is supported with DoE SBIR Phase II Grant #DE-SC0018709. A short pulse high gradient RF gun has been recently tested at Argonne Wakefield Accelerator (AWA) facility. The carried-out test showed that the 1,5-cell gun was able to inject 3 MeV, up to 100 pC bunches at room tem-perature being fed by 9 ns up to 300 MW 11.7 GHz puls-es. The cathode field was as high as about 400 MV/m. So high field is aimed to mitigate repealing Coulomb forces substantially. In accordance with simulations the emit-tance could be as low as less than 0.2 mcm. To obtain so low emittance in the experiment, the gun is assumed to be equipped with a downstream linac to be fed from the same power extractor as the gun itself. Here we report design of the RF power distribution system splitting RF power among the gun and the linac, results of low-power tests, and emittance measurement plans for upcoming new experiment at AWA.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOMS013
About •	Received ※ 01 June 2022 — Revised ※ 09 June 2022 — Accepted ※ 18 June 2022 — Issue date ※ 01 July 2022
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MOPOMS050	Rigorous Approach for Calculation of Radiation of a Charged Particle Bunch Exiting an Open-Ended Dielectrically Loaded Waveguide	radiation, electron, wakefield, acceleration	757
	S.N. Galyamin Saint Petersburg State University, Saint Petersburg, Russia S. Baturin ITMO University, Saint Petersburg, Russia
	Funding: Work supported by Russian Science Foundation (Grant No. 18-72-10137). Beam-driven radiation sources based on open-ended waveguide structures with dielectric filling are of essential interest due to their attractive possibilities to generate high-power narrow-band Cherenkov radiation. An important problem here is to effectively extract the radiation from the waveguide to the open space. Therefore, further development of this scheme requires rigorous mathematical approach describing the interaction of both charged particle bunch and produced radiation with the open end of a waveguide. In this report, we present the corresponding analytical approach based on our recent paper* where diffraction of a waveguide mode at the open end of a dielectrically loaded waveguide has been rigorously investigated. * D. Wang et al., Rev. Sci. Instruments, Vol. 89, 093301 (2018). ** S.N. Galyamin et al., IEEE Trans. Microwave Theory Techn., Vol. 69, 2429-2438 (2021).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOMS050
About •	Received ※ 09 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 03 July 2022
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TUPOST002	Upgrade of the 25 MW RF Station for the Linear Accelerator LINAC2 at ELSA	klystron, electron, linac, monitoring	838
	D. Proft, K. Desch, D. Elsner, M.T. Switka ELSA, Bonn, Germany
	At the Electron Stretcher Facility ELSA in Bonn the first acceleration stage consists of a 3 GHz traveling wave linear accelerator. It was powered by a 25 MW pulsed high power klystron amplifier, which had been in use for the last thirty years. After a major failure and due to the lack of spare part availability the RF station was rebuilt. In addition to a new klystron including its high voltage tank, the new setup also consists of major upgrades of the infrastructure, the pulse forming network and the safety interlocks to satisfy the contemporary requirements. A new monitoring system consisting of multi-channel sampling ADCs allows for automatic pulse-by-pulse analysis of the klystron parameters and simultaneous evaluation of RF performance and stability. In this contribution we will present the new RF station setup, which has successfully been operating since the beginning of 2021 as well as the new monitoring capabilities.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOST002
About •	Received ※ 04 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 03 July 2022
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TUPOST015	Commissioning and First Results of an X-Band LLRF System for TEX Test Facility at LNF-INFN	LLRF, MMI, klystron, network	876
	L. Piersanti, D. Alesini, M. Bellaveglia, S. Bini, B. Buonomo, F. Cardelli, C. Di Giulio, E. Di Pasquale, M. Diomede, L. Faillace, A. Falone, G. Franzini, A. Gallo, G. Giannetti, A. Liedl, D. Moriggi, S. Pioli, S. Quaglia, L. Sabbatini, M. Scampati, G. Scarselletta, A. Stella, S. Tocci, L. Zelinotti LNF-INFN, 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, the commissioning of the TEst stand for X-band (TEX) facility has started in 2021 at Frascati National Laboratories of INFN. Born as a collaboration with CERN to test high gradient accelerating structures, during 2022 TEX aims at feeding the first EuPRAXIA@SPARC_LAB X-band structure prototype. During 2021 the commissioning has been successfully carried out up to 48 MW. The power unit is driven by an X-band low level RF system, that employs a commercial S-band (2.856 GHz) Libera digital LLRF (manufactured by Instrumentation Technologies), with an up/down conversion stage and a reference generation and distribution system able to produce coherent frequencies for the American S-band and European X-band (11.994 GHz), both designed and realized at LNF. The performance of the system, with a particular focus on amplitude and phase resolution, together with klystron and driver amplifier jitter measurements, will be reviewed in this paper. Moreover, considerations on its suitability and main limitations in view of EuPRAXIA@SPARC_LAB project will be discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOST015
About •	Received ※ 20 May 2022 — Revised ※ 13 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 28 June 2022
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TUPOST058	Badger: The Missing Optimizer in ACR	interface, controls, operation, framework	999
	Z. Zhang, A.L. Edelen, J.R. Garrahan, C.E. Mayes, S.A. Miskovich, D.F. Ratner, R.J. Roussel, J. Shtalenkova SLAC, Menlo Park, California, USA M. Böse, S. Tomin DESY, Hamburg, Germany Y. Hidaka, G.M. Wang BNL, Upton, New York, USA
	Badger is an optimizer specifically designed for Accelerator Control Room (ACR). It’s the spiritual successor of Ocelot optimizer. Badger abstracts an optimization run as an optimization algorithm interacts with an environment, by following some pre-defined rules. The environment is controlled by the algorithm and tunes/observes the control system/machine through an interface, while the users control/monitor the optimization flow through a graphical user interface (GUI) or a command line interface (CLI). This paper would introduce the design principles and applications of Badger.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOST058
About •	Received ※ 08 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 17 June 2022
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TUPOPT032	Simulating Beam Transport with Permanent Magnet Chicane for THz Fel	electron, FEL, undulator, laser	1077
	A.C. Fisher, M.P. Lenz, P. Musumeci, A. Ody, Y. Park UCLA, Los Angeles, USA R.B. Agustsson, T.J. Hodgetts, A.Y. Murokh RadiaBeam, Santa Monica, California, USA
	Funding: This work was supported by NSF grant PHY-1734215 and DOE grant No. DE-SC0009914 and DE-SC0021190. The undulator construction has been carried out under SBIR/STTR DE-SC0017102 and DE-SC0018559. Free electron lasers are an attractive option for high average and peak power radiation in the THz gap, a region of the electromagnetic spectrum where radiation sources are scarce, as the required beam and undulator parameters are readily achievable with current technology. However, slippage effects require the FEL to be driven with relatively long and low current electron bunches, limiting amplification gain and output power. Previous work demonstrated that a waveguide could be used to match the radiation and e-beam velocities in a meter-long strongly-tapered helical undulator, resulting in 10\% energy extraction from an ultrashort 200 pC, 5.5 MeV electron beam. We present simulations for a follow-up experiment targeting higher frequencies with improvements to the e-beam transport including a permanent magnet chicane for strong beam compression. FEL simulations show >20\% extraction efficiency from a 125 pC, 7.4 MeV electron beam at 0.32 THz.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOPT032
About •	Received ※ 07 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 28 June 2022
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TUPOPT061	Status and Commissioning of the First X-Band RF Source of the TEX Facility	klystron, MMI, LLRF, controls	1148
	F. Cardelli, D. Alesini, M. Bellaveglia, S. Bini, M. Ceccarelli, C. Di Giulio, A. Falone, G. Franzini, A. Gallo, L. Piersanti, L. Sabbatini INFN/LNF, Frascati, Italy B. Buonomo, G. Catuscelli, R. Ceccarelli, A. Cecchinelli, R. Clementi, E. Di Pasquale, A. Liedl, D. Moriggi, G. Piermarini, S. Pioli, S. Quaglia, L.A. Rossi, M. Scampati, G. Scarselletta, S. Strabioli, S. Tocci, R. Zarlenga LNF-INFN, Frascati, Italy
	In 2021 started the commissioning of the TEX (Test stand for X-band) facility at the Frascati National laboratories of INFN. This facility has been founded in the framework of the LATINO (Laboratory in Advanced Technologies for INnOvation) project. The current facility layout includes an high power X-band (11.994 GHz) RF source, realized in collaboration with CERN, which will be used for validation and development of the X-band RF high gradient technology in view of the EuPRAXIA@SPARC_LAB project. The RF source is based on a CPI VKX8311 Klystron and a solid state ScandiNova k400 modulator to generate a maximum RF output power of 50 MW at 50 Hz, that will be mainly used for accelerating structure conditioning and waveguide components testing. In this paper the layout, the installation, commissioning and stability measurements of this source are described in detail. The test stand will be soon operative and ready to test the first X-band accelerating structure prototype.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOPT061
About •	Received ※ 08 June 2022 — Revised ※ 11 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 10 July 2022
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TUPOTK048	Optimization of a 600 MHz Two-Cell Slotted Waveguide Elliptical Cavity for FCC-ee	cavity, impedance, HOM, collider	1323
	S. Gorgi Zadeh, O. Brunner, F. Peauger, I. Syratchev CERN, Meyrin, Switzerland
	The radio-frequency (RF) system of the future circular lepton collider (FCC-ee) must cope with different machine parameters ranging from Ampere-class operation required for the Z-peak working point to the high-gradient operation for the ttbar threshold. The Superconducting Slotted Waveguide Elliptical cavity (SWELL) concept was recently proposed as an alternative to the challenging RF baseline design of the FCC-ee. In this paper, random optimization methods are used to minimize the peak surface magnetic field and the maximum longitudinal impedance of the higher order modes (HOM) of a two-cell \unit[600]{MHz} SWELL cavity. In the next step, the waveguide slots are optimized to first have a smooth transition from the cavity to the slots to avoid large peak surface fields and second to achieve high transmission at dipole mode frequencies and low transmission at fundamental mode frequency while keeping the design compact.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK048
About •	Received ※ 23 May 2022 — Revised ※ 12 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 15 June 2022
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TUPOMS044	Dielectric Loaded THz Waveguide Experimentally Optimized by Dispersion Measurements	experiment, electron, higher-order-mode, acceleration	1526
	M.J. Kellermeier, R.W. Aßmann, K. Flöttmann, F. Lemery DESY, Hamburg, Germany R.W. Aßmann LNF-INFN, Frascati, Italy W. Hillert University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
	Emerging high power THz sources pave the road for THz- driven acceleration of ultra-short bunches, and enable their manipulation for diagnostic purposes. Due to the small feature sizes of THz-guiding devices new methods are necessary for their electromagnetic characterization. A new technique has recently been developed which characterizes THz waveguides with respect to their dispersion relations and attenuation. Here, the method is applied to circular waveguides, partially filled with polymer capillaries of different thicknesses, to find a suitable size for THz driven streaking at 287 GHz. Further, rough 3d-printed metallic waveguides are measured to study the effect of roughness on attenuation and phase constant. In general, additive manufacturing techniques show promise for advanced integrated designs of THz driven structures.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOMS044
About •	Received ※ 05 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 28 June 2022
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TUPOMS051	Prototype Fabrication of an Active Normal Conducting Third Harmonic Cavity for the ALBA Storage Ring	cavity, HOM, simulation, storage-ring	1542
	J.R. Ocampo, J.M. Álvarez, B. Bravo, F. Pérez, A. Salom, P. Solans ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
	Funding: Co-funded by the European Regional Development Fund (ERDF) ALBA has designed a normal conducting active 1.5 GHz HOM damped cavity for the active third harmonic RF system for the ALBA Storage Ring (SR), which also will serve for the upgraded ALBA II. The third harmonic cavity at ALBA will be used to increase the bunch length in order to improve the beam lifetime and increase the beam stability thresholds. A prototype has been constructed by the company AVS in collaboration with VITZRO. This paper presents the design of the cavity, the constructed prototype, the Acceptance Tests measurements, and the future plans.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOMS051
About •	Received ※ 07 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 30 June 2022 — Issue date ※ 01 July 2022
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TUPOMS057	Design Study of HOM Couplers for the C-Band Accelerating Structure	factory, damping, dipole, cavity	1561
	D. Kim, E.I. Simakov LANL, Los Alamos, New Mexico, USA S. Biedron UNM-ECE, Albuquerque, USA Z. Li SLAC, Menlo Park, California, USA
	Funding: High Energy Physics (HEP) at the U.S. Department of Energy (DOE) A cold copper distributed coupling accelerator, with a high accelerating gradient at cryogenic temperatures (~77 K), is proposed as a baseline structure for the next generation of linear colliders. This novel technology improves accelerator performance and allows more degrees of freedom for optimization of individual cavities. It has been suggested that C-band accelerating structures at 5.712 GHz may allow to maintain high efficiency, achieve high accelerating gradient, and be suitable beam dynamics with wakefield damping and detuning of the cavities. The optimization of the cavity shape was performed and we computed quality factor, shunt impedance, and beam kick factor for each of the proposed cavity geometries using CST microwave studio. Next, we proposed a configuration for higher order mode (HOM) suppression that includes waveguide slots running parallel to the axis of the accelerator. This presentation will report details of the parametric study of performance of the HOM suppression waveguide, and the dependence of HOM Q-factors and kick-factors on the cavity’s and HOM waveguide’s geometries.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOMS057
About •	Received ※ 08 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 09 July 2022
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TUPOMS058	C-Band High Gradient Testing of the Benchmark a/λ=0.105 Cavity	cavity, coupling, klystron, electron	1564
	E.I. Simakov, V. Gorelov, T. Tajima, M.R.A. Zuboraj LANL, Los Alamos, New Mexico, USA S. Biedron Element Aero, Chicago, USA S. Biedron UNM-ECE, Albuquerque, USA M.E. Middendorf ORNL RAD, Oak Ridge, Tennessee, USA
	Funding: Los Alamos National Laboratory LDRD Program This poster will report the results of high gradient testing of the benchmark C-band RF cavity. Modern applications such as X-ray sources require accelerators with optimized cost of construction and operation, naturally calling for high-gradient acceleration. At LANL we commissioned a test stand (CERF-NM) powered by a 50 MW, 5.712 GHz Canon klystron. The test stand is capable of conditioning accelerating cavities for operation at surface electric fields in excess of 300 MV/m. CERF-NM is the first high gradient C-band test facility in the United States. An important milestone for this test stand is to demonstrate conditioning and high gradient testing of the most basic high gradient RF cavity with a geometry that has been extensively studied at other frequencies, such as X-band. The cavity is the three-cell structure with the highest gradient in the central cell and two coupling cells, and the ratio of the radius of the coupling iris to the wavelength a/\lamda=0.105. This presentation will report achieved gradients, breakdown probabilities, and other characteristics measured during the high power operation of this cavity.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOMS058
About •	Received ※ 08 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 17 June 2022
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WEOXSP3	mm-Wave Structure Development for High Gradient Acceleration	cavity, coupling, simulation, distributed	1606
	E.J.C. Snively, A.E. Gabriel, E.A. Nanni, M.A.K. Othman, A.V. Sy SLAC, Menlo Park, California, USA A.E. Gabriel UCSC, Santa Cruz, California, USA
	Funding: This work is supported by U.S. Department of Energy Contract No. DE-AC02-76SF00515, SLAC LDRD project 21-014 and Internal Agency Agreement 21-0007-IA (MIPR HR0011150657). We report on the design of mm-wave accelerator structures operating near 100 GHz. Simulations of the cavity geometry and RF coupling are performed in ANSYS-HFSS and using SLAC’s parallel electromagnetic code suite ACE3P. We present experimental results for structures fabricated from copper, niobium, and copper plated with NbTiNi. We report on techniques for tuning these high frequency structures, as well as preliminary brazing results. A mm-wave accelerator cavity enables not only a high achievable gradient due to higher breakdown thresholds, but also reduced fill times which decrease pulsed heating and allow for higher repetition rates. We discuss the potential advantages and challenges for applications requiring ultra-compact structures.
	Slides WEOXSP3 [1.800 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEOXSP3
About •	Received ※ 08 June 2022 — Revised ※ 11 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 16 June 2022
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WEPOST035	Spectroscopic Measurements as Diagnostic Tool for Plasma-Filled Capillaries	plasma, electron, acceleration, laser	1776
	S. Arjmand, L. Crincoli, D. Pellegrini INFN/LNF, Frascati, Italy M.P. Anania, A. Biagioni, G. Costa, M. Ferrario, M. Galletti, V.L. Lollo, R. Pompili LNF-INFN, Frascati, Italy M. Del Franco ENEA C.R. Frascati, Frascati (Roma), Italy D. Giulietti UNIPI, Pisa, Italy A. Zigler The Hebrew University of Jerusalem, The Racah Institute of Physics, Jerusalem, Israel
	The research concerns the study of the plasma sources for plasma-based accelerators (PBAs) at the SPARC_LAB test-facility (LNF-INFN). The interest in compact accelerators, overcoming the gigantism of the conventional radio-frequency (RF) accelerators, is growing in High Energy Physics. The plasma-based accelerating gradients can attain the GV/m scale. At the SPARC_LAB test-facility, a plasma device is under development. It consists of a capillary in which one or more inlets inject neutral gas (Hydrogen), ionized by a high-voltage (HV) discharge. Electron density has been measured as a function of time through the Stark broadening profiles of the Balmer line.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST035
About •	Received ※ 08 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 23 June 2022 — Issue date ※ 04 July 2022
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WEPOPT006	Investigation of Spin-Decoherence in the NICA Storage Ring for the Future EDM-Measurement Experiment	polarization, experiment, storage-ring, dipole	1835
	A.E. Aksentyev, A.A. Melnikov, Y. Senichev RAS/INR, Moscow, Russia A.E. Aksentyev MEPhI, Moscow, Russia V. Ladygin, E. Syresin JINR, Dubna, Moscow Region, Russia
	Funding: We acknowledge support by the joint Deutsche ForschungsGemeinschaft (DFG) and Russian Science Foundation (RSF) grant 22-42-04419 A new experiment to measure electric dipole moments (EDMs) of elementary particles, based on the Frequency Domain method, has been proposed for implementation at the NICA facility (JINR, Russia). EDM experiments in general, being measurement-of-polarization experiments, require long spin-coherence times at around 1,000 seconds. The FD method involves a further complication (well paid off in orders of precision) of switching the polarity of the guiding field as part of its CW-CCW injection procedure. This latter procedure necessitates a calibration process, during which the beam polarization axis changes its orientation from the radial (used for the measurement) to the vertical (used for the calibration) direction. If this change occurs adiabatically, the beam particles’ spin-vectors follow the direction of the polarization axis, which undermines the calibration technique; however, concerns were raised as to whether violation of adiabaticity could damage spin-coherence.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT006
About •	Received ※ 16 May 2022 — Accepted ※ 15 June 2022 — Issue date ※ 22 June 2022
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WEPOPT012	MAD-X for Future Accelerators	coupling, optics, closed-orbit, simulation	1858
	T.H.B. Persson, H. Burkhardt, R. De Maria, L. Deniau, E.J. Høydalsvik, A. Latina, P.K. Skowroński, R. Tomás García, L. van Riesen-Haupt CERN, Meyrin, Switzerland
	The development of MAD-X was started more than 20 years ago and it still remains the main tool for single particle dynamics for both optics design, error studies as well as for operational model-based software at CERN. In this article, we outline some of the recent development of MAD-X and plans for the future. In particular, we focus on the development of the twiss module used to calculate optics functions in MAD-X which is based on first and second order matrices. These have traditionally been calculated as an expansion around the ideal orbit. In this paper, we describe explicitly how an expansion around the closed orbit can be employed instead, in order to get more precise results. We also describe the latest development of the beam-beam long range wire compensator in MAD-X, an element that has been implemented using the aforementioned approach.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT012
About •	Received ※ 08 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 23 June 2022 — Issue date ※ 01 July 2022
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WEPOPT021	A Discharge Plasma Source Development Platform for Accelerators: The ADVANCE Lab at DESY	plasma, diagnostics, laser, MMI	1886
	J.M. Garland, R.T.P. D’Arcy, M. Dinter, S. Karstensen, S. Kottler, G. Loisch, K. Ludwig, J. Osterhoff, A. Rahali, A. Schleiermacher, S. Wesch DESY, Hamburg, Germany
	Novel plasma-based accelerators, as well as advanced, high-gradient beam-manipulation techniques’for example passive or active plasma lenses’require reliable and well-characterized plasma sources, each optimized for their individual task. A very efficient and proven way of producing plasmas for these applications is by directly discharging an electrical current through a confined gas volume. To host the development of such discharge-based plasma sources for advanced accelerators, the ATHENA Discharge deVelopment ANd Characterization Experiment (ADVANCE) laboratory has been established at DESY. In this contribution we introduce the laboratory, give a summary of available infrastructure and diagnostics, as well as a brief overview of current and planned scientific goals.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT021
About •	Received ※ 08 June 2022 — Revised ※ 16 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 09 July 2022
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WEPOTK010	The Second Long Shutdown of the LHC and Its Injectors: Feedback from the Accelerator Coordination and Engineering Group	site, operation, experiment, database	2052
	A.-L. Perrot, M. Bernardini, S. Chemli, J.-P. Corso, J. Coupard, F.B. Dos Santos Pedrosa, J. Etheridge, K. Foraz, S. Grillot, J.M. Jimenez, B. Nicquevert, S. Petit, J.Ph.G.L. Tock, E. Vergara Fernandez CERN, Meyrin, Switzerland
	The operation of the Large Hadron Collider (LHC) at CERN started in September 2008. Every 5 or 6 years, Long Shutdowns (LS) are programmed to execute time-intensive ordinary and extra-ordinary maintenance of the LHC and its injectors. The second LS (LS2) started in December 2018 and was completed end 2020 for the injectors and early 2022 for the LHC. A huge number of maintenance, consolidation and upgrade activities, especially the upgrade of the injectors complex, were performed with challenges at various levels, from technical, to organizational and managerial. This paper presents the applied methodology put in place by the Accelerator Coordination & Engineering (EN-ACE) Group, in charge of the technical coordination of the activities for the interventions and changes to the LHC and its injectors, to ensure that the installation activities are performed safely, meeting the required high level of quality, while optimizing the schedule. It highlights key points of success and lessons learnt in terms of general coordination, quality assurance, configuration and layout management, spatial integration, planning and scheduling, operational safety, logistics and worksite coordination
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK010
About •	Received ※ 03 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 03 July 2022
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WEPOTK037	Radiation of a Particle Moving Along a Helical Trajectory in a Resistive-Wall Cylindrical Waveguide	radiation, undulator, laser, electron	2150
	M. Ivanyan, A. Grigoryan, B. Grigoryan, B.K. Sargsyan CANDLE SRI, Yerevan, Armenia K. Flöttmann, F. Lemery DESY, Hamburg, Germany A. Grigoryan YSU, Yerevan, Armenia
	Funding: The work was supported by the Science Committee of RA, in the frames of the research project 21T-1C239 The radiation field of a particle moving on a helical trajectory in a cylindrical waveguide with resistive walls is calculated. The deformation of the energy spectrum of radiation, as a result of the finite conductivity of the walls, is investigated.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK037
About •	Received ※ 31 May 2022 — Revised ※ 11 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 30 June 2022
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WEPOTK039	Radiation of a Particle Moving Along a Helical Trajectory in a Semi-Infinite Cylindrical Waveguide	radiation, undulator, HOM, injection	2154
	M. Ivanyan, A. Grigoryan, B. Grigoryan, V.G. Khachatryan, B.K. Sargsyan CANDLE SRI, Yerevan, Armenia K. Flöttmann, F. Lemery DESY, Hamburg, Germany A. Grigoryan YSU, Yerevan, Armenia
	Funding: The work was supported by the Science Committee of RA, in the frames of the research project 21T-1C239 The radiation field of a particle which suddenly appears in an ideal waveguide and moves on a helical trajectory under the influence ofexternal magnetic fields is calculated. The shape and character of the front of the propagating wave is determined. The time dependence of radiation energy accumulated in the waveguide is investigated.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK039
About •	Received ※ 31 May 2022 — Revised ※ 10 June 2022 — Accepted ※ 05 July 2022 — Issue date ※ 06 July 2022
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WEPOTK063	A Wireless Method to Obtain the Impedance From Scattering Parameters	impedance, coupling, simulation, scattering	2213
	C. Antuono, M. Migliorati, E. Métral, C. Zannini CERN, Meyrin, Switzerland M. Migliorati, A. Mostacci LNF-INFN, Frascati, Italy A. Mostacci Sapienza University of Rome, Rome, Italy
	The coaxial wire method is a common and appreciated choice to assess the beam coupling impedance of an accelerator element from scattering parameters. Nevertheless, the results obtained from wire measurements could be inaccurate due to the presence of the stretched conductive wire that artificially creates the conditions for the propagation of a Transverse ElectroMagnetic (TEM) mode. The aim of this work is to establish a solid technique to obtain the beam coupling impedance from electromagnetic simulations, without modifications of the device under test. In this framework, we identified a new relation to get the resistive wall beam coupling impedance of a circular chamber directly from the scattering parameters and demonstrated that it reduces to the exact theoretical expression. Furthermore, a possible generalization of the method to arbitrary cross section geometries has been studied and validated with numerical simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK063
About •	Received ※ 07 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 20 June 2022
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THPOST008	Status of the FLUTE RF System Upgrade	linac, electron, solenoid, storage-ring	2452
	A. Malygin, O. Manzhura, A.-S. Müller, R. Ruprecht, M. Schuh, N.J. Smale KIT, Karlsruhe, Germany
	FLUTE (Ferninfrarot Linac- Und Test-Experiment) is a compact versatile linac-based accelerator test facility at KIT. Its main goal is to serve as a platform for a variety of accelerator studies and to generate strong ultra-short THz pulses for photon science. It will also serve as an injector for a Very Large Acceptance compact Storage Ring (VLA-cSR), which will be realized at KIT in the framework of the compact STorage Ring for Accelerator Research and Technology (cSTART) project. To achieve acceleration of electrons in the RF photoinjector and LINAC (from FLUTE) with high stability, it is necessary to provide stable RF power. For this goal, an upgrade of the existing RF system design has been proposed and is currently being implemented. This contribution will report on the updated RF system design and the commissioning status of the new RF system components.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOST008
About •	Received ※ 08 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 17 June 2022
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THPOST020	Visualisation of Pareto Optimal Spaces and Optimisation Solution Selection Using Parallel Coordinate Plots	cavity, impedance, ECR, RF-structure	2487
	S.J. Smith, R. Apsimon, G. Burt, M.J.W. Southerby Cockcroft Institute, Lancaster University, Lancaster, United Kingdom S. Setiniyaz Cockcroft Institute, Warrington, Cheshire, United Kingdom S. Setiniyaz Lancaster University, Lancaster, United Kingdom
	In this paper, we build on previous work where multi-objective genetic algorithms were used to optimise RF cavities using non-uniform rational basis splines (NURBS) to improve the cavity geometries and reduce peak fields. These optimisations can produce thousands of Pareto optimal solutions, from which a final cavity solution must be selected based on design criteria, such as accelerating gradient and power requirements. As all points are considered equally optimal, this can prove difficult without further analysis. Here we focus on the visualisation of the Pareto optimal points and the final solution selection process. We have found that the use of clustering algorithms and parallel coordinate plots (PCPs) provide the best way to represent the data and perform the necessary trade-offs between the peak fields and shunt impedance required to pick a final design.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOST020
About •	Received ※ 08 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 29 June 2022
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THPOST026	Design of the Magnetic Shield for VSR DEMO	cavity, simulation, shielding, SRF	2501
	H.-W. Glock, P. Anumula, F. Glöckner, J. Knobloch, F. Pflocksch, A. Vélez HZB, Berlin, Germany J. Knobloch University of Siegen, Siegen, Germany A. Vélez Technical University Dortmund, Dortmund, Germany
	Funding: Work supported by grants of the Helmholtz Association The VSR DEMO module, recently under development at HZB, will house two 4-cell 1.5 GHz superconducting RF cavities with a particularly powerful HOM damping scheme based on five waveguide HOM absorbers per cavity. A magnetic shield made of high-permeable material is needed around the cavities in order to prevent the ambient magnetic field exceeding very few µT thereby causing considerable unwanted RF losses. The shield needs to accommodate the waveguides, the fundamental power coupler, two beam pipes, two He feed / return lines, the tuner and the support structures, whilst being manufacturable and mountable. The paper discusses those difficulties and presents the matured magnetic shield design. Numerical simulations are used to evaluate the efficacy of the shield.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOST026
About •	Received ※ 14 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 22 June 2022 — Issue date ※ 22 June 2022
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THPOTK050	CFD Studies of the Convective Heat Transfer Coefficients and Pressure Drops in Geometries Applied to Water Cooling Channels of the Crotch Absorbers of ALBA Synchrotron Light Source	experiment, simulation, synchrotron, storage-ring	2887
	S. Grozavu, G.A. Raush ESEIAAT, Terrassa, Spain J.J. Casas, C. Colldelram, M. Quispe ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
	Currently, the storage ring vacuum chambers of ALBA are protected by 156 crotch absorbers made of copper and Glidcop. After more than 10 years of operation as a third-generation light source, the ALBA II project arose, aiming to transform this infrastructure into a fourth-generation synchrotron. This introduces new challenges in terms of the thermal and mechanical design of the future absorbers. The absorbers’ cooling channels consist of a set of 8-mm-diameter holes parallel to each other and drilled into the body of the absorbers. In each hole, there is a 6x1 mm stainless steel concentric inner tube coiled in spiral wires, whose aim is to enhance the heat transfer. The convective heat transfer coefficients used for the original design of the absorbers come from experimental correlations from the literature, and are applied as a global value for the whole system. In this work, Heat Transfer-Computational Fluid Dynamics (HT-CFD) studies of the convective heat transfer coefficients and pressure gradients in three different cooling channel geometries are carried out, aiming at leading the way of designing the cooling systems toward the CFD simulations rather than applying global experimental values. This information will be useful for the sizing of the new absorbers for the ALBA II project.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOTK050
About •	Received ※ 08 June 2022 — Revised ※ 11 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 16 June 2022
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THPOMS031	VHEE High Dose Rate Dosimetry Studies in CLEAR	radiation, real-time, electron, status	3026
	V. Rieker, R. Corsini, L.A. Dyks CERN, Meyrin, Switzerland J.J. Bateman JAI, Oxford, United Kingdom W. Farabolini CEA-DRF-IRFU, France P. Korysko Oxford University, Physics Department, Oxford, Oxon, United Kingdom
	The 200 MeV electron beam of the CERN Linear Accelerator for Research (CLEAR) user facility at CERN has been intensively used to study the potential use of Very High Energy Electrons (VHEE) in cancer radiotherapy. In particular, irradiation tests have been performed in the high dose rate regime, which has gained a lot of interest for the so called FLASH biological effect, in which cancer cells are damaged while healthy tissue is largely spared. High dose rate dosimetry, though, poses a number of challenges: to validate standard or new methods of passive dosimetry, like radiochromic films and alanine pellets, and especially to develop new methods for real-time dosimetry since the normally used ionization chambers suffer from non-linear effects at high dose rates. In this paper we describe the results of experimental activities at CLEAR aimed at developing solid, high-dose rate dosimetry standards adapted to VHEE beams.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOMS031
About •	Received ※ 08 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 06 July 2022
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Paper

Title

Other Keywords

Page

MOPOTK065

Minimising Transverse Multipoles in Accelerating RF Cavities via Azimuthally Modulated Designs

cavity, multipole, simulation, coupling

610

L.M. Wroe
JAI, Oxford, United Kingdom
R. Apsimon
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
M. Dosanjh
CERN, Meyrin, Switzerland
S.L. Sheehy
The University of Melbourne, Melbourne, Victoria, Australia

In this paper, we build upon previous work of designing RF structures that support modes with tailored multipolar fields by applying the concept to negate the transverse multipoles in accelerating RF cavities caused by the incorporation of waveguide slots and tuning deformations. We outline a systematic method for designing structures that minimise these transverse multipoles and present analysis of simulations of two different minimisation designs.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOTK065

About •

Received ※ 08 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 06 July 2022

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MOPOMS007

Optimized Dielectric Loaded Waveguide Terahertz LINACs

electron, acceleration, linac, vacuum

634

M. Vahdani
University of Hamburg, Hamburg, Germany
M. Fakhari
DESY, Hamburg, Germany
F.X. Kärtner
The Hamburg Center for Ultrafast Imaging, University of Hamburg, Hamburg, Germany
F.X. Kärtner
Deutsches Elektronen Synchrotron (DESY) and Center for Free Electron Science (CFEL), Hamburg, Germany
M. Vahdani
CFEL, Hamburg, Germany

Dielectric loaded waveguides (DLW) powered by multicycle terahertz (THz) pulses have shown promising performance as compact linear accelerators due to higher breakdown fields at THz frequencies compared to conventional RF components. By changing the dielectric dimensions one can control phase and group velocities of the THz pulse inside the DLW. Since optimum waveguide dimensions are dependent on initial electron energy, THz pulse energy, and etc., it is worthwhile to determine optimum values for different conditions to maximize final kinetic energy. In this work, we present a combined analytical/numerical guide to determine the optimum DLW parameters for single on-axis electron acceleration. We also introduce normalized graphic representations to visualize optimum designs for different initial electron and THz pulse energies.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOMS007

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Received ※ 09 June 2022 — Revised ※ 09 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 21 June 2022

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MOPOMS012

Simulation Studies of Drive Beam Instability in a Dielectric Wakefield Accelerator

wakefield, simulation, focusing, quadrupole

645

W.H. Tan, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
A. Huebl, R. Jambunathan, R. Lehé, A. Myers, T. Rheaume, J.-L. Vay, W. Zhang
LBNL, Berkeley, USA
P. Piot
ANL, Lemont, Illinois, USA

Funding: This work is supported by the US DOE award DE-SC0018656 with NIU and DE-AC02-06CH11357 with ANL. This work used resources from NERSC, supported by DOE contract DE-AC02-05CH11231. This research used WarpX, which is supported by the US DOE Exascale Computing Project. Primary WarpX contributors are with LBNL, LLNL, CEA-LIDYL, SLAC, DESY, CERN, and Modern Electron.
Beam-driven collinear wakefield acceleration using structure wakefield accelerators promises a high gradient acceleration within a smaller physical footprint. Sustainable extraction of energy from the drive beam relies on precise understanding of its long term dynamics and the possible onset or mitigation of the beam instability. The advance of computational power and tools makes it possible to model the full physics of beam-driven wakefield acceleration. Here we report on the long-term beam dynamics studies of a drive beam considering the example of a dielectric waveguide using high fidelity particle-in-cell simulations performed with WarpX.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOMS012

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Received ※ 08 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 16 June 2022

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MOPOMS013

Toward Emittance Measurements at 11.7 GHz Short-Pulse High-Gradient RF Gun

gun, linac, emittance, experiment

649

S.V. Kuzikov, C.-J. Jing, E.W. Knight
Euclid TechLabs, Solon, Ohio, USA
G. Chen, C.-J. Jing, P. Piot, E.E. Wisniewski
ANL, Lemont, Illinois, USA
C.-J. Jing
Euclid Beamlabs, Bolingbrook, USA
P. Piot
Fermilab, Batavia, Illinois, USA
P. Piot, W.H. Tan
Northern Illinois University, DeKalb, Illinois, USA

Funding: This project is supported with DoE SBIR Phase II Grant #DE-SC0018709.
A short pulse high gradient RF gun has been recently tested at Argonne Wakefield Accelerator (AWA) facility. The carried-out test showed that the 1,5-cell gun was able to inject 3 MeV, up to 100 pC bunches at room tem-perature being fed by 9 ns up to 300 MW 11.7 GHz puls-es. The cathode field was as high as about 400 MV/m. So high field is aimed to mitigate repealing Coulomb forces substantially. In accordance with simulations the emit-tance could be as low as less than 0.2 mcm. To obtain so low emittance in the experiment, the gun is assumed to be equipped with a downstream linac to be fed from the same power extractor as the gun itself. Here we report design of the RF power distribution system splitting RF power among the gun and the linac, results of low-power tests, and emittance measurement plans for upcoming new experiment at AWA.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOMS013

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Received ※ 01 June 2022 — Revised ※ 09 June 2022 — Accepted ※ 18 June 2022 — Issue date ※ 01 July 2022

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MOPOMS050

Rigorous Approach for Calculation of Radiation of a Charged Particle Bunch Exiting an Open-Ended Dielectrically Loaded Waveguide

radiation, electron, wakefield, acceleration

757

S.N. Galyamin
Saint Petersburg State University, Saint Petersburg, Russia
S. Baturin
ITMO University, Saint Petersburg, Russia

Funding: Work supported by Russian Science Foundation (Grant No. 18-72-10137).
Beam-driven radiation sources based on open-ended waveguide structures with dielectric filling are of essential interest due to their attractive possibilities to generate high-power narrow-band Cherenkov radiation*. An important problem here is to effectively extract the radiation from the waveguide to the open space. Therefore, further development of this scheme requires rigorous mathematical approach describing the interaction of both charged particle bunch and produced radiation with the open end of a waveguide. In this report, we present the corresponding analytical approach based on our recent paper** where diffraction of a waveguide mode at the open end of a dielectrically loaded waveguide has been rigorously investigated.
* D. Wang et al., Rev. Sci. Instruments, Vol. 89, 093301 (2018).
** S.N. Galyamin et al., IEEE Trans. Microwave Theory Techn., Vol. 69, 2429-2438 (2021).

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOMS050

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Received ※ 09 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 03 July 2022

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TUPOST002

Upgrade of the 25 MW RF Station for the Linear Accelerator LINAC2 at ELSA

klystron, electron, linac, monitoring

838

D. Proft, K. Desch, D. Elsner, M.T. Switka
ELSA, Bonn, Germany

At the Electron Stretcher Facility ELSA in Bonn the first acceleration stage consists of a 3 GHz traveling wave linear accelerator. It was powered by a 25 MW pulsed high power klystron amplifier, which had been in use for the last thirty years. After a major failure and due to the lack of spare part availability the RF station was rebuilt. In addition to a new klystron including its high voltage tank, the new setup also consists of major upgrades of the infrastructure, the pulse forming network and the safety interlocks to satisfy the contemporary requirements. A new monitoring system consisting of multi-channel sampling ADCs allows for automatic pulse-by-pulse analysis of the klystron parameters and simultaneous evaluation of RF performance and stability. In this contribution we will present the new RF station setup, which has successfully been operating since the beginning of 2021 as well as the new monitoring capabilities.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOST002

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Received ※ 04 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 03 July 2022

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TUPOST015

Commissioning and First Results of an X-Band LLRF System for TEX Test Facility at LNF-INFN

LLRF, MMI, klystron, network

876

L. Piersanti, D. Alesini, M. Bellaveglia, S. Bini, B. Buonomo, F. Cardelli, C. Di Giulio, E. Di Pasquale, M. Diomede, L. Faillace, A. Falone, G. Franzini, A. Gallo, G. Giannetti, A. Liedl, D. Moriggi, S. Pioli, S. Quaglia, L. Sabbatini, M. Scampati, G. Scarselletta, A. Stella, S. Tocci, L. Zelinotti
LNF-INFN, 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, the commissioning of the TEst stand for X-band (TEX) facility has started in 2021 at Frascati National Laboratories of INFN. Born as a collaboration with CERN to test high gradient accelerating structures, during 2022 TEX aims at feeding the first EuPRAXIA@SPARC_LAB X-band structure prototype. During 2021 the commissioning has been successfully carried out up to 48 MW. The power unit is driven by an X-band low level RF system, that employs a commercial S-band (2.856 GHz) Libera digital LLRF (manufactured by Instrumentation Technologies), with an up/down conversion stage and a reference generation and distribution system able to produce coherent frequencies for the American S-band and European X-band (11.994 GHz), both designed and realized at LNF. The performance of the system, with a particular focus on amplitude and phase resolution, together with klystron and driver amplifier jitter measurements, will be reviewed in this paper. Moreover, considerations on its suitability and main limitations in view of EuPRAXIA@SPARC_LAB project will be discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOST015

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Received ※ 20 May 2022 — Revised ※ 13 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 28 June 2022

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TUPOST058

Badger: The Missing Optimizer in ACR

interface, controls, operation, framework

999

Z. Zhang, A.L. Edelen, J.R. Garrahan, C.E. Mayes, S.A. Miskovich, D.F. Ratner, R.J. Roussel, J. Shtalenkova
SLAC, Menlo Park, California, USA
M. Böse, S. Tomin
DESY, Hamburg, Germany
Y. Hidaka, G.M. Wang
BNL, Upton, New York, USA

Badger is an optimizer specifically designed for Accelerator Control Room (ACR). It’s the spiritual successor of Ocelot optimizer. Badger abstracts an optimization run as an optimization algorithm interacts with an environment, by following some pre-defined rules. The environment is controlled by the algorithm and tunes/observes the control system/machine through an interface, while the users control/monitor the optimization flow through a graphical user interface (GUI) or a command line interface (CLI). This paper would introduce the design principles and applications of Badger.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOST058

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Received ※ 08 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 17 June 2022

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TUPOPT032

Simulating Beam Transport with Permanent Magnet Chicane for THz Fel

electron, FEL, undulator, laser

1077

A.C. Fisher, M.P. Lenz, P. Musumeci, A. Ody, Y. Park
UCLA, Los Angeles, USA
R.B. Agustsson, T.J. Hodgetts, A.Y. Murokh
RadiaBeam, Santa Monica, California, USA

Funding: This work was supported by NSF grant PHY-1734215 and DOE grant No. DE-SC0009914 and DE-SC0021190. The undulator construction has been carried out under SBIR/STTR DE-SC0017102 and DE-SC0018559.
Free electron lasers are an attractive option for high average and peak power radiation in the THz gap, a region of the electromagnetic spectrum where radiation sources are scarce, as the required beam and undulator parameters are readily achievable with current technology. However, slippage effects require the FEL to be driven with relatively long and low current electron bunches, limiting amplification gain and output power. Previous work demonstrated that a waveguide could be used to match the radiation and e-beam velocities in a meter-long strongly-tapered helical undulator, resulting in 10\% energy extraction from an ultrashort 200 pC, 5.5 MeV electron beam. We present simulations for a follow-up experiment targeting higher frequencies with improvements to the e-beam transport including a permanent magnet chicane for strong beam compression. FEL simulations show >20\% extraction efficiency from a 125 pC, 7.4 MeV electron beam at 0.32 THz.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOPT032

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Received ※ 07 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 28 June 2022

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TUPOPT061

Status and Commissioning of the First X-Band RF Source of the TEX Facility

klystron, MMI, LLRF, controls

1148

F. Cardelli, D. Alesini, M. Bellaveglia, S. Bini, M. Ceccarelli, C. Di Giulio, A. Falone, G. Franzini, A. Gallo, L. Piersanti, L. Sabbatini
INFN/LNF, Frascati, Italy
B. Buonomo, G. Catuscelli, R. Ceccarelli, A. Cecchinelli, R. Clementi, E. Di Pasquale, A. Liedl, D. Moriggi, G. Piermarini, S. Pioli, S. Quaglia, L.A. Rossi, M. Scampati, G. Scarselletta, S. Strabioli, S. Tocci, R. Zarlenga
LNF-INFN, Frascati, Italy

In 2021 started the commissioning of the TEX (Test stand for X-band) facility at the Frascati National laboratories of INFN. This facility has been founded in the framework of the LATINO (Laboratory in Advanced Technologies for INnOvation) project. The current facility layout includes an high power X-band (11.994 GHz) RF source, realized in collaboration with CERN, which will be used for validation and development of the X-band RF high gradient technology in view of the EuPRAXIA@SPARC_LAB project. The RF source is based on a CPI VKX8311 Klystron and a solid state ScandiNova k400 modulator to generate a maximum RF output power of 50 MW at 50 Hz, that will be mainly used for accelerating structure conditioning and waveguide components testing. In this paper the layout, the installation, commissioning and stability measurements of this source are described in detail. The test stand will be soon operative and ready to test the first X-band accelerating structure prototype.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOPT061

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Received ※ 08 June 2022 — Revised ※ 11 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 10 July 2022

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TUPOTK048

Optimization of a 600 MHz Two-Cell Slotted Waveguide Elliptical Cavity for FCC-ee

cavity, impedance, HOM, collider

1323

S. Gorgi Zadeh, O. Brunner, F. Peauger, I. Syratchev
CERN, Meyrin, Switzerland

The radio-frequency (RF) system of the future circular lepton collider (FCC-ee) must cope with different machine parameters ranging from Ampere-class operation required for the Z-peak working point to the high-gradient operation for the ttbar threshold. The Superconducting Slotted Waveguide Elliptical cavity (SWELL) concept was recently proposed as an alternative to the challenging RF baseline design of the FCC-ee. In this paper, random optimization methods are used to minimize the peak surface magnetic field and the maximum longitudinal impedance of the higher order modes (HOM) of a two-cell \unit[600]{MHz} SWELL cavity. In the next step, the waveguide slots are optimized to first have a smooth transition from the cavity to the slots to avoid large peak surface fields and second to achieve high transmission at dipole mode frequencies and low transmission at fundamental mode frequency while keeping the design compact.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK048

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Received ※ 23 May 2022 — Revised ※ 12 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 15 June 2022

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TUPOMS044

Dielectric Loaded THz Waveguide Experimentally Optimized by Dispersion Measurements

experiment, electron, higher-order-mode, acceleration

1526

M.J. Kellermeier, R.W. Aßmann, K. Flöttmann, F. Lemery
DESY, Hamburg, Germany
R.W. Aßmann
LNF-INFN, Frascati, Italy
W. Hillert
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany

Emerging high power THz sources pave the road for THz- driven acceleration of ultra-short bunches, and enable their manipulation for diagnostic purposes. Due to the small feature sizes of THz-guiding devices new methods are necessary for their electromagnetic characterization. A new technique has recently been developed which characterizes THz waveguides with respect to their dispersion relations and attenuation. Here, the method is applied to circular waveguides, partially filled with polymer capillaries of different thicknesses, to find a suitable size for THz driven streaking at 287 GHz. Further, rough 3d-printed metallic waveguides are measured to study the effect of roughness on attenuation and phase constant. In general, additive manufacturing techniques show promise for advanced integrated designs of THz driven structures.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOMS044

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Received ※ 05 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 28 June 2022

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TUPOMS051

Prototype Fabrication of an Active Normal Conducting Third Harmonic Cavity for the ALBA Storage Ring

cavity, HOM, simulation, storage-ring

1542

J.R. Ocampo, J.M. Álvarez, B. Bravo, F. Pérez, A. Salom, P. Solans
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain

Funding: Co-funded by the European Regional Development Fund (ERDF)
ALBA has designed a normal conducting active 1.5 GHz HOM damped cavity for the active third harmonic RF system for the ALBA Storage Ring (SR), which also will serve for the upgraded ALBA II. The third harmonic cavity at ALBA will be used to increase the bunch length in order to improve the beam lifetime and increase the beam stability thresholds. A prototype has been constructed by the company AVS in collaboration with VITZRO. This paper presents the design of the cavity, the constructed prototype, the Acceptance Tests measurements, and the future plans.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOMS051

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Received ※ 07 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 30 June 2022 — Issue date ※ 01 July 2022

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TUPOMS057

Design Study of HOM Couplers for the C-Band Accelerating Structure

factory, damping, dipole, cavity

1561

D. Kim, E.I. Simakov
LANL, Los Alamos, New Mexico, USA
S. Biedron
UNM-ECE, Albuquerque, USA
Z. Li
SLAC, Menlo Park, California, USA

Funding: High Energy Physics (HEP) at the U.S. Department of Energy (DOE)
A cold copper distributed coupling accelerator, with a high accelerating gradient at cryogenic temperatures (~77 K), is proposed as a baseline structure for the next generation of linear colliders. This novel technology improves accelerator performance and allows more degrees of freedom for optimization of individual cavities. It has been suggested that C-band accelerating structures at 5.712 GHz may allow to maintain high efficiency, achieve high accelerating gradient, and be suitable beam dynamics with wakefield damping and detuning of the cavities. The optimization of the cavity shape was performed and we computed quality factor, shunt impedance, and beam kick factor for each of the proposed cavity geometries using CST microwave studio. Next, we proposed a configuration for higher order mode (HOM) suppression that includes waveguide slots running parallel to the axis of the accelerator. This presentation will report details of the parametric study of performance of the HOM suppression waveguide, and the dependence of HOM Q-factors and kick-factors on the cavity’s and HOM waveguide’s geometries.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOMS057

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Received ※ 08 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 09 July 2022

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TUPOMS058

C-Band High Gradient Testing of the Benchmark a/λ=0.105 Cavity

cavity, coupling, klystron, electron

1564

E.I. Simakov, V. Gorelov, T. Tajima, M.R.A. Zuboraj
LANL, Los Alamos, New Mexico, USA
S. Biedron
Element Aero, Chicago, USA
S. Biedron
UNM-ECE, Albuquerque, USA
M.E. Middendorf
ORNL RAD, Oak Ridge, Tennessee, USA

Funding: Los Alamos National Laboratory LDRD Program
This poster will report the results of high gradient testing of the benchmark C-band RF cavity. Modern applications such as X-ray sources require accelerators with optimized cost of construction and operation, naturally calling for high-gradient acceleration. At LANL we commissioned a test stand (CERF-NM) powered by a 50 MW, 5.712 GHz Canon klystron. The test stand is capable of conditioning accelerating cavities for operation at surface electric fields in excess of 300 MV/m. CERF-NM is the first high gradient C-band test facility in the United States. An important milestone for this test stand is to demonstrate conditioning and high gradient testing of the most basic high gradient RF cavity with a geometry that has been extensively studied at other frequencies, such as X-band. The cavity is the three-cell structure with the highest gradient in the central cell and two coupling cells, and the ratio of the radius of the coupling iris to the wavelength a/\lamda=0.105. This presentation will report achieved gradients, breakdown probabilities, and other characteristics measured during the high power operation of this cavity.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOMS058

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Received ※ 08 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 17 June 2022

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WEOXSP3

mm-Wave Structure Development for High Gradient Acceleration

cavity, coupling, simulation, distributed

1606

E.J.C. Snively, A.E. Gabriel, E.A. Nanni, M.A.K. Othman, A.V. Sy
SLAC, Menlo Park, California, USA
A.E. Gabriel
UCSC, Santa Cruz, California, USA

Funding: This work is supported by U.S. Department of Energy Contract No. DE-AC02-76SF00515, SLAC LDRD project 21-014 and Internal Agency Agreement 21-0007-IA (MIPR HR0011150657).
We report on the design of mm-wave accelerator structures operating near 100 GHz. Simulations of the cavity geometry and RF coupling are performed in ANSYS-HFSS and using SLAC’s parallel electromagnetic code suite ACE3P. We present experimental results for structures fabricated from copper, niobium, and copper plated with NbTiNi. We report on techniques for tuning these high frequency structures, as well as preliminary brazing results. A mm-wave accelerator cavity enables not only a high achievable gradient due to higher breakdown thresholds, but also reduced fill times which decrease pulsed heating and allow for higher repetition rates. We discuss the potential advantages and challenges for applications requiring ultra-compact structures.

Slides WEOXSP3 [1.800 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEOXSP3

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Received ※ 08 June 2022 — Revised ※ 11 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 16 June 2022

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WEPOST035

Spectroscopic Measurements as Diagnostic Tool for Plasma-Filled Capillaries

plasma, electron, acceleration, laser

1776

S. Arjmand, L. Crincoli, D. Pellegrini
INFN/LNF, Frascati, Italy
M.P. Anania, A. Biagioni, G. Costa, M. Ferrario, M. Galletti, V.L. Lollo, R. Pompili
LNF-INFN, Frascati, Italy
M. Del Franco
ENEA C.R. Frascati, Frascati (Roma), Italy
D. Giulietti
UNIPI, Pisa, Italy
A. Zigler
The Hebrew University of Jerusalem, The Racah Institute of Physics, Jerusalem, Israel

The research concerns the study of the plasma sources for plasma-based accelerators (PBAs) at the SPARC_LAB test-facility (LNF-INFN). The interest in compact accelerators, overcoming the gigantism of the conventional radio-frequency (RF) accelerators, is growing in High Energy Physics. The plasma-based accelerating gradients can attain the GV/m scale. At the SPARC_LAB test-facility, a plasma device is under development. It consists of a capillary in which one or more inlets inject neutral gas (Hydrogen), ionized by a high-voltage (HV) discharge. Electron density has been measured as a function of time through the Stark broadening profiles of the Balmer line.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST035

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Received ※ 08 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 23 June 2022 — Issue date ※ 04 July 2022

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WEPOPT006

Investigation of Spin-Decoherence in the NICA Storage Ring for the Future EDM-Measurement Experiment

polarization, experiment, storage-ring, dipole

1835

A.E. Aksentyev, A.A. Melnikov, Y. Senichev
RAS/INR, Moscow, Russia
A.E. Aksentyev
MEPhI, Moscow, Russia
V. Ladygin, E. Syresin
JINR, Dubna, Moscow Region, Russia

Funding: We acknowledge support by the joint Deutsche ForschungsGemeinschaft (DFG) and Russian Science Foundation (RSF) grant 22-42-04419
A new experiment to measure electric dipole moments (EDMs) of elementary particles, based on the Frequency Domain method, has been proposed for implementation at the NICA facility (JINR, Russia). EDM experiments in general, being measurement-of-polarization experiments, require long spin-coherence times at around 1,000 seconds. The FD method involves a further complication (well paid off in orders of precision) of switching the polarity of the guiding field as part of its CW-CCW injection procedure. This latter procedure necessitates a calibration process, during which the beam polarization axis changes its orientation from the radial (used for the measurement) to the vertical (used for the calibration) direction. If this change occurs adiabatically, the beam particles’ spin-vectors follow the direction of the polarization axis, which undermines the calibration technique; however, concerns were raised as to whether violation of adiabaticity could damage spin-coherence.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT006

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Received ※ 16 May 2022 — Accepted ※ 15 June 2022 — Issue date ※ 22 June 2022

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WEPOPT012

MAD-X for Future Accelerators

coupling, optics, closed-orbit, simulation

1858

T.H.B. Persson, H. Burkhardt, R. De Maria, L. Deniau, E.J. Høydalsvik, A. Latina, P.K. Skowroński, R. Tomás García, L. van Riesen-Haupt
CERN, Meyrin, Switzerland

The development of MAD-X was started more than 20 years ago and it still remains the main tool for single particle dynamics for both optics design, error studies as well as for operational model-based software at CERN. In this article, we outline some of the recent development of MAD-X and plans for the future. In particular, we focus on the development of the twiss module used to calculate optics functions in MAD-X which is based on first and second order matrices. These have traditionally been calculated as an expansion around the ideal orbit. In this paper, we describe explicitly how an expansion around the closed orbit can be employed instead, in order to get more precise results. We also describe the latest development of the beam-beam long range wire compensator in MAD-X, an element that has been implemented using the aforementioned approach.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT012

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Received ※ 08 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 23 June 2022 — Issue date ※ 01 July 2022

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WEPOPT021

A Discharge Plasma Source Development Platform for Accelerators: The ADVANCE Lab at DESY

plasma, diagnostics, laser, MMI

1886

J.M. Garland, R.T.P. D’Arcy, M. Dinter, S. Karstensen, S. Kottler, G. Loisch, K. Ludwig, J. Osterhoff, A. Rahali, A. Schleiermacher, S. Wesch
DESY, Hamburg, Germany

Novel plasma-based accelerators, as well as advanced, high-gradient beam-manipulation techniques’for example passive or active plasma lenses’require reliable and well-characterized plasma sources, each optimized for their individual task. A very efficient and proven way of producing plasmas for these applications is by directly discharging an electrical current through a confined gas volume. To host the development of such discharge-based plasma sources for advanced accelerators, the ATHENA Discharge deVelopment ANd Characterization Experiment (ADVANCE) laboratory has been established at DESY. In this contribution we introduce the laboratory, give a summary of available infrastructure and diagnostics, as well as a brief overview of current and planned scientific goals.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT021

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Received ※ 08 June 2022 — Revised ※ 16 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 09 July 2022

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WEPOTK010

The Second Long Shutdown of the LHC and Its Injectors: Feedback from the Accelerator Coordination and Engineering Group

site, operation, experiment, database

2052

A.-L. Perrot, M. Bernardini, S. Chemli, J.-P. Corso, J. Coupard, F.B. Dos Santos Pedrosa, J. Etheridge, K. Foraz, S. Grillot, J.M. Jimenez, B. Nicquevert, S. Petit, J.Ph.G.L. Tock, E. Vergara Fernandez
CERN, Meyrin, Switzerland

The operation of the Large Hadron Collider (LHC) at CERN started in September 2008. Every 5 or 6 years, Long Shutdowns (LS) are programmed to execute time-intensive ordinary and extra-ordinary maintenance of the LHC and its injectors. The second LS (LS2) started in December 2018 and was completed end 2020 for the injectors and early 2022 for the LHC. A huge number of maintenance, consolidation and upgrade activities, especially the upgrade of the injectors complex, were performed with challenges at various levels, from technical, to organizational and managerial. This paper presents the applied methodology put in place by the Accelerator Coordination & Engineering (EN-ACE) Group, in charge of the technical coordination of the activities for the interventions and changes to the LHC and its injectors, to ensure that the installation activities are performed safely, meeting the required high level of quality, while optimizing the schedule. It highlights key points of success and lessons learnt in terms of general coordination, quality assurance, configuration and layout management, spatial integration, planning and scheduling, operational safety, logistics and worksite coordination

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK010

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Received ※ 03 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 03 July 2022

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WEPOTK037

Radiation of a Particle Moving Along a Helical Trajectory in a Resistive-Wall Cylindrical Waveguide

radiation, undulator, laser, electron

2150

M. Ivanyan, A. Grigoryan, B. Grigoryan, B.K. Sargsyan
CANDLE SRI, Yerevan, Armenia
K. Flöttmann, F. Lemery
DESY, Hamburg, Germany
A. Grigoryan
YSU, Yerevan, Armenia

Funding: The work was supported by the Science Committee of RA, in the frames of the research project 21T-1C239
The radiation field of a particle moving on a helical trajectory in a cylindrical waveguide with resistive walls is calculated. The deformation of the energy spectrum of radiation, as a result of the finite conductivity of the walls, is investigated.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK037

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Received ※ 31 May 2022 — Revised ※ 11 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 30 June 2022

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WEPOTK039

Radiation of a Particle Moving Along a Helical Trajectory in a Semi-Infinite Cylindrical Waveguide

radiation, undulator, HOM, injection

2154

M. Ivanyan, A. Grigoryan, B. Grigoryan, V.G. Khachatryan, B.K. Sargsyan
CANDLE SRI, Yerevan, Armenia
K. Flöttmann, F. Lemery
DESY, Hamburg, Germany
A. Grigoryan
YSU, Yerevan, Armenia

Funding: The work was supported by the Science Committee of RA, in the frames of the research project 21T-1C239
The radiation field of a particle which suddenly appears in an ideal waveguide and moves on a helical trajectory under the influence ofexternal magnetic fields is calculated. The shape and character of the front of the propagating wave is determined. The time dependence of radiation energy accumulated in the waveguide is investigated.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK039

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Received ※ 31 May 2022 — Revised ※ 10 June 2022 — Accepted ※ 05 July 2022 — Issue date ※ 06 July 2022

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WEPOTK063

A Wireless Method to Obtain the Impedance From Scattering Parameters

impedance, coupling, simulation, scattering

2213

C. Antuono, M. Migliorati, E. Métral, C. Zannini
CERN, Meyrin, Switzerland
M. Migliorati, A. Mostacci
LNF-INFN, Frascati, Italy
A. Mostacci
Sapienza University of Rome, Rome, Italy

The coaxial wire method is a common and appreciated choice to assess the beam coupling impedance of an accelerator element from scattering parameters. Nevertheless, the results obtained from wire measurements could be inaccurate due to the presence of the stretched conductive wire that artificially creates the conditions for the propagation of a Transverse ElectroMagnetic (TEM) mode. The aim of this work is to establish a solid technique to obtain the beam coupling impedance from electromagnetic simulations, without modifications of the device under test. In this framework, we identified a new relation to get the resistive wall beam coupling impedance of a circular chamber directly from the scattering parameters and demonstrated that it reduces to the exact theoretical expression. Furthermore, a possible generalization of the method to arbitrary cross section geometries has been studied and validated with numerical simulations.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK063

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Received ※ 07 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 20 June 2022

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THPOST008

Status of the FLUTE RF System Upgrade

linac, electron, solenoid, storage-ring

2452

A. Malygin, O. Manzhura, A.-S. Müller, R. Ruprecht, M. Schuh, N.J. Smale
KIT, Karlsruhe, Germany

FLUTE (Ferninfrarot Linac- Und Test-Experiment) is a compact versatile linac-based accelerator test facility at KIT. Its main goal is to serve as a platform for a variety of accelerator studies and to generate strong ultra-short THz pulses for photon science. It will also serve as an injector for a Very Large Acceptance compact Storage Ring (VLA-cSR), which will be realized at KIT in the framework of the compact STorage Ring for Accelerator Research and Technology (cSTART) project. To achieve acceleration of electrons in the RF photoinjector and LINAC (from FLUTE) with high stability, it is necessary to provide stable RF power. For this goal, an upgrade of the existing RF system design has been proposed and is currently being implemented. This contribution will report on the updated RF system design and the commissioning status of the new RF system components.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOST008

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Received ※ 08 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 17 June 2022

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THPOST020

Visualisation of Pareto Optimal Spaces and Optimisation Solution Selection Using Parallel Coordinate Plots

cavity, impedance, ECR, RF-structure

2487

S.J. Smith, R. Apsimon, G. Burt, M.J.W. Southerby
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
S. Setiniyaz
Cockcroft Institute, Warrington, Cheshire, United Kingdom
S. Setiniyaz
Lancaster University, Lancaster, United Kingdom

In this paper, we build on previous work where multi-objective genetic algorithms were used to optimise RF cavities using non-uniform rational basis splines (NURBS) to improve the cavity geometries and reduce peak fields. These optimisations can produce thousands of Pareto optimal solutions, from which a final cavity solution must be selected based on design criteria, such as accelerating gradient and power requirements. As all points are considered equally optimal, this can prove difficult without further analysis. Here we focus on the visualisation of the Pareto optimal points and the final solution selection process. We have found that the use of clustering algorithms and parallel coordinate plots (PCPs) provide the best way to represent the data and perform the necessary trade-offs between the peak fields and shunt impedance required to pick a final design.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOST020

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Received ※ 08 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 29 June 2022

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THPOST026

Design of the Magnetic Shield for VSR DEMO

cavity, simulation, shielding, SRF

2501

H.-W. Glock, P. Anumula, F. Glöckner, J. Knobloch, F. Pflocksch, A. Vélez
HZB, Berlin, Germany
J. Knobloch
University of Siegen, Siegen, Germany
A. Vélez
Technical University Dortmund, Dortmund, Germany

Funding: Work supported by grants of the Helmholtz Association
The VSR DEMO module, recently under development at HZB, will house two 4-cell 1.5 GHz superconducting RF cavities with a particularly powerful HOM damping scheme based on five waveguide HOM absorbers per cavity. A magnetic shield made of high-permeable material is needed around the cavities in order to prevent the ambient magnetic field exceeding very few µT thereby causing considerable unwanted RF losses. The shield needs to accommodate the waveguides, the fundamental power coupler, two beam pipes, two He feed / return lines, the tuner and the support structures, whilst being manufacturable and mountable. The paper discusses those difficulties and presents the matured magnetic shield design. Numerical simulations are used to evaluate the efficacy of the shield.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOST026

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Received ※ 14 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 22 June 2022 — Issue date ※ 22 June 2022

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THPOTK050

CFD Studies of the Convective Heat Transfer Coefficients and Pressure Drops in Geometries Applied to Water Cooling Channels of the Crotch Absorbers of ALBA Synchrotron Light Source

experiment, simulation, synchrotron, storage-ring

2887

S. Grozavu, G.A. Raush
ESEIAAT, Terrassa, Spain
J.J. Casas, C. Colldelram, M. Quispe
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain

Currently, the storage ring vacuum chambers of ALBA are protected by 156 crotch absorbers made of copper and Glidcop. After more than 10 years of operation as a third-generation light source, the ALBA II project arose, aiming to transform this infrastructure into a fourth-generation synchrotron. This introduces new challenges in terms of the thermal and mechanical design of the future absorbers. The absorbers’ cooling channels consist of a set of 8-mm-diameter holes parallel to each other and drilled into the body of the absorbers. In each hole, there is a 6x1 mm stainless steel concentric inner tube coiled in spiral wires, whose aim is to enhance the heat transfer. The convective heat transfer coefficients used for the original design of the absorbers come from experimental correlations from the literature, and are applied as a global value for the whole system. In this work, Heat Transfer-Computational Fluid Dynamics (HT-CFD) studies of the convective heat transfer coefficients and pressure gradients in three different cooling channel geometries are carried out, aiming at leading the way of designing the cooling systems toward the CFD simulations rather than applying global experimental values. This information will be useful for the sizing of the new absorbers for the ALBA II project.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOTK050

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Received ※ 08 June 2022 — Revised ※ 11 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 16 June 2022

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THPOMS031

VHEE High Dose Rate Dosimetry Studies in CLEAR

radiation, real-time, electron, status

3026

V. Rieker, R. Corsini, L.A. Dyks
CERN, Meyrin, Switzerland
J.J. Bateman
JAI, Oxford, United Kingdom
W. Farabolini
CEA-DRF-IRFU, France
P. Korysko
Oxford University, Physics Department, Oxford, Oxon, United Kingdom

The 200 MeV electron beam of the CERN Linear Accelerator for Research (CLEAR) user facility at CERN has been intensively used to study the potential use of Very High Energy Electrons (VHEE) in cancer radiotherapy. In particular, irradiation tests have been performed in the high dose rate regime, which has gained a lot of interest for the so called FLASH biological effect, in which cancer cells are damaged while healthy tissue is largely spared. High dose rate dosimetry, though, poses a number of challenges: to validate standard or new methods of passive dosimetry, like radiochromic films and alanine pellets, and especially to develop new methods for real-time dosimetry since the normally used ionization chambers suffer from non-linear effects at high dose rates. In this paper we describe the results of experimental activities at CLEAR aimed at developing solid, high-dose rate dosimetry standards adapted to VHEE beams.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOMS031

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Received ※ 08 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 06 July 2022

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