LINAC2022 - Table of Session: THPOJO (Poster Session)

Paper	Title	Page
THPOJO01	The ARES Linac at DESY	691
	F. Burkart, R.W. Aßmann, H. Dinter, S. Jaster-Merz, W. Kuropka, F. Mayet, T. Vinatier DESY, Hamburg, Germany
	The generation and acceleration of ultra-short, high quality electron beams has attracted more and more interest in accelerator science. Electron bunches with these properties are necessary to operate and test novel diagnostics and advanced high gradient accelerating schemes. Furthermore, several medical and industrial applications require high-brightness electron beams. The dedicated R&D linac ARES at DESY (Deutsches Elektronen-Synchrotron) is now fully operational and able to produce these electron beams at the nominal energy of 155 MeV and deliver it to users. This paper gives an overview of the ARES linac and summarizes the beam parameter measurements. The possibilities for user operation will be described in detail.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO01
About •	Received ※ 23 August 2022 — Revised ※ 31 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 06 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOJO02	Commissioning of a Movable Bunch Compressor for Sub-fs Electron Bunches	695
	W. Kuropka, R.W. Aßmann, F. Burkart, H. Dinter, S. Jaster-Merz, F. Lemery, F. Mayet, B. Stacey, T. Vinatier DESY, Hamburg, Germany R.W. Aßmann LNF-INFN, Frascati, Italy S. Jaster-Merz University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
	Funding: DESY is a research center within the Helmholtz association HGF. We present the first commissioning results of the movable bunch compressor (BC) designed for the ARES linac at DESY. The development and simulated performance has been reported earlier and predicts sub-fs electron bunches with high charge densities. Commissioning results of the injector part of the ARES linac delivered promising beam quality results to achieve these numbers. The bunch compressor system is foreseen to be used to bench mark numerical models for coherent synchrotron radiation (CSR) and space charge (SC) for ultra-short electron bunches. Here we will present first measurements of the dispersion as well as calculations for the longitudinal dispersion. In the future the PolariX transverse deflecting structure (TDS) will be commissioned to fully characterize the ARES electron beam.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO02
About •	Received ※ 25 August 2022 — Revised ※ 23 August 2022 — Accepted ※ 31 August 2022 — Issue date ※ 15 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOJO03	RF Performance of a Next-Generation L-Band RF Gun at PITZ	699
	M. Krasilnikov, Z. Aboulbanine, G.D. Adhikari, N. Aftab, P. Boonpornprasert, M.E. Castro Carballo, G.Z. Georgiev, J. Good, M. Groß, A. Hoffmann, C. Koschitzki, X.-K. Li, A. Lueangaramwong, D. Melkumyan, R. Niemczyk, A. Oppelt, B. Petrosyan, S. Philipp, M. Pohl, H.J. Qian, C.J. Richard, J. Schultze, F. Stephan, G. Vashchenko, T. Weilbach DESY Zeuthen, Zeuthen, Germany M. Bousonville, F. Brinker, M. Hoffmann, K. Knebel, D. Kostin, S. Lederer, L. Lilje, S. Pfeiffer, R. Ritter, S. Schreiber, H. Weise, J. Ziegler DESY, Hamburg, Germany G. Shu IHEP, Beijing, People’s Republic of China M. Wenskat University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
	A new generation of normal conducting 1.3GHz RF gun was developed to provide a high-quality electron source for superconducting linac driven free-electron lasers like FLASH and European XFEL. Compared to the Gun4 series, Gun5 aims for a 50% increase of the duration of the RF pulse (up to 1 ms at 10 Hz repetition rate) combined with high gradients (up to ~60 MV/m at the cathode). In addition to the improved impedance, the new cavity is equipped with an RF probe to measure and control the amplitude and phase of the RF field inside the gun. The first prototype of the new RF gun was manufactured at DESY and installed at the Photo Injector Test facility at DESY in Zeuthen (PITZ) in October 2021. In mid-October 2021 the RF conditioning began, aiming for achieving the aforementioned RF parameters. The conditioning procedure involves a slow gradual increase in repetition rate, RF pulse duration and peak power while carefully monitoring vacuum conditions and signals from interlock sensors. The results of RF conditioning will be reported.
	Poster THPOJO03 [2.241 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO03
About •	Received ※ 26 August 2022 — Revised ※ 31 August 2022 — Accepted ※ 03 September 2022 — Issue date ※ 15 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOJO07	Status and Reliability Enhancements of the ALBA Linac	703
	D. Lanaia, R. Muñoz Horta, F. Pérez ALBA-CELLS, Cerdanyola del Vallès, Spain
	Along the years, efforts to enhance the ALBA Linac performances and reliability have been devoted, resulting in an improvement of the Linac to Booster beam transmission efficiency, and of its mean time between failures. The performance enhancement has been based on the use of optimization and control routines of the beam parameters, but also by the application of regular preventive hardware maintenance procedures. Besides, the Linac reliability has been improved also by the implementation of alternative working modes in case of hardware failures, like operating at 67 MeV, with only one klystron and one accelerating section. In this respect, a new upgrade of the RF waveguide system is being implemented, with the aim to produce 80 MeV electron beam using only one klystron that will feed both accelerating sections. Furthermore, the possibility to install a thermionic RF-gun to inject directly into the first accelerating section is under study, ensuring the Linac’s reliability even in case of a major event. Details of the Linac performance during the past years and a description of the new hardware upgrades are presented in this work.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO07
About •	Received ※ 24 August 2022 — Revised ※ 31 August 2022 — Accepted ※ 07 September 2022 — Issue date ※ 15 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOJO08	RF Design of Traveling-Wave Accelerating Structures for the FCC-ee Pre-injector Complex	707
	H.W. Pommerenke, A. Grudiev, A. Latina CERN, Meyrin, Switzerland S. Bettoni, P. Craievich, J.-Y. Raguin, M. Schaer PSI, Villigen PSI, Switzerland
	Funding: This project received funding from the EU’s Horizon 2020 research program (grant No 951754), and was done under the auspices of CHART (Swiss Accelerator Research and Technology Collaboration). The linacs of the FCCee (Future Circular Electron-Positron Collider) injector complex will both provide the drive beam for positron production and accelerate nominal electron and positron beams up to 6 GeV. Several linacs comprise different traveling-wave (TW) accelerating structures fulfilling the beam dynamics and rf constraints. Notably, high-phase advance large-aperture structures accelerate the positron beam at low energies. All TW structures are rotationally symmetric for easier production. Long-range wakes are damped by HOM detuning. Operating mode and HOM parameters were calculated based on lookup tables and analytic formulas, allowing for rapidly scanning large parameter spaces. In this paper, we present both methodology and realization of the rf design of the TW structures including their pulse compressors.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO08
About •	Received ※ 24 August 2022 — Accepted ※ 08 September 2022 — Issue date ※ 15 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOJO09	Status of CLARA at Daresbury Laboratory	711
	D. Angal-Kalinin, A.R. Bainbridge, A.D. Brynes, R.K. Buckley, S.R. Buckley, H.M. Castañeda Cortés, J.A. Clarke, L.S. Cowie, K.D. Dumbell, D.J. Dunning, A.J. Gilfellon, A.R. Goulden, J. Henderson, S. Hitchen, F. Jackson, C.R. Jenkins, M.A. Johnson, J.K. Jones, N.Y. Joshi, M.P. King, S.L. Mathisen, J.W. McKenzie, R. Mclean, K.J. Middleman, B.L. Militsyn, K.T. Morrow, A.J. Moss, B.D. Muratori, T.C.Q. Noakes, W.A. Okell, H.L. Owen, T.H. Pacey, A.E. Pollard, M.D. Roper, Y.M. Saveliev, D.J. Scott, B.J.A. Shepherd, R.J. Smith, E.W. Snedden, N. Thompson, C. Tollervey, R. Valizadeh, D.A. Walsh, A.E. Wheelhouse, P.H. Williams STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom A.R. Bainbridge, A.D. Brynes, J.A. Clarke, L.S. Cowie, K.D. Dumbell, D.J. Dunning, C.R. Jenkins, K.J. Middleman, A.J. Moss, B.D. Muratori, H.L. Owen, Y.M. Saveliev, D.J. Scott, B.J.A. Shepherd, N. Thompson, R. Valizadeh, A.J. Vick, A.E. Wheelhouse Cockcroft Institute, Warrington, Cheshire, United Kingdom A.D. Brynes Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy R.J. Cash, R.F. Clarke, M. Colling, G. Cox, B.D. Fell, S.A. Griffiths, M.D. Hancock, T. Hartnett, J.P. Hindley, C. Hodgkinson, G. Marshall, A. Oates, A.J. Vick, J.T.G. Wilson STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom J. Henderson Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
	CLARA (Compact Linear Accelerator for Research and Applications) is a test facility for Free Electron Laser (FEL) research and other applications at STFC’s Daresbury Laboratory. The Front End of CLARA has been used for user exploitation programme from 2018. The second exploitation period in 2021-22 provided a range of beam parameters to 8 user experiments. We report on the status, further machine development, and future plans for CLARA including Full Energy Beam Exploitation (FEBE) beamline which will provide 250 MeV/c high brightness beam for novel experiments.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO09
About •	Received ※ 19 August 2022 — Revised ※ 28 August 2022 — Accepted ※ 05 September 2022 — Issue date ※ 15 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOJO10	RF Design and Characterisation of the CLARA 10 Hz Gun with Photocathode Load/Lock Upgrade	715
	A.J. Gilfellon, L.S. Cowie, T.J. Jones, B.L. Militsyn, R. Valizadeh STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	The 2.5 cell S-band 10 Hz repetition rate electron gun (Gun-10) for the CLARA (Compact Linear Accelerator for Research and Applications) facility underwent an upgrade during the scheduled shutdown period during the summer of 2019. The existing photocathode/back plate was replaced by a new back plate with interchangeable photocathode socket connected to a load/lock system capable of rapid exchanges of photocathode plugs. Here we outline motivation and RF design of the back plate and also detail the low power RF testing and characterisation of the upgraded gun in terms of the unloaded quality factor, the RF power coupling match, the percent field flatness and the operating frequency of the cavity, calculated from the frequency measured in the laboratory. Finally, via simulations using CST MWS and ASTRA, we produce a dependence of expected beam momentum vs forward power that we predict the gun will deliver once it goes back online.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO10
About •	Received ※ 25 August 2022 — Revised ※ 31 August 2022 — Accepted ※ 31 August 2022 — Issue date ※ 16 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOJO11	Wakefield Monitor System for X-Band Lineariser Linac on CLARA	718
	N.Y. Joshi, A.C. Aiken, C.R. Jenkins, A.J. Moss STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Funding: STFC-UKRI CLARA linear accelerator in phase-2 will utilise an X-band fourth harmonic linac to linearise bunch phase space. Beam induced transverse higher order modes (HOMs) between 15.3 to 16.2GHz will be coupled out through HOM ports, which can be used to correct both position offset and angle misalignment to minimise beam degradation due to HOMs. In this paper we present design of a wakefield monitor system under development, with capability to use either baseband broadband signal for basic alignment, and also carry a detailed narrow-band spectrum analysis on all four (X and Y transverse modes from two couplers) signals. Initial laboratory testing of its subsystem is also presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO11
About •	Received ※ 22 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 08 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOJO12	LCLS-II-HE Cryomodule Testing at Fermilab	721
	A.T. Cravatta, T.T. Arkan, D. Bafia, B.E. Chase, M. Checchin, C. Contreras-Martinez, B. Giaccone, B.J. Hansen, E.R. Harms, B.D. Hartsell, J.A. Kaluzny, D.D. Lambert, J.N. Makara, H. Maniar, M. Martinello, Y.M. Pischalnikov, S. Posen, J. Reid, N. Solyak, D. Sun, A. Syed, R. Wang, M.J. White, G. Wu Fermilab, Batavia, Illinois, USA S. Aderhold, A.L. Benwell, J.D. Fuerst, D. Gonnella, T. Hiatt, S.L. Hoobler, J.T. Maniscalco, J. Nelson, L.M. Zacarias SLAC, Menlo Park, California, USA L.R. Doolittle, S. Paiagua, C. Serrano LBNL, Berkeley, California, USA
	22 Linac Coherent Light Source II (LCLS-II) cryomodules were successfully tested at the Cryomodule Test Facility (CMTF) at Fermilab. Following the completion of the LCLS-II testing program, CMTF has shifted to testing cryomodules for the LCLS-II High Energy upgrade (LCLS-II-HE). The first LCLS-II-HE cryomodule, the verification cryomodule (vCM), was successfully tested and verified the readiness of LCLS-II-HE cryomodule testing at CMTF, and production cryomodule testing has begun. Presented here are the production cryomodule test acceptance criteria, testing plan, and cryomodule test results so far.
	Poster THPOJO12 [0.899 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO12
About •	Received ※ 18 August 2022 — Revised ※ 27 August 2022 — Accepted ※ 06 September 2022 — Issue date ※ 15 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOJO14	Distributed Coupling Linac for Efficient Acceleration of High Charge Electron Bunches	724
	A. Dhar, M. Bai, Z. Li, E.A. Nanni, M.A.K. Othman, S.G. Tantawi, G.R. White SLAC, Menlo Park, California, USA
	Funding: This work was supported by the Department of Energy Contract No. DE-AC02-76SF00515. The Electron Ion Collider requires a pre-injector linac to accelerate large electron bunches from 4 MeV up to 400 MeV over 35 m. Currently this linac is being designed with 3 m long traveling wave structures, which provide a gradient of 16 MV/m. We propose the use of a 1 m distributed coupling design as a potential alternative and future upgrade path to this design. Distributed coupling allows power to be fed into each cavity directly via a waveguide manifold, avoiding on-axis coupling. A distributed coupling structure at S-band was designed to optimize for shunt impedance and large aperture size. This design provides greater efficiency, thereby lowering the number of klystrons required to power the full linac. In addition, particle tracking analysis shows that this linac maintains lower emittance as bunch charge increases to 14 nC and wakefields become more prevalent. We present the design of this distributed coupling structure, as well as progress on structure manufacturing and characterization. F. Willeke, "Electron ion collider conceptual design report 2021," tech. rep., United States, 2021. ** S. Tantawi et al., Phys. Rev. Accel. Beams, vol. 23, p. 092001, Sep 2020.
	Poster THPOJO14 [5.280 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO14
About •	Received ※ 24 August 2022 — Revised ※ 31 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 15 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOJO16	High Efficiency Traveling Wave Linac With Tunable Energy	727
	V.A. Dolgashev, A.K. Krasnykh, A. Romero SLAC, Menlo Park, California, USA P. Borchard Dymenso LLC, San Francisco, USA R.A. Kostin, S.V. Kuzikov Euclid TechLabs, Solon, Ohio, USA
	Funding: US DOE Research Opportunities in Accelerator Stewardship DE-FOA-0002463 We will present a physics design of a compact, highly efficient, energy-tunable linac to generate up to 500 W of 10 MeV electron beam power for medical and security applications. This linac will employ a patented travelling wave accelerating structure with outside power flow which combines the advantages of high efficiency with energy tunability of traveling wave cavities. Unlike standing wave structures, the proposed structure has little power reflected back to the RF source, eliminating the need for a heavy, lossy waveguide isolator. In contrast to the side-coupled cavity designs, the proposed structure is symmetrical and therefore it does not have deflecting axial fields that impair the beam transport. The high shunt impedance will allow the linac to achieve an output energy of up to 10 MeV when powered by a compact commercial 9.3 GHz 1.7 MW magnetron. For pulse-to-pulse tuning of the beam output energy we will change of the beam-loaded gradient by varying the triode gun current.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO16
About •	Received ※ 30 August 2022 — Revised ※ 01 September 2022 — Accepted ※ 07 September 2022 — Issue date ※ 16 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOJO21	Higher Order Modes Investigation in the PERLE Superconducting RF Cavity	731
SUPCGE01	use link to see paper's listing under its alternate paper code
	C. Barbagallo, P. Duchesne, W. Kaabi, G. Olry, Z.F. Zomer Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France R.A. Rimmer, H. Wang JLab, Newport News, Virginia, USA
	The regenerative Beam Break Up (BBU) excited by the dipole Higher Order Modes (HOMs) in superconducting RF (SRF) cavities is a crucial issue for continuous-wave high-current energy recovery linacs. Beam-induced monopole HOMs can increase the cryogenic losses of the linac also. One of the ways to limit these effects is to use HOM couplers on the beam tubes of cavities to absorb and untrap cavity eigenmodes. These couplers feature antennas designed to damp dangerous HOMs and adequately reject the fundamental mode. This study illustrates an investigation of the HOMs of a 5-cell 801.58 MHz elliptical SRF cavity designed for PERLE (Powerful Energy Recovery Linac for Experiments), a multi-turn energy recovery linac (ERL) currently under study and later to be hosted at IJCLab in Orsay. Time-domain wakefield and frequency-domain eigenmode simulations have been used to calculate the cavity broadband HOM impedance spectra and identify the dangerous BBU HOMs. The transmission characteristics of several coaxial HOM couplers have been studied. The efficiencies of several HOM-damping schemes have been compared to propose a HOM endgroup to be fabricated and added to the existing bare SRF cavity.
	Poster THPOJO21 [2.090 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO21
About •	Received ※ 24 August 2022 — Revised ※ 27 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 23 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOJO22	A Ground Experimental Approach Toward Understanding Mysterious Astrophysical Fast Radio Bursts	735
THOPA03	use link to see paper's listing under its alternate paper code
	Y. Sumitomo, T. Asai, D. Kobayashi, S. Kumagai, K. Kusaka, Y. Onishi, T. Seki, R. Yanagi Nihon University, Tokyo, Japan Y. Hayakawa, T. Sakai LEBRA, Funabashi, Japan S. Kisaka HU ADSE, Hiroshima, Japan H. Koguchi AIST, Tsukuba, Japan
	Funding: Nihon University CST Project Research Grant (2021 Apr. ~), Japan Society for the Promotion of Science (JSPS), Grant-in-Aid for Scientific Research (KAKENHI), Grant Number JP19K12631 The Fast Radio Bursts are astrophysical events that get much more attentions increasing year by year, due to their mysterious properties of signals. The major properties of signals include a class of the brightest astrophysical events, short durations of emissions, and larger dispersion measures than the known short duration events. Interestingly, the large values of dispersion measures suggest the existence of abundant plasma around the parent bodies of emissions. To have a better understanding of basic mechanism of the Fast Radio Burst emissions, we initiated a ground-based research project at our 100 MeV electron LINAC facility, in combination with the high-beta plasma generation knowledge matured also at Nihon University, that mimics plasma fields in space. In this presentation, we overview our project and report on the status of the experiment for the induced enhanced emissions from integrated iterative interactions with plasma fields.
	Slides THPOJO22 [0.678 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO22
About •	Received ※ 12 August 2022 — Revised ※ 21 August 2022 — Accepted ※ 31 August 2022 — Issue date ※ 23 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOJO25	HOM Damping in Multi-Cell Superconducting Cavities for the Future Electron Source BriXSinO	739
SUPCGE08	use link to see paper's listing under its alternate paper code
	S. Samsam, A. Bacci, C. Curatolopresenter, I. Drebot, D. Giove, V. Petrillo, M. Rossetti Conti, A.R. Rossi, L. Serafini INFN-Milano, Milano, Italy A. Bosotti, D. Giove, L. Monaco, R. Paparella, D. Sertore INFN/LASA, Segrate (MI), Italy M.R. Masullo, A. Passarelli INFN-Napoli, Napoli, Italy V. Petrillo Universita’ degli Studi di Milano, Milano, Italy
	High order modes (HOMs) in multi-cell superconducting cavities are of particular concern in beam dynamics of linear accelerators, mainly those operating in CW mode with high current and high repetition rate. These undesired modes may invoke beam instabilities, beam breakup and increase the energy spread if not correctly pulled out and damped. The study reported in this paper is applied for damping the HOMs in the main Linac of BriXSinO, an ongoing project of an Energy Recovery Linac at LASA INFN laboratory. We developed a numerical model to study the interaction of monopole HOMs with the beam in long timescale. The presented model, named HOMEN (High Order Modes Evolution based on eNergy budget), allows the evaluation of the loss factor Kloss, crucial for evaluating the perturbing modes. At the same time, electromagnetic simulations of the standing wave multicell cavity, highlighted the dangerous modes and revealed a tolerable beam energy spread induced by HOMs. This method allows us to distinguish all dangerous modes of our interest for implementing the necessary damping mechanisms.
	Poster THPOJO25 [1.111 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO25
About •	Received ※ 22 August 2022 — Revised ※ 17 August 2022 — Accepted ※ 29 August 2022 — Issue date ※ 15 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOJO26	Conceptual Design of the PERLE Injector	743
	B. Hounsell, M. Klein, C.P. Welsch The University of Liverpool, Liverpool, United Kingdom B. Hounsell, B.L. Militsyn, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom B. Hounsell, W. Kaabi Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France B.L. Militsyn STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Energy Recovery Linacs such as PERLE require high average current high brightness beams. This sets particular requirements on the kind of injectors that they can use as the injectors must be capable of producing bunches at MHz repetition rates, compressing the bunches to the specified value and transporting those bunches while they are still in the space charge dominated regime into the main ERL all while keeping the emittance low. In particular, PERLE will require a 20 mA beam consisting of 500 pC bunches with a repetition rate of 40 MHz. These bunches will be required to have rms lengths of 3mm, a total beam energy of 7 MeV, appropriate Twiss parameters to match them to the main loop and transverse emittances of < 6 mm mrad. In this paper, a DC gun based injector capable of meeting this specification will be presented with beam dynamics simulation showing the behaviour of the beam from the photocathode to the exit of the first main linac pass. The beam dynamics challenges will be discussed in terms of both the transverse emittance growth and the sources of non-linearity in the longitudinal phase space.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO26
About •	Received ※ 20 August 2022 — Revised ※ 24 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 15 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

The ARES Linac at DESY

691

F. Burkart, R.W. Aßmann, H. Dinter, S. Jaster-Merz, W. Kuropka, F. Mayet, T. Vinatier
DESY, Hamburg, Germany

The generation and acceleration of ultra-short, high quality electron beams has attracted more and more interest in accelerator science. Electron bunches with these properties are necessary to operate and test novel diagnostics and advanced high gradient accelerating schemes. Furthermore, several medical and industrial applications require high-brightness electron beams. The dedicated R&D linac ARES at DESY (Deutsches Elektronen-Synchrotron) is now fully operational and able to produce these electron beams at the nominal energy of 155 MeV and deliver it to users. This paper gives an overview of the ARES linac and summarizes the beam parameter measurements. The possibilities for user operation will be described in detail.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO01

About •

Received ※ 23 August 2022 — Revised ※ 31 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 06 September 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOJO02

Commissioning of a Movable Bunch Compressor for Sub-fs Electron Bunches

695

W. Kuropka, R.W. Aßmann, F. Burkart, H. Dinter, S. Jaster-Merz, F. Lemery, F. Mayet, B. Stacey, T. Vinatier
DESY, Hamburg, Germany
R.W. Aßmann
LNF-INFN, Frascati, Italy
S. Jaster-Merz
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany

Funding: DESY is a research center within the Helmholtz association HGF.
We present the first commissioning results of the movable bunch compressor (BC) designed for the ARES linac at DESY. The development and simulated performance has been reported earlier and predicts sub-fs electron bunches with high charge densities. Commissioning results of the injector part of the ARES linac delivered promising beam quality results to achieve these numbers. The bunch compressor system is foreseen to be used to bench mark numerical models for coherent synchrotron radiation (CSR) and space charge (SC) for ultra-short electron bunches. Here we will present first measurements of the dispersion as well as calculations for the longitudinal dispersion. In the future the PolariX transverse deflecting structure (TDS) will be commissioned to fully characterize the ARES electron beam.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO02

About •

Received ※ 25 August 2022 — Revised ※ 23 August 2022 — Accepted ※ 31 August 2022 — Issue date ※ 15 September 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOJO03

RF Performance of a Next-Generation L-Band RF Gun at PITZ

699

M. Krasilnikov, Z. Aboulbanine, G.D. Adhikari, N. Aftab, P. Boonpornprasert, M.E. Castro Carballo, G.Z. Georgiev, J. Good, M. Groß, A. Hoffmann, C. Koschitzki, X.-K. Li, A. Lueangaramwong, D. Melkumyan, R. Niemczyk, A. Oppelt, B. Petrosyan, S. Philipp, M. Pohl, H.J. Qian, C.J. Richard, J. Schultze, F. Stephan, G. Vashchenko, T. Weilbach
DESY Zeuthen, Zeuthen, Germany
M. Bousonville, F. Brinker, M. Hoffmann, K. Knebel, D. Kostin, S. Lederer, L. Lilje, S. Pfeiffer, R. Ritter, S. Schreiber, H. Weise, J. Ziegler
DESY, Hamburg, Germany
G. Shu
IHEP, Beijing, People’s Republic of China
M. Wenskat
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany

A new generation of normal conducting 1.3GHz RF gun was developed to provide a high-quality electron source for superconducting linac driven free-electron lasers like FLASH and European XFEL. Compared to the Gun4 series, Gun5 aims for a 50% increase of the duration of the RF pulse (up to 1 ms at 10 Hz repetition rate) combined with high gradients (up to ~60 MV/m at the cathode). In addition to the improved impedance, the new cavity is equipped with an RF probe to measure and control the amplitude and phase of the RF field inside the gun. The first prototype of the new RF gun was manufactured at DESY and installed at the Photo Injector Test facility at DESY in Zeuthen (PITZ) in October 2021. In mid-October 2021 the RF conditioning began, aiming for achieving the aforementioned RF parameters. The conditioning procedure involves a slow gradual increase in repetition rate, RF pulse duration and peak power while carefully monitoring vacuum conditions and signals from interlock sensors. The results of RF conditioning will be reported.

Poster THPOJO03 [2.241 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO03

About •

Received ※ 26 August 2022 — Revised ※ 31 August 2022 — Accepted ※ 03 September 2022 — Issue date ※ 15 September 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOJO07

Status and Reliability Enhancements of the ALBA Linac

703

D. Lanaia, R. Muñoz Horta, F. Pérez
ALBA-CELLS, Cerdanyola del Vallès, Spain

Along the years, efforts to enhance the ALBA Linac performances and reliability have been devoted, resulting in an improvement of the Linac to Booster beam transmission efficiency, and of its mean time between failures. The performance enhancement has been based on the use of optimization and control routines of the beam parameters, but also by the application of regular preventive hardware maintenance procedures. Besides, the Linac reliability has been improved also by the implementation of alternative working modes in case of hardware failures, like operating at 67 MeV, with only one klystron and one accelerating section. In this respect, a new upgrade of the RF waveguide system is being implemented, with the aim to produce 80 MeV electron beam using only one klystron that will feed both accelerating sections. Furthermore, the possibility to install a thermionic RF-gun to inject directly into the first accelerating section is under study, ensuring the Linac’s reliability even in case of a major event. Details of the Linac performance during the past years and a description of the new hardware upgrades are presented in this work.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO07

About •

Received ※ 24 August 2022 — Revised ※ 31 August 2022 — Accepted ※ 07 September 2022 — Issue date ※ 15 September 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOJO08

RF Design of Traveling-Wave Accelerating Structures for the FCC-ee Pre-injector Complex

707

H.W. Pommerenke, A. Grudiev, A. Latina
CERN, Meyrin, Switzerland
S. Bettoni, P. Craievich, J.-Y. Raguin, M. Schaer
PSI, Villigen PSI, Switzerland

Funding: This project received funding from the EU’s Horizon 2020 research program (grant No 951754), and was done under the auspices of CHART (Swiss Accelerator Research and Technology Collaboration).
The linacs of the FCCee (Future Circular Electron-Positron Collider) injector complex will both provide the drive beam for positron production and accelerate nominal electron and positron beams up to 6 GeV. Several linacs comprise different traveling-wave (TW) accelerating structures fulfilling the beam dynamics and rf constraints. Notably, high-phase advance large-aperture structures accelerate the positron beam at low energies. All TW structures are rotationally symmetric for easier production. Long-range wakes are damped by HOM detuning. Operating mode and HOM parameters were calculated based on lookup tables and analytic formulas, allowing for rapidly scanning large parameter spaces. In this paper, we present both methodology and realization of the rf design of the TW structures including their pulse compressors.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO08

About •

Received ※ 24 August 2022 — Accepted ※ 08 September 2022 — Issue date ※ 15 September 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOJO09

Status of CLARA at Daresbury Laboratory

711

D. Angal-Kalinin, A.R. Bainbridge, A.D. Brynes, R.K. Buckley, S.R. Buckley, H.M. Castañeda Cortés, J.A. Clarke, L.S. Cowie, K.D. Dumbell, D.J. Dunning, A.J. Gilfellon, A.R. Goulden, J. Henderson, S. Hitchen, F. Jackson, C.R. Jenkins, M.A. Johnson, J.K. Jones, N.Y. Joshi, M.P. King, S.L. Mathisen, J.W. McKenzie, R. Mclean, K.J. Middleman, B.L. Militsyn, K.T. Morrow, A.J. Moss, B.D. Muratori, T.C.Q. Noakes, W.A. Okell, H.L. Owen, T.H. Pacey, A.E. Pollard, M.D. Roper, Y.M. Saveliev, D.J. Scott, B.J.A. Shepherd, R.J. Smith, E.W. Snedden, N. Thompson, C. Tollervey, R. Valizadeh, D.A. Walsh, A.E. Wheelhouse, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
A.R. Bainbridge, A.D. Brynes, J.A. Clarke, L.S. Cowie, K.D. Dumbell, D.J. Dunning, C.R. Jenkins, K.J. Middleman, A.J. Moss, B.D. Muratori, H.L. Owen, Y.M. Saveliev, D.J. Scott, B.J.A. Shepherd, N. Thompson, R. Valizadeh, A.J. Vick, A.E. Wheelhouse
Cockcroft Institute, Warrington, Cheshire, United Kingdom
A.D. Brynes
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
R.J. Cash, R.F. Clarke, M. Colling, G. Cox, B.D. Fell, S.A. Griffiths, M.D. Hancock, T. Hartnett, J.P. Hindley, C. Hodgkinson, G. Marshall, A. Oates, A.J. Vick, J.T.G. Wilson
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
J. Henderson
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom

CLARA (Compact Linear Accelerator for Research and Applications) is a test facility for Free Electron Laser (FEL) research and other applications at STFC’s Daresbury Laboratory. The Front End of CLARA has been used for user exploitation programme from 2018. The second exploitation period in 2021-22 provided a range of beam parameters to 8 user experiments. We report on the status, further machine development, and future plans for CLARA including Full Energy Beam Exploitation (FEBE) beamline which will provide 250 MeV/c high brightness beam for novel experiments.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO09

About •

Received ※ 19 August 2022 — Revised ※ 28 August 2022 — Accepted ※ 05 September 2022 — Issue date ※ 15 September 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOJO10

RF Design and Characterisation of the CLARA 10 Hz Gun with Photocathode Load/Lock Upgrade

715

A.J. Gilfellon, L.S. Cowie, T.J. Jones, B.L. Militsyn, R. Valizadeh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

The 2.5 cell S-band 10 Hz repetition rate electron gun (Gun-10) for the CLARA (Compact Linear Accelerator for Research and Applications) facility underwent an upgrade during the scheduled shutdown period during the summer of 2019. The existing photocathode/back plate was replaced by a new back plate with interchangeable photocathode socket connected to a load/lock system capable of rapid exchanges of photocathode plugs. Here we outline motivation and RF design of the back plate and also detail the low power RF testing and characterisation of the upgraded gun in terms of the unloaded quality factor, the RF power coupling match, the percent field flatness and the operating frequency of the cavity, calculated from the frequency measured in the laboratory. Finally, via simulations using CST MWS and ASTRA, we produce a dependence of expected beam momentum vs forward power that we predict the gun will deliver once it goes back online.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO10

About •

Received ※ 25 August 2022 — Revised ※ 31 August 2022 — Accepted ※ 31 August 2022 — Issue date ※ 16 September 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOJO11

Wakefield Monitor System for X-Band Lineariser Linac on CLARA

718

N.Y. Joshi, A.C. Aiken, C.R. Jenkins, A.J. Moss
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Funding: STFC-UKRI
CLARA linear accelerator in phase-2 will utilise an X-band fourth harmonic linac to linearise bunch phase space. Beam induced transverse higher order modes (HOMs) between 15.3 to 16.2GHz will be coupled out through HOM ports, which can be used to correct both position offset and angle misalignment to minimise beam degradation due to HOMs. In this paper we present design of a wakefield monitor system under development, with capability to use either baseband broadband signal for basic alignment, and also carry a detailed narrow-band spectrum analysis on all four (X and Y transverse modes from two couplers) signals. Initial laboratory testing of its subsystem is also presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO11

About •

Received ※ 22 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 08 September 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOJO12

LCLS-II-HE Cryomodule Testing at Fermilab

721

A.T. Cravatta, T.T. Arkan, D. Bafia, B.E. Chase, M. Checchin, C. Contreras-Martinez, B. Giaccone, B.J. Hansen, E.R. Harms, B.D. Hartsell, J.A. Kaluzny, D.D. Lambert, J.N. Makara, H. Maniar, M. Martinello, Y.M. Pischalnikov, S. Posen, J. Reid, N. Solyak, D. Sun, A. Syed, R. Wang, M.J. White, G. Wu
Fermilab, Batavia, Illinois, USA
S. Aderhold, A.L. Benwell, J.D. Fuerst, D. Gonnella, T. Hiatt, S.L. Hoobler, J.T. Maniscalco, J. Nelson, L.M. Zacarias
SLAC, Menlo Park, California, USA
L.R. Doolittle, S. Paiagua, C. Serrano
LBNL, Berkeley, California, USA

22 Linac Coherent Light Source II (LCLS-II) cryomodules were successfully tested at the Cryomodule Test Facility (CMTF) at Fermilab. Following the completion of the LCLS-II testing program, CMTF has shifted to testing cryomodules for the LCLS-II High Energy upgrade (LCLS-II-HE). The first LCLS-II-HE cryomodule, the verification cryomodule (vCM), was successfully tested and verified the readiness of LCLS-II-HE cryomodule testing at CMTF, and production cryomodule testing has begun. Presented here are the production cryomodule test acceptance criteria, testing plan, and cryomodule test results so far.

Poster THPOJO12 [0.899 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO12

About •

Received ※ 18 August 2022 — Revised ※ 27 August 2022 — Accepted ※ 06 September 2022 — Issue date ※ 15 September 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOJO14

Distributed Coupling Linac for Efficient Acceleration of High Charge Electron Bunches

724

A. Dhar, M. Bai, Z. Li, E.A. Nanni, M.A.K. Othman, S.G. Tantawi, G.R. White
SLAC, Menlo Park, California, USA

Funding: This work was supported by the Department of Energy Contract No. DE-AC02-76SF00515.
The Electron Ion Collider requires a pre-injector linac to accelerate large electron bunches from 4 MeV up to 400 MeV over 35 m*. Currently this linac is being designed with 3 m long traveling wave structures, which provide a gradient of 16 MV/m. We propose the use of a 1 m distributed coupling design as a potential alternative and future upgrade path to this design. Distributed coupling allows power to be fed into each cavity directly via a waveguide manifold, avoiding on-axis coupling**. A distributed coupling structure at S-band was designed to optimize for shunt impedance and large aperture size. This design provides greater efficiency, thereby lowering the number of klystrons required to power the full linac. In addition, particle tracking analysis shows that this linac maintains lower emittance as bunch charge increases to 14 nC and wakefields become more prevalent. We present the design of this distributed coupling structure, as well as progress on structure manufacturing and characterization.
* F. Willeke, "Electron ion collider conceptual design report 2021," tech. rep., United States, 2021.
** S. Tantawi et al., Phys. Rev. Accel. Beams, vol. 23, p. 092001, Sep 2020.

Poster THPOJO14 [5.280 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO14

About •

Received ※ 24 August 2022 — Revised ※ 31 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 15 September 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOJO16

High Efficiency Traveling Wave Linac With Tunable Energy

727

V.A. Dolgashev, A.K. Krasnykh, A. Romero
SLAC, Menlo Park, California, USA
P. Borchard
Dymenso LLC, San Francisco, USA
R.A. Kostin, S.V. Kuzikov
Euclid TechLabs, Solon, Ohio, USA

Funding: US DOE Research Opportunities in Accelerator Stewardship DE-FOA-0002463
We will present a physics design of a compact, highly efficient, energy-tunable linac to generate up to 500 W of 10 MeV electron beam power for medical and security applications. This linac will employ a patented travelling wave accelerating structure with outside power flow which combines the advantages of high efficiency with energy tunability of traveling wave cavities. Unlike standing wave structures, the proposed structure has little power reflected back to the RF source, eliminating the need for a heavy, lossy waveguide isolator. In contrast to the side-coupled cavity designs, the proposed structure is symmetrical and therefore it does not have deflecting axial fields that impair the beam transport. The high shunt impedance will allow the linac to achieve an output energy of up to 10 MeV when powered by a compact commercial 9.3 GHz 1.7 MW magnetron. For pulse-to-pulse tuning of the beam output energy we will change of the beam-loaded gradient by varying the triode gun current.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO16

About •

Received ※ 30 August 2022 — Revised ※ 01 September 2022 — Accepted ※ 07 September 2022 — Issue date ※ 16 September 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOJO21

Higher Order Modes Investigation in the PERLE Superconducting RF Cavity

731

SUPCGE01

use link to see paper's listing under its alternate paper code

C. Barbagallo, P. Duchesne, W. Kaabi, G. Olry, Z.F. Zomer
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
R.A. Rimmer, H. Wang
JLab, Newport News, Virginia, USA

The regenerative Beam Break Up (BBU) excited by the dipole Higher Order Modes (HOMs) in superconducting RF (SRF) cavities is a crucial issue for continuous-wave high-current energy recovery linacs. Beam-induced monopole HOMs can increase the cryogenic losses of the linac also. One of the ways to limit these effects is to use HOM couplers on the beam tubes of cavities to absorb and untrap cavity eigenmodes. These couplers feature antennas designed to damp dangerous HOMs and adequately reject the fundamental mode. This study illustrates an investigation of the HOMs of a 5-cell 801.58 MHz elliptical SRF cavity designed for PERLE (Powerful Energy Recovery Linac for Experiments), a multi-turn energy recovery linac (ERL) currently under study and later to be hosted at IJCLab in Orsay. Time-domain wakefield and frequency-domain eigenmode simulations have been used to calculate the cavity broadband HOM impedance spectra and identify the dangerous BBU HOMs. The transmission characteristics of several coaxial HOM couplers have been studied. The efficiencies of several HOM-damping schemes have been compared to propose a HOM endgroup to be fabricated and added to the existing bare SRF cavity.

Poster THPOJO21 [2.090 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO21

About •

Received ※ 24 August 2022 — Revised ※ 27 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 23 September 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOJO22

A Ground Experimental Approach Toward Understanding Mysterious Astrophysical Fast Radio Bursts

735

THOPA03

use link to see paper's listing under its alternate paper code

Y. Sumitomo, T. Asai, D. Kobayashi, S. Kumagai, K. Kusaka, Y. Onishi, T. Seki, R. Yanagi
Nihon University, Tokyo, Japan
Y. Hayakawa, T. Sakai
LEBRA, Funabashi, Japan
S. Kisaka
HU ADSE, Hiroshima, Japan
H. Koguchi
AIST, Tsukuba, Japan

Funding: Nihon University CST Project Research Grant (2021 Apr. ~), Japan Society for the Promotion of Science (JSPS), Grant-in-Aid for Scientific Research (KAKENHI), Grant Number JP19K12631
The Fast Radio Bursts are astrophysical events that get much more attentions increasing year by year, due to their mysterious properties of signals. The major properties of signals include a class of the brightest astrophysical events, short durations of emissions, and larger dispersion measures than the known short duration events. Interestingly, the large values of dispersion measures suggest the existence of abundant plasma around the parent bodies of emissions. To have a better understanding of basic mechanism of the Fast Radio Burst emissions, we initiated a ground-based research project at our 100 MeV electron LINAC facility, in combination with the high-beta plasma generation knowledge matured also at Nihon University, that mimics plasma fields in space. In this presentation, we overview our project and report on the status of the experiment for the induced enhanced emissions from integrated iterative interactions with plasma fields.

Slides THPOJO22 [0.678 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO22

About •

Received ※ 12 August 2022 — Revised ※ 21 August 2022 — Accepted ※ 31 August 2022 — Issue date ※ 23 September 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOJO25

HOM Damping in Multi-Cell Superconducting Cavities for the Future Electron Source BriXSinO

739

SUPCGE08

use link to see paper's listing under its alternate paper code

S. Samsam, A. Bacci, C. Curatolopresenter, I. Drebot, D. Giove, V. Petrillo, M. Rossetti Conti, A.R. Rossi, L. Serafini
INFN-Milano, Milano, Italy
A. Bosotti, D. Giove, L. Monaco, R. Paparella, D. Sertore
INFN/LASA, Segrate (MI), Italy
M.R. Masullo, A. Passarelli
INFN-Napoli, Napoli, Italy
V. Petrillo
Universita’ degli Studi di Milano, Milano, Italy

High order modes (HOMs) in multi-cell superconducting cavities are of particular concern in beam dynamics of linear accelerators, mainly those operating in CW mode with high current and high repetition rate. These undesired modes may invoke beam instabilities, beam breakup and increase the energy spread if not correctly pulled out and damped. The study reported in this paper is applied for damping the HOMs in the main Linac of BriXSinO, an ongoing project of an Energy Recovery Linac at LASA INFN laboratory. We developed a numerical model to study the interaction of monopole HOMs with the beam in long timescale. The presented model, named HOMEN (High Order Modes Evolution based on eNergy budget), allows the evaluation of the loss factor Kloss, crucial for evaluating the perturbing modes. At the same time, electromagnetic simulations of the standing wave multicell cavity, highlighted the dangerous modes and revealed a tolerable beam energy spread induced by HOMs. This method allows us to distinguish all dangerous modes of our interest for implementing the necessary damping mechanisms.

Poster THPOJO25 [1.111 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO25

About •

Received ※ 22 August 2022 — Revised ※ 17 August 2022 — Accepted ※ 29 August 2022 — Issue date ※ 15 September 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOJO26

Conceptual Design of the PERLE Injector

743

B. Hounsell, M. Klein, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
B. Hounsell, B.L. Militsyn, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
B. Hounsell, W. Kaabi
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
B.L. Militsyn
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Energy Recovery Linacs such as PERLE require high average current high brightness beams. This sets particular requirements on the kind of injectors that they can use as the injectors must be capable of producing bunches at MHz repetition rates, compressing the bunches to the specified value and transporting those bunches while they are still in the space charge dominated regime into the main ERL all while keeping the emittance low. In particular, PERLE will require a 20 mA beam consisting of 500 pC bunches with a repetition rate of 40 MHz. These bunches will be required to have rms lengths of 3mm, a total beam energy of 7 MeV, appropriate Twiss parameters to match them to the main loop and transverse emittances of < 6 mm mrad. In this paper, a DC gun based injector capable of meeting this specification will be presented with beam dynamics simulation showing the behaviour of the beam from the photocathode to the exit of the first main linac pass. The beam dynamics challenges will be discussed in terms of both the transverse emittance growth and the sources of non-linearity in the longitudinal phase space.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO26

About •

Received ※ 20 August 2022 — Revised ※ 24 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 15 September 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)