LINAC2022 - List of Keywords (gun)

Paper	Title	Other Keywords	Page
MOPOJO04	LightHouse - A Superconducting LINAC for Producing Medical Isotopes	target, electron, cathode, radiation	35
	J.M. Krämer, G. Blokesch, M. Grewe, B. Keune, V. Kümper, M. Pekeler, C. Piel, C. Quitmann, T.T. Trinh, P. vom Stein RI Research Instruments GmbH, Bergisch Gladbach, Germany
	The medical isoptope Mo-99 is used for diagnosing several 10 million patients every year. Up to now it is produced from enriched Uranium using high-flux neutron reactors. The Institute for Radio Elements (IRE), Belgium has ordered the design of a high-power superconducting linac for producing Mo-99 without use of nuclear fission as part of their SMART project. The LightHouse accelerator consists of a photo gun and 7 superconducting RF modules"", a beam splitter and target illumination optics. It will deliver two electron beam of 75MeV and 1.5MW each. Photocathodes are prepared and transfered in-situ. We report on the design principles and the Beam Test Facility operating since April 2022. Based on Cornell CBeta design
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPOJO04
About •	Received ※ 19 August 2022 — Revised ※ 24 August 2022 — Accepted ※ 26 August 2022 — Issue date ※ 01 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPOJO12	Design of a Compact Linac for High Average Power Radiotherapy	cavity, linac, coupling, GUI	53
	C.D. Nantista, G.B. Bowden, Z. Li, M. Shumail, S.G. Tantawi SLAC, Menlo Park, California, USA B.W. Loo Stanford University, Stanford, California, USA
	We present the design of a compact, 10 MeV, 300 mA pulsed X-band linac developed for medical application. The layout, <1 m including gun, buncher, capture section and current monitor, is of a recent configuration in which the 36 main linac cavities are individually fed in parallel through side waveguide manifolds, allowing for split fabrication. Initially destined for experimental study of FLASH irradiation of mouse tumors, the design was developed as a prototype for realization of a PHASER cancer treatment machine, in which multiple linacs, powered sequentially from a common RF source, are to provide rapid treatment to patients from multiple directions without mechanical movement, delivering dosage on a time scale that essentially freezes the patient. In this paper, we focus on the RF design, beam capture optimization, mechanical design and fabrication of the linac itself, deferring discussion of other important aspects such as window and target design, experimental specification setting, radiation shielding and operations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPOJO12
About •	Received ※ 22 August 2022 — Revised ※ 26 August 2022 — Accepted ※ 02 September 2022 — Issue date ※ 06 September 2022
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MOPOJO14	New X-Band and S-Band Linear Accelerators at Varex Imaging	linac, GUI, target, electron	56
	A.V. Mishin, B. Howe, J. Stammetti Varex Imaging, Salt Lake City, USA
	We have designed, built, and high power tested advanced linear accelerators equipped with our new 3 MeV X-Band Accelerator Beam Centerline ABC-3-X-T-X and a Reduced Spot (RS) S-Band ABC-7ER-S-T-RS-X with broad 3 MeV to 8 MeV energy regulation, which demonstrated excellent performance and superior beam quality. We are immensely proud of these recent accomplishments and would like to share the news with the community.
	Poster MOPOJO14 [0.350 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPOJO14
About •	Received ※ 19 August 2022 — Revised ※ 21 August 2022 — Accepted ※ 28 August 2022 — Issue date ※ 16 October 2022
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MOPOJO17	Design and Optimization of a 100 kV DC Thermionic Electron Gun and Transport Channel for a 1.3 GHz High Intensity Compact Superconducting Electron Accelerator (HICSEA)	electron, solenoid, cathode, cavity	65
	P. Nama, A. Pathak, R. Varma IIT Mumbai, Mumbai, India
	Here we present, the design and optimization of a 100 kV DC thermionic electron gun, and a transport channel that provides transverse focusing through a normal conducting solenoid and longitudinal bunching with the help of a single gap buncher for a 1.3 GHz, 40 kW, 1 MeV superconducting electron accelerator. The accelerator is proposed to treat various contaminants present in potable water resources. A 100 kV thermionic electron gun with LaB6 as its cathode material was intended to extract a maximum beam current of 500 mA. To minimize beam emittance, gun geometry i.e. cathode radius, and height and radius of the focusing electrode are optimized. The minimal obtained emittance at the gun exit is 0.3 mm.mrad. A normal conducting focusing solenoid with an iron encasing is designed and optimized to match and transport the beam from gun exit to the superconducting cavity. Finally, a 1.3 GHz ELBE type buncher is designed and optimized to bunch the electron beam for further acceleration.
	Slides MOPOJO17 [1.268 MB]
	Poster MOPOJO17 [0.813 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPOJO17
About •	Received ※ 23 August 2022 — Revised ※ 24 August 2022 — Accepted ※ 27 August 2022 — Issue date ※ 31 August 2022
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TU1PA01	A Discussion of Key Concepts for the Next Generation of High Brightness Injectors	FEL, 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.

	please see instructions how to view/control embeded videos
	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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TUPOPA24	Design of an X-Band Bunching and Accelerating System for AWAKE Run 2	cavity, acceleration, electron, bunching	458
	J.M. Arnesano, S. Döbert CERN, Meyrin, Switzerland
	The AWAKE experiment at CERN demonstrated in its Run 1 that it is possible to accelerate electrons in plasma wakefields driven by a self-modulated proton bunch. In Run2, AWAKE aims to increase the accelerating gradient in the plasma even further and demonstrate beam quality in order to be ready for high-energy physics experiments. In this framework, a new electron injector, consisting of an S-band RF-gun and a subsequent X-band bunching and accelerating section, capable of producing very short bunches with a small emittance, has been designed. In this paper, two different configurations of the X-band section and their corresponding high-power distribution systems are presented. The first one consists of three identical cavities to bunch and accelerate the beam while the second one uses a separate short structure for velocity bunching followed by three long, pure accelerating structures. A discussion of the strengths and weaknesses of each configuration is carried out and beam dynamics aspects are analyzed. Finally the X-Band power distribution systems are described with particular attention to the choice of the klystron, the pulse compression system and the waveguide distribution.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA24
About •	Received ※ 12 August 2022 — Revised ※ 21 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 16 September 2022
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THPOJO03	RF Performance of a Next-Generation L-Band RF Gun at PITZ	vacuum, cavity, electron, FEL	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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THPOJO07	Status and Reliability Enhancements of the ALBA Linac	linac, klystron, operation, booster	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
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THPOJO09	Status of CLARA at Daresbury Laboratory	experiment, MMI, laser, linac	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
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THPOJO10	RF Design and Characterisation of the CLARA 10 Hz Gun with Photocathode Load/Lock Upgrade	cathode, simulation, cavity, vacuum	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
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THPOJO16	High Efficiency Traveling Wave Linac With Tunable Energy	linac, electron, cavity, GUI	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
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THPORI09	Design and Optimization of a 1.3 GHz Gridded Thermionic Electron Gun for High-Intensity Compact Superconducting Electron Accelerator (HICSEA)	cathode, emittance, electron, focusing	851
	A.B. Kavar, A. Pathak, R. Varma IIT Mumbai, Mumbai, India
	The design and optimization of the proposed 1.3 GHz gridded thermionic electron gun aims to drive a conduction cooled superconducting electron accelerator that will be used to treat contaminants of emerging concern in water bodies. The gun geometry is Pierce-type and optimized for beam current of 1A with LaB6 as cathode material at cathode potential of -100 kV. The final optimized cathode radius and angle of inclination of the focusing electrode are found to be 1.5 mm, and 77 degree respectively. For an emittance compensation electrode, the optimized values for thickness and potential are 2 mm and -50 kV respectively, and separation between cathode and compensator is 8 mm. Beam dynamics calculations have been performed with self-developed particle tracking code that assumes space charge interactions and imported fields. The beam dynamics simulations show that with an initial bunch length of 50 ps having a bunch charge of 5 pC, the bunch length of the bunch reduces to 33 ps. The diameter, transverse and longitudinal emittance obtained are 2.8 mm, 1 mm-mrad and 5 mm-mrad respectively.
	Poster THPORI09 [1.238 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPORI09
About •	Received ※ 11 August 2022 — Revised ※ 14 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 16 September 2022
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THPORI15	Operation of the CLARA Linear Accelerator with 2.5 Cell 10 Hz Photocathode Gun with Interchangeable Photocathodes	cathode, operation, cavity, MMI	854
	B.L. Militsyn, D. Angal-Kalinin, A.R. Bainbridge, L.S. Cowie, A.J. Gilfellon, F. Jackson, N.Y. Joshi, K.J. Middleman, K.T. Morrow, T.C.Q. Noakes, M.D. Roper, R. Valizadeh, D.A. Walsh STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom R.J. Cash, B.D. Fell, T.J. Jones, A.J. Vick STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
	During commissioning and operation run in 2021-2022 the photoinjector of the CLARA-VELA facility a 2.5 cell cavity S-band photocathode gun originally developed for the APEX experiment was used. The copper back wall of the cavity also served as the gun photocathode. In order to reduce significant time required for replacement and/or reactivation of the photocathode and improve the flexibility of the injector the gun has been upgraded for operation with DESY/INFN style interchangeable photocathodes. This upgrade included a new design of the cavity back wall to accommodate the photocathode socket and equipping the gun with a load-lock system. Modification of the gun also required replacement of the bucking coil, which zeros field in the photocathode emission plane. After the upgrade, the gun was commissioned and then operated with a hybrid Cu/Mo photocathode during the last two years. During winter-spring 2022 experimental run the gun steadily operated with a cathode field of 60 MV/m, limited by the RF power available and with an off-centre diamond turned photocathode which delivered stable bunches with a charge of 100 pC.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPORI15
About •	Received ※ 24 August 2022 — Revised ※ 08 September 2022 — Accepted ※ 12 September 2022 — Issue date ※ 15 October 2022
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THPORI16	Machine Learning for RF Breakdown Detection at CLARA	cavity, network, detector, operation	858
	A.E. Pollard, D.J. Dunning, A.J. Gilfellon STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Maximising the accelerating gradient of RF structures is fundamental to improving accelerator facility performance and cost-effectiveness. Structures must be subjected to a conditioning process before operational use, in which the gradient is gradually increased up to the operating value. A limiting effect during this process is breakdown or vacuum arcing, which can cause damage that limits the ultimate operating gradient. Techniques to efficiently condition the cavities while minimising the number of breakdowns are therefore important. In this paper, machine learning techniques are applied to detect breakdown events in RF pulse traces by approaching the problem as anomaly detection, using a variational autoencoder. This process detects deviations from normal operation and classifies them with near perfect accuracy. Offline data from various sources has been used to develop the techniques, which we aim to test at the CLARA facility at Daresbury Laboratory. Deployment of the machine learning system on the high repetition rate gun upgrade at CLARA has begun.
	Poster THPORI16 [2.099 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPORI16
About •	Received ※ 22 August 2022 — Revised ※ 30 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 15 October 2022
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Paper

Title

Other Keywords

Page

MOPOJO04

LightHouse - A Superconducting LINAC for Producing Medical Isotopes

target, electron, cathode, radiation

35

J.M. Krämer, G. Blokesch, M. Grewe, B. Keune, V. Kümper, M. Pekeler, C. Piel, C. Quitmann, T.T. Trinh, P. vom Stein
RI Research Instruments GmbH, Bergisch Gladbach, Germany

The medical isoptope Mo-99 is used for diagnosing several 10 million patients every year. Up to now it is produced from enriched Uranium using high-flux neutron reactors. The Institute for Radio Elements (IRE), Belgium has ordered the design of a high-power superconducting linac for producing Mo-99 without use of nuclear fission as part of their SMART project. The LightHouse accelerator consists of a photo gun and 7 superconducting RF modules"*", a beam splitter and target illumination optics. It will deliver two electron beam of 75MeV and 1.5MW each. Photocathodes are prepared and transfered in-situ. We report on the design principles and the Beam Test Facility operating since April 2022.
*Based on Cornell CBeta design

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPOJO04

About •

Received ※ 19 August 2022 — Revised ※ 24 August 2022 — Accepted ※ 26 August 2022 — Issue date ※ 01 September 2022

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

MOPOJO12

Design of a Compact Linac for High Average Power Radiotherapy

cavity, linac, coupling, GUI

53

C.D. Nantista, G.B. Bowden, Z. Li, M. Shumail, S.G. Tantawi
SLAC, Menlo Park, California, USA
B.W. Loo
Stanford University, Stanford, California, USA

We present the design of a compact, 10 MeV, 300 mA pulsed X-band linac developed for medical application. The layout, <1 m including gun, buncher, capture section and current monitor, is of a recent configuration in which the 36 main linac cavities are individually fed in parallel through side waveguide manifolds, allowing for split fabrication. Initially destined for experimental study of FLASH irradiation of mouse tumors, the design was developed as a prototype for realization of a PHASER cancer treatment machine, in which multiple linacs, powered sequentially from a common RF source, are to provide rapid treatment to patients from multiple directions without mechanical movement, delivering dosage on a time scale that essentially freezes the patient. In this paper, we focus on the RF design, beam capture optimization, mechanical design and fabrication of the linac itself, deferring discussion of other important aspects such as window and target design, experimental specification setting, radiation shielding and operations.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPOJO12

About •

Received ※ 22 August 2022 — Revised ※ 26 August 2022 — Accepted ※ 02 September 2022 — Issue date ※ 06 September 2022

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

MOPOJO14

New X-Band and S-Band Linear Accelerators at Varex Imaging

linac, GUI, target, electron

56

A.V. Mishin, B. Howe, J. Stammetti
Varex Imaging, Salt Lake City, USA

We have designed, built, and high power tested advanced linear accelerators equipped with our new 3 MeV X-Band Accelerator Beam Centerline ABC-3-X-T-X and a Reduced Spot (RS) S-Band ABC-7ER-S-T-RS-X with broad 3 MeV to 8 MeV energy regulation, which demonstrated excellent performance and superior beam quality. We are immensely proud of these recent accomplishments and would like to share the news with the community.

Poster MOPOJO14 [0.350 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPOJO14

About •

Received ※ 19 August 2022 — Revised ※ 21 August 2022 — Accepted ※ 28 August 2022 — Issue date ※ 16 October 2022

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

MOPOJO17

Design and Optimization of a 100 kV DC Thermionic Electron Gun and Transport Channel for a 1.3 GHz High Intensity Compact Superconducting Electron Accelerator (HICSEA)

electron, solenoid, cathode, cavity

65

P. Nama, A. Pathak, R. Varma
IIT Mumbai, Mumbai, India

Here we present, the design and optimization of a 100 kV DC thermionic electron gun, and a transport channel that provides transverse focusing through a normal conducting solenoid and longitudinal bunching with the help of a single gap buncher for a 1.3 GHz, 40 kW, 1 MeV superconducting electron accelerator. The accelerator is proposed to treat various contaminants present in potable water resources. A 100 kV thermionic electron gun with LaB6 as its cathode material was intended to extract a maximum beam current of 500 mA. To minimize beam emittance, gun geometry i.e. cathode radius, and height and radius of the focusing electrode are optimized. The minimal obtained emittance at the gun exit is 0.3 mm.mrad. A normal conducting focusing solenoid with an iron encasing is designed and optimized to match and transport the beam from gun exit to the superconducting cavity. Finally, a 1.3 GHz ELBE type buncher is designed and optimized to bunch the electron beam for further acceleration.

Slides MOPOJO17 [1.268 MB]

Poster MOPOJO17 [0.813 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPOJO17

About •

Received ※ 23 August 2022 — Revised ※ 24 August 2022 — Accepted ※ 27 August 2022 — Issue date ※ 31 August 2022

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TU1PA01

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

FEL, 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

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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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TUPOPA24

Design of an X-Band Bunching and Accelerating System for AWAKE Run 2

cavity, acceleration, electron, bunching

458

J.M. Arnesano, S. Döbert
CERN, Meyrin, Switzerland

The AWAKE experiment at CERN demonstrated in its Run 1 that it is possible to accelerate electrons in plasma wakefields driven by a self-modulated proton bunch. In Run2, AWAKE aims to increase the accelerating gradient in the plasma even further and demonstrate beam quality in order to be ready for high-energy physics experiments. In this framework, a new electron injector, consisting of an S-band RF-gun and a subsequent X-band bunching and accelerating section, capable of producing very short bunches with a small emittance, has been designed. In this paper, two different configurations of the X-band section and their corresponding high-power distribution systems are presented. The first one consists of three identical cavities to bunch and accelerate the beam while the second one uses a separate short structure for velocity bunching followed by three long, pure accelerating structures. A discussion of the strengths and weaknesses of each configuration is carried out and beam dynamics aspects are analyzed. Finally the X-Band power distribution systems are described with particular attention to the choice of the klystron, the pulse compression system and the waveguide distribution.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA24

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Received ※ 12 August 2022 — Revised ※ 21 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 16 September 2022

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THPOJO03

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

vacuum, cavity, electron, FEL

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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THPOJO07

Status and Reliability Enhancements of the ALBA Linac

linac, klystron, operation, booster

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.

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

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

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THPOJO09

Status of CLARA at Daresbury Laboratory

experiment, MMI, laser, linac

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.

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

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

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THPOJO10

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

cathode, simulation, cavity, vacuum

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.

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

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

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THPOJO16

High Efficiency Traveling Wave Linac With Tunable Energy

linac, electron, cavity, GUI

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.

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

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

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THPORI09

Design and Optimization of a 1.3 GHz Gridded Thermionic Electron Gun for High-Intensity Compact Superconducting Electron Accelerator (HICSEA)

cathode, emittance, electron, focusing

851

A.B. Kavar, A. Pathak, R. Varma
IIT Mumbai, Mumbai, India

The design and optimization of the proposed 1.3 GHz gridded thermionic electron gun aims to drive a conduction cooled superconducting electron accelerator that will be used to treat contaminants of emerging concern in water bodies. The gun geometry is Pierce-type and optimized for beam current of 1A with LaB6 as cathode material at cathode potential of -100 kV. The final optimized cathode radius and angle of inclination of the focusing electrode are found to be 1.5 mm, and 77 degree respectively. For an emittance compensation electrode, the optimized values for thickness and potential are 2 mm and -50 kV respectively, and separation between cathode and compensator is 8 mm. Beam dynamics calculations have been performed with self-developed particle tracking code that assumes space charge interactions and imported fields. The beam dynamics simulations show that with an initial bunch length of 50 ps having a bunch charge of 5 pC, the bunch length of the bunch reduces to 33 ps. The diameter, transverse and longitudinal emittance obtained are 2.8 mm, 1 mm-mrad and 5 mm-mrad respectively.

Poster THPORI09 [1.238 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPORI09

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Received ※ 11 August 2022 — Revised ※ 14 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 16 September 2022

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THPORI15

Operation of the CLARA Linear Accelerator with 2.5 Cell 10 Hz Photocathode Gun with Interchangeable Photocathodes

cathode, operation, cavity, MMI

854

B.L. Militsyn, D. Angal-Kalinin, A.R. Bainbridge, L.S. Cowie, A.J. Gilfellon, F. Jackson, N.Y. Joshi, K.J. Middleman, K.T. Morrow, T.C.Q. Noakes, M.D. Roper, R. Valizadeh, D.A. Walsh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
R.J. Cash, B.D. Fell, T.J. Jones, A.J. Vick
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom

During commissioning and operation run in 2021-2022 the photoinjector of the CLARA-VELA facility a 2.5 cell cavity S-band photocathode gun originally developed for the APEX experiment was used. The copper back wall of the cavity also served as the gun photocathode. In order to reduce significant time required for replacement and/or reactivation of the photocathode and improve the flexibility of the injector the gun has been upgraded for operation with DESY/INFN style interchangeable photocathodes. This upgrade included a new design of the cavity back wall to accommodate the photocathode socket and equipping the gun with a load-lock system. Modification of the gun also required replacement of the bucking coil, which zeros field in the photocathode emission plane. After the upgrade, the gun was commissioned and then operated with a hybrid Cu/Mo photocathode during the last two years. During winter-spring 2022 experimental run the gun steadily operated with a cathode field of 60 MV/m, limited by the RF power available and with an off-centre diamond turned photocathode which delivered stable bunches with a charge of 100 pC.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPORI15

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Received ※ 24 August 2022 — Revised ※ 08 September 2022 — Accepted ※ 12 September 2022 — Issue date ※ 15 October 2022

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THPORI16

Machine Learning for RF Breakdown Detection at CLARA

cavity, network, detector, operation

858

A.E. Pollard, D.J. Dunning, A.J. Gilfellon
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Maximising the accelerating gradient of RF structures is fundamental to improving accelerator facility performance and cost-effectiveness. Structures must be subjected to a conditioning process before operational use, in which the gradient is gradually increased up to the operating value. A limiting effect during this process is breakdown or vacuum arcing, which can cause damage that limits the ultimate operating gradient. Techniques to efficiently condition the cavities while minimising the number of breakdowns are therefore important. In this paper, machine learning techniques are applied to detect breakdown events in RF pulse traces by approaching the problem as anomaly detection, using a variational autoencoder. This process detects deviations from normal operation and classifies them with near perfect accuracy. Offline data from various sources has been used to develop the techniques, which we aim to test at the CLARA facility at Daresbury Laboratory. Deployment of the machine learning system on the high repetition rate gun upgrade at CLARA has begun.

Poster THPORI16 [2.099 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPORI16

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Received ※ 22 August 2022 — Revised ※ 30 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 15 October 2022

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