LINAC2022 - List of Keywords (FEL)

Paper	Title	Other Keywords	Page
MOPOPA02	Identification of the Mechanical Dynamics of the Superconducting Radio-Frequency Cavities for the European XFEL CW Upgrade	cavity, controls, SRF, experiment	76
	W.H. Syed, A. Bellandi, J. Branlard, A. Eichler DESY, Hamburg, Germany
	The European X-Ray Free-Electron Laser (EuXFEL) is to-date the largest X-ray research facility around the world which spans over 3.4 km. EuXFEL is currently being operated in a pulsed mode with a repetition rate of 10Hz. One upgrade scenario consists of operating the EuXFEL also in a Continuous-Wave (CW) mode of operation to improve the quality of experiments. This upgrade brings new challenges and requires new algorithms to deal with controlling a stable accelerating field inside the Superconducting Radiofrequency (SRF) accelerating cavities and keeping them on resonance in this new mode of operation. The purpose of this research work is to identify the mechanical dynamics of the cavities which will facilitate the development of the resonance controller for the CW upgrade. To this extent, experiments were conducted at a test bench. For the first time, in this work, two different types of spectrally rich excitation signals: multi-sine and stepped-sine are used to excite the mechanical dynamics of the cavities using the piezo actuator. After the analysis of experimental data, mechanical modes are successfully identified and will be used to design the controller.
	Poster MOPOPA02 [0.687 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPOPA02
About •	Received ※ 23 August 2022 — Revised ※ 25 August 2022 — Accepted ※ 26 August 2022 — Issue date ※ 01 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPOPA03	Beam-Transient-Based LLRF Voltage Signal Calibration for the European XFEL	cavity, LLRF, linac, operation	80
	N. Walker, V. Ayvazyan, J. Branlard, S. Pfeiffer, Ch. Schmidt DESY, Hamburg, Germany
	The European XFEL linac consists of 25 superconducting RF (SRF) stations. With the exception of the first station which is part of the injector, each station comprises 32 1.3-GHz SRF TESLA cavities, driven by a single 10-MW klystron. A sophisticated state-of-the-art low-level RF (LLRF) system maintains the complex vector sum of each RF station. Monitoring and maintaining the calibration of the cavity electric field (gradient) probe signals has proven critical in achieving the maximum energy performance and availability of the SRF linac. Since there are no dedicated diagnostics for cross-checking calibration of the LLRF system, a procedure has been implemented based on simultaneously measuring the beam transient in open-loop operation of all cavities. Based on methods originally developed at FLASH, the European XFEL procedure makes use of automation and the XFEL LLRF DAQ system to provide a robust and relatively fast (minutes) way of extracting the transient data, and is now routinely scheduled once per week. In this paper, we will report on the background, implementation, analysis methods, typical results, and their subsequent application for machine operation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPOPA03
About •	Received ※ 13 August 2022 — Revised ※ 23 August 2022 — Accepted ※ 14 September 2022 — Issue date ※ 27 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPOPA04	Simulation Study of an Accelerator-based THz FEL for Pump-Probe Experiments at the European XFEL	simulation, undulator, experiment, electron	83
	P. Boonpornprasert, G.Z. Georgiev, M. Krasilnikov, X.-K. Li, A. Lueangaramwong DESY Zeuthen, Zeuthen, Germany
	The European XFEL considers to perform THz-pump and X-ray-probe experiments. A promising concept to provide the THz pulses with satisfactory properties for the experiments is to generate them using a linear accelerator-based free-electron laser (FEL). A simulation study of a THz FEL facility capable of generating powerful tunable coherent THz radiation that covers the wavelength range of 25 ’m to 100 ’m was performed. An accelerator beamline layout based on the Photo Injector Test Facility at DESY in Zeuthen (PITZ) and an APPLE-II undulator with a period length of 40 mm were used in the simulation study. Results of the study are presented and discussed in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPOPA04
About •	Received ※ 25 August 2022 — Revised ※ 27 August 2022 — Accepted ※ 30 August 2022 — Issue date ※ 05 September 2022
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TU1PA01	A Discussion of Key Concepts for the Next Generation of High Brightness Injectors	gun, brightness, electron, cathode	324
	T.G. Lucas, P. Craievich, S. Reiche PSI, Villigen PSI, Switzerland
	The production of high brightness electron beams has been key to the success of the X-ray free-electron laser (XFEL) as the new frontier in X-ray sources. The past two decades have seen the commissioning of numerous XFEL facilities, which quickly surpassed Synchrotron light sources to become the most brilliant X-ray sources. Such facilities have, so far, heavily relied on room temperature S-band RF photoguns to produce the high brightness electron bunches required for lasing, however such photoguns are reaching their peak performance limit and new methods must be investigated to continue to increase the brightness of these facilities. This talk will begin with a review of the design and performance of several electron guns currently operational in XFELs. Following will be a discussion of current efforts in continuing to increase this peak brightness including moving to cold cathode schemes and the use of very high gradients on the cathode. Finally we will describe ongoing activities at PSI to develop the next generation of high gradient RF photoguns for increased peak brightness.

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	Slides TU1PA01 [1.781 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TU1PA01
About •	Received ※ 24 August 2022 — Revised ※ 27 August 2022 — Accepted ※ 07 September 2022 — Issue date ※ 16 September 2022
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TUPOPA17	Solving the USB Communication Problem of the High-Voltage Modulator Control System in the European XFEL	controls, electron, interface, operation	451
	M. Bousonville, S. Choroba, T. Grevsmühl, S. Göller, A. Hauberg, T. Weinhausen DESY, Hamburg, Germany
	Since the commissioning of the modulators in the European XFEL in 2016, it happened from time to time that the modulator control system hung up. The reason for the problem was unknown at that time. Initially, the MTBF (Mean Time Between Failure) was 10⁴ days, which was so rare that other problems with the RF system clearly dominated and were addressed first. Over the next 2 years, the error became more frequent and occurred on average every 18 days. After the winter shutdown of the XFEL in 2020, the problem became absolutely dominant, with an MTBF of 2 days. Therefore, the fault was investigated with top priority and was finally identified. Two units of the control electronics communicate via USB 2.0 with the main server. Using special measurement technology, it was possible to prove that weak signal levels in the USB signal led to bit errors and thus to the crash of the control electronics. This article describes the troubleshooting process, how to measure the signal quality of USB signals and how the problem was solved in the end.
	Poster TUPOPA17 [6.650 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA17
About •	Received ※ 22 August 2022 — Revised ※ 19 August 2022 — Accepted ※ 29 August 2022 — Issue date ※ 15 September 2022
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TUPORI14	A Start-to-End Optimisation Strategy for the CompactLight Accelerator Beamline	electron, undulator, emittance, simulation	573
	Y. Zhao, A. Latina CERN, Meyrin, Switzerland A. Aksoy Ankara University, Accelerator Technologies Institute, Golbasi, Turkey H.M. Castañeda Cortés, D.J. Dunning, N. Thompson STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	The CompactLight collaboration designed a compact and cost-effective hard X-ray FEL facility, complemented by a soft X-ray option, based on X-band acceleration, capable of operating at 1 kHz pulse repetition rate. In this paper, we present a new simple start-to-end optimisation strategy that is developed for the CompactLight accelerator beamline, focusing on the hard X-ray mode. The optimisation is divided into two steps. The first step improves the electron beam quality that finally leads to a better FEL performance by optimising the major parameters of the beamline. The second step provides matched twiss parameters for the FEL undulator by tuning the matching quadrupoles at the end of the accelerator beamline. A single objective optimisation method, with different objective functions, is used to optimise the performance. The sensitivity of the results to jitters is also minimised by including their effects in the final objective function.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPORI14
About •	Received ※ 15 August 2022 — Revised ※ 31 August 2022 — Accepted ※ 31 August 2022 — Issue date ※ 15 September 2022
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TUPORI18	The Design of the Full Energy Beam Exploitation (FEBE) Beamline on CLARA	experiment, laser, electron, diagnostics	585
	D. Angal-Kalinin, A.R. Bainbridge, J.K. Jones, T.H. Pacey, Y.M. Saveliev, E.W. Snedden STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	The CLARA facility at Daresbury Laboratory was orig-inally designed for the study of novel FEL physics utilis-ing high-quality electron bunches at up to 250 MeV/c. To maximise the exploitation of the accelerator complex, a dedicated full energy beam exploitation (FEBE) beam-line has been designed and is currently being installed in a separate vault on the CLARA accelerator. FEBE will allow the use of high charge (up to 250 pC), moderate energy (up to 250 MeV), electron bunches for a wide variety of accelerator applications critical to ongoing accelerator development in the UK and international communities. The facility consists of a shielded enclo-sure, accessible during beam running in CLARA, with two very large experimental chambers compatible with a wide range of experimental proposals. High-power laser beams (up to 100 TW) will be available for electron-beam interactions in the first chamber, and there are concrete plans for a wide variety of advanced diagnostics (includ-ing a high-field permanent magnet spectrometer and dielectric longitudinal streaker), essential for multiple experimental paradigms, in the second chamber. FEBE will be commissioned in 2024.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPORI18
About •	Received ※ 19 August 2022 — Revised ※ 23 August 2022 — Accepted ※ 28 August 2022 — Issue date ※ 15 September 2022
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WE2AA01	The CompactLight Design Study	linac, photon, electron, undulator	642
	A. Latina CERN, Meyrin, Switzerland G. D’Auria, R.A. Rochow Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	CompactLight (XLS) is an H2020 Design Study funded by the European Union under grant agreement No. 777431 and carried out by an international collaboration of 23 international laboratories and academic institutions, three private companies, and five third parties. The project, which started in January 2018 with a duration of 48 months, aimed to design an innovative, compact, and cost-effective hard X-ray FEL facility complemented by a soft X-ray source. In December 2021, the Conceptual Design Report was completed. The result is an accelerator that can be operated at up to 1 kHz pulse repetition rate, beyond today’s state of the art, using the latest concepts for high brightness electron photoinjectors, very high gradient accelerating structures in X-band, and novel short-period undulators. This paper gives an overview of the current status, focusing particularly on the technological challenges addressed and their future applications to compact accelerator-based facilities.

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	Slides WE2AA01 [6.522 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-WE2AA01
About •	Received ※ 19 August 2022 — Revised ※ 25 August 2022 — Accepted ※ 30 August 2022 — Issue date ※ 02 September 2022
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WE2AA02	RELIEF: Tanning of Leather with e-beam	electron, simulation, site, radiation	645
	R. Apsimon, D.A. Turner Cockcroft Institute, Lancaster University, Lancaster, United Kingdom K.A. Dewhurst CERN, Meyrin, Switzerland S. Setiniyaz Lancaster University, Lancaster, United Kingdom R. Seviour University of Huddersfield, Huddersfield, United Kingdom W.R. Wise University of Northampton, Northampton, United Kingdom
	Funding: STFC through the grant reference ST/S002189/1, and the Cockcroft Institute core grant, STFC grant reference ST/P002056/1. Tanning of leather for clothing, shoes and handbags uses potentially harmful chemicals that are often run off into local water supplies or require a large carbon footprint to safely recover these pollutants. In regions of the world with significant leather production this can lead to a significant environmental impact. However recent studies have suggested that leather can instead be tanned using a combination of electron beams in a process inspired by the industrial crosslinking of polymers, to drastically reduce the quantity of wastewater produced in the process; thereby resulting in a reduced environmental impact as well as potential cost savings on wastewater treatment. In this talk, initial studies of leather tanning will be presented as well as accelerator designs for use in leather irradiation.

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	Slides WE2AA02 [1.803 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-WE2AA02
About •	Received ※ 02 August 2022 — Revised ※ 16 August 2022 — Accepted ※ 31 August 2022 — Issue date ※ 16 September 2022
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TH1AA03	Accelerator development for Global Security	electron, radiation, laser, free-electron-laser	657
	S. Biedron Element Aero, Chicago, USA
	Many facilities and projects in global security have to do with global security concerns. From direct interrogation to radiation testing, there are myriad of security applications of particle accelerators. . This paper will review accelerator design and technology development including novel sources being developed.
	Slides TH1AA03 [24.972 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TH1AA03
About •	Received ※ 31 August 2022 — Revised ※ 06 September 2022 — Accepted ※ 16 September 2022 — Issue date ※ 23 September 2022
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TH2AA02	RF System Performance in the SwissFEL Linac	klystron, linac, operation, multipactoring	679
	C.D. Beard, J. Alex, H.-H. Braun, P. Craievich, Z. Geng, N. Hiller, R. Kalt, C. Kittel, T. Lippuner, T.G. Lucas, M. Pedrozzi, E. Prat, S. Reiche, T. Schietinger, W.T. Tron, D. Voulot, R. Zennaro PSI, Villigen PSI, Switzerland
	The Hard X-ray FEL machine SwissFEL at the Paul Scherrer Institut in Switzerland is commissioned and transiting to user operation smoothly. FEL operation requires stringent requirements for the beam stability at the linac output, such as the electron bunch arrival time, peak current and beam energy. Among other things, a highly stable RF system is required to guarantee the beam stability. RF performance often dominates the overall performance and availability of FELs, and for this reason the SwissFEL RF system has been designed based on the state-of-the-art technologies that have enabled excellent RF stability, resulting in an arrival time jitter of ~10 fs rms and relative beam energy stability of 10^-4 rms. This paper aims to provide an understanding of the peak performance of the RF systems and to highlight possible limitation currently faced, focusing on the S-, C- and X-Band systems.

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	Slides TH2AA02 [4.813 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TH2AA02
About •	Received ※ 20 August 2022 — Revised ※ 26 August 2022 — Accepted ※ 30 August 2022 — Issue date ※ 02 September 2022
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THPOJO03	RF Performance of a Next-Generation L-Band RF Gun at PITZ	gun, vacuum, cavity, electron	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
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THPOJO22	A Ground Experimental Approach Toward Understanding Mysterious Astrophysical Fast Radio Bursts	plasma, electron, experiment, status	735
	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
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THPOPA01	FLASH2020+ Upgrade - Modification of RF Power Waveguide Distribution for the Free-electron Laser FLASH at DESY	GUI, cryomodule, cavity, klystron	747
	B. Yildirim, S. Choroba, V.V. Katalev, P. Morozov, Y. Nachtigal, N.V. Vladimirov DESY, Hamburg, Germany
	The goal of FLASH2020+ upgrade is to increase the energy of the FLASH accelerator, which allows the use of even shorter wavelengths, which, in turn, will allow new research. For this purpose, during the shutdown in 2022, two superconducting accelerator modules for ACC2 and ACC3 will be replaced by new ones. To fully realize the potential of these cryomodules XFEL type of waveguide distributions will be installed on them. In addition, the existing ACC4 and ACC5 cryomodules will also be equipped with the new waveguide distributions, similar XFEL type. These waveguide distributions will be modified and improved so that the machine can operate with the maximum energy due to individual power supply for each cavity. Furthermore, three RF stations will receive a new klystron waveguide distribution, which will improve the reliability of all systems. The specific waveguide distributions have been developed, produced and tested at the Waveguide Assembly and Test Facility (WATF) at DESY. All together will lead to increasing the electron beam energy from 1.25 to 1.35 GeV. This paper presents data on the production and tuning of waveguide distribution systems for the FLASH2020+ upgrade at DESY.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOPA01
About •	Received ※ 16 August 2022 — Revised ※ 28 August 2022 — Accepted ※ 02 September 2022 — Issue date ※ 02 September 2022
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THPOPA26	Machine Learning Assisted Cavity Quench Identification at the European XFEL	cavity, operation, software, hardware	798
	J. Branlard, A. Eichler, J.H.K. Timm, N. Walker DESY, Hamburg, Germany
	A server-based quench detection system is used since the beginning of operation at the European XFEL (2017) to stop driving superconducting cavities if they experience a quench. While this approach effectively detects quenches, it also generates false positives, tripping the accelerating stations when failures other than quenches occur. Using the post-mortem data snapshots generated for every trip, an additional signal (referred to as residual) is systematically computed based on the standard cavity model. Following an initial training on a set of such residuals derived from quench as well as non-quench events, two independent machine learning engines analyze routinely the trip snapshots and their residuals to identify if a trip was indeed triggered by a quench or has another root cause. The outcome of the analysis is automatically appended to the data snapshots and distributed to a team of experts. This constitutes a fully deployed example of machine-learning-assisted failure classification to identify quenches, supporting experts in their daily routine of monitoring and documenting the accelerator uptime and availability.
	Slides THPOPA26 [0.695 MB]
	Poster THPOPA26 [0.975 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOPA26
About •	Received ※ 19 August 2022 — Revised ※ 24 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 01 September 2022
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Paper

Title

Other Keywords

Page

Identification of the Mechanical Dynamics of the Superconducting Radio-Frequency Cavities for the European XFEL CW Upgrade

cavity, controls, SRF, experiment

76

W.H. Syed, A. Bellandi, J. Branlard, A. Eichler
DESY, Hamburg, Germany

The European X-Ray Free-Electron Laser (EuXFEL) is to-date the largest X-ray research facility around the world which spans over 3.4 km. EuXFEL is currently being operated in a pulsed mode with a repetition rate of 10Hz. One upgrade scenario consists of operating the EuXFEL also in a Continuous-Wave (CW) mode of operation to improve the quality of experiments. This upgrade brings new challenges and requires new algorithms to deal with controlling a stable accelerating field inside the Superconducting Radiofrequency (SRF) accelerating cavities and keeping them on resonance in this new mode of operation. The purpose of this research work is to identify the mechanical dynamics of the cavities which will facilitate the development of the resonance controller for the CW upgrade. To this extent, experiments were conducted at a test bench. For the first time, in this work, two different types of spectrally rich excitation signals: multi-sine and stepped-sine are used to excite the mechanical dynamics of the cavities using the piezo actuator. After the analysis of experimental data, mechanical modes are successfully identified and will be used to design the controller.

Poster MOPOPA02 [0.687 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPOPA02

About •

Received ※ 23 August 2022 — Revised ※ 25 August 2022 — Accepted ※ 26 August 2022 — Issue date ※ 01 September 2022

Cite •

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

MOPOPA03

Beam-Transient-Based LLRF Voltage Signal Calibration for the European XFEL

cavity, LLRF, linac, operation

80

N. Walker, V. Ayvazyan, J. Branlard, S. Pfeiffer, Ch. Schmidt
DESY, Hamburg, Germany

The European XFEL linac consists of 25 superconducting RF (SRF) stations. With the exception of the first station which is part of the injector, each station comprises 32 1.3-GHz SRF TESLA cavities, driven by a single 10-MW klystron. A sophisticated state-of-the-art low-level RF (LLRF) system maintains the complex vector sum of each RF station. Monitoring and maintaining the calibration of the cavity electric field (gradient) probe signals has proven critical in achieving the maximum energy performance and availability of the SRF linac. Since there are no dedicated diagnostics for cross-checking calibration of the LLRF system, a procedure has been implemented based on simultaneously measuring the beam transient in open-loop operation of all cavities. Based on methods originally developed at FLASH, the European XFEL procedure makes use of automation and the XFEL LLRF DAQ system to provide a robust and relatively fast (minutes) way of extracting the transient data, and is now routinely scheduled once per week. In this paper, we will report on the background, implementation, analysis methods, typical results, and their subsequent application for machine operation.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPOPA03

About •

Received ※ 13 August 2022 — Revised ※ 23 August 2022 — Accepted ※ 14 September 2022 — Issue date ※ 27 September 2022

Cite •

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MOPOPA04

Simulation Study of an Accelerator-based THz FEL for Pump-Probe Experiments at the European XFEL

simulation, undulator, experiment, electron

83

P. Boonpornprasert, G.Z. Georgiev, M. Krasilnikov, X.-K. Li, A. Lueangaramwong
DESY Zeuthen, Zeuthen, Germany

The European XFEL considers to perform THz-pump and X-ray-probe experiments. A promising concept to provide the THz pulses with satisfactory properties for the experiments is to generate them using a linear accelerator-based free-electron laser (FEL). A simulation study of a THz FEL facility capable of generating powerful tunable coherent THz radiation that covers the wavelength range of 25 ’m to 100 ’m was performed. An accelerator beamline layout based on the Photo Injector Test Facility at DESY in Zeuthen (PITZ) and an APPLE-II undulator with a period length of 40 mm were used in the simulation study. Results of the study are presented and discussed in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPOPA04

About •

Received ※ 25 August 2022 — Revised ※ 27 August 2022 — Accepted ※ 30 August 2022 — Issue date ※ 05 September 2022

Cite •

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

TU1PA01

A Discussion of Key Concepts for the Next Generation of High Brightness Injectors

gun, brightness, electron, cathode

324

T.G. Lucas, P. Craievich, S. Reiche
PSI, Villigen PSI, Switzerland

The production of high brightness electron beams has been key to the success of the X-ray free-electron laser (XFEL) as the new frontier in X-ray sources. The past two decades have seen the commissioning of numerous XFEL facilities, which quickly surpassed Synchrotron light sources to become the most brilliant X-ray sources. Such facilities have, so far, heavily relied on room temperature S-band RF photoguns to produce the high brightness electron bunches required for lasing, however such photoguns are reaching their peak performance limit and new methods must be investigated to continue to increase the brightness of these facilities. This talk will begin with a review of the design and performance of several electron guns currently operational in XFELs. Following will be a discussion of current efforts in continuing to increase this peak brightness including moving to cold cathode schemes and the use of very high gradients on the cathode. Finally we will describe ongoing activities at PSI to develop the next generation of high gradient RF photoguns for increased peak brightness.

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Slides TU1PA01 [1.781 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TU1PA01

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Received ※ 24 August 2022 — Revised ※ 27 August 2022 — Accepted ※ 07 September 2022 — Issue date ※ 16 September 2022

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TUPOPA17

Solving the USB Communication Problem of the High-Voltage Modulator Control System in the European XFEL

controls, electron, interface, operation

451

M. Bousonville, S. Choroba, T. Grevsmühl, S. Göller, A. Hauberg, T. Weinhausen
DESY, Hamburg, Germany

Since the commissioning of the modulators in the European XFEL in 2016, it happened from time to time that the modulator control system hung up. The reason for the problem was unknown at that time. Initially, the MTBF (Mean Time Between Failure) was 10⁴ days, which was so rare that other problems with the RF system clearly dominated and were addressed first. Over the next 2 years, the error became more frequent and occurred on average every 18 days. After the winter shutdown of the XFEL in 2020, the problem became absolutely dominant, with an MTBF of 2 days. Therefore, the fault was investigated with top priority and was finally identified. Two units of the control electronics communicate via USB 2.0 with the main server. Using special measurement technology, it was possible to prove that weak signal levels in the USB signal led to bit errors and thus to the crash of the control electronics. This article describes the troubleshooting process, how to measure the signal quality of USB signals and how the problem was solved in the end.

Poster TUPOPA17 [6.650 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA17

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Received ※ 22 August 2022 — Revised ※ 19 August 2022 — Accepted ※ 29 August 2022 — Issue date ※ 15 September 2022

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TUPORI14

A Start-to-End Optimisation Strategy for the CompactLight Accelerator Beamline

electron, undulator, emittance, simulation

573

Y. Zhao, A. Latina
CERN, Meyrin, Switzerland
A. Aksoy
Ankara University, Accelerator Technologies Institute, Golbasi, Turkey
H.M. Castañeda Cortés, D.J. Dunning, N. Thompson
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

The CompactLight collaboration designed a compact and cost-effective hard X-ray FEL facility, complemented by a soft X-ray option, based on X-band acceleration, capable of operating at 1 kHz pulse repetition rate. In this paper, we present a new simple start-to-end optimisation strategy that is developed for the CompactLight accelerator beamline, focusing on the hard X-ray mode. The optimisation is divided into two steps. The first step improves the electron beam quality that finally leads to a better FEL performance by optimising the major parameters of the beamline. The second step provides matched twiss parameters for the FEL undulator by tuning the matching quadrupoles at the end of the accelerator beamline. A single objective optimisation method, with different objective functions, is used to optimise the performance. The sensitivity of the results to jitters is also minimised by including their effects in the final objective function.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPORI14

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

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TUPORI18

The Design of the Full Energy Beam Exploitation (FEBE) Beamline on CLARA

experiment, laser, electron, diagnostics

585

D. Angal-Kalinin, A.R. Bainbridge, J.K. Jones, T.H. Pacey, Y.M. Saveliev, E.W. Snedden
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

The CLARA facility at Daresbury Laboratory was orig-inally designed for the study of novel FEL physics utilis-ing high-quality electron bunches at up to 250 MeV/c. To maximise the exploitation of the accelerator complex, a dedicated full energy beam exploitation (FEBE) beam-line has been designed and is currently being installed in a separate vault on the CLARA accelerator. FEBE will allow the use of high charge (up to 250 pC), moderate energy (up to 250 MeV), electron bunches for a wide variety of accelerator applications critical to ongoing accelerator development in the UK and international communities. The facility consists of a shielded enclo-sure, accessible during beam running in CLARA, with two very large experimental chambers compatible with a wide range of experimental proposals. High-power laser beams (up to 100 TW) will be available for electron-beam interactions in the first chamber, and there are concrete plans for a wide variety of advanced diagnostics (includ-ing a high-field permanent magnet spectrometer and dielectric longitudinal streaker), essential for multiple experimental paradigms, in the second chamber. FEBE will be commissioned in 2024.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPORI18

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Received ※ 19 August 2022 — Revised ※ 23 August 2022 — Accepted ※ 28 August 2022 — Issue date ※ 15 September 2022

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WE2AA01

The CompactLight Design Study

linac, photon, electron, undulator

642

A. Latina
CERN, Meyrin, Switzerland
G. D’Auria, R.A. Rochow
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

CompactLight (XLS) is an H2020 Design Study funded by the European Union under grant agreement No. 777431 and carried out by an international collaboration of 23 international laboratories and academic institutions, three private companies, and five third parties. The project, which started in January 2018 with a duration of 48 months, aimed to design an innovative, compact, and cost-effective hard X-ray FEL facility complemented by a soft X-ray source. In December 2021, the Conceptual Design Report was completed. The result is an accelerator that can be operated at up to 1 kHz pulse repetition rate, beyond today’s state of the art, using the latest concepts for high brightness electron photoinjectors, very high gradient accelerating structures in X-band, and novel short-period undulators. This paper gives an overview of the current status, focusing particularly on the technological challenges addressed and their future applications to compact accelerator-based facilities.

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Slides WE2AA01 [6.522 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-WE2AA01

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Received ※ 19 August 2022 — Revised ※ 25 August 2022 — Accepted ※ 30 August 2022 — Issue date ※ 02 September 2022

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WE2AA02

RELIEF: Tanning of Leather with e-beam

electron, simulation, site, radiation

645

R. Apsimon, D.A. Turner
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
K.A. Dewhurst
CERN, Meyrin, Switzerland
S. Setiniyaz
Lancaster University, Lancaster, United Kingdom
R. Seviour
University of Huddersfield, Huddersfield, United Kingdom
W.R. Wise
University of Northampton, Northampton, United Kingdom

Funding: STFC through the grant reference ST/S002189/1, and the Cockcroft Institute core grant, STFC grant reference ST/P002056/1.
Tanning of leather for clothing, shoes and handbags uses potentially harmful chemicals that are often run off into local water supplies or require a large carbon footprint to safely recover these pollutants. In regions of the world with significant leather production this can lead to a significant environmental impact. However recent studies have suggested that leather can instead be tanned using a combination of electron beams in a process inspired by the industrial crosslinking of polymers, to drastically reduce the quantity of wastewater produced in the process; thereby resulting in a reduced environmental impact as well as potential cost savings on wastewater treatment. In this talk, initial studies of leather tanning will be presented as well as accelerator designs for use in leather irradiation.

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Slides WE2AA02 [1.803 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-WE2AA02

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Received ※ 02 August 2022 — Revised ※ 16 August 2022 — Accepted ※ 31 August 2022 — Issue date ※ 16 September 2022

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TH1AA03

Accelerator development for Global Security

electron, radiation, laser, free-electron-laser

657

S. Biedron
Element Aero, Chicago, USA

Many facilities and projects in global security have to do with global security concerns. From direct interrogation to radiation testing, there are myriad of security applications of particle accelerators. . This paper will review accelerator design and technology development including novel sources being developed.

Slides TH1AA03 [24.972 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TH1AA03

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Received ※ 31 August 2022 — Revised ※ 06 September 2022 — Accepted ※ 16 September 2022 — Issue date ※ 23 September 2022

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TH2AA02

RF System Performance in the SwissFEL Linac

klystron, linac, operation, multipactoring

679

C.D. Beard, J. Alex, H.-H. Braun, P. Craievich, Z. Geng, N. Hiller, R. Kalt, C. Kittel, T. Lippuner, T.G. Lucas, M. Pedrozzi, E. Prat, S. Reiche, T. Schietinger, W.T. Tron, D. Voulot, R. Zennaro
PSI, Villigen PSI, Switzerland

The Hard X-ray FEL machine SwissFEL at the Paul Scherrer Institut in Switzerland is commissioned and transiting to user operation smoothly. FEL operation requires stringent requirements for the beam stability at the linac output, such as the electron bunch arrival time, peak current and beam energy. Among other things, a highly stable RF system is required to guarantee the beam stability. RF performance often dominates the overall performance and availability of FELs, and for this reason the SwissFEL RF system has been designed based on the state-of-the-art technologies that have enabled excellent RF stability, resulting in an arrival time jitter of ~10 fs rms and relative beam energy stability of 10^-4 rms. This paper aims to provide an understanding of the peak performance of the RF systems and to highlight possible limitation currently faced, focusing on the S-, C- and X-Band systems.

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Slides TH2AA02 [4.813 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TH2AA02

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Received ※ 20 August 2022 — Revised ※ 26 August 2022 — Accepted ※ 30 August 2022 — Issue date ※ 02 September 2022

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THPOJO03

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

gun, vacuum, cavity, electron

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]

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

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

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THPOJO22

A Ground Experimental Approach Toward Understanding Mysterious Astrophysical Fast Radio Bursts

plasma, electron, experiment, status

735

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]

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

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

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THPOPA01

FLASH2020+ Upgrade - Modification of RF Power Waveguide Distribution for the Free-electron Laser FLASH at DESY

GUI, cryomodule, cavity, klystron

747

B. Yildirim, S. Choroba, V.V. Katalev, P. Morozov, Y. Nachtigal, N.V. Vladimirov
DESY, Hamburg, Germany

The goal of FLASH2020+ upgrade is to increase the energy of the FLASH accelerator, which allows the use of even shorter wavelengths, which, in turn, will allow new research. For this purpose, during the shutdown in 2022, two superconducting accelerator modules for ACC2 and ACC3 will be replaced by new ones. To fully realize the potential of these cryomodules XFEL type of waveguide distributions will be installed on them. In addition, the existing ACC4 and ACC5 cryomodules will also be equipped with the new waveguide distributions, similar XFEL type. These waveguide distributions will be modified and improved so that the machine can operate with the maximum energy due to individual power supply for each cavity. Furthermore, three RF stations will receive a new klystron waveguide distribution, which will improve the reliability of all systems. The specific waveguide distributions have been developed, produced and tested at the Waveguide Assembly and Test Facility (WATF) at DESY. All together will lead to increasing the electron beam energy from 1.25 to 1.35 GeV. This paper presents data on the production and tuning of waveguide distribution systems for the FLASH2020+ upgrade at DESY.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOPA01

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Received ※ 16 August 2022 — Revised ※ 28 August 2022 — Accepted ※ 02 September 2022 — Issue date ※ 02 September 2022

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THPOPA26

Machine Learning Assisted Cavity Quench Identification at the European XFEL

cavity, operation, software, hardware

798

J. Branlard, A. Eichler, J.H.K. Timm, N. Walker
DESY, Hamburg, Germany

A server-based quench detection system is used since the beginning of operation at the European XFEL (2017) to stop driving superconducting cavities if they experience a quench. While this approach effectively detects quenches, it also generates false positives, tripping the accelerating stations when failures other than quenches occur. Using the post-mortem data snapshots generated for every trip, an additional signal (referred to as residual) is systematically computed based on the standard cavity model. Following an initial training on a set of such residuals derived from quench as well as non-quench events, two independent machine learning engines analyze routinely the trip snapshots and their residuals to identify if a trip was indeed triggered by a quench or has another root cause. The outcome of the analysis is automatically appended to the data snapshots and distributed to a team of experts. This constitutes a fully deployed example of machine-learning-assisted failure classification to identify quenches, supporting experts in their daily routine of monitoring and documenting the accelerator uptime and availability.

Slides THPOPA26 [0.695 MB]

Poster THPOPA26 [0.975 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOPA26

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Received ※ 19 August 2022 — Revised ※ 24 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 01 September 2022

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