IPAC2021 - List of Keywords (linac)

Paper	Title	Other Keywords	Page
MOPAB042	Beam Dynamics Investigation for a New Project of Compton Back Scattering Photon Source at NRNU MEPhI	photon, electron, scattering, laser	186
	V.S. Dyubkov, I.A. Ashanin, M. Gusarova, Yu.D. Kliuchevskaia, M.V. Lalayan, S.M. Polozov, A.I. Pronikov, V.I. Rashchikov MEPhI, Moscow, Russia
	Funding: This project is supported by Russian Foundation for Basic Research, Grant no. 19-29-12036. The activities on physical models design of a compact monochromatic radiation source in the x-ray range based on inverse Compton scattering are started at NRNU MEPhI. There are comparison of two schemes of the photon source here: one of them is considered to be based on linac with variable energy of 20-60 MeV only and the other one is considered as accelerator complex where linac is supposed to be used as injector to medium size storage ring (energy up to 60 MeV). Preliminary results of linac structures and storage ring design as well as electron dynamics simulation are discussed
	Poster MOPAB042 [0.962 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB042
About •	paper received ※ 13 May 2021 paper accepted ※ 20 May 2021 issue date ※ 10 August 2021
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MOPAB066	Dual Octupole Emittance Growth Correction of the CompactLight XFEL Bunch Compressors	octupole, emittance, FEL, lattice	272
	R. Auchettl, R.T. Dowd AS - ANSTO, Clayton, Australia
	An optimized CompactLight X-Ray Free Electron Laser (FEL) bunch compressor design is presented. In this work, we insert an octupole into the center of the two sequential bunch compressors. We show how this scheme can adjust the compression, while correcting the undesirable peak current profile and emittance growth.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB066
About •	paper received ※ 24 May 2021 paper accepted ※ 28 May 2021 issue date ※ 24 August 2021
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MOPAB075	Proposal of the Southern Advanced Photon Source and Current Physics Design Study	photon, storage-ring, lattice, emittance	300
	S. Wang, J. Chen, L. Huang, Y. Jiao, B. Li, Z.P. Li, W. Liu, S.Y. Xu IHEP, Beijing, People’s Republic of China Y. Han, X.H. Lu, Y. Zhao IHEP CSNS, Guangdong Province, People’s Republic of China X. Liu Department of Energy Sciences, Tokyo Institute of Technology, Yokohama, Japan
	It has been considered to build a mid-energy fourth-generation storage ring light source neighbouring the China Spallation Neutron Source, in Guangdong Province, the south of China. The light source is named the Southern Advanced Photon Source (SAPS). Preliminary physics design studies on the SAPS have been implemented for a few years. In this paper, we will describe considerations of technical roadmap and key parameter choice for this light source, and introduce the up-to-date lattice designs and related physics studies on the SAPS.
	Poster MOPAB075 [1.689 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB075
About •	paper received ※ 12 May 2021 paper accepted ※ 20 May 2021 issue date ※ 21 August 2021
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MOPAB092	Project of Wuhan Photon Source	storage-ring, cavity, injection, dipole	346
	H.H. Li, Y. Deng, J.H. He, Y. Nie, L. Tang, J. Wang, Y.X. Zhu IAS, Wuhan City, People’s Republic of China
	Wuhan Photon Source (WHPS) has been designed as a fourth-generation light source, which consists of a low energy storage ring (1.5 GeV), a medium energy storage ring (4.0 GeV), and a linac working as a full energy injector. It has been planned to build the low energy light source first as the Phase I project, and then the medium energy light source after its completion. The low energy storage ring has been optimized with the main design parameters as following: An 8-cell, 500 mA storage ring, with a circumference of 180 m and nature emittance 238.4 pm-rad. Based on hybrid-7BA lattice structure, it reaches the soft X-ray diffraction limit. And at the middle of each cell, a 3.5 T superB magnet is used to extend the photon energy to the hard X-ray region. The swap-out injection is chosen due to the small dynamic aperture and a full energy S-band LINAC will be used as its injector. A 3rd harmonic cavity is designed for bunch lengthening to keep a sufficient lifetime. More details of the WHPS phase I project will be described in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB092
About •	paper received ※ 10 June 2021 paper accepted ※ 23 June 2021 issue date ※ 24 August 2021
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MOPAB098	LCLS Multi-Bunch Improvement Plan	laser, FEL, electron, experiment	365
	A. Halavanau, S. Carbajo, F.-J. Decker, A.K. Krasnykh, A.A. Lutman, A. Marinelli, C.E. Mayes, D.C. Nguyen SLAC, Menlo Park, California, USA
	Current and future experiments at LCLS require XFEL pulse trains of variable time separation. The cavity based XFEL (CBXFEL) project requires multiple pulses separated by 220 ns, the X-ray Laser Oscillator (XLO) uses 15 ns spaced pulse trains and Matter under Extreme Conditions (MEC) experiments need a shortly spaced (less than 5 ns) pulse trains. In this proceeding, we discuss the LCLS multi-bunch improvement plan and report on its recently status and progress.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB098
About •	paper received ※ 19 May 2021 paper accepted ※ 27 July 2021 issue date ※ 20 August 2021
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MOPAB107	RF Plans for the Diamond-II Upgrade	cavity, HOM, booster, gun	391
	C. Christou, P. Gu, P.J. Marten, S.A. Pande, A.F. Rankin DLS, Oxfordshire, United Kingdom
	The RF system for the proposed Diamond-II upgrade will be based on normal-conducting EU HOM-damped cavities powered by high powered solid state amplifiers and controlled by digital low level RF systems built on the microTCA platform. Reasons for these design choices are discussed, and experience of the selected technologies in the Diamond-I ring are reviewed. The storage ring will also include a third harmonic cavity, and the different design options for this device are discussed. RF design of the booster ring is presented, and details are given of an upgraded linac and gun design intended to improve the charge delivered for top-up.
	Poster MOPAB107 [1.703 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB107
About •	paper received ※ 18 May 2021 paper accepted ※ 20 May 2021 issue date ※ 12 August 2021
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MOPAB120	Update on Injector for the New Synchrotron Light Source in Thailand	storage-ring, synchrotron, injection, photon	435
	T. Chanwattana, S. Chunjarean, N. Juntong, K. Kittimanapun, S. Klinkhieo, P. Sudmuang SLRI, Nakhon Ratchasima, Thailand K. Manasatitpong Synchrotron Light Research Institute (SLRI), Muang District, Thailand
	Design of the new 3-GeV synchrotron light source in Thailand, Siam Photon Source II (SPS-II), has been updated. The SPS-II accelerator complex consists of a 150-MeV injector linac, a 3-GeV booster synchrotron and a 3-GeV storage ring. The RF system of both storage ring and booster is based on a frequency of 119 MHz. In this paper, design considerations and specifications of the SPS-II injector linac are presented. A study on the injector linac in multi-bunch mode (MBM) and single-bunch mode (SBM) was done to get appropriate parameters for top-up injection and different filling patterns in the storage ring.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB120
About •	paper received ※ 18 May 2021 paper accepted ※ 20 May 2021 issue date ※ 24 August 2021
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MOPAB133	Recovering the Positron Beam After Muon Production in the Lemma Muon Source	target, emittance, positron, injection	470
	I. Drebot INFN-Milano, Milano, Italy M.E. Biagini, O.R. Blanco-García, A. Giribono, S. Guiducci, C. Vaccarezza, A. Variola INFN/LNF, Frascati, Italy S.M. Liuzzo ESRF, Grenoble, France
	In the LEMMA muon source proposal* a positron beam at 45 GeV is used to produce muons at threshold by interaction with some targets. In order to release the required intensity on the main positron source, orders of magnitude higher than the state of the art, the possibility to recover the primary positron beam after the interaction with the targets was studied. The particles distribution, with a strongly degraded energy spread after the interac- tion, was injected back into a low emittance, large energy acceptance 45 GeV ring. Studies of injection efficiency were performed. The possibility of compressing the beam in a linac before injection was also studied. As a result, even without compression, about 80% of the disrupted e⁺ beam can be injected back into the ring. * D. Alesini et al, "Positron driven muon source for a muon collider", arXiv:1905.05747v2 [physics.acc-ph], May 2019
	Poster MOPAB133 [4.171 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB133
About •	paper received ※ 17 May 2021 paper accepted ※ 24 May 2021 issue date ※ 20 August 2021
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MOPAB142	A Compact, Low-Field, Broadband Matching Section for Externally-Powered X-Band Dielectric-Loaded Accelerating Structures	vacuum, coupling, GUI, simulation	495
	Y. Wei, C.P. Welsch The University of Liverpool, Liverpool, United Kingdom H. Bursali Sapienza University of Rome, Rome, Italy N. Catalán Lasheras, S. Gonzalez Anton, A. Grudiev, R. Wegner, Y. Wei CERN, Meyrin, Switzerland B.T. Freemire, C.-J. Jing Euclid TechLabs, Solon, Ohio, USA J. Sauza-Bedolla Lancaster University, Lancaster, United Kingdom Y. Wei, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom
	It has been technically challenging to efficiently couple external radiofrequency (RF) power to cylindrical dielectric-loaded accelerating (DLA) structures. This is especially true when the DLA structure has a high dielectric constant. This contribution presents a novel design of a matching section for coupling the RF power from a circular waveguide to an X-band DLA structure with a dielectric constant ε_r=16.66 and a loss tangent \tanθ = 3.43× 10^-5. It consists of a very compact dielectric disk with a width of 2.035 mm and a tilt angle of 60 degrees, resulting in a broadband coupling at a low RF field which has the potential to survive in the high-power environment. To prevent a sharp dielectric corner break, a 45-degree chamfer is added. Moreover, a microscale vacuum gap, caused by metallic clamping between the thin coating and the outer thick copper jacket, is studied in detail. Based on simulation studies, a prototype of the DLA structure with the matching sections was fabricated. Results from preliminary bench measurements and their comparison with design values will also be discussed.
	Poster MOPAB142 [2.617 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB142
About •	paper received ※ 11 May 2021 paper accepted ※ 21 May 2021 issue date ※ 19 August 2021
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MOPAB163	First Synchronous Measurement of Single-Bunched Electron and Positron Beams with a Wideband Feedthrough-BPM at the Positron Capture Section of the SuperKEKB Injector Linac	positron, electron, solenoid, wakefield	557
	M.A. Rehman, F. Miyahara, T. Suwada KEK, Ibaraki, Japan
	The SuperKEKB is an asymmetric e⁻/e⁺ collider with 40 times higher luminosity than the KEKB project, to explore the new physics beyond the standard model. For the SuperKEKB, the positrons are created by striking the accelerated electrons at a tungsten target. The secondary electrons are also produced during the positron creation process and accelerated in the capture section. Because of phase slipping in the capture section, the secondary electron bunch is only ∼ 180 ps away from the positron. Conventional stripline-type BPM cannot detect such closely spaced and opposite polarity signals due to slow frequency response and high cable losses. Therefore, a new wideband feedthrough-type beam position monitor was developed. It was successfully employed at the positron capture section of the SuperKEKB injector linac for the first synchronous measurement of the electron and positron beams. The cable losses effect also has been de-embedded to reveal correct signal properties. This paper describes the initial results of synchronous measurement of e⁻/e⁺ transverse position.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB163
About •	paper received ※ 20 May 2021 paper accepted ※ 27 May 2021 issue date ※ 16 August 2021
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MOPAB190	An 8 GeV Linac as the Booster Replacement in the Fermilab Power Upgrade	injection, cavity, cryomodule, booster	643
	D.V. Neuffer, S.A. Belomestnykh, M. Checchin, D.E. Johnson, S. Posen, E. Pozdeyev, V.S. Pronskikh, N. Solyak, V.P. Yakovlev Fermilab, Batavia, Illinois, USA
	Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. Increasing the Main Injector (MI) beam power above ~1.2 MW requires replacement of the 8 GeV Booster by a higher intensity alternative. Previously, rapid-cycling synchrotron (RCS) and Linac solutions were considered for this purpose. In this paper, we consider the Linac version that produces 8 GeV H⁻ beam for injection into the Recycler Ring (RR) or Main Injector (MI). The Linac takes ~1 GeV beam from the PIP-II Linac and accelerates it to ~2 GeV in a cw SRF linac, followed by a ~2-8 GeV pulsed linac using 1300 MHz cryomodules. The linac components incorporate recent improvements in SRF technology. The linac configuration and beam dynamics requirements are presented. Injection options are discussed. Research needed to implement the Booster replacement is described.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB190
About •	paper received ※ 15 May 2021 paper accepted ※ 28 May 2021 issue date ※ 10 August 2021
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MOPAB191	Method Development for Cavity Failure Compensation in a Superconducting Linac	cavity, emittance, lattice, ECR	647
	F. Bouly LPSC, Grenoble Cedex, France
	Reliability is a major challenge within the perspective of improving the performances and sustainability of MegaWatt class accelerators. To optimize the operational costs of such accelerators the availability requirements are becoming more and more challenging. These requirements are even more stringent in the case of Accelerator Driven systems (ADS). As an example, for the MYRRHA (Multipurpose Hybrid Research Reactor for High-tech Applications) ADS demonstrator, the actual availability limit is set to a maximum of 10 beam interruptions (longer than 3 seconds) over a 3-month operating cycle. For this purpose, the accelerator design is based on a redundant and fault-tolerant scheme to enable rapid mitigation of a cavity failure. The adopted strategy is to apply for local compensation: a failed cavity is compensated by several neighboring cavities. Beam dynamics studies and method developments to apply such a failure compensation scheme are here reviewed. First simulation results for superconducting linac retuning and potential future improvements will be discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB191
About •	paper received ※ 19 May 2021 paper accepted ※ 21 May 2021 issue date ※ 20 August 2021
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MOPAB192	LILac Energy Upgrade to 13 MeV	cavity, proton, controls, LLRF	651
	B. Koubek, S. Altürk, M. Busch, H. Höltermann, J.D. Kaiser, H. Podlech, U. Ratzinger, M. Schuett, M. Schwarz, W. Schweizer, D. Strehl, R. Tiede, C. Trageser BEVATECH, Frankfurt, Germany A. Brunzel, P. Nonn, H. Schlarb DESY, Hamburg, Germany A.V. Butenko, D.E. Donets, B.V. Golovenskiy, A. Govorov, K.A. Levterov, D.A. Lyuosev, A.A. Martynov, V.A. Monchinsky, D.O. Ponkin, K.V. Shevchenko, I.V. Shirikov, E. Syresin JINR, Dubna, Moscow Region, Russia
	In the frame of the NICA (Nuclotron-based Ion Collider fAcility) ion collider upgrade a new light ion LINAC for protons and ions will be built in collaboration between JINR and BEVATECH GmbH. While ions with a mass-to-charge ratio up to 3 will be fed into the NUCLOTRON ring with an energy of 7 MeV/u, protons are supposed to be accelerated up to an energy of 13 MeV using a third IH structure. This energy upgrade comprises a third IH structure, a dual-use Debuncher cavity as well as an extension of the LLRF control system built on MicroTCA technology.
	Poster MOPAB192 [4.914 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB192
About •	paper received ※ 11 May 2021 paper accepted ※ 31 May 2021 issue date ※ 20 August 2021
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MOPAB194	First 3D Printed IH-Type Linac Structure - Proof-of-Concept for Additive Manufacturing of Linac rf Cavities	cavity, vacuum, cyclotron, experiment	654
	H. Hähnel, U. Ratzinger IAP, Frankfurt am Main, Germany
	Additive manufacturing (or "3D printing") has become a powerful tool for rapid prototyping and manufacturing of complex geometries. As technology is evolving, the quality and accuracy of parts manufactured this way is ever improving. Especially interesting for the world of particle accelerators is the process of 3D printing of stainless steel (and copper) parts. We present the first fully functional IH-type drift tube structure manufactured by metal 3D printing. A 433 MHz prototype cavity has been constructed to act as a proof-of-concept for the technology. The cavity is designed to be UHV capable and includes cooling channels reaching into the stems of the DTL structure. We present the first experimental results for this prototype.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB194
About •	paper received ※ 18 May 2021 paper accepted ※ 01 June 2021 issue date ※ 02 September 2021
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MOPAB195	Development of a Disk-and-Washer Cavity for the J-PARC Muon g-2/EDM Experiment	cavity, experiment, quadrupole, coupling	658
	Y. Takeuchi, J. Tojo Kyushu University, Fukuoka, Japan E. Cicek, K. Futatsukawa, N. Kawamura, T. Mibe, M. Otani, T. Yamazaki, M. Yoshida KEK, Ibaraki, Japan Y. Iwashita Kyoto ICR, Uji, Kyoto, Japan R. Kitamura, Y. Kondo, T. Morishita JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan Y. Nakazawa Ibaraki University, Hitachi, Ibaraki, Japan N. Saito J-PARC, KEK & JAEA, Ibaraki-ken, Japan Y. Sue, K. Sumi, M. Yotsuzuka Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan H.Y. Yasuda University of Tokyo, Tokyo, Japan
	At J-PARC, an experiment using muons accelerated by a linac is planned to measure the anomalous magnetic moment of muons and to search for the electric dipole moment. A 1296 MHz disk and washer (DAW) coupled cavity linac (CCL) is being developed for use in the middle beta section of the muon linac. The DAW CCL consists of 14 tanks with 11 cells each. All tanks are connected by bridge couplers and electromagnetic quadrupole doublets for focusing are installed in each bridge coupler. The basic design of the DAW cavity has already been completed, and now detailed cavity design studies and manufacturing process studies are underway. In this poster, we will report about these studies and the preparation status of manufacturing the DAW cavity.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB195
About •	paper received ※ 20 May 2021 paper accepted ※ 01 June 2021 issue date ※ 23 August 2021
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MOPAB203	Benchmark of Superconducting Cavity Models at SNS Linac	cavity, superconducting-cavity, simulation, operation	671
	A.P. Shishlo ORNL, Oak Ridge, Tennessee, USA
	Funding: This manuscript has been authored by UT-Battelle, LLC, under Contract No. DE-AC0500OR22725 with the U.S. Department of Energy. A benchmark of superconducting cavity models against Time-of-Flight measurements at the SNS linac is presented. The superconducting part of SNS linac (SCL) includes 81 RF cavities that accelerates H⁻ beam from 185.6 MeV to the final energy of 1 GeV. During the operation some of cavities can become unstable, and its amplitudes should be reduced, or they should be completely switched off. In this case, the SCL is retuned by using a linac simulation code. This simulation tool relay on an accuracy of the superconducting cavity model. This paper describes the comparison of the measured beam acceleration by one of the SCL cavities and simulations of this process. Different cavity models are used in simulations. The subject of this study is limited to the longitudinal beam dynamics, so no effects on transverse beam characteristics have been considered.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB203
About •	paper received ※ 14 May 2021 paper accepted ※ 20 May 2021 issue date ※ 24 August 2021
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MOPAB205	Minerva (MYRRHA Phase 1) RFQ Beam Commissioning	rfq, LEBT, emittance, MMI	675
	A. Gatera, J. Belmans, F. Davin, W. De Cock, F. Doucet, L. Parez, F. Pompon, A. Ponton, D. Vandeplassche SCK•CEN, Mol, Belgium F. Bouly LPSC, Grenoble Cedex, France C. Joly, L. Perrot Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France H. Podlech IAP, Frankfurt am Main, Germany J. Tamura JAEA/J-PARC, Tokai-mura, Japan C. Zhang GSI, Darmstadt, Germany
	Funding: Part of this work was supported by the European Commission Framework Programme H₂020, MYRTE project nr. 662186 The MYRRHA project aims at coupling a 600 MeV proton accelerator to a subcritical fission core operating at a thermal power of 60 MW. The nominal proton beam for this ADS has an intensity of 4 mA and is delivered in a quasi-CW mode. Phase 1 of the project will realize a 100 MeV, 4 mA superconducting linac with the mission of ensuring the ADS requirements in terms of reliability and fault tolerance. As part of the reliability optimization program the integrated prototyping of the MINERVA injector is ongoing. The front-end of the injector is composed of an ECR proton source, a 2.6 m long LEBT (low energy beam transport line) and a four-rod RFQ accelerating the beam to 1.5 MeV. The present contribution focuses on the current beam tests on the RFQ, including beam matching, RF conditioning, assessment of the cavities’ performances and accelerated beam characterisation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB205
About •	paper received ※ 19 May 2021 paper accepted ※ 31 May 2021 issue date ※ 24 August 2021
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MOPAB206	The RF Parameters of Heavy Ions Linac	cavity, DTL, rfq, MEBT	679
	A. Sitnikov, G. Kropachev, T. Kulevoy, D.N. Selesnev, A.I. Semennikov ITEP, Moscow, Russia M.L. Smetanin, A.V. Telnov, N.V. Zavyalov VNIIEF, Sarov, Russia
	The new linac for A/Z = 8, output energy 4 MeV/u and 3 mA current is under development at NRC "Kurchatov Institute"-ITEP. The linac consists of Radio-Frequency Quadrupole (RFQ) with operating frequency 40 MHz and two sections of Drift Tube Linac (DTL) with operating frequency 80 and 160 MHz, correspondently. Both DTL has a modular structure and consists of separated individually phased resonators with focusing magnetic quadrupoles located between the cavities. The DTL₁ is based on the quarter-wave resonators meanwhile DTL₂ is based on IH 5-gap resonators. The 6D beam matching between RFQ and DTLs is provided by magnetic quadrupole lenses and 2-gaps RF-bunchers. The paper presents results of the radio-frequency (RF) design of linac accelerating structures.
	Poster MOPAB206 [0.559 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB206
About •	paper received ※ 14 May 2021 paper accepted ※ 01 July 2021 issue date ※ 29 August 2021
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MOPAB207	Design Guideline for Minimizing Space-Charge-Induced Emittance Growth	emittance, rfq, proton, space-charge	682
	C. Zhang GSI, Darmstadt, Germany
	Space-charge-induced emittance growth is a big concern for designing low-energy and high-intensity linacs. The Equipartitioning Principle was introduced to minimize space-charge-induced emittance growth by removing free energy between the transverse and longitudinal degrees of freedom. In this study, a different design guideline is being proposed. It suggests holding the ratio of longitudinal emittance to transverse emittance around one and take advantage of low emittance transfer for minimizing emittance growth. Using a high-intensity RFQ accelerator as an example, a comparison between the two design methods has been made.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB207
About •	paper received ※ 17 May 2021 paper accepted ※ 21 May 2021 issue date ※ 01 September 2021
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MOPAB210	High-Gradient Booster for Enhanced Proton Radiography at LANSCE	booster, cavity, proton, focusing	693
	S.S. Kurennoy, Y.K. Batygin LANL, Los Alamos, New Mexico, USA
	Increasing energy of proton beam at LANSCE from 800 MeV to 3 GeV improves radiography resolution ~10 times. We propose accomplishing this energy boost with a compact cost-effective linac based on cryo-cooled normal conducting high-gradient RF accelerating structures. High-gradient structures exceeding 100 MV/m have been developed for electron acceleration and operate with short RF pulse lengths below 1 us. Though such parameters are unusual for typical proton linacs, they fit perfectly for proton radiography (pRad) applications. The pRad limits contiguous trains of beam micro-pulses to less than 80 ns to prevent blur in images. For a compact pRad booster at LANSCE, we develop a staged design: a short section to capture and compress the 800-MeV proton beam followed by the main high-gradient linac. Our beam dynamics study addresses the beam magnetic focusing and minimizing its energy spread, which are challenging in high-gradient structures but very important for successful pRad operation.
	Poster MOPAB210 [0.809 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB210
About •	paper received ※ 10 May 2021 paper accepted ※ 17 August 2021 issue date ※ 11 August 2021
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MOPAB216	20-24 GeV FFA CEBAF Energy Upgrade	booster, lattice, optics, emittance	715
	S.A. Bogacz, J.F. Benesch, R.M. Bodenstein, B.R. Gamage, G.A. Krafft, V.S. Morozov, Y. Roblin JLab, Newport News, Virginia, USA J.S. Berg, S.J. Brooks, D. Trbojevic BNL, Upton, New York, USA D. Douglas Douglas Consulting, York, Virginia, USA G.H. Hoffstaetter Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177 A proposal was formulated to increase the CEBAF energy from the present 12 GeV to 20-24 GeV by replacing the highest-energy arcs with Fixed Field Alternating Gradient (FFA) arcs. The new pair of arcs would provide six or seven new beam passes, going through this magnet array, allowing the energy to be nearly doubled using the existing CEBAF SRF cavity system. One of the immediate accelerator design tasks is to develop a proof-of-principle FFA arc magnet lattice that would support simultaneous transport of 6-7 passes with energies spanning a factor of two. We also examine the possibility of using combined function magnets to configure a cascade, six-way beam split switchyard. Finally, a novel multi-pass linac optics based on a weakly focusing lattice is being explored.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB216
About •	paper received ※ 19 May 2021 paper accepted ※ 02 June 2021 issue date ※ 29 August 2021
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MOPAB236	Ion Beam Dynamics in Linac-100 Facility at Jinr	cavity, acceleration, emittance, rfq	767
	S.M. Polozov, V.S. Dyubkov, Y. Lozeev, T.A. Lozeeva, A.V. Samoshin MEPhI, Moscow, Russia
	The heavy-ion linac LINAC-100 is a superconducting driver-accelerator proposed as one of the prospective projects at JINR. Its goal is to accelerate primary stable isotope CW high-intensity beams to energies up to 100 MeV/u. This linac is discussed as the first stage of a new rare isotope facility DERICA (Dubna Electron-Radioactive Ion Collider fAcility), being under development at JINR since 2017. LINAC-100 is supposed to work with a wide range of beams with A/Z 3.5/7, Uranium U³⁴⁺ being the heaviest. Its concept has undergone many changes, mostly considering stripping cells to increase accelerator efficiency. During the latest investigations of various stripping cells [, *], Uranium beam stripping at the energy 10 MeV/u and utilizing three adjacent charge states 59-61+ resulted in 60% output beam intensity preservation (or 30 pA overall output current). The current layout of the LINAC-100 is the following: one or two (separately for light and heavy ions) normal conducting front-end linacs, gas stripper cell at 10 MeV/u, and the SC section. In this paper three charge state Uranium beam dynamics in the current version of SC LINAC-100 section is presented. S Polozov 2020 PhysScr 95 084006 A S Fomichev Phys Usp 62(7) 675-690 2019 Tolstikhina I 2018 Basic At Int of Acc H Ions in Matter 98 1 *** W Barth J Phys Conf Ser 1350:012096
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB236
About •	paper received ※ 20 May 2021 paper accepted ※ 17 August 2021 issue date ※ 26 August 2021
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MOPAB246	Design of the MEBT for the JAEA-ADS Project	MEBT, emittance, rfq, quadrupole	790
	B. Yee-Rendón, Y. Kondo, F.M. Maekawa, S.I. Meigo, J. Tamura JAEA/J-PARC, Tokai-mura, Japan
	The Medium Energy Beam Transport (MEBT) will transport a CW proton beam with a current of 20 mA and energy of 2.5 MeV from the exit of the normal conducting Radiofrequency Quadrupole (RFQ) to the superconducting Half-Wave resonator (HWR) section. The MEBT must provide a good matching between the RFQ and HWR, effective control of the emittance growth and the halo formation, enough space for all the beam diagnostics devices, among others. This work reports the first lattice design and the beam dynamics studies for the MEBT of the JAEA-ADS.
	Poster MOPAB246 [0.827 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB246
About •	paper received ※ 10 May 2021 paper accepted ※ 02 June 2021 issue date ※ 19 August 2021
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MOPAB263	Preliminary Beam Dynamics Studies for 200 MeV Superconducting Linac Planned at KOMAC	proton, DTL, radiation, lattice	837
	S. Lee, J.J. Dang, H.S. Kim, H.-J. Kwon Korea Atomic Energy Research Institute (KAERI), Gyeongbuk, Republic of Korea Y.-S. Cho KAERI, Daejon, Republic of Korea
	Funding: This work has been supported through KOMAC operation fund of KAERI by the Korea government (MSIT). Korea Multi-purpose Accelerator Complex (KOMAC) is planning an energy upgrade of the existing 100 MeV proton linac to 200 MeV using a superconducting Half Wave Resonator (HWR) operating at 350 MHz. A cryomodule is planned to house four HWR cavities with a warm doublet focusing lattice structure. Matching between the already existing DTL section and HWR section is designed and studied. We report the preliminary study of the beam dynamics of the 200 MeV superconducting linac carried out at KOMAC.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB263
About •	paper received ※ 20 May 2021 paper accepted ※ 01 July 2021 issue date ※ 24 August 2021
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MOPAB266	Start-to-End Study on Laser and RF Jitter Effects for MAX-IV SXL	FEL, laser, radiation, simulation	844
	S.P. Pirani, B.S. Kyle MAX IV Laboratory, Lund University, Lund, Sweden F. Curbis, M.A. Pop, S. Werin Lund University, Lund, Sweden W. Qin DESY, Hamburg, Germany
	A Soft X-ray free electron laser (FEL) for the MAX IV Laboratory is currently in the design phase and it will use the existing 3 GeV linac. Present stability limits in the RF and the photocathode laser will affect the performance of the FEL. One of the critical elements for the design of a FEL is to have an estimation on jitter effects of the accelerator parameters on the X-ray radiation. In this regard, we implemented a start-to-end study using Astra, Elegant and Genesis in order to assess possible variations in pulse energy, photon pulse length and spectral width in the Soft X-ray Laser (SXL) radiation. This investigation provides insights on the final SXL performance variation due to RF and laser related jitter affecting the electron beam.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB266
About •	paper received ※ 19 May 2021 paper accepted ※ 26 July 2021 issue date ※ 24 August 2021
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MOPAB268	Design of a Continuous Wave Heavy Ion RFQ for BISOL	rfq, emittance, ISOL, LEBT	851
	S. Liu, M.Y. Han, Y.R. Lu, Q.Y. Tan, Z. Wang PKU, Beijing, People’s Republic of China
	The Beijing isotope separation online (BISOL) facility will be used to study the new physics and technologies at the limit of the nuclear stability. The post accelerator for BISOL facility aims to accelerate radioactive beams to 150MeV/u. As an injector for the downstream superconducting linac, a 4-vane RFQ operating at 81.25MHz is needed to accelerate high-charge-state ions such as 132Sn²²⁺ from 3keV/u to 500keV/u in CW mode. We have compared two kinds of beam dynamics of BISOL RFQ with and without a Multi-Harmonic Buncher (MHB) bunching the continuous wave beam up-stream of the RFQ. The results indicate that it is possible to keep transverse emittance growth within tolerable limits while the longitudinal emittance is much smaller than the design without an external buncher. The acceleration of multi-charge beams simultaneously in the RFQ is also discussed in this paper.
	Poster MOPAB268 [1.829 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB268
About •	paper received ※ 19 May 2021 paper accepted ※ 25 May 2021 issue date ※ 16 August 2021
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MOPAB281	Research on Resolution Evaluation of Stripline BPM at SXFEL-UF	FEL, network, electron, experiment	892
	B. Gao, J. Chen, Y.B. Leng SSRF, Shanghai, People’s Republic of China
	48 stripline BPMs are installed in the injection section and linear acceleration section of Shanghai X-ray Free Electron Laser (SXFEL) for electron beam position measurement. These two sections require resolution of 20 µm@100pC. Resolution evaluation is an important step in BPM installation and commissioning. This paper presents BPM resolution evaluation methods based on correlation analysis. Experimental methods, data processing and result analysis will be discussed
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB281
About •	paper received ※ 19 May 2021 paper accepted ※ 27 May 2021 issue date ※ 02 September 2021
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MOPAB299	STRUCTURAL OPTIMIZATION DESIGN OF FARADAY CUP FOR BEAM COMMISSIONING OF CSNS	target, MMI, proton, neutron	943
	A.X. Wang, L. Kang, M. Meng, J.L. Sun IHEP, Beijing, People’s Republic of China J.X. Chen, H.Y. He, L. Liu, R.H. Liu, X.J. Nie, C.J. Ning, R.Y. Qiu, G.Y. Wang, T. Yang, J.B. Yu, Y.J. Yu, J.S. Zhang, D.H. Zhu IHEP CSNS, Guangdong Province, People’s Republic of China
	Faraday cup is used to absorb and stop the beam during the two phases of beam commissioning, such as the front end (FE) system and the temporary line after the drift tube linac (DTL) at the Chinese Spallation Neutron Source (CSNS). According to the beam physical parameters, graphite is selected to stop the beam directly, and oxygen-free copper which is just behind the graphite as the thermal conductive material. By the analysis and comparison of the target type and cooling efficiency, the single slant target is adopted. The incident angle between the target surface and the beam is set as 10°, meanwhile a new waterfall type water-cooling structure with parallel tunnels is designed to improve the cooling efficiency. The finite element software ANSYS is used for thermal analysis of the model, by which the diameter and interval of water cooling tunnels are optimized. The faraday cup discussed in this paper is finally successfully installed in the beam commissioning line and went well.
	Poster MOPAB299 [1.113 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB299
About •	paper received ※ 13 May 2021 paper accepted ※ 08 July 2021 issue date ※ 19 August 2021
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MOPAB302	Characterization of the Full Transverse Phase Space of Electron Bunches at ARES	simulation, experiment, electron, quadrupole	952
	S. Jaster-Merz, R.W. Aßmann, R. Brinkmann, F. Burkart, H. Dinter, W. Kuropka, F. Mayet, T. Vinatier DESY, Hamburg, Germany R.W. Aßmann INFN/LNF, Frascati, Italy S. Jaster-Merz University of Hamburg, Hamburg, Germany
	The ARES linear accelerator at the SINBAD facility (DESY) is dedicated to perform accelerator R&D studies with sub-fs short electron bunches to test novel acceleration techniques and diagnostics devices. Currently, the commissioning of the linac is ongoing and first experiments are being performed. For this, the knowledge of the full phase space of the particle beams is of high interest to, for example, optimize the accelerator performance and identify possible errors in the beam line. Tomographic methods can be used to gain insight into the full 4D transverse phase space and its correlations. Here, simulation results and first experimental preparations of a 4D transverse phase-space tomography of electron bunches at ARES are presented and discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB302
About •	paper received ※ 17 May 2021 paper accepted ※ 16 June 2021 issue date ※ 30 August 2021
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MOPAB315	Beam Diagnostics for Commissioning and Operation of the FAIR Proton Linac	proton, diagnostics, rfq, MMI	972
	T. Sieber, P. Forck, S. Udrea GSI, Darmstadt, Germany J. Herranz, A. Vizcaino-de-Julian Proactive Research and Development, Sabadell, Spain
	For the planned antiproton experiments at FAIR a dedicated proton injector Linac is currently under construction. It will be connected via the old UNILAC transfer beamline to SIS18 and has a length of ~30 m. The Linac will accelerate protons up to a final energy of 68 MeV, at a pulse length of 35 µs and a maximum repetition rate of 4 Hz. It will operate at 325 MHz and consists of a new so called "Ladder" RFQ type, followed by a chain of CH-cavities, partially coupled by rf-coupling cells. We have worked out a diagnostics system, which allows detailed measurement and study of all beam parameters during commissioning and later during regular operation. The diagnostics devices will - in a first step - be installed on a diagnostics testbench for stepwise commissioning. We present the concepts for Linac and testbench with some special emphasis on energy measurements with spectrometer and SEM Grid profile measurements.
	Poster MOPAB315 [3.149 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB315
About •	paper received ※ 14 May 2021 paper accepted ※ 24 June 2021 issue date ※ 30 August 2021
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MOPAB316	Commissioning the New CERN Beam Instrumentation Following the Upgrade of the LHC Injector Chain	MMI, electron, diagnostics, instrumentation	976
	F. Roncarolo, S. Bart Pedersen, J.M. Belleman, D. Belohrad, M. Bozzolan, C. Bracco, S. Di Carlo, J. Emery, A. Goldblatt, A. Guerrero, S. Levasseur, A. Navarro Fernandez, E. Renner, H.S. Sandberg, J.W. Storey, J. Tan, J. Tassan-Viol CERN, Geneva, Switzerland A. Navarro Fernandez UPC, Barcelona, Spain E. Renner TU Vienna, Wien, Austria
	The LHC injectors Upgrade (LIU) program has been fully implemented during the second long shutdown (LS2), which took place in 2019-20. In this context, new or upgraded beam instrumentation was developed to cope with H⁻ beam in LINAC4 and the new Proton Synchrotron Booster (PSB) injection systems which would provide high brightness proton beams in the rest of the injector complex. After a short overview of the newly installed diagnostics, the main focus of this paper will move to the instruments already commissioned with the beam. This will include LINAC4 diagnostics, the PSB H⁰/H⁻ monitor, the PSB Trajectory Measurement System, and the PS beam gas ionization monitor. In addition, particular emphasis will be given to the first operational experience with the new generation of fast wire scanners installed in all injector synchronous.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB316
About •	paper received ※ 19 May 2021 paper accepted ※ 17 June 2021 issue date ※ 14 August 2021
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MOPAB321	Schlieren Imaging for Flow Visualisation of Gas Jet in Vacuum for Accelerator Applications	vacuum, controls, laser, solenoid	989
	S. Rosily, B. Dikshit, S. Krishnagopal Homi Bhbha National Institute (HBNI), DAE, Mumbai, India S. Krishnagopal, S. Rosily BARC, Mumbai, India
	Schlieren imaging was explored for flow visualising of a gas jet in vacuum for beam profile monitor application. In supersonic gas jet based beam profile monitors, the high density jet flows through various differentially pumped skimmer stages before being shaped into a sheet. Schlieren imaging is a well known technique used in aerodynamic studies to visualise gas flow. This technique is explained in the paper along with a gist of other flow visualisation techniques. An Z-type schlieren imaging setup used to view the high density flow features of a pulsed supersonic gas jet inside vacuum is described in detail. Flow around a Pitot probe in supersonic flow was simulated and the resultant density profile obtained was compared with the image obtained using schlieren imaging. The flow features including a detached shock around the tip of the probe was observable at medium and high vacuum after processing the image. Image processing algorithms and tools useful for this application are also discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB321
About •	paper received ※ 20 May 2021 paper accepted ※ 26 May 2021 issue date ※ 29 August 2021
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MOPAB325	Development of Bunch Width Monitor with High Time Resolution for Low Emittance Muon Beam in the J-PARC Muon g-2 / EDM Experiment	emittance, experiment, acceleration, laser	1004
	M. Yotsuzuka, T. Iijima, K. Inami, Y. Sue, K. Sumi Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan T. Iijima KMI, Nagoya, AIchi Prefecture, Japan Y. Kondo JAEA, Ibaraki-ken, Japan T. Mibe KEK, Tsukuba, Japan Y. Nakazawa Ibaraki University, Ibaraki, Japan M. Otani, N. Saito J-PARC, KEK & JAEA, Ibaraki-ken, Japan Y. Takeuchi Kyushu University, Fukuoka, Japan H.Y. Yasuda University of Tokyo, Tokyo, Japan
	The J-PARC muon g-2/EDM experiment plans to measure the muon anomalous magnetic moment and electric dipole moment sensitive to new physics with high precision. This experiment uses a novel method using the low-emittance muon beam achieved by cooling and re-acceleration. In the muon linac consisting of four different accelerating cavities, the main cause of the emittance growth is the beam mismatch between the different cavities. Especially for the cavity in the low-beta section (ß=0.08-0.27), the longitudinal acceptance is narrow and beam mismatch has a significant impact. In order to perform beam matching in the low-beta cavity, a new beam monitor that can measure the low-emittance muon beam with high time resolution is required. Therefore, we developed a bunch width monitor (BWM) using a microchannel plate. The time resolution of the BWM was measured to be 40 picoseconds on the test bench using a picosecond pulse laser. It means that the BWM is possible to perform diagnosis with a phase accuracy of 1% for the acceleration phase of 324 MHz. We also evaluated factors that limit the current time resolution. In this presentation, the results of an evaluation of the BWM are reported.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB325
About •	paper received ※ 19 May 2021 paper accepted ※ 08 June 2021 issue date ※ 10 August 2021
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MOPAB326	Maximum Entropy Reconstruction of 4D Transverse Phase Space from 2D Projections: with Application to Laser Wire Measurements in the SNS HEBT	laser, emittance, neutron, coupling	1008
	C.Y. Wong, A.P. Shishlo ORNL, Oak Ridge, Tennessee, USA
	We employ the principle of maximum entropy (MENT) to reconstruct 4D transverse phase space from its 2D projections. Emittance devices commonly measure two specific 2D projections, i.e. the horizontal and vertical phase space distributions. We show that: 1) given only these two 2D projections, their product is the analytic MENT solution to the 4D distribution; and 2) additional 2D projections provide information on inter-plane coupling in the MENT reconstruction of the 4D phase space which can be solved numerically. At the Spallation Neutron Source (SNS), laser wires in the high energy beam transport (HEBT) enable non-invasive two-slit type transverse phase space measurements. Laser wires play the role of the first slit whereas physical wires downstream of a drift act as the second slit. We reconstruct the 4D phase space in the HEBT using all four horizontal/vertical permutations of the two slits where: 1) the two configurations with parallel slits constitute ordinary 2D phase space measurements in either plane; and 2) the two configurations with perpendicular slits carry coupling information.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB326
About •	paper received ※ 20 May 2021 paper accepted ※ 19 July 2021 issue date ※ 17 August 2021
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MOPAB329	Operations of Copper Cavities at Cryogenic Temperatures	cavity, coupling, cryogenics, ECR	1020
	H. Wang, U. Ratzinger, M. Schuett IAP, Frankfurt am Main, Germany
	How the anomalous skin effect by copper affects the efficiency of copper- cavities will be studied in the experiment, especially at lower temperatures. The accurate quality factor Q and resonant frequency of three coaxial cavities will be measured over the temperature range from 300 to 22 K. The three coaxial cavities have the same structure, but different lengths, which correspond to resonant frequencies: around 100 MHz, 220 MHz and 340 MHz. The motivation is to check the feasibility of an efficient pulsed, liquid nitrogen cooled ion linac.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB329
About •	paper received ※ 19 May 2021 paper accepted ※ 07 June 2021 issue date ※ 02 September 2021
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MOPAB335	SNS Warm Linac Circulator Breakdown Considerations for the PPU Project	operation, simulation, DTL, proton	1041
	G.D. Toby, Y.W. Kang, S.-H. Kim, S.W. Lee, J.S. Moss ORNL, Oak Ridge, Tennessee, USA
	Funding: * This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under contract number DE-AC05-00OR22725. Multipacting in accelerating structures is a complex phenomenon about which there is much to be understood. While multipacting research efforts have primarily been focused on superconducting radio frequency (SRF) systems, normal conducting accelerating structures which have a higher thermal capacity, and a greater vacuum pressure tolerance could benefit from additional investigation. This research details multipacting simulation methods and the results of 3-D electromagnetic simulations of RF vacuum windows used on normal conducting linac (NCL) cavities. Benchmarking of the peak electric fields in these structures, benefits of material processing and possible techniques for reducing or eliminating multipacting activities are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB335
About •	paper received ※ 17 May 2021 paper accepted ※ 28 May 2021 issue date ※ 23 August 2021
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MOPAB337	Design Study of the Spiral Buncher Cavities for the High Current Injector at IUAC	cavity, impedance, bunching, rfq	1048
	S. Kedia, R. Ahuja, R. Mehta, C.P. Safvan IUAC, New Delhi, India
	Two high energy beam transport (HEBT) cavities have been designed to provide the longitudinal beam bunching between drift tube linac and superconducting super-buncher of the superconducting linear (SC-LINAC) accelerator. The spiral type cavities were chosen over standard quarter wave-type geometry due to its higher shunt impedance. The TRACE-3D ion-optical codes have been used to determine the bunching voltage and physical location of the cavities. The two-gap RF cavity requires 80 kV/gap to provide the longitudinal beam bunching at the entrance of the superconducting buncher. The CST-MWS simulations were performed to design the spiral type bunching cavities. The various parameters including shunt impedance, quality factor, average accelerating field, and total power loss were determined using CST-MWS simulations. The ratio of drift tube radius to the gap was optimized to achieve the maximum effective electric field with minimum field penetration within the gap. The SolidWorks software has been used to prepare a mechanical model for the fabrication.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB337
About •	paper received ※ 15 May 2021 paper accepted ※ 26 May 2021 issue date ※ 26 August 2021
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MOPAB344	Machine Learning Models for Breakdown Prediction in RF Cavities for Accelerators	cavity, operation, network, vacuum	1068
	C. Obermair, A. Apollonio, T. Cartier-Michaud, N. Catalán Lasheras, L. Felsberger, W.L. Millar, W. Wuensch CERN, Geneva, Switzerland C. Obermair, F. Pernkopf TUG, Graz, Austria
	Radio Frequency (RF) breakdowns are one of the most prevalent limits in RF cavities for particle accelerators. During a breakdown, field enhancement associated with small deformations on the cavity surface results in electrical arcs. Such arcs degrade a passing beam and if they occur frequently, they can cause irreparable damage to the RF cavity surface. In this paper, we propose a machine learning approach to predict the occurrence of breakdowns in CERN’s Compact LInear Collider (CLIC) accelerating structures. We discuss state-of-the-art algorithms for data exploration with unsupervised machine learning, breakdown prediction with supervised machine learning, and result validation with Explainable-Artificial Intelligence (Explainable AI). By interpreting the model parameters of various approaches, we go further in addressing opportunities to elucidate the physics of a breakdown and improve accelerator reliability and operation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB344
About •	paper received ※ 20 May 2021 paper accepted ※ 16 July 2021 issue date ※ 11 August 2021
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MOPAB348	Portable 2.5 MeV X-Band Linear Accelerator Structure	GUI, gun, radiation, target	1084
	A.V. Mishin, K. Brown, M. Denney, D. Fischer, N.P. Hanson, S. Proskin, J. Stammetti Varex Imaging, Salt Lake City, USA
	Two versions of 2.5 MeV X-Band linear accelerator structure have been designed and tested. The first is a traditional single input linac, and the other one is a dual input, two section linac with power input through a 3 dB coupler. The linac is designed for a portable linac system, which can be used for security screening, non-destructive testing, medical and industrial CT, and, perhaps, some other applications.
	Poster MOPAB348 [1.490 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB348
About •	paper received ※ 15 May 2021 paper accepted ※ 28 May 2021 issue date ※ 23 August 2021
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MOPAB349	New Accelerator Beam Centerline (ABC) Production Line at Varex Imaging Corporation	gun, betatron, detector, GUI	1087
	A.V. Mishin Varex Imaging, Salt Lake City, USA
	In January 2017, a Salt Lake City Component Division of Varian Medical (Varian), producer of X-ray tubes, detectors, and imaging panels has been spun off, giving birth to a new public company Varex Imaging Corporation (Varex), which also includes the Security and Inspection Products (SIP) linac producer in Las Vegas. Based on Varian asset acquisition of two small LLCs** in May 2016, 8 months prior to the transition, a new business branch within Varex has been established, which included distribution of the betatrons and detector arrays as well as pilot production line for Accelerator Beam Centerlines (ABC). In 3 years, we moved ABC production from Fremont, CA to Salt Lake in Utah and improved it; several ABCs have been designed, produced, and qualified. A number of new products in energy range of 1-20 MeV are under development, based on the new ABCs used as components for SIP linear accelerator systems and ABCs sold to third parties for applications other than Security and NDT. The new products will brag broad energy and dose rate regulation, smooth and reliable operation, providing extended benefits to our customers. * - https://www.varian.com/ - https://www.vareximaging.com/ * - both Thought One LLC and Radmedex LLC have been dissolved in 2018 upon completion of the transition process
	Poster MOPAB349 [2.182 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB349
About •	paper received ※ 13 May 2021 paper accepted ※ 27 May 2021 issue date ※ 21 August 2021
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MOPAB357	The New Design of the RF System for the SPS-II Light Source	cavity, storage-ring, booster, impedance	1110
	N. Juntong, T. Chanwattana, S. Chunjarean, S. Krainara, T. Phimsen, T. Pulampong SLRI, Nakhon Ratchasima, Thailand K. Manasatitpong Synchrotron Light Research Institute (SLRI), Muang District, Thailand
	The new light source facility in Thailand, SPS-II, is a ring-based 3 GeV light source with a circumference of approximately 330 m. The target stored beam current is 300 mA with an emittance of below 1.0 nm rad. The injector has been changed from a full energy linac to a booster injector with 150 MeV linac. The main RF frequency has been reconsidered to a low-frequency range at 119 MHz. Low frequency is chosen with the benefit of low RF voltage for a high RF acceptance together with experience with the present ring RF system of 118 MHz. Details of RF frequency consideration will be discussed. The requirements and details of the RF systems in the booster ring and the storage ring will be presented.
	Poster MOPAB357 [1.696 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB357
About •	paper received ※ 17 May 2021 paper accepted ※ 08 June 2021 issue date ※ 14 August 2021
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MOPAB370	X-Band RF Spiral Load Optimization for Additive Manufacturing Mass Production	GUI, vacuum, simulation, ECR	1143
	H. Bursali Sapienza University of Rome, Rome, Italy N. Catalán Lasheras, R.L. Gerard, A. Grudiev, O. Gumenyuk, P. Morales Sanchez, B. Riffaud CERN, Geneva, Switzerland J. Sauza-Bedolla Lancaster University, Lancaster, United Kingdom
	The CLIC main linac uses X-band traveling-wave normal conducting accelerating structures. The RF power not used for beam acceleration nor dissipated in the resistive wall is absorbed in two high power RF loads that should be as compact as possible to minimize the total footprint of the machine. In recent years, CERN has designed, fabricated and successfully tested several loads produced by additive manufacturing. With the current design, only one load can be produced in the 3D printing machine at a time. The aim of this study is optimizing the internal cross-section of loads in order to create a stackable design to increase the number of produced parts per manufacturing cycle and thus decrease the unit price. This paper presents the new design with an optimization of the internal vacuum part of the so-called RF spiral load. In this case, RF and mechanical designs were carried out in parallel. The new cross section has showed good RF reflection reaching less than -30 dB in simulations. The final load is now ready to be manufactured and high-power tested. This new load will not only provide cost saving but also faster manufacturing for mass production.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB370
About •	paper received ※ 18 May 2021 paper accepted ※ 26 May 2021 issue date ※ 23 August 2021
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MOPAB384	Nb₃Sn Coating of Twin Axis Cavity for Accelerator Applications	cavity, niobium, SRF, dipole	1175
	J.K. Tiskumara, S.U. De Silva, J.R. Delayen, H. Park ODU, Norfolk, Virginia, USA J.R. Delayen, H. Park, U. Pudasaini, C.E. Reece JLab, Newport News, Virginia, USA G.V. Eremeev Fermilab, Batavia, Illinois, USA
	Funding: Research supported by DOE Office of Science Accelerator Stewardship Program Award DE- SC0019399. Partially authored by Jefferson Science Associates under contract no. DEAC0506OR23177 A Superconducting twin axis cavity consisting of two identical beam pipes that can accelerate and decelerate beams within the same structure has been proposed for the Energy Recovery Linac (ERL) applications. There are two niobium twin axis cavities at JLab fabricated with the intention of later Nb₃Sn coating and now we are progressing to coat them using vapor diffusion method. Nb₃Sn is a potential alternate material for replacing Nb in SRF cavities for better performance and reducing operational costs. Because of advanced geometry, larger surface area, increased number of ports and hard to reach areas of the twin axis cavities, the usual coating approach developed for typical elliptical single-axis cavities must be evaluated and requires to be adjusted. In this contribution, we report the first results from the coating of a twin axis cavity and discuss current challenges with an outlook for the future.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB384
About •	paper received ※ 19 May 2021 paper accepted ※ 24 May 2021 issue date ※ 27 August 2021
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MOPAB386	Development of Nitrogen-Doping Technology for SHINE	cavity, SRF, niobium, ECR	1182
	Y. Zong, X. Huang, Z. Wang SINAP, Shanghai, People’s Republic of China J.F. Chen, H.T. Hou, D. Wang, J.N. Wu, Y.X. Zhang SARI-CAS, Pudong, Shanghai, People’s Republic of China P.C. Dong Shanghai Advanced Research Institute, Pudong, Shanghai, People’s Republic of China Y.W. Huang ShanghaiTech University, Shanghai, People’s Republic of China J. Rong SSRF, Shanghai, People’s Republic of China
	The Shanghai HIgh repetition rate XFEL aNd Extreme light facility (SHINE) is under construction, which needs six hundred 1.3GHz cavities with high quality factor. In this paper, we present the newest studies on single cell cavities with nitrogen doping and cold EP treatment, showing an obvious improvement compared with the previous results.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB386
About •	paper received ※ 21 May 2021 paper accepted ※ 08 June 2021 issue date ※ 20 August 2021
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MOPAB405	Study of Targets to Produce Molybdenum-99 Using 30 MeV Electron Linear Accelerator	target, electron, photon, radiation	1222
	T.S. Dixit, A.P. Deshpande, R. Krishnan, A. Shaikh SAMEER, Mumbai, India
	Funding: Ministry of Electronics and Information Technology, Government of India (MeitY) Two approaches to produce 99Mo are studied using GEANT4 are reported in this paper. First, in converter target approach, bremsstrahlung photons are generated in a high Z target. The emitted photons then hit 100Mo secondary target, producing 99Mo through (gamma, n) reaction. Second, in direct target approach, high energy electron beam hits 100Mo target, where both (e, gamma) and (gamma, n) reactions take place simultaneously. A 30 MeV, 5-10 kW beam power electron linac is under development at SAMEER. The acceleration gradient required to achieve 30 MeV energy will be provided by two linacs operated in series configuration and the high average beam power will be achieved by running the system at high duty operation. Main aim of this study is to optimize experimental parameters to maximize specific activity of 99Mo. Since, 100Mo is very expensive material therefore judicious use of the material is very important. Hence, optimization of electron beam energy and target dimensions are studied in detail in both the approaches. It is found that the direct target approach gives higher specific activity compared to the converter target approach.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB405
About •	paper received ※ 19 May 2021 paper accepted ※ 06 June 2021 issue date ※ 14 August 2021
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MOPAB410	Preliminary Studies of a Compact VHEE Linear Accelerator System for FLASH Radiotherapy	radiation, electron, operation, impedance	1229
	L. Giuliano, F. Bosco, M. Carillo, D. De Arcangelis, L. Faillace, L. Ficcadenti, M. Migliorati, A. Mostacci, L. Palumbo Sapienza University of Rome, Rome, Italy D. Alesini, M. Behtouei, B. Spataro INFN/LNF, Frascati, Italy G. Cuttone, G. Torrisi INFN/LNS, Catania, Italy V. Favaudon, S. Heinrich, A. Patriarca Institut Curie - Centre de Protonthérapie d’Orsay, Orsay, France
	Funding: The work is supported by La Sapienza University, research grant "grandi progetti di ricerca 2020". The Flash Radio Therapy is a revolutionary new technique in the cancer cure: it spares healthy tissue from the damage of the ionizing radiation maintaining the tumor control as efficient as in conventional radiotherapy. To allow the implementation of the FLASH Therapy concept into actual clinical use, it is necessary to have a linear accelerator able to deliver the very high dose and very high dose rate (>10⁶ Gy/s) in a very short irradiation time (beam on time < 100ms). Low energy S-band Linacs (up to 7 MeV) are being used in Radiobiology and pre-clinic applications but in order to treat deep tumors, the energy of the electrons should achieve the range of 60-100 MeV. In this paper, we address the main issues in the design of a compact C band (5.712 GHz) electron linac-VHEE for FLASH Radio Therapy. We present preliminary studies on C-band structures at La Sapienza and at INFN-LNS, aiming to reach a high accelerating gradient and high current necessary to deliver a dose >1 Gy/pulse, with very short electron pulse.
	Poster MOPAB410 [0.650 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB410
About •	paper received ※ 19 May 2021 paper accepted ※ 09 June 2021 issue date ※ 21 August 2021
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MOPAB413	The Next Ion Medical Machine Study at CERN: Towards a Next Generation Cancer Research and Therapy Facility with Ion Beams	synchrotron, proton, superconducting-magnet, operation	1240
	M. Vretenar, V. Bencini, E. Benedetto, M.R. Khalvati, A.M. Lombardi, M. Sapinski, D. Tommasini CERN, Meyrin, Switzerland E. Benedetto, M. Sapinski TERA, Novara, Italy P. Foka GSI, Darmstadt, Germany
	Cancer therapy with ions has several advantages over X-ray and proton therapy, but its diffusion remains limited primarily because of the size and cost of the accelerator. To develop technologies that might improve performance and reduce accelerator cost with respect to present facilities, CERN has recently launched the Next Ion Medical Machine Study (NIMMS), leveraging CERN expertise in accelerator fields to disseminate technologies developed for basic science. A perspective user and key partner of NIMMS is the SEEIIST (South East European International Institute for Sustainable Technologies), established to build in the region an innovative facility for combined cancer therapy and biomedical research with ion beams. For SEEIIST and other potential users, three options are being considered. Conceptual designs of a warm-magnet synchrotron at high beam intensity, of a compact superconducting synchrotron, and of a high-frequency linear accelerator have been compared in terms of cost, risk and development time. The development of curved superconducting magnets, of compact synchrotrons and ion gantries, and of linacs is being pursued within EU-funded projects or specific collaborations
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB413
About •	paper received ※ 18 May 2021 paper accepted ※ 20 July 2021 issue date ※ 13 August 2021
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MOPAB415	Failure Rates and Downtimes of Multi-Leaf Collimators in Indonesia	radiation, target, gun, power-supply	1248
	G.S. Peiris, S.L. Sheehy The University of Melbourne, Melbourne, Victoria, Australia M.F. Kasim, S.A. Pawiro University of Indonesia, Depok, Jawa Barat, Indonesia
	One of the greatest barriers to cancer treatment in Low and Middle-Income Countries (LMICs) is the access to Radiotherapy Linear Accelerators (LINACs). Not only are the LINACs complex, the harsh environment of LMICs cause frequent breakdowns resulting in downtimes ranging from days to months. Recent research has identified a disparity between LMICs and High Income Countries (HICs) and determined the Multi-Leaf Collimator (MLC) as a component needing re-evaluation. The MLC causes over 30% of the problems in RT LINACs, but the modes of failure and quantify the extent of the damage done are yet to be quantified. Using data from across Indonesia, we show the pathways to failure of RT Machines and frequency of breakdowns over time. A component of the MLC needs to be replaced every 9.98 faults per 1000 patients treated and the MLC itself breaks down on average every 36±1.8 days. When comparing the downtime by leaf width, the data shows 5mm leaves contribute 18.27±6.5% to all breakdowns while 10mm makes up 15.87±4.3%. These results outline the need to reassess the current generation of RT LINACs and ultimately work towards guiding future designs to be robust enough for all environments.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB415
About •	paper received ※ 19 May 2021 paper accepted ※ 09 June 2021 issue date ※ 16 August 2021
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TUXC08	Simulation and Beam Experiments of a Multi-Harmonics Buncher in SSC-Linac	simulation, experiment, rfq, heavy-ion	1319
	Q.Y. Kong, H. Du, P. Jin, L. Jing, X.N. Li, Z.S. Li, Zh. Liu, J.W. Xia, X. Yin, Y. Zhang IMP/CAS, Lanzhou, People’s Republic of China
	Funding: This work was supported by the National Natural Science Foundation of China(No. 11375243) and Guangdong Innovative and Entrepreneurial Research Team Program(No.2016ZT06G373). A compact dual-gap Multi-Harmonics Buncher has been successfully used at the SSC-Linac, a linear accelerator dedicates to beam injection into SSC in HIRFL. SSC-Linac operates at 53.667MHz, which is forth time of the RF frequency of the SSC. In order to increase the longitudinal capture efficiency, and enhance the current out of SSC, an independent MHB(Multi-Harmonics Buncher) had been installed into the LEBT of SSC-Linac. The fundamental frequency of the MHB is 13.417MHz. The buncher adopts the mechanical structure of dual-gap and sawtooth waveform is generated by multi-harmonics synthetic technology. Beam performance simulation with MHB have been done with code BEAMPATH. Besides, 84Kr¹⁴⁺ beam has been bunched successfully using the MHB in our experiments, the maximum bunch efficiency of 86.1% has been measured in experiments.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUXC08
About •	paper received ※ 31 May 2021 paper accepted ※ 12 July 2021 issue date ※ 11 August 2021
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TUPAB015	Beam Loading Compensation of APS Cavity with Off-Crest Acceleration in ILC e-Driven Positron Source	positron, beam-loading, electron, target	1368
	M. Kuriki, S. Konno, H. Nagoshi HU/AdSM, Higashi-Hiroshima, Japan T. Omori, J. Urakawa, K. Yokoya KEK, Ibaraki, Japan T. Takahashi Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan
	In E-Driven positron source of ILC, the generated positron is captured by RF accelerator by APS cavity. The positron is initially placed at the deceleration phase and gradually slipped down to acceleration phase. Because the beam-loading is expected to be more than 1A with a multi-bunch format, the compensation is essential to obtain uniform intensity over the pulse. A conventional method for the compensation is controlling the timing, but it doesn’t work in off-crest case. In this manuscript, we discuss the compensation with the phase and amplitude modulation on the input RF.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB015
About •	paper received ※ 19 May 2021 paper accepted ※ 27 July 2021 issue date ※ 26 August 2021
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TUPAB017	Study of Conduction-Cooled Superconducting Quadrupole Magnets Combined with Dipole Correctors for the ILC Main Linac	quadrupole, dipole, SRF, cavity	1375
	Y. Arimoto, S. Michizono, Y. Morikawa, N. Ohuchi, T. Oki, H. Shimizu, K. Umemori, X. Wang, A. Yamamoto, Y. Yamamoto, Z.G. Zong KEK, Ibaraki, Japan V.S. Kashikhin Fermilab, Batavia, Illinois, USA
	A superconducting rf (SRF) cryomodule for International Linear Collider(ILC) Main Linac equips focus/steering magnets. The magnets are "superferric" magnets with four superconducting (SC) race track coils conductively cooled from the cryomodule LHe supply pipe. The quadrupole field gradient and dipole field are 40 T/m and 0.1 T, respectively. The magnet length and iron-pole radius are 1 m and 0.045 m, respectively. It is known that dark current is generated at SRF cavities and accelerated through the following linac string. The dark current reaches and heats the SC magnets. It is estimated that the power deposition in the magnet may reach more than a few watts and temperature of the SC coils may locally reach to critical temperature of NbTi. It is important to make the magnet not reach quench with sufficient conduction cooling. We aim to realize the SC magnet which can stably operate under such condition. We plan to develop test coils made of three types of SC materials, NbTi, Nb₃Sn, and MgB₂ and study thermal characteristics and stability . We will develop a short model magnet, based on the test coil results. Here, we will present the magnet design study and the R&D plan.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB017
About •	paper received ※ 19 May 2021 paper accepted ※ 16 June 2021 issue date ※ 18 August 2021
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TUPAB028	Permanent Magnets Future Electron Ion Colliders at RHIC and LHeC	electron, permanent-magnet, focusing, collider	1401
	D. Trbojevic, S.J. Brooks, V. Litvinenko, T. Roser BNL, Upton, New York, USA G.H. Hoffstaetter Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA V. Litvinenko Stony Brook University, Stony Brook, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. We present a new ’green energy’ approach to the Energy Recovery Linac (ERL) and Recirculating Linac Accelerators (RLA) for the future Electron Ion Colliders (EIC) using single beam line made of very strong focusing combined function permanent magnets and the Fixed Field Alternating Linear Gradient (FFA-LG) principle. We are basing our design on recent very successful commissioning results of the Cornell University and Brookhaven National Laboratory ERL Test Accelerator.
	Poster TUPAB028 [2.720 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB028
About •	paper received ※ 17 May 2021 paper accepted ※ 27 May 2021 issue date ※ 30 August 2021
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TUPAB035	ESS Medium Beta Cavities Status at INFN LASA	cavity, SRF, multipactoring, controls	1420
	D. Sertore, M. Bertucci, M. Bonezzi, A. Bosotti, A. D’Ambros, A.T. Grimaldi, P. Michelato, L. Monaco, R. Paparella INFN/LASA, Segrate (MI), Italy C. Pagani Università degli Studi di Milano & INFN, Segrate, Italy
	INFN Milano contributes in-kind to the ESS ERIC Superconducting Linac supplying 36 cavities for the Medium Beta section of the proton accelerator. The production has reached completion, being all the cavities mechanical fabricated, BCP treated and, for most of them, also qualified with vertical test at cold. In this paper, we report on the results and lessons learnt and the actions taken both for quality control managing and recovery of the few cavities that did not reach the project goal after the first qualification test.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB035
About •	paper received ※ 19 May 2021 paper accepted ※ 14 June 2021 issue date ※ 18 August 2021
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TUPAB036	The Accelerator Design Progress for EIC Strong Hadron Cooling	electron, hadron, proton, emittance	1424
	E. Wang, S. Peggs, V. Ptitsyn, F.J. Willeke, W. Xu BNL, Upton, New York, USA S.V. Benson JLab, Newport News, Virginia, USA D. Douglas Douglas Consulting, York, Virginia, USA C.M. Gulliford, G.H. Hoffstaetter Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA C.E. Mayes Xelera Research LLC, Ithaca, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy, The Electron-Ion Collider will achieve a luminosity of 10³⁴ cm^-2 s⁻¹ by incorporating strong hadron cooling to counteract hadron Intra-Beam Scattering, using a coherent electron cooling scheme. An accelerator will deliver the beams with key parameters, such as 1 nC bunch charge, and 1e-4 energy spread. The paper presents the design and beam dynamics simulation results. Methods to minimize beam noise, the challenges of the accelerator design, and the R&D topics being pursued are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB036
About •	paper received ※ 16 May 2021 paper accepted ※ 11 June 2021 issue date ※ 01 September 2021
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TUPAB037	The Design of a High Charge Polarized Preinjector for the Electron-Ion Collider	cathode, gun, cavity, electron	1428
	E. Wang, W. Liu, V.H. Ranjbar, J. Skaritka, N. Tsoupas BNL, Upton, New York, USA J.M. Grames, J. Guo JLab, Newport News, Virginia, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy The design of the electron pre-injector of the Electron-Ion Collider (EIC) project to generate 4 x 7 nC bunch has been advancing to meet the requirements for injection into the Rapid Cycling Synchrotron (RCS). The major challenges are high charge transport and achieving small energy spread from 3 GHz traveling-wave plate(TWP). The designed preinjector includes the polarized electron source, bunching section, TWP Linac, zigzag phase space manipulation and spin rotator. In this report, we will discuss the RF frequency selection and the way to reduce energy spread down to 0.2% by longitudinal phase space manipulate. We will also report the results of beamline simulation using space charge code and the conceptual design of spin rotator.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB037
About •	paper received ※ 16 May 2021 paper accepted ※ 15 June 2021 issue date ※ 27 August 2021
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TUPAB038	Simulation of the Filling Pattern Dependent Regenerative Beam Breakup Instabilities in Energy Recover Linacs	HOM, cavity, simulation, electron	1431
	S. Setiniyaz, P.H. Williams Cockcroft Institute, Warrington, Cheshire, United Kingdom R. Apsimon Cockcroft Institute, Lancaster University, Lancaster, United Kingdom P.H. Williams STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	The interaction of a transversely displaced beam with the higher modes (HOM) of the accelerating cavities causes building up HOM voltages in the cavity, which in turn kicks the beam and increases the offset further. This is known as regenerative beam breakup (BBU) instability and it sets the beam threshold current for the stable beam operation. A study by Setiniyaz et al.~[Setiniyaz2020] showed the filling pattern and recombination schemes of multi-turn energy recovery linacs (ERLs) can create many different beam loading transients, which can have a big impact on the cavity fundamental mode voltage and RF stabilizes. In this work, we extend the study of the filling pattern and recombination schemes to the BBU instabilities and threshold current. In the ERLs, the accelerated and decelerated bunches can be ordered differently while they pass through the cavity and form different filling patterns. Each pattern has a unique bunch energy sequence and bunch arrival times and hence interacts with cavity uniquely and thus drives BBU differently. In this paper, we introduce a simulation tool to investigate the filling pattern dependence of the ERL BBU instability. * S. Setiniyaz, R. Apsimon, and P. H. Williams, Phys. Rev. Accel. Beams 23, 072002, 2020.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB038
About •	paper received ※ 20 May 2021 paper accepted ※ 09 June 2021 issue date ※ 15 August 2021
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TUPAB045	The Low Energy Injector Design for the Southern Advanced Photon Source	electron, cavity, gun, bunching	1450
	Y. Han IHEP CSNS, Guangdong Province, People’s Republic of China Y. Jiao, B. Li, X. Liu, S. Wang IHEP, Beijing, People’s Republic of China
	The Southern Advanced Photon Source (SAPS) is a project under design, which aims at constructing a 4th generation storage ring with emittance below 100 pm.rad at the electron beam energy of around 3.5 GeV. At present, two injector options are under consideration. One is a full energy booster plus a low energy injector, and another is a full energy linac injector. In this paper, a preliminary design of the low energy injector is presented, which consists of an DC thermionic electron gun, a bunching section and an accelerating section. The beam energy at the end of the injector is about 150 MeV.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB045
About •	paper received ※ 17 May 2021 paper accepted ※ 09 June 2021 issue date ※ 18 August 2021
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TUPAB046	Preliminary design of the Full Energy Linac Injector for the Southern Advanced Photon Source	FEL, gun, injection, photon	1454
	X. Liu Institute of High Energy Physics, CAS, Guangdong, People’s Republic of China Y. Jiao, B. Li, S. Wang IHEP, Beijing, People’s Republic of China
	A 4th generation mid-energy range diffraction limited storage ring, named as the Southern Advanced Photon Source (SAPS), is under consideration to be built at the same campus as China Spallation Neutron Source (CSNS), providing a charming one-stop solution for fundamental sciences and industrial applications. While the design of the ring is still under study, a full energy Linac has been proposed as one candidate option for its injector, with the capability of being used as an X-ray Free Electron Laser (XFEL) in the near future. In this paper, an overview of the preliminary design of the Linac is given and simulation results are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB046
About •	paper received ※ 18 May 2021 paper accepted ※ 10 June 2021 issue date ※ 10 August 2021
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TUPAB047	Bunch Compressor Design in the Full Energy Linac Injector for the Southern Advanced Photon Source	electron, simulation, bunching, laser	1458
	B. Li IHEP CSNS, Guangdong Province, People’s Republic of China Y. Jiao, X. Liu, S. Wang IHEP, Beijing, People’s Republic of China
	A mid-energy fourth-generation storage ring light source named the Southern Advanced Photon Source (SAPS), has been considered to be built neighboring the China Spallation Neutron Source (CSNS). A full energy linac has been proposed as an injector to the storage ring, with the capability to generate high brightness electron beams to feed a Free Electron Laser (FEL) at a later stage. To achieve the high peak current in FELs, space charge, RF structure wakefield, coherent synchrotron radiation (CSR), RF curvature, and the second-order momentum compaction factor should be carefully considered and optimized during the bunch compression processes. In this paper, physic design and simulation results of the bunch compressors are described.
	Poster TUPAB047 [1.918 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB047
About •	paper received ※ 15 May 2021 paper accepted ※ 09 June 2021 issue date ※ 28 August 2021
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TUPAB076	High-Gradient Breakdown Studies of an X-Band Accelerating Structure Operated in the Reversed Taper Direction	accelerating-gradient, linear-collider, klystron, collider	1543
	X.W. Wu, N. Catalán Lasheras, A. Grudiev, G. McMonagle, I. Syratchev, W. Wuensch CERN, Meyrin, Switzerland M. Boronat IFIC, Valencia, Spain A. Castilla, A.V. Edwards, W.L. Millar Lancaster University, Lancaster, United Kingdom
	The results of high-gradient tests of a tapered X-band traveling-wave accelerator structure powered in reversed direction are presented. Powering the tapered structure from the small aperture, normally output, at the end of the structure provides unique conditions for the study of gradient limits. This allows high fields in the first cell for a comparatively low input power and a field distribution that rapidly falls off along the length of the structure. A maximum gradient of 130 MV/m in the first cell at a pulse length of 100 ns was reached for an input power of 31.9 MW. Details of the conditioning and operation at high-gradient are presented. Various breakdown rate measurements were conducted at different power levels and rf pulse widths. The structure was standard T24 CLIC test structure and was tested in Xbox-3 at CERN.
	Poster TUPAB076 [1.077 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB076
About •	paper received ※ 19 May 2021 paper accepted ※ 12 July 2021 issue date ※ 12 August 2021
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TUPAB080	Design and Status of the Beam Switchyard of the Shanghai Soft X-Ray FEL User Facility	FEL, electron, kicker, undulator	1559
	S. Chen, R. Wang SSRF, Shanghai, People’s Republic of China H.X. Deng, C. Feng, X. Fu, B. Liu SARI-CAS, Pudong, Shanghai, People’s Republic of China
	SXFEL-UF, a soft X-ray FEL user facility located in Shanghai, has been upgraded from the existing test facility. Electron energy increases from 840 MeV to 1.5 GeV and a SASE FEL line will be added besides the existing seeding FEL line. It has started commissioning since early this year. In order for simultaneous operation of the two FEL lines, a beam switchyard is built between the linac and the two FEL lines. In this paper, the physics design of the beam switchyard is described.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB080
About •	paper received ※ 19 May 2021 paper accepted ※ 11 June 2021 issue date ※ 20 August 2021
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TUPAB081	Design of the Beam Distribution System of SHINE	undulator, electron, septum, kicker	1562
	S. Chen, M. Gu, R. Wang SSRF, Shanghai, People’s Republic of China H.X. Deng, X. Fu SARI-CAS, Pudong, Shanghai, People’s Republic of China
	In shanghai, a hard X-ray free electron laser project named SHINE is under design. It will be based on a superconducting linac running in CW mode. On the first stage, there will be three parallel undulator lines downstream the linac. For simultaneous operation of the three undulator lines, a beam distribution system based on fast kickers will be installed between linac and undulator lines. The physics design of this beam distribution system is described in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB081
About •	paper received ※ 19 May 2021 paper accepted ※ 14 June 2021 issue date ※ 22 August 2021
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TUPAB082	Analysis of the Effect of Energy Chirp in Implementing EEHG at SXL	bunching, electron, simulation, FEL	1566
	M.A. Pop, F. Curbis, B.S. Kyle, S.P. Pirani, W. Qin, S. Werin MAX IV Laboratory, Lund University, Lund, Sweden F. Curbis, S. Werin Lund University, Lund, Sweden W. Qin DESY, Hamburg, Germany
	As a part of the efforts to improve the longitudinal coherence in the design of the Soft X-ray FEL (the SXL) at MAX IV, we present a possible implementation of the EEHG harmonic seeding scheme partly integrated into the second bunch compressor of the existing LINAC. A special focus is given to the effect of CSR on the resulting EEHG bunching and on how this unwanted effect might be controlled.
	Poster TUPAB082 [1.825 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB082
About •	paper received ※ 15 May 2021 paper accepted ※ 28 July 2021 issue date ※ 17 August 2021
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TUPAB083	Dual Energies in the LCLS Copper Linac	quadrupole, feedback, klystron, betatron	1570
	F.-J. Decker, C. Bianchini Mattison, D.K. Bohler, A. Brachmann, W.S. Colocho, S. Condamoor, M.L. Gibbs, K.H. Kim, A.A. Lutman, T.J. Maxwell, J.A. Mock, H.-D. Nuhn, J.C. Sheppard, H. Smith, T.J. Smith, M. Stanek, S. Zelazny, Z. Zhang, C.M. Zimmer SLAC, Menlo Park, California, USA
	For LCLS-II two undulators were installed at SLAC, one for soft and one for hard x-rays. Before the superconducting linac gets turned on the copper linac is providing beams at 120 Hz to these two beam destinations. The 120 Hz can be split in many different ratios between soft and hard via a pulsed magnet. To get an optimized beam for the quite different photon energies the pulsed linac components like modulators and RF can provide many different beam parameters, mainly energies and bunch lengths for the two undulator lines. How this was implemented with timing setups of triggers and finally after the split the necessary matching of the transverse phase space will be discussed.
	Poster TUPAB083 [0.479 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB083
About •	paper received ※ 19 May 2021 paper accepted ※ 27 May 2021 issue date ※ 21 August 2021
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TUPAB087	Full Characterization of the Bunch-Compressor Dipoles for FLUTE	dipole, electron, HOM, controls	1585
	Y. Nie, A. Bernhard, E. Bründermann, A.-S. Müller, M.J. Nasse, R. Ruprecht, J. Schäfer, M. Schuh, Y. Tong KIT, Karlsruhe, Germany
	Funding: This work is supported by the BMBF project 05H18VKRB1 HIRING (Federal Ministry of Education and Research). The Ferninfrarot Linac- Und Test-Experiment (FLUTE) is a KIT-operated linac-based test facility for accelerator research and development as well as a compact, ultra-broadband and short-pulse terahertz (THz) source. As a key component of FLUTE, the bunch compressor (chicane) consisting of four specially designed dipoles will be used to compress the 40-50 MeV electron bunches after the linac down to single fs bunch length. The maximum vertical magnetic field of the dipoles reach 0.22 T, with an effective length of 200 mm. The good field region is ±40 mm and ±10.5 mm in the horizontal and vertical direction, respectively. The latest measurement results of the dipoles in terms of field homogeneity, excitation and field reproducibility within the good field regions will be reported, which meet the predefined specifications. The measured 3D magnetic field distributions have been used to perform beam dynamics simulations of the bunch compressor. Effects of the real field properties on the beam dynamics, which are different from that of the ASTRA built-in dipole field, will be discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB087
About •	paper received ※ 10 May 2021 paper accepted ※ 27 May 2021 issue date ※ 01 September 2021
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TUPAB113	Highlights From the Conceptual Design Report of the Soft X-Ray Laser at MAX IV	FEL, undulator, electron, laser	1651
	F. Curbis, J. Andersson, L. Isaksson, B.S. Kyle, F. Lindau, E. Mansten, H. Tarawneh, P.F. Tavares, S. Thorin, A.S. Vorozhtsov MAX IV Laboratory, Lund University, Lund, Sweden S. Bonetti Stockholm University, Stockholm, Sweden V.A. Goryashko, P.M. Salén Uppsala University, Uppsala, Sweden P. Johnsson, S.P. Pirani, M.A. Pop, W. Qin, S. Werin Lund University, Lund, Sweden M. Larsson Stockholm University, Department of Physics, Stockholm, Sweden A. Nilsson FYSIKUM, AlbaNova, Stockholm University, Stockholm, Sweden J.A. Sellberg KTH Physics, Stockholm, Sweden
	Funding: Knut and Alice Wallenberg Foundation The SXL (Soft X-ray Laser) project developed a conceptual design for a soft X-ray Free Electron Laser in the 1–5 nm wavelength range, driven by the existing MAX IV 3 GeV linac. In this contribution we will focus on the FEL operation modes developed for the first phase of the project based on two different linac modes. The design work was supported by the Knut and Alice Wallenberg foundation and by several Swedish universities and organizations (Stockholm, Uppsala, KTH Royal Institute of Technology, Stockholm-Uppsala FEL center, MAX IV laboratory and Lund University).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB113
About •	paper received ※ 19 May 2021 paper accepted ※ 17 June 2021 issue date ※ 19 August 2021
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TUPAB129	Beam Based Alignment in a Compact THz-FEL Facility	quadrupole, FEL, alignment, undulator	1692
	Q.S. Chen, T. Hu, K.F. Liu, B. Qin, Y.Q. Xiong HUST, Wuhan, People’s Republic of China
	In this paper, we presented the beam based alignment results in a compact THz-FEL facility. The alignment was divided into two sections, the transport line and the optical line. In the transport line, all the five quadrupoles upstream of the undulator were adjusted one by one to fit the electron beam from the traveling wave linac. In the optical line, a set of auxiliary coils were winded on the yokes of the quadrupole downstream of the double bend achromat (DBA) to produce a vertical steering force. Another combined steering magnet, together with the auxiliary coils, corrected the beam orbit in the optical line. With the dispersion free test, the displacement between the magnetic centers of the quads and the beam orbit was less than 0.1mm.
	Poster TUPAB129 [0.673 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB129
About •	paper received ※ 18 May 2021 paper accepted ※ 17 June 2021 issue date ※ 27 August 2021
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TUPAB134	Linac-to-Booster Optimization Procedure Towards High Transmission for the Alba Injector	booster, quadrupole, alignment, operation	1703
	R. Muñoz Horta, D. Lanaia, E. Marín, F. Pérez ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
	ALBA is a third generation synchrotron light source that consists of 3 accelerators (Linac, Booster and Storage ring) and two transfer lines, Linac-to-Booster (LTB) and Booster-to-Storage (BTS). The ALBA accelerators team has defined a robust procedure that optimizes the beam performance from Linac to Booster in terms of transmission and stability. The implemented beam-based alignment and global orbit correction techniques have been investigated first in simulations and afterwards successfully implemented in the machine.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB134
About •	paper received ※ 18 May 2021 paper accepted ※ 26 May 2021 issue date ※ 16 August 2021
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TUPAB166	A New Design of a Dressed Balloon Cavity with Superior Mechanical Properties	cavity, multipactoring, SRF, software	1769
	R.A. Kostin, C. Jing, S. Ross Euclid Beamlabs, Bolingbrook, USA I.V. Gonin, T.N. Khabiboulline, G.V. Romanov, V.P. Yakovlev Fermilab, Batavia, Illinois, USA M.P. Kelly ANL, Lemont, Illinois, USA R.E. Laxdal TRIUMF, Vancouver, Canada

Paper

Title

Other Keywords

Page

MOPAB042

Beam Dynamics Investigation for a New Project of Compton Back Scattering Photon Source at NRNU MEPhI

photon, electron, scattering, laser

186

V.S. Dyubkov, I.A. Ashanin, M. Gusarova, Yu.D. Kliuchevskaia, M.V. Lalayan, S.M. Polozov, A.I. Pronikov, V.I. Rashchikov
MEPhI, Moscow, Russia

Funding: This project is supported by Russian Foundation for Basic Research, Grant no. 19-29-12036.
The activities on physical models design of a compact monochromatic radiation source in the x-ray range based on inverse Compton scattering are started at NRNU MEPhI. There are comparison of two schemes of the photon source here: one of them is considered to be based on linac with variable energy of 20-60 MeV only and the other one is considered as accelerator complex where linac is supposed to be used as injector to medium size storage ring (energy up to 60 MeV). Preliminary results of linac structures and storage ring design as well as electron dynamics simulation are discussed

Poster MOPAB042 [0.962 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB042

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paper received ※ 13 May 2021 paper accepted ※ 20 May 2021 issue date ※ 10 August 2021

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MOPAB066

Dual Octupole Emittance Growth Correction of the CompactLight XFEL Bunch Compressors

octupole, emittance, FEL, lattice

272

R. Auchettl, R.T. Dowd
AS - ANSTO, Clayton, Australia

An optimized CompactLight X-Ray Free Electron Laser (FEL) bunch compressor design is presented. In this work, we insert an octupole into the center of the two sequential bunch compressors. We show how this scheme can adjust the compression, while correcting the undesirable peak current profile and emittance growth.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB066

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

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MOPAB075

Proposal of the Southern Advanced Photon Source and Current Physics Design Study

photon, storage-ring, lattice, emittance

300

S. Wang, J. Chen, L. Huang, Y. Jiao, B. Li, Z.P. Li, W. Liu, S.Y. Xu
IHEP, Beijing, People’s Republic of China
Y. Han, X.H. Lu, Y. Zhao
IHEP CSNS, Guangdong Province, People’s Republic of China
X. Liu
Department of Energy Sciences, Tokyo Institute of Technology, Yokohama, Japan

It has been considered to build a mid-energy fourth-generation storage ring light source neighbouring the China Spallation Neutron Source, in Guangdong Province, the south of China. The light source is named the Southern Advanced Photon Source (SAPS). Preliminary physics design studies on the SAPS have been implemented for a few years. In this paper, we will describe considerations of technical roadmap and key parameter choice for this light source, and introduce the up-to-date lattice designs and related physics studies on the SAPS.

Poster MOPAB075 [1.689 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB075

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paper received ※ 12 May 2021 paper accepted ※ 20 May 2021 issue date ※ 21 August 2021

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MOPAB092

Project of Wuhan Photon Source

storage-ring, cavity, injection, dipole

346

H.H. Li, Y. Deng, J.H. He, Y. Nie, L. Tang, J. Wang, Y.X. Zhu
IAS, Wuhan City, People’s Republic of China

Wuhan Photon Source (WHPS) has been designed as a fourth-generation light source, which consists of a low energy storage ring (1.5 GeV), a medium energy storage ring (4.0 GeV), and a linac working as a full energy injector. It has been planned to build the low energy light source first as the Phase I project, and then the medium energy light source after its completion. The low energy storage ring has been optimized with the main design parameters as following: An 8-cell, 500 mA storage ring, with a circumference of 180 m and nature emittance 238.4 pm-rad. Based on hybrid-7BA lattice structure, it reaches the soft X-ray diffraction limit. And at the middle of each cell, a 3.5 T superB magnet is used to extend the photon energy to the hard X-ray region. The swap-out injection is chosen due to the small dynamic aperture and a full energy S-band LINAC will be used as its injector. A 3rd harmonic cavity is designed for bunch lengthening to keep a sufficient lifetime. More details of the WHPS phase I project will be described in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB092

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paper received ※ 10 June 2021 paper accepted ※ 23 June 2021 issue date ※ 24 August 2021

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MOPAB098

LCLS Multi-Bunch Improvement Plan

laser, FEL, electron, experiment

365

A. Halavanau, S. Carbajo, F.-J. Decker, A.K. Krasnykh, A.A. Lutman, A. Marinelli, C.E. Mayes, D.C. Nguyen
SLAC, Menlo Park, California, USA

Current and future experiments at LCLS require XFEL pulse trains of variable time separation. The cavity based XFEL (CBXFEL) project requires multiple pulses separated by 220 ns, the X-ray Laser Oscillator (XLO) uses 15 ns spaced pulse trains and Matter under Extreme Conditions (MEC) experiments need a shortly spaced (less than 5 ns) pulse trains. In this proceeding, we discuss the LCLS multi-bunch improvement plan and report on its recently status and progress.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB098

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paper received ※ 19 May 2021 paper accepted ※ 27 July 2021 issue date ※ 20 August 2021

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MOPAB107

RF Plans for the Diamond-II Upgrade

cavity, HOM, booster, gun

391

C. Christou, P. Gu, P.J. Marten, S.A. Pande, A.F. Rankin
DLS, Oxfordshire, United Kingdom

The RF system for the proposed Diamond-II upgrade will be based on normal-conducting EU HOM-damped cavities powered by high powered solid state amplifiers and controlled by digital low level RF systems built on the microTCA platform. Reasons for these design choices are discussed, and experience of the selected technologies in the Diamond-I ring are reviewed. The storage ring will also include a third harmonic cavity, and the different design options for this device are discussed. RF design of the booster ring is presented, and details are given of an upgraded linac and gun design intended to improve the charge delivered for top-up.

Poster MOPAB107 [1.703 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB107

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paper received ※ 18 May 2021 paper accepted ※ 20 May 2021 issue date ※ 12 August 2021

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MOPAB120

Update on Injector for the New Synchrotron Light Source in Thailand

storage-ring, synchrotron, injection, photon

435

T. Chanwattana, S. Chunjarean, N. Juntong, K. Kittimanapun, S. Klinkhieo, P. Sudmuang
SLRI, Nakhon Ratchasima, Thailand
K. Manasatitpong
Synchrotron Light Research Institute (SLRI), Muang District, Thailand

Design of the new 3-GeV synchrotron light source in Thailand, Siam Photon Source II (SPS-II), has been updated. The SPS-II accelerator complex consists of a 150-MeV injector linac, a 3-GeV booster synchrotron and a 3-GeV storage ring. The RF system of both storage ring and booster is based on a frequency of 119 MHz. In this paper, design considerations and specifications of the SPS-II injector linac are presented. A study on the injector linac in multi-bunch mode (MBM) and single-bunch mode (SBM) was done to get appropriate parameters for top-up injection and different filling patterns in the storage ring.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB120

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paper received ※ 18 May 2021 paper accepted ※ 20 May 2021 issue date ※ 24 August 2021

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MOPAB133

Recovering the Positron Beam After Muon Production in the Lemma Muon Source

target, emittance, positron, injection

470

I. Drebot
INFN-Milano, Milano, Italy
M.E. Biagini, O.R. Blanco-García, A. Giribono, S. Guiducci, C. Vaccarezza, A. Variola
INFN/LNF, Frascati, Italy
S.M. Liuzzo
ESRF, Grenoble, France

In the LEMMA muon source proposal* a positron beam at 45 GeV is used to produce muons at threshold by interaction with some targets. In order to release the required intensity on the main positron source, orders of magnitude higher than the state of the art, the possibility to recover the primary positron beam after the interaction with the targets was studied. The particles distribution, with a strongly degraded energy spread after the interac- tion, was injected back into a low emittance, large energy acceptance 45 GeV ring. Studies of injection efficiency were performed. The possibility of compressing the beam in a linac before injection was also studied. As a result, even without compression, about 80% of the disrupted e⁺ beam can be injected back into the ring.
* D. Alesini et al, "Positron driven muon source for a muon collider", arXiv:1905.05747v2 [physics.acc-ph], May 2019

Poster MOPAB133 [4.171 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB133

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paper received ※ 17 May 2021 paper accepted ※ 24 May 2021 issue date ※ 20 August 2021

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MOPAB142

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

vacuum, coupling, GUI, simulation

495

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

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

Poster MOPAB142 [2.617 MB]

DOI •

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

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

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MOPAB163

First Synchronous Measurement of Single-Bunched Electron and Positron Beams with a Wideband Feedthrough-BPM at the Positron Capture Section of the SuperKEKB Injector Linac

positron, electron, solenoid, wakefield

557

M.A. Rehman, F. Miyahara, T. Suwada
KEK, Ibaraki, Japan

The SuperKEKB is an asymmetric e⁻/e⁺ collider with 40 times higher luminosity than the KEKB project, to explore the new physics beyond the standard model. For the SuperKEKB, the positrons are created by striking the accelerated electrons at a tungsten target. The secondary electrons are also produced during the positron creation process and accelerated in the capture section. Because of phase slipping in the capture section, the secondary electron bunch is only ∼ 180 ps away from the positron. Conventional stripline-type BPM cannot detect such closely spaced and opposite polarity signals due to slow frequency response and high cable losses. Therefore, a new wideband feedthrough-type beam position monitor was developed. It was successfully employed at the positron capture section of the SuperKEKB injector linac for the first synchronous measurement of the electron and positron beams. The cable losses effect also has been de-embedded to reveal correct signal properties. This paper describes the initial results of synchronous measurement of e⁻/e⁺ transverse position.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB163

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paper received ※ 20 May 2021 paper accepted ※ 27 May 2021 issue date ※ 16 August 2021

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MOPAB190

An 8 GeV Linac as the Booster Replacement in the Fermilab Power Upgrade

injection, cavity, cryomodule, booster

643

D.V. Neuffer, S.A. Belomestnykh, M. Checchin, D.E. Johnson, S. Posen, E. Pozdeyev, V.S. Pronskikh, N. Solyak, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
Increasing the Main Injector (MI) beam power above ~1.2 MW requires replacement of the 8 GeV Booster by a higher intensity alternative. Previously, rapid-cycling synchrotron (RCS) and Linac solutions were considered for this purpose. In this paper, we consider the Linac version that produces 8 GeV H⁻ beam for injection into the Recycler Ring (RR) or Main Injector (MI). The Linac takes ~1 GeV beam from the PIP-II Linac and accelerates it to ~2 GeV in a cw SRF linac, followed by a ~2-8 GeV pulsed linac using 1300 MHz cryomodules. The linac components incorporate recent improvements in SRF technology. The linac configuration and beam dynamics requirements are presented. Injection options are discussed. Research needed to implement the Booster replacement is described.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB190

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paper received ※ 15 May 2021 paper accepted ※ 28 May 2021 issue date ※ 10 August 2021

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MOPAB191

Method Development for Cavity Failure Compensation in a Superconducting Linac

cavity, emittance, lattice, ECR

647

F. Bouly
LPSC, Grenoble Cedex, France

Reliability is a major challenge within the perspective of improving the performances and sustainability of MegaWatt class accelerators. To optimize the operational costs of such accelerators the availability requirements are becoming more and more challenging. These requirements are even more stringent in the case of Accelerator Driven systems (ADS). As an example, for the MYRRHA (Multipurpose Hybrid Research Reactor for High-tech Applications) ADS demonstrator, the actual availability limit is set to a maximum of 10 beam interruptions (longer than 3 seconds) over a 3-month operating cycle. For this purpose, the accelerator design is based on a redundant and fault-tolerant scheme to enable rapid mitigation of a cavity failure. The adopted strategy is to apply for local compensation: a failed cavity is compensated by several neighboring cavities. Beam dynamics studies and method developments to apply such a failure compensation scheme are here reviewed. First simulation results for superconducting linac retuning and potential future improvements will be discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB191

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

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MOPAB192

LILac Energy Upgrade to 13 MeV

cavity, proton, controls, LLRF

651

B. Koubek, S. Altürk, M. Busch, H. Höltermann, J.D. Kaiser, H. Podlech, U. Ratzinger, M. Schuett, M. Schwarz, W. Schweizer, D. Strehl, R. Tiede, C. Trageser
BEVATECH, Frankfurt, Germany
A. Brunzel, P. Nonn, H. Schlarb
DESY, Hamburg, Germany
A.V. Butenko, D.E. Donets, B.V. Golovenskiy, A. Govorov, K.A. Levterov, D.A. Lyuosev, A.A. Martynov, V.A. Monchinsky, D.O. Ponkin, K.V. Shevchenko, I.V. Shirikov, E. Syresin
JINR, Dubna, Moscow Region, Russia

In the frame of the NICA (Nuclotron-based Ion Collider fAcility) ion collider upgrade a new light ion LINAC for protons and ions will be built in collaboration between JINR and BEVATECH GmbH. While ions with a mass-to-charge ratio up to 3 will be fed into the NUCLOTRON ring with an energy of 7 MeV/u, protons are supposed to be accelerated up to an energy of 13 MeV using a third IH structure. This energy upgrade comprises a third IH structure, a dual-use Debuncher cavity as well as an extension of the LLRF control system built on MicroTCA technology.

Poster MOPAB192 [4.914 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB192

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paper received ※ 11 May 2021 paper accepted ※ 31 May 2021 issue date ※ 20 August 2021

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MOPAB194

First 3D Printed IH-Type Linac Structure - Proof-of-Concept for Additive Manufacturing of Linac rf Cavities

cavity, vacuum, cyclotron, experiment

654

H. Hähnel, U. Ratzinger
IAP, Frankfurt am Main, Germany

Additive manufacturing (or "3D printing") has become a powerful tool for rapid prototyping and manufacturing of complex geometries. As technology is evolving, the quality and accuracy of parts manufactured this way is ever improving. Especially interesting for the world of particle accelerators is the process of 3D printing of stainless steel (and copper) parts. We present the first fully functional IH-type drift tube structure manufactured by metal 3D printing. A 433 MHz prototype cavity has been constructed to act as a proof-of-concept for the technology. The cavity is designed to be UHV capable and includes cooling channels reaching into the stems of the DTL structure. We present the first experimental results for this prototype.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB194

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paper received ※ 18 May 2021 paper accepted ※ 01 June 2021 issue date ※ 02 September 2021

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MOPAB195

Development of a Disk-and-Washer Cavity for the J-PARC Muon g-2/EDM Experiment

cavity, experiment, quadrupole, coupling

658

Y. Takeuchi, J. Tojo
Kyushu University, Fukuoka, Japan
E. Cicek, K. Futatsukawa, N. Kawamura, T. Mibe, M. Otani, T. Yamazaki, M. Yoshida
KEK, Ibaraki, Japan
Y. Iwashita
Kyoto ICR, Uji, Kyoto, Japan
R. Kitamura, Y. Kondo, T. Morishita
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
Y. Nakazawa
Ibaraki University, Hitachi, Ibaraki, Japan
N. Saito
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
Y. Sue, K. Sumi, M. Yotsuzuka
Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan
H.Y. Yasuda
University of Tokyo, Tokyo, Japan

At J-PARC, an experiment using muons accelerated by a linac is planned to measure the anomalous magnetic moment of muons and to search for the electric dipole moment. A 1296 MHz disk and washer (DAW) coupled cavity linac (CCL) is being developed for use in the middle beta section of the muon linac. The DAW CCL consists of 14 tanks with 11 cells each. All tanks are connected by bridge couplers and electromagnetic quadrupole doublets for focusing are installed in each bridge coupler. The basic design of the DAW cavity has already been completed, and now detailed cavity design studies and manufacturing process studies are underway. In this poster, we will report about these studies and the preparation status of manufacturing the DAW cavity.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB195

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paper received ※ 20 May 2021 paper accepted ※ 01 June 2021 issue date ※ 23 August 2021

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MOPAB203

Benchmark of Superconducting Cavity Models at SNS Linac

cavity, superconducting-cavity, simulation, operation

671

A.P. Shishlo
ORNL, Oak Ridge, Tennessee, USA

Funding: This manuscript has been authored by UT-Battelle, LLC, under Contract No. DE-AC0500OR22725 with the U.S. Department of Energy.
A benchmark of superconducting cavity models against Time-of-Flight measurements at the SNS linac is presented. The superconducting part of SNS linac (SCL) includes 81 RF cavities that accelerates H⁻ beam from 185.6 MeV to the final energy of 1 GeV. During the operation some of cavities can become unstable, and its amplitudes should be reduced, or they should be completely switched off. In this case, the SCL is retuned by using a linac simulation code. This simulation tool relay on an accuracy of the superconducting cavity model. This paper describes the comparison of the measured beam acceleration by one of the SCL cavities and simulations of this process. Different cavity models are used in simulations. The subject of this study is limited to the longitudinal beam dynamics, so no effects on transverse beam characteristics have been considered.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB203

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paper received ※ 14 May 2021 paper accepted ※ 20 May 2021 issue date ※ 24 August 2021

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MOPAB205

Minerva (MYRRHA Phase 1) RFQ Beam Commissioning

rfq, LEBT, emittance, MMI

675

A. Gatera, J. Belmans, F. Davin, W. De Cock, F. Doucet, L. Parez, F. Pompon, A. Ponton, D. Vandeplassche
SCK•CEN, Mol, Belgium
F. Bouly
LPSC, Grenoble Cedex, France
C. Joly, L. Perrot
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
H. Podlech
IAP, Frankfurt am Main, Germany
J. Tamura
JAEA/J-PARC, Tokai-mura, Japan
C. Zhang
GSI, Darmstadt, Germany

Funding: Part of this work was supported by the European Commission Framework Programme H₂020, MYRTE project nr. 662186
The MYRRHA project aims at coupling a 600 MeV proton accelerator to a subcritical fission core operating at a thermal power of 60 MW. The nominal proton beam for this ADS has an intensity of 4 mA and is delivered in a quasi-CW mode. Phase 1 of the project will realize a 100 MeV, 4 mA superconducting linac with the mission of ensuring the ADS requirements in terms of reliability and fault tolerance. As part of the reliability optimization program the integrated prototyping of the MINERVA injector is ongoing. The front-end of the injector is composed of an ECR proton source, a 2.6 m long LEBT (low energy beam transport line) and a four-rod RFQ accelerating the beam to 1.5 MeV. The present contribution focuses on the current beam tests on the RFQ, including beam matching, RF conditioning, assessment of the cavities’ performances and accelerated beam characterisation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB205

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paper received ※ 19 May 2021 paper accepted ※ 31 May 2021 issue date ※ 24 August 2021

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MOPAB206

The RF Parameters of Heavy Ions Linac

cavity, DTL, rfq, MEBT

679

A. Sitnikov, G. Kropachev, T. Kulevoy, D.N. Selesnev, A.I. Semennikov
ITEP, Moscow, Russia
M.L. Smetanin, A.V. Telnov, N.V. Zavyalov
VNIIEF, Sarov, Russia

The new linac for A/Z = 8, output energy 4 MeV/u and 3 mA current is under development at NRC "Kurchatov Institute"-ITEP. The linac consists of Radio-Frequency Quadrupole (RFQ) with operating frequency 40 MHz and two sections of Drift Tube Linac (DTL) with operating frequency 80 and 160 MHz, correspondently. Both DTL has a modular structure and consists of separated individually phased resonators with focusing magnetic quadrupoles located between the cavities. The DTL₁ is based on the quarter-wave resonators meanwhile DTL₂ is based on IH 5-gap resonators. The 6D beam matching between RFQ and DTLs is provided by magnetic quadrupole lenses and 2-gaps RF-bunchers. The paper presents results of the radio-frequency (RF) design of linac accelerating structures.

Poster MOPAB206 [0.559 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB206

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paper received ※ 14 May 2021 paper accepted ※ 01 July 2021 issue date ※ 29 August 2021

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MOPAB207

Design Guideline for Minimizing Space-Charge-Induced Emittance Growth

emittance, rfq, proton, space-charge

682

C. Zhang
GSI, Darmstadt, Germany

Space-charge-induced emittance growth is a big concern for designing low-energy and high-intensity linacs. The Equipartitioning Principle was introduced to minimize space-charge-induced emittance growth by removing free energy between the transverse and longitudinal degrees of freedom. In this study, a different design guideline is being proposed. It suggests holding the ratio of longitudinal emittance to transverse emittance around one and take advantage of low emittance transfer for minimizing emittance growth. Using a high-intensity RFQ accelerator as an example, a comparison between the two design methods has been made.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB207

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paper received ※ 17 May 2021 paper accepted ※ 21 May 2021 issue date ※ 01 September 2021

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MOPAB210

High-Gradient Booster for Enhanced Proton Radiography at LANSCE

booster, cavity, proton, focusing

693

S.S. Kurennoy, Y.K. Batygin
LANL, Los Alamos, New Mexico, USA

Increasing energy of proton beam at LANSCE from 800 MeV to 3 GeV improves radiography resolution ~10 times. We propose accomplishing this energy boost with a compact cost-effective linac based on cryo-cooled normal conducting high-gradient RF accelerating structures. High-gradient structures exceeding 100 MV/m have been developed for electron acceleration and operate with short RF pulse lengths below 1 us. Though such parameters are unusual for typical proton linacs, they fit perfectly for proton radiography (pRad) applications. The pRad limits contiguous trains of beam micro-pulses to less than 80 ns to prevent blur in images. For a compact pRad booster at LANSCE, we develop a staged design: a short section to capture and compress the 800-MeV proton beam followed by the main high-gradient linac. Our beam dynamics study addresses the beam magnetic focusing and minimizing its energy spread, which are challenging in high-gradient structures but very important for successful pRad operation.

Poster MOPAB210 [0.809 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB210

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paper received ※ 10 May 2021 paper accepted ※ 17 August 2021 issue date ※ 11 August 2021

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MOPAB216

20-24 GeV FFA CEBAF Energy Upgrade

booster, lattice, optics, emittance

715

S.A. Bogacz, J.F. Benesch, R.M. Bodenstein, B.R. Gamage, G.A. Krafft, V.S. Morozov, Y. Roblin
JLab, Newport News, Virginia, USA
J.S. Berg, S.J. Brooks, D. Trbojevic
BNL, Upton, New York, USA
D. Douglas
Douglas Consulting, York, Virginia, USA
G.H. Hoffstaetter
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177
A proposal was formulated to increase the CEBAF energy from the present 12 GeV to 20-24 GeV by replacing the highest-energy arcs with Fixed Field Alternating Gradient (FFA) arcs. The new pair of arcs would provide six or seven new beam passes, going through this magnet array, allowing the energy to be nearly doubled using the existing CEBAF SRF cavity system. One of the immediate accelerator design tasks is to develop a proof-of-principle FFA arc magnet lattice that would support simultaneous transport of 6-7 passes with energies spanning a factor of two. We also examine the possibility of using combined function magnets to configure a cascade, six-way beam split switchyard. Finally, a novel multi-pass linac optics based on a weakly focusing lattice is being explored.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB216

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paper received ※ 19 May 2021 paper accepted ※ 02 June 2021 issue date ※ 29 August 2021

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MOPAB236

Ion Beam Dynamics in Linac-100 Facility at Jinr

cavity, acceleration, emittance, rfq

767

S.M. Polozov, V.S. Dyubkov, Y. Lozeev, T.A. Lozeeva, A.V. Samoshin
MEPhI, Moscow, Russia

The heavy-ion linac LINAC-100 is a superconducting driver-accelerator proposed as one of the prospective projects at JINR. Its goal is to accelerate primary stable isotope CW high-intensity beams to energies up to 100 MeV/u*. This linac is discussed as the first stage of a new rare isotope facility DERICA (Dubna Electron-Radioactive Ion Collider fAcility), being under development at JINR since 2017**. LINAC-100 is supposed to work with a wide range of beams with A/Z 3.5/7, Uranium U³⁴⁺ being the heaviest. Its concept has undergone many changes, mostly considering stripping cells to increase accelerator efficiency. During the latest investigations of various stripping cells [***, ****], Uranium beam stripping at the energy 10 MeV/u and utilizing three adjacent charge states 59-61+ resulted in 60% output beam intensity preservation (or 30 pA overall output current). The current layout of the LINAC-100 is the following: one or two (separately for light and heavy ions) normal conducting front-end linacs, gas stripper cell at 10 MeV/u, and the SC section. In this paper three charge state Uranium beam dynamics in the current version of SC LINAC-100 section is presented.
*S Polozov 2020 PhysScr 95 084006
**A S Fomichev Phys Usp 62(7) 675-690 2019
***Tolstikhina I 2018 Basic At Int of Acc H Ions in Matter 98 1
**** W Barth J Phys Conf Ser 1350:012096

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB236

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paper received ※ 20 May 2021 paper accepted ※ 17 August 2021 issue date ※ 26 August 2021

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MOPAB246

Design of the MEBT for the JAEA-ADS Project

MEBT, emittance, rfq, quadrupole

790

B. Yee-Rendón, Y. Kondo, F.M. Maekawa, S.I. Meigo, J. Tamura
JAEA/J-PARC, Tokai-mura, Japan

The Medium Energy Beam Transport (MEBT) will transport a CW proton beam with a current of 20 mA and energy of 2.5 MeV from the exit of the normal conducting Radiofrequency Quadrupole (RFQ) to the superconducting Half-Wave resonator (HWR) section. The MEBT must provide a good matching between the RFQ and HWR, effective control of the emittance growth and the halo formation, enough space for all the beam diagnostics devices, among others. This work reports the first lattice design and the beam dynamics studies for the MEBT of the JAEA-ADS.

Poster MOPAB246 [0.827 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB246

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paper received ※ 10 May 2021 paper accepted ※ 02 June 2021 issue date ※ 19 August 2021

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MOPAB263

Preliminary Beam Dynamics Studies for 200 MeV Superconducting Linac Planned at KOMAC

proton, DTL, radiation, lattice

837

S. Lee, J.J. Dang, H.S. Kim, H.-J. Kwon
Korea Atomic Energy Research Institute (KAERI), Gyeongbuk, Republic of Korea
Y.-S. Cho
KAERI, Daejon, Republic of Korea

Funding: This work has been supported through KOMAC operation fund of KAERI by the Korea government (MSIT).
Korea Multi-purpose Accelerator Complex (KOMAC) is planning an energy upgrade of the existing 100 MeV proton linac to 200 MeV using a superconducting Half Wave Resonator (HWR) operating at 350 MHz. A cryomodule is planned to house four HWR cavities with a warm doublet focusing lattice structure. Matching between the already existing DTL section and HWR section is designed and studied. We report the preliminary study of the beam dynamics of the 200 MeV superconducting linac carried out at KOMAC.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB263

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paper received ※ 20 May 2021 paper accepted ※ 01 July 2021 issue date ※ 24 August 2021

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MOPAB266

Start-to-End Study on Laser and RF Jitter Effects for MAX-IV SXL

FEL, laser, radiation, simulation

844

S.P. Pirani, B.S. Kyle
MAX IV Laboratory, Lund University, Lund, Sweden
F. Curbis, M.A. Pop, S. Werin
Lund University, Lund, Sweden
W. Qin
DESY, Hamburg, Germany

A Soft X-ray free electron laser (FEL) for the MAX IV Laboratory is currently in the design phase and it will use the existing 3 GeV linac. Present stability limits in the RF and the photocathode laser will affect the performance of the FEL. One of the critical elements for the design of a FEL is to have an estimation on jitter effects of the accelerator parameters on the X-ray radiation. In this regard, we implemented a start-to-end study using Astra, Elegant and Genesis in order to assess possible variations in pulse energy, photon pulse length and spectral width in the Soft X-ray Laser (SXL) radiation. This investigation provides insights on the final SXL performance variation due to RF and laser related jitter affecting the electron beam.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB266

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paper received ※ 19 May 2021 paper accepted ※ 26 July 2021 issue date ※ 24 August 2021

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MOPAB268

Design of a Continuous Wave Heavy Ion RFQ for BISOL

rfq, emittance, ISOL, LEBT

851

S. Liu, M.Y. Han, Y.R. Lu, Q.Y. Tan, Z. Wang
PKU, Beijing, People’s Republic of China

The Beijing isotope separation online (BISOL) facility will be used to study the new physics and technologies at the limit of the nuclear stability. The post accelerator for BISOL facility aims to accelerate radioactive beams to 150MeV/u. As an injector for the downstream superconducting linac, a 4-vane RFQ operating at 81.25MHz is needed to accelerate high-charge-state ions such as 132Sn²²⁺ from 3keV/u to 500keV/u in CW mode. We have compared two kinds of beam dynamics of BISOL RFQ with and without a Multi-Harmonic Buncher (MHB) bunching the continuous wave beam up-stream of the RFQ. The results indicate that it is possible to keep transverse emittance growth within tolerable limits while the longitudinal emittance is much smaller than the design without an external buncher. The acceleration of multi-charge beams simultaneously in the RFQ is also discussed in this paper.

Poster MOPAB268 [1.829 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB268

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paper received ※ 19 May 2021 paper accepted ※ 25 May 2021 issue date ※ 16 August 2021

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MOPAB281

Research on Resolution Evaluation of Stripline BPM at SXFEL-UF

FEL, network, electron, experiment

892

B. Gao, J. Chen, Y.B. Leng
SSRF, Shanghai, People’s Republic of China

48 stripline BPMs are installed in the injection section and linear acceleration section of Shanghai X-ray Free Electron Laser (SXFEL) for electron beam position measurement. These two sections require resolution of 20 µm@100pC. Resolution evaluation is an important step in BPM installation and commissioning. This paper presents BPM resolution evaluation methods based on correlation analysis. Experimental methods, data processing and result analysis will be discussed

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB281

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paper received ※ 19 May 2021 paper accepted ※ 27 May 2021 issue date ※ 02 September 2021

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MOPAB299

STRUCTURAL OPTIMIZATION DESIGN OF FARADAY CUP FOR BEAM COMMISSIONING OF CSNS

target, MMI, proton, neutron

943

A.X. Wang, L. Kang, M. Meng, J.L. Sun
IHEP, Beijing, People’s Republic of China
J.X. Chen, H.Y. He, L. Liu, R.H. Liu, X.J. Nie, C.J. Ning, R.Y. Qiu, G.Y. Wang, T. Yang, J.B. Yu, Y.J. Yu, J.S. Zhang, D.H. Zhu
IHEP CSNS, Guangdong Province, People’s Republic of China

Faraday cup is used to absorb and stop the beam during the two phases of beam commissioning, such as the front end (FE) system and the temporary line after the drift tube linac (DTL) at the Chinese Spallation Neutron Source (CSNS). According to the beam physical parameters, graphite is selected to stop the beam directly, and oxygen-free copper which is just behind the graphite as the thermal conductive material. By the analysis and comparison of the target type and cooling efficiency, the single slant target is adopted. The incident angle between the target surface and the beam is set as 10°, meanwhile a new waterfall type water-cooling structure with parallel tunnels is designed to improve the cooling efficiency. The finite element software ANSYS is used for thermal analysis of the model, by which the diameter and interval of water cooling tunnels are optimized. The faraday cup discussed in this paper is finally successfully installed in the beam commissioning line and went well.

Poster MOPAB299 [1.113 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB299

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paper received ※ 13 May 2021 paper accepted ※ 08 July 2021 issue date ※ 19 August 2021

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MOPAB302

Characterization of the Full Transverse Phase Space of Electron Bunches at ARES

simulation, experiment, electron, quadrupole

952

S. Jaster-Merz, R.W. Aßmann, R. Brinkmann, F. Burkart, H. Dinter, W. Kuropka, F. Mayet, T. Vinatier
DESY, Hamburg, Germany
R.W. Aßmann
INFN/LNF, Frascati, Italy
S. Jaster-Merz
University of Hamburg, Hamburg, Germany

The ARES linear accelerator at the SINBAD facility (DESY) is dedicated to perform accelerator R&D studies with sub-fs short electron bunches to test novel acceleration techniques and diagnostics devices. Currently, the commissioning of the linac is ongoing and first experiments are being performed. For this, the knowledge of the full phase space of the particle beams is of high interest to, for example, optimize the accelerator performance and identify possible errors in the beam line. Tomographic methods can be used to gain insight into the full 4D transverse phase space and its correlations. Here, simulation results and first experimental preparations of a 4D transverse phase-space tomography of electron bunches at ARES are presented and discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB302

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paper received ※ 17 May 2021 paper accepted ※ 16 June 2021 issue date ※ 30 August 2021

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MOPAB315

Beam Diagnostics for Commissioning and Operation of the FAIR Proton Linac

proton, diagnostics, rfq, MMI

972

T. Sieber, P. Forck, S. Udrea
GSI, Darmstadt, Germany
J. Herranz, A. Vizcaino-de-Julian
Proactive Research and Development, Sabadell, Spain

For the planned antiproton experiments at FAIR a dedicated proton injector Linac is currently under construction. It will be connected via the old UNILAC transfer beamline to SIS18 and has a length of ~30 m. The Linac will accelerate protons up to a final energy of 68 MeV, at a pulse length of 35 µs and a maximum repetition rate of 4 Hz. It will operate at 325 MHz and consists of a new so called "Ladder" RFQ type, followed by a chain of CH-cavities, partially coupled by rf-coupling cells. We have worked out a diagnostics system, which allows detailed measurement and study of all beam parameters during commissioning and later during regular operation. The diagnostics devices will - in a first step - be installed on a diagnostics testbench for stepwise commissioning. We present the concepts for Linac and testbench with some special emphasis on energy measurements with spectrometer and SEM Grid profile measurements.

Poster MOPAB315 [3.149 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB315

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paper received ※ 14 May 2021 paper accepted ※ 24 June 2021 issue date ※ 30 August 2021

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MOPAB316

Commissioning the New CERN Beam Instrumentation Following the Upgrade of the LHC Injector Chain

MMI, electron, diagnostics, instrumentation

976

F. Roncarolo, S. Bart Pedersen, J.M. Belleman, D. Belohrad, M. Bozzolan, C. Bracco, S. Di Carlo, J. Emery, A. Goldblatt, A. Guerrero, S. Levasseur, A. Navarro Fernandez, E. Renner, H.S. Sandberg, J.W. Storey, J. Tan, J. Tassan-Viol
CERN, Geneva, Switzerland
A. Navarro Fernandez
UPC, Barcelona, Spain
E. Renner
TU Vienna, Wien, Austria

The LHC injectors Upgrade (LIU) program has been fully implemented during the second long shutdown (LS2), which took place in 2019-20. In this context, new or upgraded beam instrumentation was developed to cope with H⁻ beam in LINAC4 and the new Proton Synchrotron Booster (PSB) injection systems which would provide high brightness proton beams in the rest of the injector complex. After a short overview of the newly installed diagnostics, the main focus of this paper will move to the instruments already commissioned with the beam. This will include LINAC4 diagnostics, the PSB H⁰/H⁻ monitor, the PSB Trajectory Measurement System, and the PS beam gas ionization monitor. In addition, particular emphasis will be given to the first operational experience with the new generation of fast wire scanners installed in all injector synchronous.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB316

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paper received ※ 19 May 2021 paper accepted ※ 17 June 2021 issue date ※ 14 August 2021

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MOPAB321

Schlieren Imaging for Flow Visualisation of Gas Jet in Vacuum for Accelerator Applications

vacuum, controls, laser, solenoid

989

S. Rosily, B. Dikshit, S. Krishnagopal
Homi Bhbha National Institute (HBNI), DAE, Mumbai, India
S. Krishnagopal, S. Rosily
BARC, Mumbai, India

Schlieren imaging was explored for flow visualising of a gas jet in vacuum for beam profile monitor application. In supersonic gas jet based beam profile monitors, the high density jet flows through various differentially pumped skimmer stages before being shaped into a sheet. Schlieren imaging is a well known technique used in aerodynamic studies to visualise gas flow. This technique is explained in the paper along with a gist of other flow visualisation techniques. An Z-type schlieren imaging setup used to view the high density flow features of a pulsed supersonic gas jet inside vacuum is described in detail. Flow around a Pitot probe in supersonic flow was simulated and the resultant density profile obtained was compared with the image obtained using schlieren imaging. The flow features including a detached shock around the tip of the probe was observable at medium and high vacuum after processing the image. Image processing algorithms and tools useful for this application are also discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB321

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paper received ※ 20 May 2021 paper accepted ※ 26 May 2021 issue date ※ 29 August 2021

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MOPAB325

Development of Bunch Width Monitor with High Time Resolution for Low Emittance Muon Beam in the J-PARC Muon g-2 / EDM Experiment

emittance, experiment, acceleration, laser

1004

M. Yotsuzuka, T. Iijima, K. Inami, Y. Sue, K. Sumi
Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan
T. Iijima
KMI, Nagoya, AIchi Prefecture, Japan
Y. Kondo
JAEA, Ibaraki-ken, Japan
T. Mibe
KEK, Tsukuba, Japan
Y. Nakazawa
Ibaraki University, Ibaraki, Japan
M. Otani, N. Saito
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
Y. Takeuchi
Kyushu University, Fukuoka, Japan
H.Y. Yasuda
University of Tokyo, Tokyo, Japan

The J-PARC muon g-2/EDM experiment plans to measure the muon anomalous magnetic moment and electric dipole moment sensitive to new physics with high precision. This experiment uses a novel method using the low-emittance muon beam achieved by cooling and re-acceleration. In the muon linac consisting of four different accelerating cavities, the main cause of the emittance growth is the beam mismatch between the different cavities. Especially for the cavity in the low-beta section (ß=0.08-0.27), the longitudinal acceptance is narrow and beam mismatch has a significant impact. In order to perform beam matching in the low-beta cavity, a new beam monitor that can measure the low-emittance muon beam with high time resolution is required. Therefore, we developed a bunch width monitor (BWM) using a microchannel plate. The time resolution of the BWM was measured to be 40 picoseconds on the test bench using a picosecond pulse laser. It means that the BWM is possible to perform diagnosis with a phase accuracy of 1% for the acceleration phase of 324 MHz. We also evaluated factors that limit the current time resolution. In this presentation, the results of an evaluation of the BWM are reported.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB325

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paper received ※ 19 May 2021 paper accepted ※ 08 June 2021 issue date ※ 10 August 2021

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MOPAB326

Maximum Entropy Reconstruction of 4D Transverse Phase Space from 2D Projections: with Application to Laser Wire Measurements in the SNS HEBT

laser, emittance, neutron, coupling

1008

C.Y. Wong, A.P. Shishlo
ORNL, Oak Ridge, Tennessee, USA

We employ the principle of maximum entropy (MENT) to reconstruct 4D transverse phase space from its 2D projections. Emittance devices commonly measure two specific 2D projections, i.e. the horizontal and vertical phase space distributions. We show that: 1) given only these two 2D projections, their product is the analytic MENT solution to the 4D distribution; and 2) additional 2D projections provide information on inter-plane coupling in the MENT reconstruction of the 4D phase space which can be solved numerically. At the Spallation Neutron Source (SNS), laser wires in the high energy beam transport (HEBT) enable non-invasive two-slit type transverse phase space measurements. Laser wires play the role of the first slit whereas physical wires downstream of a drift act as the second slit. We reconstruct the 4D phase space in the HEBT using all four horizontal/vertical permutations of the two slits where: 1) the two configurations with parallel slits constitute ordinary 2D phase space measurements in either plane; and 2) the two configurations with perpendicular slits carry coupling information.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB326

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paper received ※ 20 May 2021 paper accepted ※ 19 July 2021 issue date ※ 17 August 2021

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MOPAB329

Operations of Copper Cavities at Cryogenic Temperatures

cavity, coupling, cryogenics, ECR

1020

H. Wang, U. Ratzinger, M. Schuett
IAP, Frankfurt am Main, Germany

How the anomalous skin effect by copper affects the efficiency of copper- cavities will be studied in the experiment, especially at lower temperatures. The accurate quality factor Q and resonant frequency of three coaxial cavities will be measured over the temperature range from 300 to 22 K. The three coaxial cavities have the same structure, but different lengths, which correspond to resonant frequencies: around 100 MHz, 220 MHz and 340 MHz. The motivation is to check the feasibility of an efficient pulsed, liquid nitrogen cooled ion linac.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB329

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paper received ※ 19 May 2021 paper accepted ※ 07 June 2021 issue date ※ 02 September 2021

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MOPAB335

SNS Warm Linac Circulator Breakdown Considerations for the PPU Project

operation, simulation, DTL, proton

1041

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

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

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB335

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paper received ※ 17 May 2021 paper accepted ※ 28 May 2021 issue date ※ 23 August 2021

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MOPAB337

Design Study of the Spiral Buncher Cavities for the High Current Injector at IUAC

cavity, impedance, bunching, rfq

1048

S. Kedia, R. Ahuja, R. Mehta, C.P. Safvan
IUAC, New Delhi, India

Two high energy beam transport (HEBT) cavities have been designed to provide the longitudinal beam bunching between drift tube linac and superconducting super-buncher of the superconducting linear (SC-LINAC) accelerator. The spiral type cavities were chosen over standard quarter wave-type geometry due to its higher shunt impedance. The TRACE-3D ion-optical codes have been used to determine the bunching voltage and physical location of the cavities. The two-gap RF cavity requires 80 kV/gap to provide the longitudinal beam bunching at the entrance of the superconducting buncher. The CST-MWS simulations were performed to design the spiral type bunching cavities. The various parameters including shunt impedance, quality factor, average accelerating field, and total power loss were determined using CST-MWS simulations. The ratio of drift tube radius to the gap was optimized to achieve the maximum effective electric field with minimum field penetration within the gap. The SolidWorks software has been used to prepare a mechanical model for the fabrication.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB337

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paper received ※ 15 May 2021 paper accepted ※ 26 May 2021 issue date ※ 26 August 2021

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MOPAB344

Machine Learning Models for Breakdown Prediction in RF Cavities for Accelerators

cavity, operation, network, vacuum

1068

C. Obermair, A. Apollonio, T. Cartier-Michaud, N. Catalán Lasheras, L. Felsberger, W.L. Millar, W. Wuensch
CERN, Geneva, Switzerland
C. Obermair, F. Pernkopf
TUG, Graz, Austria

Radio Frequency (RF) breakdowns are one of the most prevalent limits in RF cavities for particle accelerators. During a breakdown, field enhancement associated with small deformations on the cavity surface results in electrical arcs. Such arcs degrade a passing beam and if they occur frequently, they can cause irreparable damage to the RF cavity surface. In this paper, we propose a machine learning approach to predict the occurrence of breakdowns in CERN’s Compact LInear Collider (CLIC) accelerating structures. We discuss state-of-the-art algorithms for data exploration with unsupervised machine learning, breakdown prediction with supervised machine learning, and result validation with Explainable-Artificial Intelligence (Explainable AI). By interpreting the model parameters of various approaches, we go further in addressing opportunities to elucidate the physics of a breakdown and improve accelerator reliability and operation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB344

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paper received ※ 20 May 2021 paper accepted ※ 16 July 2021 issue date ※ 11 August 2021

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MOPAB348

Portable 2.5 MeV X-Band Linear Accelerator Structure

GUI, gun, radiation, target

1084

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

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

Poster MOPAB348 [1.490 MB]

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

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

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MOPAB349

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

gun, betatron, detector, GUI

1087

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

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

Poster MOPAB349 [2.182 MB]

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

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

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MOPAB357

The New Design of the RF System for the SPS-II Light Source

cavity, storage-ring, booster, impedance

1110

N. Juntong, T. Chanwattana, S. Chunjarean, S. Krainara, T. Phimsen, T. Pulampong
SLRI, Nakhon Ratchasima, Thailand
K. Manasatitpong
Synchrotron Light Research Institute (SLRI), Muang District, Thailand

The new light source facility in Thailand, SPS-II, is a ring-based 3 GeV light source with a circumference of approximately 330 m. The target stored beam current is 300 mA with an emittance of below 1.0 nm rad. The injector has been changed from a full energy linac to a booster injector with 150 MeV linac. The main RF frequency has been reconsidered to a low-frequency range at 119 MHz. Low frequency is chosen with the benefit of low RF voltage for a high RF acceptance together with experience with the present ring RF system of 118 MHz. Details of RF frequency consideration will be discussed. The requirements and details of the RF systems in the booster ring and the storage ring will be presented.

Poster MOPAB357 [1.696 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB357

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paper received ※ 17 May 2021 paper accepted ※ 08 June 2021 issue date ※ 14 August 2021

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MOPAB370

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

GUI, vacuum, simulation, ECR

1143

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

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

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

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

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MOPAB384

Nb₃Sn Coating of Twin Axis Cavity for Accelerator Applications

cavity, niobium, SRF, dipole

1175

J.K. Tiskumara, S.U. De Silva, J.R. Delayen, H. Park
ODU, Norfolk, Virginia, USA
J.R. Delayen, H. Park, U. Pudasaini, C.E. Reece
JLab, Newport News, Virginia, USA
G.V. Eremeev
Fermilab, Batavia, Illinois, USA

Funding: Research supported by DOE Office of Science Accelerator Stewardship Program Award DE- SC0019399. Partially authored by Jefferson Science Associates under contract no. DEAC0506OR23177
A Superconducting twin axis cavity consisting of two identical beam pipes that can accelerate and decelerate beams within the same structure has been proposed for the Energy Recovery Linac (ERL) applications. There are two niobium twin axis cavities at JLab fabricated with the intention of later Nb₃Sn coating and now we are progressing to coat them using vapor diffusion method. Nb₃Sn is a potential alternate material for replacing Nb in SRF cavities for better performance and reducing operational costs. Because of advanced geometry, larger surface area, increased number of ports and hard to reach areas of the twin axis cavities, the usual coating approach developed for typical elliptical single-axis cavities must be evaluated and requires to be adjusted. In this contribution, we report the first results from the coating of a twin axis cavity and discuss current challenges with an outlook for the future.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB384

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paper received ※ 19 May 2021 paper accepted ※ 24 May 2021 issue date ※ 27 August 2021

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MOPAB386

Development of Nitrogen-Doping Technology for SHINE

cavity, SRF, niobium, ECR

1182

Y. Zong, X. Huang, Z. Wang
SINAP, Shanghai, People’s Republic of China
J.F. Chen, H.T. Hou, D. Wang, J.N. Wu, Y.X. Zhang
SARI-CAS, Pudong, Shanghai, People’s Republic of China
P.C. Dong
Shanghai Advanced Research Institute, Pudong, Shanghai, People’s Republic of China
Y.W. Huang
ShanghaiTech University, Shanghai, People’s Republic of China
J. Rong
SSRF, Shanghai, People’s Republic of China

The Shanghai HIgh repetition rate XFEL aNd Extreme light facility (SHINE) is under construction, which needs six hundred 1.3GHz cavities with high quality factor. In this paper, we present the newest studies on single cell cavities with nitrogen doping and cold EP treatment, showing an obvious improvement compared with the previous results.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB386

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paper received ※ 21 May 2021 paper accepted ※ 08 June 2021 issue date ※ 20 August 2021

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MOPAB405

Study of Targets to Produce Molybdenum-99 Using 30 MeV Electron Linear Accelerator

target, electron, photon, radiation

1222

T.S. Dixit, A.P. Deshpande, R. Krishnan, A. Shaikh
SAMEER, Mumbai, India

Funding: Ministry of Electronics and Information Technology, Government of India (MeitY)
Two approaches to produce 99Mo are studied using GEANT4 are reported in this paper. First, in converter target approach, bremsstrahlung photons are generated in a high Z target. The emitted photons then hit 100Mo secondary target, producing 99Mo through (gamma, n) reaction. Second, in direct target approach, high energy electron beam hits 100Mo target, where both (e, gamma) and (gamma, n) reactions take place simultaneously. A 30 MeV, 5-10 kW beam power electron linac is under development at SAMEER. The acceleration gradient required to achieve 30 MeV energy will be provided by two linacs operated in series configuration and the high average beam power will be achieved by running the system at high duty operation. Main aim of this study is to optimize experimental parameters to maximize specific activity of 99Mo. Since, 100Mo is very expensive material therefore judicious use of the material is very important. Hence, optimization of electron beam energy and target dimensions are studied in detail in both the approaches. It is found that the direct target approach gives higher specific activity compared to the converter target approach.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB405

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paper received ※ 19 May 2021 paper accepted ※ 06 June 2021 issue date ※ 14 August 2021

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MOPAB410

Preliminary Studies of a Compact VHEE Linear Accelerator System for FLASH Radiotherapy

radiation, electron, operation, impedance

1229

L. Giuliano, F. Bosco, M. Carillo, D. De Arcangelis, L. Faillace, L. Ficcadenti, M. Migliorati, A. Mostacci, L. Palumbo
Sapienza University of Rome, Rome, Italy
D. Alesini, M. Behtouei, B. Spataro
INFN/LNF, Frascati, Italy
G. Cuttone, G. Torrisi
INFN/LNS, Catania, Italy
V. Favaudon, S. Heinrich, A. Patriarca
Institut Curie - Centre de Protonthérapie d’Orsay, Orsay, France

Funding: The work is supported by La Sapienza University, research grant "grandi progetti di ricerca 2020".
The Flash Radio Therapy is a revolutionary new technique in the cancer cure: it spares healthy tissue from the damage of the ionizing radiation maintaining the tumor control as efficient as in conventional radiotherapy. To allow the implementation of the FLASH Therapy concept into actual clinical use, it is necessary to have a linear accelerator able to deliver the very high dose and very high dose rate (>10⁶ Gy/s) in a very short irradiation time (beam on time < 100ms). Low energy S-band Linacs (up to 7 MeV) are being used in Radiobiology and pre-clinic applications but in order to treat deep tumors, the energy of the electrons should achieve the range of 60-100 MeV. In this paper, we address the main issues in the design of a compact C band (5.712 GHz) electron linac-VHEE for FLASH Radio Therapy. We present preliminary studies on C-band structures at La Sapienza and at INFN-LNS, aiming to reach a high accelerating gradient and high current necessary to deliver a dose >1 Gy/pulse, with very short electron pulse.

Poster MOPAB410 [0.650 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB410

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paper received ※ 19 May 2021 paper accepted ※ 09 June 2021 issue date ※ 21 August 2021

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MOPAB413

The Next Ion Medical Machine Study at CERN: Towards a Next Generation Cancer Research and Therapy Facility with Ion Beams

synchrotron, proton, superconducting-magnet, operation

1240

M. Vretenar, V. Bencini, E. Benedetto, M.R. Khalvati, A.M. Lombardi, M. Sapinski, D. Tommasini
CERN, Meyrin, Switzerland
E. Benedetto, M. Sapinski
TERA, Novara, Italy
P. Foka
GSI, Darmstadt, Germany

Cancer therapy with ions has several advantages over X-ray and proton therapy, but its diffusion remains limited primarily because of the size and cost of the accelerator. To develop technologies that might improve performance and reduce accelerator cost with respect to present facilities, CERN has recently launched the Next Ion Medical Machine Study (NIMMS), leveraging CERN expertise in accelerator fields to disseminate technologies developed for basic science. A perspective user and key partner of NIMMS is the SEEIIST (South East European International Institute for Sustainable Technologies), established to build in the region an innovative facility for combined cancer therapy and biomedical research with ion beams. For SEEIIST and other potential users, three options are being considered. Conceptual designs of a warm-magnet synchrotron at high beam intensity, of a compact superconducting synchrotron, and of a high-frequency linear accelerator have been compared in terms of cost, risk and development time. The development of curved superconducting magnets, of compact synchrotrons and ion gantries, and of linacs is being pursued within EU-funded projects or specific collaborations

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB413

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paper received ※ 18 May 2021 paper accepted ※ 20 July 2021 issue date ※ 13 August 2021

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MOPAB415

Failure Rates and Downtimes of Multi-Leaf Collimators in Indonesia

radiation, target, gun, power-supply

1248

G.S. Peiris, S.L. Sheehy
The University of Melbourne, Melbourne, Victoria, Australia
M.F. Kasim, S.A. Pawiro
University of Indonesia, Depok, Jawa Barat, Indonesia

One of the greatest barriers to cancer treatment in Low and Middle-Income Countries (LMICs) is the access to Radiotherapy Linear Accelerators (LINACs). Not only are the LINACs complex, the harsh environment of LMICs cause frequent breakdowns resulting in downtimes ranging from days to months. Recent research has identified a disparity between LMICs and High Income Countries (HICs) and determined the Multi-Leaf Collimator (MLC) as a component needing re-evaluation. The MLC causes over 30% of the problems in RT LINACs, but the modes of failure and quantify the extent of the damage done are yet to be quantified. Using data from across Indonesia, we show the pathways to failure of RT Machines and frequency of breakdowns over time. A component of the MLC needs to be replaced every 9.98 faults per 1000 patients treated and the MLC itself breaks down on average every 36±1.8 days. When comparing the downtime by leaf width, the data shows 5mm leaves contribute 18.27±6.5% to all breakdowns while 10mm makes up 15.87±4.3%. These results outline the need to reassess the current generation of RT LINACs and ultimately work towards guiding future designs to be robust enough for all environments.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB415

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paper received ※ 19 May 2021 paper accepted ※ 09 June 2021 issue date ※ 16 August 2021

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TUXC08

Simulation and Beam Experiments of a Multi-Harmonics Buncher in SSC-Linac

simulation, experiment, rfq, heavy-ion

1319

Q.Y. Kong, H. Du, P. Jin, L. Jing, X.N. Li, Z.S. Li, Zh. Liu, J.W. Xia, X. Yin, Y. Zhang
IMP/CAS, Lanzhou, People’s Republic of China

Funding: This work was supported by the National Natural Science Foundation of China(No. 11375243) and Guangdong Innovative and Entrepreneurial Research Team Program(No.2016ZT06G373).
A compact dual-gap Multi-Harmonics Buncher has been successfully used at the SSC-Linac, a linear accelerator dedicates to beam injection into SSC in HIRFL. SSC-Linac operates at 53.667MHz, which is forth time of the RF frequency of the SSC. In order to increase the longitudinal capture efficiency, and enhance the current out of SSC, an independent MHB(Multi-Harmonics Buncher) had been installed into the LEBT of SSC-Linac. The fundamental frequency of the MHB is 13.417MHz. The buncher adopts the mechanical structure of dual-gap and sawtooth waveform is generated by multi-harmonics synthetic technology. Beam performance simulation with MHB have been done with code BEAMPATH. Besides, 84Kr¹⁴⁺ beam has been bunched successfully using the MHB in our experiments, the maximum bunch efficiency of 86.1% has been measured in experiments.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUXC08

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paper received ※ 31 May 2021 paper accepted ※ 12 July 2021 issue date ※ 11 August 2021

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TUPAB015

Beam Loading Compensation of APS Cavity with Off-Crest Acceleration in ILC e-Driven Positron Source

positron, beam-loading, electron, target

1368

M. Kuriki, S. Konno, H. Nagoshi
HU/AdSM, Higashi-Hiroshima, Japan
T. Omori, J. Urakawa, K. Yokoya
KEK, Ibaraki, Japan
T. Takahashi
Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan

In E-Driven positron source of ILC, the generated positron is captured by RF accelerator by APS cavity. The positron is initially placed at the deceleration phase and gradually slipped down to acceleration phase. Because the beam-loading is expected to be more than 1A with a multi-bunch format, the compensation is essential to obtain uniform intensity over the pulse. A conventional method for the compensation is controlling the timing, but it doesn’t work in off-crest case. In this manuscript, we discuss the compensation with the phase and amplitude modulation on the input RF.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB015

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paper received ※ 19 May 2021 paper accepted ※ 27 July 2021 issue date ※ 26 August 2021

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TUPAB017

Study of Conduction-Cooled Superconducting Quadrupole Magnets Combined with Dipole Correctors for the ILC Main Linac

quadrupole, dipole, SRF, cavity

1375

Y. Arimoto, S. Michizono, Y. Morikawa, N. Ohuchi, T. Oki, H. Shimizu, K. Umemori, X. Wang, A. Yamamoto, Y. Yamamoto, Z.G. Zong
KEK, Ibaraki, Japan
V.S. Kashikhin
Fermilab, Batavia, Illinois, USA

A superconducting rf (SRF) cryomodule for International Linear Collider(ILC) Main Linac equips focus/steering magnets. The magnets are "superferric" magnets with four superconducting (SC) race track coils conductively cooled from the cryomodule LHe supply pipe. The quadrupole field gradient and dipole field are 40 T/m and 0.1 T, respectively. The magnet length and iron-pole radius are 1 m and 0.045 m, respectively. It is known that dark current is generated at SRF cavities and accelerated through the following linac string. The dark current reaches and heats the SC magnets. It is estimated that the power deposition in the magnet may reach more than a few watts and temperature of the SC coils may locally reach to critical temperature of NbTi. It is important to make the magnet not reach quench with sufficient conduction cooling. We aim to realize the SC magnet which can stably operate under such condition. We plan to develop test coils made of three types of SC materials, NbTi, Nb₃Sn, and MgB₂ and study thermal characteristics and stability . We will develop a short model magnet, based on the test coil results. Here, we will present the magnet design study and the R&D plan.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB017

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paper received ※ 19 May 2021 paper accepted ※ 16 June 2021 issue date ※ 18 August 2021

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TUPAB028

Permanent Magnets Future Electron Ion Colliders at RHIC and LHeC

electron, permanent-magnet, focusing, collider

1401

D. Trbojevic, S.J. Brooks, V. Litvinenko, T. Roser
BNL, Upton, New York, USA
G.H. Hoffstaetter
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
V. Litvinenko
Stony Brook University, Stony Brook, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
We present a new ’green energy’ approach to the Energy Recovery Linac (ERL) and Recirculating Linac Accelerators (RLA) for the future Electron Ion Colliders (EIC) using single beam line made of very strong focusing combined function permanent magnets and the Fixed Field Alternating Linear Gradient (FFA-LG) principle. We are basing our design on recent very successful commissioning results of the Cornell University and Brookhaven National Laboratory ERL Test Accelerator.

Poster TUPAB028 [2.720 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB028

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paper received ※ 17 May 2021 paper accepted ※ 27 May 2021 issue date ※ 30 August 2021

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TUPAB035

ESS Medium Beta Cavities Status at INFN LASA

cavity, SRF, multipactoring, controls

1420

D. Sertore, M. Bertucci, M. Bonezzi, A. Bosotti, A. D’Ambros, A.T. Grimaldi, P. Michelato, L. Monaco, R. Paparella
INFN/LASA, Segrate (MI), Italy
C. Pagani
Università degli Studi di Milano & INFN, Segrate, Italy

INFN Milano contributes in-kind to the ESS ERIC Superconducting Linac supplying 36 cavities for the Medium Beta section of the proton accelerator. The production has reached completion, being all the cavities mechanical fabricated, BCP treated and, for most of them, also qualified with vertical test at cold. In this paper, we report on the results and lessons learnt and the actions taken both for quality control managing and recovery of the few cavities that did not reach the project goal after the first qualification test.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB035

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

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TUPAB036

The Accelerator Design Progress for EIC Strong Hadron Cooling

electron, hadron, proton, emittance

1424

E. Wang, S. Peggs, V. Ptitsyn, F.J. Willeke, W. Xu
BNL, Upton, New York, USA
S.V. Benson
JLab, Newport News, Virginia, USA
D. Douglas
Douglas Consulting, York, Virginia, USA
C.M. Gulliford, G.H. Hoffstaetter
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
C.E. Mayes
Xelera Research LLC, Ithaca, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy,
The Electron-Ion Collider will achieve a luminosity of 10³⁴ cm^-2 s⁻¹ by incorporating strong hadron cooling to counteract hadron Intra-Beam Scattering, using a coherent electron cooling scheme. An accelerator will deliver the beams with key parameters, such as 1 nC bunch charge, and 1e-4 energy spread. The paper presents the design and beam dynamics simulation results. Methods to minimize beam noise, the challenges of the accelerator design, and the R&D topics being pursued are discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB036

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paper received ※ 16 May 2021 paper accepted ※ 11 June 2021 issue date ※ 01 September 2021

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TUPAB037

The Design of a High Charge Polarized Preinjector for the Electron-Ion Collider

cathode, gun, cavity, electron

1428

E. Wang, W. Liu, V.H. Ranjbar, J. Skaritka, N. Tsoupas
BNL, Upton, New York, USA
J.M. Grames, J. Guo
JLab, Newport News, Virginia, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy
The design of the electron pre-injector of the Electron-Ion Collider (EIC) project to generate 4 x 7 nC bunch has been advancing to meet the requirements for injection into the Rapid Cycling Synchrotron (RCS). The major challenges are high charge transport and achieving small energy spread from 3 GHz traveling-wave plate(TWP). The designed preinjector includes the polarized electron source, bunching section, TWP Linac, zigzag phase space manipulation and spin rotator. In this report, we will discuss the RF frequency selection and the way to reduce energy spread down to 0.2% by longitudinal phase space manipulate. We will also report the results of beamline simulation using space charge code and the conceptual design of spin rotator.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB037

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paper received ※ 16 May 2021 paper accepted ※ 15 June 2021 issue date ※ 27 August 2021

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TUPAB038

Simulation of the Filling Pattern Dependent Regenerative Beam Breakup Instabilities in Energy Recover Linacs

HOM, cavity, simulation, electron

1431

S. Setiniyaz, P.H. Williams
Cockcroft Institute, Warrington, Cheshire, United Kingdom
R. Apsimon
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

The interaction of a transversely displaced beam with the higher modes (HOM) of the accelerating cavities causes building up HOM voltages in the cavity, which in turn kicks the beam and increases the offset further. This is known as regenerative beam breakup (BBU) instability and it sets the beam threshold current for the stable beam operation. A study by Setiniyaz et al.~[Setiniyaz2020] showed the filling pattern and recombination schemes of multi-turn energy recovery linacs (ERLs) can create many different beam loading transients, which can have a big impact on the cavity fundamental mode voltage and RF stabilizes. In this work, we extend the study of the filling pattern and recombination schemes to the BBU instabilities and threshold current. In the ERLs, the accelerated and decelerated bunches can be ordered differently while they pass through the cavity and form different filling patterns. Each pattern has a unique bunch energy sequence and bunch arrival times and hence interacts with cavity uniquely and thus drives BBU differently. In this paper, we introduce a simulation tool to investigate the filling pattern dependence of the ERL BBU instability.
* S. Setiniyaz, R. Apsimon, and P. H. Williams, Phys. Rev. Accel. Beams 23, 072002, 2020.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB038

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paper received ※ 20 May 2021 paper accepted ※ 09 June 2021 issue date ※ 15 August 2021

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TUPAB045

The Low Energy Injector Design for the Southern Advanced Photon Source

electron, cavity, gun, bunching

1450

Y. Han
IHEP CSNS, Guangdong Province, People’s Republic of China
Y. Jiao, B. Li, X. Liu, S. Wang
IHEP, Beijing, People’s Republic of China

The Southern Advanced Photon Source (SAPS) is a project under design, which aims at constructing a 4th generation storage ring with emittance below 100 pm.rad at the electron beam energy of around 3.5 GeV. At present, two injector options are under consideration. One is a full energy booster plus a low energy injector, and another is a full energy linac injector. In this paper, a preliminary design of the low energy injector is presented, which consists of an DC thermionic electron gun, a bunching section and an accelerating section. The beam energy at the end of the injector is about 150 MeV.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB045

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paper received ※ 17 May 2021 paper accepted ※ 09 June 2021 issue date ※ 18 August 2021

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TUPAB046

Preliminary design of the Full Energy Linac Injector for the Southern Advanced Photon Source

FEL, gun, injection, photon

1454

X. Liu
Institute of High Energy Physics, CAS, Guangdong, People’s Republic of China
Y. Jiao, B. Li, S. Wang
IHEP, Beijing, People’s Republic of China

A 4th generation mid-energy range diffraction limited storage ring, named as the Southern Advanced Photon Source (SAPS), is under consideration to be built at the same campus as China Spallation Neutron Source (CSNS), providing a charming one-stop solution for fundamental sciences and industrial applications. While the design of the ring is still under study, a full energy Linac has been proposed as one candidate option for its injector, with the capability of being used as an X-ray Free Electron Laser (XFEL) in the near future. In this paper, an overview of the preliminary design of the Linac is given and simulation results are discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB046

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paper received ※ 18 May 2021 paper accepted ※ 10 June 2021 issue date ※ 10 August 2021

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TUPAB047

Bunch Compressor Design in the Full Energy Linac Injector for the Southern Advanced Photon Source

electron, simulation, bunching, laser

1458

B. Li
IHEP CSNS, Guangdong Province, People’s Republic of China
Y. Jiao, X. Liu, S. Wang
IHEP, Beijing, People’s Republic of China

A mid-energy fourth-generation storage ring light source named the Southern Advanced Photon Source (SAPS), has been considered to be built neighboring the China Spallation Neutron Source (CSNS). A full energy linac has been proposed as an injector to the storage ring, with the capability to generate high brightness electron beams to feed a Free Electron Laser (FEL) at a later stage. To achieve the high peak current in FELs, space charge, RF structure wakefield, coherent synchrotron radiation (CSR), RF curvature, and the second-order momentum compaction factor should be carefully considered and optimized during the bunch compression processes. In this paper, physic design and simulation results of the bunch compressors are described.

Poster TUPAB047 [1.918 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB047

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paper received ※ 15 May 2021 paper accepted ※ 09 June 2021 issue date ※ 28 August 2021

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TUPAB076

High-Gradient Breakdown Studies of an X-Band Accelerating Structure Operated in the Reversed Taper Direction

accelerating-gradient, linear-collider, klystron, collider

1543

X.W. Wu, N. Catalán Lasheras, A. Grudiev, G. McMonagle, I. Syratchev, W. Wuensch
CERN, Meyrin, Switzerland
M. Boronat
IFIC, Valencia, Spain
A. Castilla, A.V. Edwards, W.L. Millar
Lancaster University, Lancaster, United Kingdom

The results of high-gradient tests of a tapered X-band traveling-wave accelerator structure powered in reversed direction are presented. Powering the tapered structure from the small aperture, normally output, at the end of the structure provides unique conditions for the study of gradient limits. This allows high fields in the first cell for a comparatively low input power and a field distribution that rapidly falls off along the length of the structure. A maximum gradient of 130 MV/m in the first cell at a pulse length of 100 ns was reached for an input power of 31.9 MW. Details of the conditioning and operation at high-gradient are presented. Various breakdown rate measurements were conducted at different power levels and rf pulse widths. The structure was standard T24 CLIC test structure and was tested in Xbox-3 at CERN.

Poster TUPAB076 [1.077 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB076

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

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TUPAB080

Design and Status of the Beam Switchyard of the Shanghai Soft X-Ray FEL User Facility

FEL, electron, kicker, undulator

1559

S. Chen, R. Wang
SSRF, Shanghai, People’s Republic of China
H.X. Deng, C. Feng, X. Fu, B. Liu
SARI-CAS, Pudong, Shanghai, People’s Republic of China

SXFEL-UF, a soft X-ray FEL user facility located in Shanghai, has been upgraded from the existing test facility. Electron energy increases from 840 MeV to 1.5 GeV and a SASE FEL line will be added besides the existing seeding FEL line. It has started commissioning since early this year. In order for simultaneous operation of the two FEL lines, a beam switchyard is built between the linac and the two FEL lines. In this paper, the physics design of the beam switchyard is described.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB080

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paper received ※ 19 May 2021 paper accepted ※ 11 June 2021 issue date ※ 20 August 2021

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TUPAB081

Design of the Beam Distribution System of SHINE

undulator, electron, septum, kicker

1562

S. Chen, M. Gu, R. Wang
SSRF, Shanghai, People’s Republic of China
H.X. Deng, X. Fu
SARI-CAS, Pudong, Shanghai, People’s Republic of China

In shanghai, a hard X-ray free electron laser project named SHINE is under design. It will be based on a superconducting linac running in CW mode. On the first stage, there will be three parallel undulator lines downstream the linac. For simultaneous operation of the three undulator lines, a beam distribution system based on fast kickers will be installed between linac and undulator lines. The physics design of this beam distribution system is described in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB081

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paper received ※ 19 May 2021 paper accepted ※ 14 June 2021 issue date ※ 22 August 2021

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TUPAB082

Analysis of the Effect of Energy Chirp in Implementing EEHG at SXL

bunching, electron, simulation, FEL

1566

M.A. Pop, F. Curbis, B.S. Kyle, S.P. Pirani, W. Qin, S. Werin
MAX IV Laboratory, Lund University, Lund, Sweden
F. Curbis, S. Werin
Lund University, Lund, Sweden
W. Qin
DESY, Hamburg, Germany

As a part of the efforts to improve the longitudinal coherence in the design of the Soft X-ray FEL (the SXL) at MAX IV, we present a possible implementation of the EEHG harmonic seeding scheme partly integrated into the second bunch compressor of the existing LINAC. A special focus is given to the effect of CSR on the resulting EEHG bunching and on how this unwanted effect might be controlled.

Poster TUPAB082 [1.825 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB082

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

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TUPAB083

Dual Energies in the LCLS Copper Linac

quadrupole, feedback, klystron, betatron

1570

F.-J. Decker, C. Bianchini Mattison, D.K. Bohler, A. Brachmann, W.S. Colocho, S. Condamoor, M.L. Gibbs, K.H. Kim, A.A. Lutman, T.J. Maxwell, J.A. Mock, H.-D. Nuhn, J.C. Sheppard, H. Smith, T.J. Smith, M. Stanek, S. Zelazny, Z. Zhang, C.M. Zimmer
SLAC, Menlo Park, California, USA

For LCLS-II two undulators were installed at SLAC, one for soft and one for hard x-rays. Before the superconducting linac gets turned on the copper linac is providing beams at 120 Hz to these two beam destinations. The 120 Hz can be split in many different ratios between soft and hard via a pulsed magnet. To get an optimized beam for the quite different photon energies the pulsed linac components like modulators and RF can provide many different beam parameters, mainly energies and bunch lengths for the two undulator lines. How this was implemented with timing setups of triggers and finally after the split the necessary matching of the transverse phase space will be discussed.

Poster TUPAB083 [0.479 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB083

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paper received ※ 19 May 2021 paper accepted ※ 27 May 2021 issue date ※ 21 August 2021

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TUPAB087

Full Characterization of the Bunch-Compressor Dipoles for FLUTE

dipole, electron, HOM, controls

1585

Y. Nie, A. Bernhard, E. Bründermann, A.-S. Müller, M.J. Nasse, R. Ruprecht, J. Schäfer, M. Schuh, Y. Tong
KIT, Karlsruhe, Germany

Funding: This work is supported by the BMBF project 05H18VKRB1 HIRING (Federal Ministry of Education and Research).
The Ferninfrarot Linac- Und Test-Experiment (FLUTE) is a KIT-operated linac-based test facility for accelerator research and development as well as a compact, ultra-broadband and short-pulse terahertz (THz) source. As a key component of FLUTE, the bunch compressor (chicane) consisting of four specially designed dipoles will be used to compress the 40-50 MeV electron bunches after the linac down to single fs bunch length. The maximum vertical magnetic field of the dipoles reach 0.22 T, with an effective length of 200 mm. The good field region is ±40 mm and ±10.5 mm in the horizontal and vertical direction, respectively. The latest measurement results of the dipoles in terms of field homogeneity, excitation and field reproducibility within the good field regions will be reported, which meet the predefined specifications. The measured 3D magnetic field distributions have been used to perform beam dynamics simulations of the bunch compressor. Effects of the real field properties on the beam dynamics, which are different from that of the ASTRA built-in dipole field, will be discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB087

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paper received ※ 10 May 2021 paper accepted ※ 27 May 2021 issue date ※ 01 September 2021

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TUPAB113

Highlights From the Conceptual Design Report of the Soft X-Ray Laser at MAX IV

FEL, undulator, electron, laser

1651

F. Curbis, J. Andersson, L. Isaksson, B.S. Kyle, F. Lindau, E. Mansten, H. Tarawneh, P.F. Tavares, S. Thorin, A.S. Vorozhtsov
MAX IV Laboratory, Lund University, Lund, Sweden
S. Bonetti
Stockholm University, Stockholm, Sweden
V.A. Goryashko, P.M. Salén
Uppsala University, Uppsala, Sweden
P. Johnsson, S.P. Pirani, M.A. Pop, W. Qin, S. Werin
Lund University, Lund, Sweden
M. Larsson
Stockholm University, Department of Physics, Stockholm, Sweden
A. Nilsson
FYSIKUM, AlbaNova, Stockholm University, Stockholm, Sweden
J.A. Sellberg
KTH Physics, Stockholm, Sweden

Funding: Knut and Alice Wallenberg Foundation
The SXL (Soft X-ray Laser) project developed a conceptual design for a soft X-ray Free Electron Laser in the 1–5 nm wavelength range, driven by the existing MAX IV 3 GeV linac. In this contribution we will focus on the FEL operation modes developed for the first phase of the project based on two different linac modes. The design work was supported by the Knut and Alice Wallenberg foundation and by several Swedish universities and organizations (Stockholm, Uppsala, KTH Royal Institute of Technology, Stockholm-Uppsala FEL center, MAX IV laboratory and Lund University).

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB113

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

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TUPAB129

Beam Based Alignment in a Compact THz-FEL Facility

quadrupole, FEL, alignment, undulator

1692

Q.S. Chen, T. Hu, K.F. Liu, B. Qin, Y.Q. Xiong
HUST, Wuhan, People’s Republic of China

In this paper, we presented the beam based alignment results in a compact THz-FEL facility. The alignment was divided into two sections, the transport line and the optical line. In the transport line, all the five quadrupoles upstream of the undulator were adjusted one by one to fit the electron beam from the traveling wave linac. In the optical line, a set of auxiliary coils were winded on the yokes of the quadrupole downstream of the double bend achromat (DBA) to produce a vertical steering force. Another combined steering magnet, together with the auxiliary coils, corrected the beam orbit in the optical line. With the dispersion free test, the displacement between the magnetic centers of the quads and the beam orbit was less than 0.1mm.

Poster TUPAB129 [0.673 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB129

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paper received ※ 18 May 2021 paper accepted ※ 17 June 2021 issue date ※ 27 August 2021

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TUPAB134

Linac-to-Booster Optimization Procedure Towards High Transmission for the Alba Injector

booster, quadrupole, alignment, operation

1703

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

ALBA is a third generation synchrotron light source that consists of 3 accelerators (Linac, Booster and Storage ring) and two transfer lines, Linac-to-Booster (LTB) and Booster-to-Storage (BTS). The ALBA accelerators team has defined a robust procedure that optimizes the beam performance from Linac to Booster in terms of transmission and stability. The implemented beam-based alignment and global orbit correction techniques have been investigated first in simulations and afterwards successfully implemented in the machine.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB134

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paper received ※ 18 May 2021 paper accepted ※ 26 May 2021 issue date ※ 16 August 2021

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TUPAB166

A New Design of a Dressed Balloon Cavity with Superior Mechanical Properties

cavity, multipactoring, SRF, software

1769

R.A. Kostin, C. Jing, S. Ross
Euclid Beamlabs, Bolingbrook, USA
I.V. Gonin, T.N. Khabiboulline, G.V. Romanov, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA
M.P. Kelly
ANL, Lemont, Illinois, USA
R.E. Laxdal
TRIUMF, Vancouver, Canada

Funding: Work supported by the SBIR program of the U.S. Department of Energy, under grant DE-SC0020781
Superconducting spoke cavities are prone to multipactor - resonant raise of a number of electrons due to secondary emission. Recently proposed and tested by TRIUMF balloon-type spoke cavity showed an outstanding multipactor (MP) suppression property but unfortunately serious Q degradation at high fields. A new fully developed design of a dressed balloon cavity which can be used for any proton linac SSR2 section is developed. The design incorporates additional EP ports for high Q-factor demonstration. Superior properties are demonstrated, such as effective multipactor suppression, 40% lower Lorentz force coefficient, zero sensitivity to external pressure. This paper presents the results of coupled structural Multiphysics analysis, and engineering design of the dressed balloon cavity with EP ports.

Poster TUPAB166 [1.394 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB166

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paper received ※ 15 May 2021 paper accepted ※ 21 June 2021 issue date ※ 01 September 2021

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TUPAB168

Beam Commissioning of a 325 MHz Proton IH-DTL at XiPAF

DTL, cavity, proton, emittance

1777

P.F. Ma, X. Guan, R. Tang, M.W. Wang, X.W. Wang, Q.Z. Xing, W.B. Ye, S.X. Zheng
TUB, Beijing, People’s Republic of China
W. Chen, W.L. Liu, W. Lv, M.T. Qiu, B.C. Wang, D. Wang, M.C. Wang, Z.M. Wang, Y.H. Yan, Y. Yang, M.T. Zhao
NINT, Xi’an, People’s Republic of China

The Inter-Digital H-mode Drift Tube Linac (IH-DTL) is widely used as the main component of injectors for medical synchrotrons. This paper describes the beam commissioning of a compact 325 MHz IH-DTL with modified KONUS beam dynamics at Tsinghua University (THU). This IH-DTL accelerates the proton beam from 3 MeV to 7 MeV in 1m. The average energy of the beam is 7.0 MeV with the energy spread range of -0.6 MeV to 0.3 MeV. The output transverse normalized RMS emittance of the beam is 0.58 (x)/0.58 (y) pi mm mrad with the input emittance of 0.43 (x)/0.37 (y) pi mm mrad. The beam test results show good agreement with the beam dynamics design.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB168

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paper received ※ 08 May 2021 paper accepted ※ 16 June 2021 issue date ※ 14 August 2021

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TUPAB172

Quadrupole Magnet Design for a Heavy-Ion IH-DTL

quadrupole, heavy-ion, DTL, proton

1793

P.F. Ma, C.T. Du, X. Guan, M.W. Wang, X.W. Wang, Y.L. Wang, Q.Z. Xing, X.D. Yu, S.X. Zheng
TUB, Beijing, People’s Republic of China
W. Chen, W.L. Liu, W. Lv, M.T. Qiu, B.C. Wang, D. Wang, M.C. Wang, Z.M. Wang, Y.H. Yan, M.T. Zhao
NINT, Xi’an, People’s Republic of China

Xi’an Proton Application Facility (XiPAF) will be upgraded to provide heavy-ion beams with a heavy-ion injector. The injector consists of an ECR heavy-ion source, a Low Energy Beam Transport line (LEBT), a Radio Frequency Quadrupole (RFQ), an Interdigital H-mode Drift Tube Linac (IH-DTL), and a Linac to Ring Beam Transport line (LRBT). The IH-DTL can accelerate the ions with mass to charge up to 6.5 from 0.4 MeV/u to 2 MeV/u. To provide transverse focusing, the electro-magnetic quadrupoles are installed inside the drift tubes of IH-DTL, thus the magnet needs to be high-gradient and compact. This paper gives the quadrupole magnet design for the heavy-ion IH-DTL. The results show that the quadrupole magnet design can meet the requirements.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB172

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paper received ※ 08 May 2021 paper accepted ※ 21 June 2021 issue date ※ 23 August 2021

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TUPAB173

ESS Drift Tube Linac Manufacturing, Assembly and Tuning

DTL, cavity, alignment, emittance

1797

F. Grespan, L. Antoniazzi, A. Baldo, C. Baltador, A. Battistello, L. Bellan, P. Bottin, M. Comunian, D. Conventi, E. Fagotti, L. Ferrari, A. Palmieri, R. Panizzolo, A. Pisent, D. Scarpa
INFN/LNL, Legnaro (PD), Italy
R.A. Baron
ESS, Lund, Sweden
T. Bencivenga, P. Mereu, C. Mingioni, M. Nenni, E. Nicoletti
INFN-Torino, Torino, Italy
A.G. Colombo
INFN- Sez. di Padova, Padova, Italy
B. Jones
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

The Drift Tube Linac (DTL) for the ESS Linac will accelerate H⁺-beams of up to 62.5 mA peak current from 3.62 to 90 MeV. The structure consists of five cavities. The first cavity (DTL1) is a 7.6 m long tank containing 60 drift tubes, 23 fixed tuners, 3 movable tuners and 24 post-couplers, operating at a frequency of 352.21 MHz and an average accelerating field of 3.0 MV/m. The cavity is now assembled at ESS, the results of alignment and tuning are here presented. The DTL1 "as-built" as been analyzed from the beam dynamics point of view. The manufacturing of DTL4 and DTL3 is completed and they are now under assembly at ESS. DTL2 and DTL5 manufacturing will be completed within 2021. The paper describes the production and assembly stages, with a focus on the statistics of quality check in terms of metrology, alignment, leak tests.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB173

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paper received ※ 19 May 2021 paper accepted ※ 27 May 2021 issue date ※ 14 August 2021

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TUPAB174

Basic Design Study for Disk-Loaded Structure in Muon LINAC

accelerating-gradient, acceleration, impedance, experiment

1801

K. Sumi, T. Iijima, K. Inami, Y. Sue, M. Yotsuzuka
Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan
H. Ego, T. Mibe, M. Yoshida
KEK, Ibaraki, Japan
T. Iijima
KMI, Nagoya, AIchi Prefecture, Japan
Y. Kondo
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
Y. Nakazawa
Ibaraki University, Hitachi, Ibaraki, Japan
M. Otani, N. Saito
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
Y. Takeuchi
Kyushu University, Fukuoka, Japan
H.Y. Yasuda
University of Tokyo, Tokyo, Japan

The world’s first disk-loaded structure (DLS) at the high-velocity part of a muon LINAC is under development for the J-PARC muon g-2/EDM experiment. We have simulated the first designed constant impedance DLS to accelerate muons from ß = 0.7 to 0.94 at an operating frequency of 1296 MHz and a phase of -10 degrees to ensure longitudinal acceptance and have shown the quality of the beam meets our requirements. Because the structure needs a high RF power of 80 MW to generate a gradient of 20 MV/m, a constant gradient DLS with the higher acceleration efficiency is being studied for lower operating RF power. In this poster, we will show the cell structure design yielding a gradient of 20 MV/m with lower RF power.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB174

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

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TUPAB175

ESSnuSB Linac and Transfer Line: Lattice Design and Error Studies

lattice, dipole, proton, DTL

1805

N. Blaskovic Kraljevic, M. Eshraqi, B.T. Folsom
ESS, Lund, Sweden

Funding: ESSnuSB has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 777419.
The ESS neutrino superbeam (ESSnuSB) project is being studied as an upgrade to the European Spallation Source (ESS). This proposed upgrade consists of adding an H⁻ source to the existing beamline in order to send H⁻ pulses in between proton pulses, effectively doubling the beam power from 5 MW to 10 MW. In this contribution, we present the 2.5 GeV linear accelerator (linac) lattice and the design of the transfer line from the linac to the accumulator ring, where pulses would be stacked to achieve short proton pulses of high intensity. The results of error studies, quantifying the effect of accelerator imperfections and H⁻ ion stripping losses on the beam transport through the linac and transfer line, are also presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB175

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paper received ※ 19 May 2021 paper accepted ※ 14 June 2021 issue date ※ 31 August 2021

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TUPAB176

ESS Proton Beam Trajectory Correction

MEBT, DTL, simulation, ion-source

1809

N. Blaskovic Kraljevic, M. Eshraqi, N. Milas, R. Miyamoto
ESS, Lund, Sweden

The proton linac of the European Spallation Source (ESS) is under construction in Lund, Sweden. Beam trajectory correction is essential to mitigate the effect of accelerator element misalignment, constituting the first step to minimise beam losses. The correction will be performed using correctors distributed along the accelerator, based on the beam position monitor (BPM) readout. Three trajectory correction techniques are considered: one-to-one steering, Singular Value Decomposition (SVD), and MICADO (selecting a subset of correctors for the trajectory correction). The performance of the three methods is simulated for the ESS linac and a comparison of the outcomes is presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB176

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paper received ※ 19 May 2021 paper accepted ※ 15 June 2021 issue date ※ 27 August 2021

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TUPAB198

ESS DTL Tuning Using Machine Learning Methods

network, cavity, DTL, proton

1872

J.S. Lundquist, N. Milas, E. Nilsson
ESS, Lund, Sweden
S. Werin
Lund University, Lund, Sweden

The European Spallation Source, currently under construction in Lund, Sweden, will be the world’s most powerful neutron source. It is driven by a proton linac with a current of 62.5 mA, 2.86 ms long pulses at 14 Hz. The final section of its normal-conducting front-end consists of a 39 m long drift tube linac (DTL) divided into five tanks, designed to accelerate the proton beam from 3.6 MeV to 90 MeV. The high beam current and power impose challenges to the design and tuning of the machine and the RF amplitude and phase have to be set within 1% and 1 degree of the design values. The usual method used to define the RF set-point is signature matching, which can be a time consuming and challenging process, and new techniques to meet the growing complexity of accelerator facilities are highly desirable. In this paper we study the usage of Machine Learning to determine the RF optimum amplitude and phase. The data from a simulated phase scan is fed into an artificial neural network in order to identify the needed changes to achieve the best tuning. Our test for the ESS DTL1 shows promising results, and further development of the method will be outlined.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB198

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paper received ※ 17 May 2021 paper accepted ※ 21 June 2021 issue date ※ 13 August 2021

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TUPAB199

Progress on the Proton Power Upgrade at the Spallation Neutron Source

target, klystron, cryomodule, proton

1876

M.S. Champion, C.N. Barbier, M.S. Connell, J. Galambos, M.P. Howell, S.-H. Kim, J.S. Moss, B.W. Riemer, K.S. White
ORNL, Oak Ridge, Tennessee, USA
E. Daly
JLab, Newport News, Virginia, USA
N.J. Evans, G.D. Johns
ORNL RAD, Oak Ridge, Tennessee, USA

Funding: ORNL is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. This research was supported by the DOE Office of Science, Basic Energy Science.
The Proton Power Upgrade Project at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory will double the proton power capability from 1.4 to 2.8 MW. This will be accomplished through an energy increase from 1.0 to 1.3 GeV and a beam current increase from 26 to 38 mA. The energy increase will be accomplished through the addition of 7 cryomodules to the linear accelerator (Linac). The beam current increase will be supported by upgrading several radio-frequency systems in the normal-conducting section of the Linac. Upgrades to the accumulator ring injection and extraction regions will accommodate the increase in beam energy. A new 2-MW-capable target and supporting systems will be developed and installed. Conventional facility upgrades include build-out of the existing klystron gallery and construction of a tunnel stub to facilitate future beam transport to the second target station. The project received approval to proceed with construction in October 2020. Procurements are in progress, and some installation activities have already occurred. Most of the installation will take place during three outages in 2022-2023. The project early finish is planned for 2025.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB199

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paper received ※ 10 May 2021 paper accepted ※ 28 May 2021 issue date ※ 21 August 2021

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TUPAB203

Electromagnetic Simulations of a Novel Proton Linac Using VSim on HPC

rfq, simulation, operation, controls

1887

S.I. Sosa Guitron, S. Biedron, T.B. Bolin
UNM-ECE, Albuquerque, USA
J.R. Cary
Tech-X, Boulder, Colorado, USA
M.S. Curtin, B. Hartman, T. Pressnall, D.A. Swenson
Ion Linac Systems, Inc., Albuquerque, USA

Funding: This work is supported by the U.S. Department of Energy, award number DE-SC0019468; It used resources of the Argonne Leadership Computing Facility, contract DE-AC02-06CH11357, and from Element Aero.
We discuss electromagnetic simulations of accelerating structures in a high performance computing (HPC) system. Our overarching goal is to resolve the linac operation in a large ensemble of initial beam conditions. This requires a symbiotic relation between the electromagnetic solver and HPC. The linac is being developed by Ion Linac Systems to produce a low-energy, high-current, proton beam. We use VSim, an electromagnetic solver and PIC software developed by Tech-X to determine the electromagnetic fundamental mode of operation of the accelerating structures and discuss its implementation at the THETA supercomputer in the Argonne Leadership Computing Facility.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB203

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paper received ※ 20 May 2021 paper accepted ※ 17 June 2021 issue date ※ 10 August 2021

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TUPAB204

Upgrade of Los Alamos Accelerator Facility as a Fusion Prototypic Neutron Source

target, neutron, radiation, proton

1890

Y.K. Batygin, E.J. Pitcher
LANL, Los Alamos, New Mexico, USA

Funding: Work supported by US DOE under contract 89233218CNA000001
The Fusion Prototypic Neutron Source (FPNS) is considered to be a testbed for scientific understanding of material degradation in future nuclear fusion reactors. The primary mission of FPNS is to provide a damage rate in samples of 8-11 dpa/calendar year with He/dpa ratio of 10 appm in irradiation volume of 50 cubic cm or larger with irradiation temperature 300-1000 deg C and flux gradient less than 20%/cm in the plane of the sample. Los Alamos Neutron Science Center (LANSCE) is an attractive candidate for FPNS project. Accelerator Facility was designed and operated for an extended period as a 0.8-MW Meson Factory. Existing setup of the LANSCE accelerator complex can nearly fulfill requirements of the fusion neutron source station. The primary function of the upgraded accelerator systems is the safe and reliable delivery of a 1.25-mA continuous proton beam current at 800-MeV beam energy from the switchyard to the target assembly to create 1 MW power of proton beam interacting with a solid tungsten target. The present study describes existing accelerator setup and further development required to meet the needs of FPNS project.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB204

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paper received ※ 14 May 2021 paper accepted ※ 02 June 2021 issue date ※ 21 August 2021

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TUPAB205

Advancement of LANSCE Front End Accelerator Facility

rfq, DTL, proton, neutron

1894

Y.K. Batygin, D. Gorelov, S.S. Kurennoy, J.W. Lewellen, N.A. Moody, L. Rybarcyk
LANL, Los Alamos, New Mexico, USA

Funding: Work supported by US DOE under contract 89233218CNA000001
The LANSCE accelerator started routine operation in 1972 as a high-power facility for fundamental research and national security applications. To reduce long-term operational risk, we propose to develop a new Front End of accelerator facility. It contains 100-keV injector with 3-MeV RFQ, and 6-tanks Drift Tube Linac to accelerate particles up to energy of 100 MeV. The low-energy injector concept includes two independent transports merging H⁺ and H⁻ beams at the entrance of RFQ. Beamlines are aimed to perform preliminary beam bunching in front of accelerator section with subsequent simultaneous acceleration of two different beams in a single RFQ. The paper discusses design topics of new Front End of accelerator facility.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB205

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paper received ※ 12 May 2021 paper accepted ※ 28 May 2021 issue date ※ 14 August 2021

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TUPAB211

The Accelerator System of IFMIF-DONES Multi-MW Facility

cavity, rfq, SRF, cryomodule

1910

I. Podadera, A. Ibarra, D. Jimenez-Rey, J. Mollá, C. Oliver, D. Regidor, R. Varela, C. de la Morena
CIEMAT, Madrid, Spain
F. Arbeiter, V. Hauer
KIT, Eggenstein-Leopoldshafen, Germany
N. Bazin, J. Dumas, L. Seguí
CEA-IRFU, Gif-sur-Yvette, France
L. Bellan, E. Fagotti, A. Palmieri, A. Pisent
INFN/LNL, Legnaro (PD), Italy
N. Chauvin, S. Chel, J. Plouin
CEA-DRF-IRFU, France
G. Duglue, H. Dzitko
F4E, Germany
W.C. Grabowski, A. Wysocka-Rabin
NCBJ, Świerk/Otwock, Poland
M. Jaksic, T. Tadic
RBI, Zagreb, Croatia
W. Królas
IFJ-PAN, Kraków, Poland
R. López, A. Muñoz, C. Prieto
Empresarios Agrupados, Madrid, Spain
O. Nomen, M. Sanmartí, F.J. Saura Esteban, B.K. Singh, D. Sánchez-Herranz
IREC, Sant Adria del Besos, Spain

Funding: Work carried out within EUROfusion Consortium and DONES-PreP and received funding from the Euratom research and training programme 2014-2018 & 2019-2020 under grants agreement No. 633053 & 870186
The IFMIF-DONES (DEMO-Oriented Neutron Early Source) facility has passed the preliminary design phase and the detailed design phase is very much advanced. Next step will be the preparation phase for the construction of the facility. The DONES facility aims at developing a database of fusion-like radiation effects on materials to be used in future fusion reactors up to damage levels expected in the EU DEMO. It will be based on an intense neutron source created by an accelerated deuteron beam (125 mA CW, 40 MeV) impinging on a liquid lithium curtain. The DONES Accelerator Systems (AS) will be responsible of delivering this 5 MW D⁺ beam with very high availability. The beam acceleration will be performed by several stages: an ion source and LEBT, an RFQ, a MEBT, an SRF Linac and a HEBT transporting and delivering an optimized profile down to the target. A high power RF system and several ancillaries will ensure the equipment is properly operated. This contribution will report the present status of the AS design, the main challenges faced, the R&D programme to overcome them, and the prospects for the construction and commissioning of the DONES accelerator in Granada (Spain).

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB211

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paper received ※ 19 May 2021 paper accepted ※ 17 June 2021 issue date ※ 27 August 2021

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TUPAB277

Bunch Length Characterizations for the Solaris Injector LINAC

radiation, electron, diagnostics, experiment

2117

A. Curcio, M.A. Knafel, G.W. Kowalski, R. Panaś, M. Waniczek, A.I. Wawrzyniak
NSRC SOLARIS, Kraków, Poland

During 2020 the first characterization of bunch length and bunch profile in the Solaris injector LINAC has been performed since the start of its operation. In absence of more sophisticated bunch length diagnostics, we have adopted an inversion algorithm applied to beam energy spectra. In practice, the method applies a transformation matrix which maps the particle energy into the particle longitudinal coordinate along the bunch. The construction of this matrix is made analytically, based on the solution of the Liouville equation for the study of the longitudinal beam dynamics. The analytic approach has been benchmarked with experimental measurements of the beam properties along the machine and cross-checked with other tools, as particle tracking and/or beam optics codes. The final results are presented. Moreover, a new diagnostic station at the end of the LINAC has been installed which will host experiments of coherent radiation emission that will be used to confirm the validity of our observations. Preliminary simulations of the coherent spectra are finally reported.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB277

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paper received ※ 18 May 2021 paper accepted ※ 17 June 2021 issue date ※ 12 August 2021

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TUPAB284

BPM for the High Energy Beam Transport Line of MINERVA Project at SCK•CEN

instrumentation, experiment, electron, proton

2143

H. Kraft, L. Perrot
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France

This paper presents the status of developments concerning button type BPM. Results of our analytical model BPMOK will compare the measurements done at IPHI facility at CEA-Saclay and GANIL/SPIRAL2 in Caen. The measurements aims to compare the response of the analytical model depending on beam positions, sizes, intensities and energies. BPMOK is validated to predict BPM responses in order to make parametric studies. Starting from already existing BPM built for the MINERVA LINAC, the analytical model is used to design the BPM for the HEBT.

Poster TUPAB284 [1.475 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB284

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paper received ※ 10 May 2021 paper accepted ※ 02 June 2021 issue date ※ 28 August 2021

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TUPAB286

Experience with On-line Optimizers for APS Linac Front End Optimization

gun, operation, controls, injection

2151

H. Shang, M. Borland, X. Huang, Y. Sun
ANL, Lemont, Illinois, USA
M. Song, Z. Zhang
SLAC, Menlo Park, California, USA

Funding: * Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357 and BES R&D project FWP 2020-ANL-34573
While the APS linac lattice is set up using a model developed with ELEGANT, the thermionic RF gun front end beam dynamics has been difficult to model. One of the issues is that beam properties from the thermionic gun can vary from time to time. As a result, linac front end beam tuning is required to establish good matching and maximize the charge transported through the linac. We have been using a traditional simplex optimizer to find the best settings for the gun front end magnets and steering magnets. However, it takes a long time and requires some fair initial conditions. Therefore, we imported other on-line optimizers, such as robust conjugate direction search (RCDS) which is a classic optimizer as simplex, multi-objective particle swarm (MOPSO), and multi-generation gaussian process optimizer (MG-GPO) which is based on machine learning technique. In this paper we report our experience with these on-line optimizers for maximum bunch charge transportation efficiency through the linac.

Poster TUPAB286 [2.964 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB286

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paper received ※ 12 May 2021 paper accepted ※ 08 July 2021 issue date ※ 29 August 2021

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TUPAB287

Application of Artificial Neural Network in the APS Linac Bunch Charge Transmission Efficiency

operation, kicker, controls, photon

2155

H. Shang, R. Maulik, Y. Sun
ANL, Lemont, Illinois, USA
T. Xu
Northern Illinois University, DeKalb, Illinois, USA

Funding: * Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
In recent years there has been a rapid growth in machine learning (ML) and artificial intelligence (AI) applications in accelerators. As the scale of complexity and sophistication of modern accelerators grows, the difficulties in modeling the machine increase greatly in order to include all the interacting subsystems and to consider the limitation of various diagnostics to benchmark against measurements. Tools based on ML can help substantially in revealing correlations of machine condition and beam parameters that are not easily discovered using traditional physics model-based simulations, reducing machine tuning up time etc among the many possible applications. While at APS we have many excellent tools for the optimization, diagnostics, and controls of the accelerators, we do not yet have ML-based tools established. It is our desire to test ML in our machine operation, optimization, and controls. In this paper, we introduce the application of neural networks to the APS linac bunch charge transmission efficiency.

Poster TUPAB287 [0.781 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB287

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paper received ※ 12 May 2021 paper accepted ※ 16 June 2021 issue date ※ 29 August 2021

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TUPAB290

Demonstration of Machine Learning Front-End Optimization of the Advanced Photon Source Linac

controls, gun, electron, photon

2163

A. Hanuka, J.P. Duris
SLAC, Menlo Park, California, USA
H. Shang, Y. Sun
ANL, Lemont, Illinois, USA

The electron beam for the Advanced Photon Source (APS) at Argonne National Laboratory is generated from a thermionic RF gun and accelerated by an S-band linear accelerator – the APS linac. While the APS linac lattice is set up using a model developed with ELEGANT, the thermionic RF gun front-end beam dynamics have been difficult to model. One of the issues is that beam properties from thermionic guns can vary. As a result, linac front-end beam tuning is required to establish good matching and maximize the charge transported through the linac. A traditional Nelder-Mead simplex optimizer has been used to find the best settings for the sixteen quadrupoles and steering magnets. However, it takes a long time and requires some fair initial conditions. The Gaussian Process (GP) optimizer does not have the initial condition limitation and runs several times faster. In this paper, we report our data collection and analysis for the training of the GP hyperparameters and discuss the application of GP optimizer on the APS linac front-end optimization for maximum bunch charge transportation efficiency through the linac.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB290

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paper received ※ 09 May 2021 paper accepted ※ 28 July 2021 issue date ※ 27 August 2021

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TUPAB292

Automation of the ReAccelerator Linac Phasing

cavity, detector, controls, interface

2170

D.J. Barofsky, A.I. Henriques, T.J. Kabana, A.S. Plastun
FRIB, East Lansing, Michigan, USA
D.B. Crisp, A. Lapierre, S. Nash, A.C.C. Villari
NSCL, East Lansing, Michigan, USA

Funding: This work is supported by the National Science Foundation under Grant No. PHY-1565546
The ReAccelerator (ReA) at the National Superconducting Cyclotron Laboratory at Michigan State University is a unique facility, as it offers the possibility to reaccelerate not only stable, but rare-isotope beams produced by fast-projectile fragmentation or fission. At ReA, beams are accelerated using a Radio-Frequency-Quadrupole and a superconducting linear accelerator before being delivered to experiments. Beam preparation time plays a major role in the availability of beams to experiments. One of the major time consuming tasks is the linac phasing, since there are 23 resonator cavities to be phased, usually with very low beam intensities. This procedure was automated using a combination of EPICS (Experimental Physics and Industrial Controls System) In/Output Controllers (IOCs) and IOC triggered scripts to scan the resonator phase delay and measure the change in beam energy. We have developed user-friendly tools to phase the linac, which have been tested, making the task of phasing substantially easier. In this presentation, we will present our methodology, challenges faced, tools developed, and initial results of the application for automating the phasing of the ReA linac.

Poster TUPAB292 [1.140 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB292

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paper received ※ 19 May 2021 paper accepted ※ 02 June 2021 issue date ※ 29 August 2021

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TUPAB325

Data-Driven Risk Matrices for CERN’s Accelerators

operation, proton, synchrotron, machine-protect

2260

T. Cartier-Michaud, A. Apollonio, G.B. Blarasin, B. Todd, J.A. Uythoven
CERN, Geneva, Switzerland

Funding: Research supported by the HL-LHC project.
A risk matrix is a common tool used in risk assessment, defining risk levels with respect to the severity and probability of the occurrence of an undesired event. Risk levels can then be used for different purposes, e.g. defining subsystem reliability or personnel safety requirements. Over the history of the Large Hadron Collider (LHC), several risk matrices have been defined to guide system design. Initially, these were focused on machine protection systems, more recently these have also been used to prioritize consolidation activities. A new data-driven development of risk matrices for CERN’s accelerators is presented in this paper, based on data collected in the CERN Accelerator Fault Tracker (AFT). The data-driven approach improves the granularity of the assessment, and limits uncertainty in the risk estimation, as it is based on operational experience. In this paper the authors introduce the mathematical framework, based on operational failure data, and present the resulting risk matrix for LHC.

Poster TUPAB325 [0.499 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB325

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paper received ※ 19 May 2021 paper accepted ※ 24 June 2021 issue date ※ 17 August 2021

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TUPAB328

Machine Learning for Time Series Prediction of an Accelerator Beam to Recognize Equipment Malfunction

cavity, SRF, ion-source, neutron

2272

C.C. Peters
ORNL RAD, Oak Ridge, Tennessee, USA
W. Blokland, D.L. Brown, F. Liu, C.D. Long, D. Lu, P. Ramuhalli, D.E. Womble, J. Zhang, A.P. Zhukov
ORNL, Oak Ridge, Tennessee, USA

Funding: ORNL is managed by UT-Battelle, LLC, under contract DE-AC05- 00OR22725 for the U.S. Department of Energy.
The Spallation Neutron Source (SNS) is an accelerator based pulsed neutron source based on a 1 GeV pulsed proton Superconducting Radio Frequency (SRF) linear accelerator (linac). Since beginning high power beam operation in 2006 correlations have been found linking abrupt beam loss events to SRF cavity instabilities. With the planned upgrades to double the beam power we expect increased rates of degradation and the importance of minimizing these beam loss events will become ever more important. To further limit degradation, we are developing machine learning approaches to monitor the beam and to detect, predict and prevent beam loss events. Initial research has shown that precursors to beam loss events are detectable. The initial steps are to use ML-based classification to recognize anomalies and to use Long Short-Term Memory (LSTM) autoencoders to predict beam loss. In this paper, we describe recent progress in applying machine learning for recognizing anomalies and predicting beam loss and present initial results of our research using acquired data from different diagnostics and the Machine Protection System (MPS).

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB328

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

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TUPAB329

Pattern Based Parameter Setup of the SNS Linac

cavity, DTL, operation, beam-losses

2276

C.C. Peters
ORNL RAD, Oak Ridge, Tennessee, USA
A.P. Shishlo
ORNL, Oak Ridge, Tennessee, USA

Funding: ORNL is managed by UT-Battelle, LLC, under contract DE-AC05- 00OR22725 for the U.S. Department of Energy.
Theoretical and practical aspects of beam tuning procedures used for the SNS linac are discussed. The SNS linac includes two sections of beam acceleration. Acceleration in the first section up to 185.5 MeV is done with a room temperature copper linac which consists of both Drift Tube Linac (DTL) and Coupled Cavity Linac (CCL) Radio Frequency (RF) cavities. The second section consists of 81 Superconducting RF (SRF) cavities which accelerate the beam to the final beam energy of 1 GeV. The linac is currently capable of delivering an average beam power output of 1.44 MW with typical yearly operating hours of around 4500 hours. Due to the high power output and high availability of the linac, activation of accelerator equipment is a significant concern. The linac tuning process consists of three stages: model based setup of amplitudes and phases of the RF cavities, empirical beam loss reduction, and then documentation of the final amplitudes and phases of RF cavities after the empirical tuning. The final step is needed to ensure fast recovery from an SRF cavity failure. This paper discusses models, algorithms, diagnostic tools, software, and practices that are used for these stages.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB329

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paper received ※ 22 May 2021 paper accepted ※ 28 May 2021 issue date ※ 25 August 2021

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TUPAB355

Design and Implementation of a Production Model Bias Tee

multipactoring, high-voltage, MMI, cavity

2339

T.L. Larter, E. Gutierrez, S.H. Kim, D.G. Morris, J.T. Popielarski, T. Xu, S. Zhao
FRIB, East Lansing, Michigan, USA

Funding: This work is supported by the US Department of Energy Office of Science under Cooperative Agreement DE-SC0000661, the State of Michigan and Michigan State University.
The Facility for Rare Isotope Beams (FRIB) includes two types of half wave SC resonators (HWR) operating at 322MHz. The fundamental power couplers used to transmit RF power into the HWRs commonly suffer from multipacting which can result in long conditioning times. A bias tee can be used to apply a high voltage to the couplers to help alleviate multipacting. A production version of the bias tee was commissioned for use at FRIB. The bias tee went through several design revisions to diagnose and correct thermal dissipation issues. This paper will discuss details of design and challenges faced during production validation of the bias tee.

Poster TUPAB355 [0.630 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB355

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paper received ※ 19 May 2021 paper accepted ※ 28 May 2021 issue date ※ 12 August 2021

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TUPAB356

Electron Beam Driven Cavities

electron, cavity, simulation, klystron

2342

M. Schuett, U. Ratzinger
IAP, Frankfurt am Main, Germany

State of the art high power feeder for RF cavities used as accelerators generally require RF amplifiers consisting of a vacuum tube, such as a klystron or Grid Tubes. In addition, a number of cost intensive RF auxiliary devices are needed: Modulator, waveguides, circulator, power dump and couplers. The equipment requires significant floor space within the linac building. Alternatively, we propose a direct driven system. Aμbunched electron beam is injected directly into the cavity. A high perveance bunched electron beam can be generated by a standard electron gun combined with a deflecting beam chopper*, an off-the-shelf IOT or klystron, respectively. The pulse rate is determined by the resonance frequency of the cavity. The resonator hereby acts like the output cavity of a klystron: Within its propagation through the cavity the beam is decelerated increasing the stored energy of the accelerator. We present 3D particle PIC simulations evaluating the geometry and beam properties in order to optimize the coupling efficiency and cavity excitation of state-of-art CH particle accelerator structures.
* S. Setzer, T. Weiland and U. Ratzinger, A Chopped Electron Beam Driver for H-Type Cavities, 20th ‘International Linac Conference, Monterey, California, August 21-25, 2000, pp. 1001-1003

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB356

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

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TUPAB357

Development of the X-Band Megawatt-Class Coaxial Magnetrons

radiation, high-voltage, electron, experiment

2346

J.Y. Liu, H.B. Chen, Y.S. Han, J. Shi, C.-X. Tang, C.J. Wang, J. Wang, H. Zha
TUB, Beijing, People’s Republic of China

X-band coaxial magnetrons are preferred for industrial and medical accelerators owing to the compact size, low cost and high efficiency. A conditioning and high power test stand for X-band magnetrons has been built in Tsinghua University. Two X-band magnetrons named "MGT-1#" and "MGT-2#" were tested at this stand. The maximum anode currents of both magnetrons reached 100 A after the conditioning process. Maximum peak output power of 1.71 MW and 1.89 MW was achieved for "MGT-1#" and "MGT-2#", respectively. The efficiencies of the two magnetrons are both about 50%.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB357

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paper received ※ 19 May 2021 paper accepted ※ 02 June 2021 issue date ※ 28 August 2021

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TUPAB361

Study and Design of a Fast Switching Magnet for the MYRRHA Project

dipole, proton, optics, beam-transport

2356

E. Froidefond, F. Bouly, P.-O. Dumont
LPSC, Grenoble Cedex, France
D. Vandeplassche
SCK•CEN, Mol, Belgium

Funding: Work supported by SCK•CEN, CNRS/IN2P3, Univ. Grenoble Alpes.
The MYRRHA project aims at building an Accelerator Driven System demonstrator, which consists of two injectors and a superconducting linac. The proton beam from the first injector accelerated up to 17 MeV goes to the linac (600 MeV) through a Medium Energy Beam Transfer line (MEBT). Whereas in the meantime, the beam from the second injector is sent to a beam dump. In case of failure in the first injector, the beam of the awaiting injector is sent to the linac. A switching magnet located at the junction of the two injection lines performs this beam switch in less than 1.5 seconds. A magnetic design and a mechanical structure of this magnet proposed to the MYRRHA project are presented.
*emmanuel.froidefond@lpsc.in2p3.fr

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB361

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paper received ※ 19 May 2021 paper accepted ※ 19 July 2021 issue date ※ 23 August 2021

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TUPAB388

Efficiency, Power Loss, and Power Factor Measurement of Quadrupole Magnet Power Supplies at the Spallation Neutron Source

power-supply, controls, quadrupole, neutron

2428

S. Harave
ORNL, Oak Ridge, Tennessee, USA
B. Morris
SLAC, Menlo Park, California, USA

The linear accelerator (LINAC) quadrupole magnets are powered by 42 silicon-controlled rectifier (SCR) based power supplies at the Spallation Neutron Source (SNS) facility of Oak Ridge National Laboratory. These 35V, 525A power supplies are bulky, inefficient and require both air and water cooling. The reliability of the SNS facility is impacted due to water leaks internal to power supplies and current readback issues associated with their unique control system interface, resulting in multiple downtime events. Hence, an alternate solution is necessary for the continued reliable operation of the SNS. To mitigate the above-mentioned problems, this paper proposes the use of off-the-shelf Switch Mode Power Supplies (SMPS) rated for 20V, 500A with serial control interface. These SMPS are air-cooled, more efficient and more compact owing to their switching speeds of approximately 160 kHz. The performance enhancements of the SMPS in comparison with the existing SCR power supply are discussed in detail in this paper. The features of the SMPS, along with experimental results for both power supplies, like efficiency, power losses and stability, are presented. Ongoing work is also discussed.

Poster TUPAB388 [0.420 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB388

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paper received ※ 17 May 2021 paper accepted ※ 31 May 2021 issue date ※ 17 August 2021

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TUPAB395

Vacuum System Models for Minerva Linac Design

vacuum, cavity, rfq, MEBT

2443

S. Rey, M.A. Baylac, F. Bouly, E. Froidefond
LPSC, Grenoble Cedex, France
F. Davin, D. Vandeplassche
SCK•CEN, Mol, Belgium
L. Perrot, H. Saugnac
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France

The goal of the MYRRHA project is to demonstrate the technical feasibility of transmutation in a 100 MW Accelerator Driven System (ADS) by building a new flexible irradiation complex at Mol (Belgium). The MYRRHA facility requires a 600 MeV accelerator delivering a maximum proton current of 4 mA in continuous wave operation, with an additional requirement for exceptional reliability. Supported by SCK•CEN and the Belgian federal government the project has entered in its phase I: this includes the development and the construction of the linac first part, up to 100 MeV. We here review the MINERVA linac vacuum system modelling studies that enabled to validate the choice of materials and vacuum equipment. The strengths and weaknesses of the vacuum design, highlighted by the models, will be discussed as well as the required improvements.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB395

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paper received ※ 19 May 2021 paper accepted ※ 01 June 2021 issue date ※ 28 August 2021

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TUPAB398

Vacuum Issues with Argon Gas in the LANSCE Accelerator

vacuum, neutron, monitoring, operation

2450

T. Tajima, J.E. Bernal, D.A. Byers, J.P. Chamberlin, P. Pizzol, A. Poudel, K.A. Stephens
LANL, Los Alamos, New Mexico, USA

Funding: US DOE NNSA
In the Los Alamos Neutron Science Center (LANSCE) accelerator, there are about 220 500-L/s ion pumps running all the time. The oldest pumps recorded in the current system were installed in 1983. All the ion pumps are diode type ion pumps. In 2017, we started to suffer from ion pumps trips in an accelerator module 15 (M15) that includes 3 500-L/s ion pumps and they caused beam down times of the accelerator during the production run cycles. This paper reports the details of these trips, how we found it was argon gas that was causing the trips and how we tried to reduce it.

Poster TUPAB398 [0.817 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB398

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paper received ※ 19 May 2021 paper accepted ※ 01 June 2021 issue date ※ 28 August 2021

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TUPAB402

Review of Technologies for Ion Therapy Accelerators

synchrotron, extraction, proton, heavy-ion

2465

H.X.Q. Norman, R.B. Appleby, A.F. Steinberg
UMAN, Manchester, United Kingdom
E. Benedetto
TERA, Novara, Italy
E. Benedetto, M. Sapinski
CERN, Meyrin, Switzerland
H.L. Owen
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
H.L. Owen
Cockcroft Institute, Warrington, Cheshire, United Kingdom
M. Sapinski
GSI, Darmstadt, Germany
S.L. Sheehy
The University of Melbourne, Melbourne, Victoria, Australia

Cancer therapy using protons and heavier ions such as carbon has demonstrated advantages over other radiotherapy treatments. To bring about the next generation of clinical facilities, the requirements are likely to reduce the footprint, obtain beam intensities above 1E10 particles per spill, and achieve faster extraction for more rapid, flexible treatment. This review follows the technical development of ion therapy, discussing how machine parameters have evolved, as well as trends emerging in technologies for novel treatments such as FLASH. To conclude, the future prospects of ion therapy accelerators are evaluated.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB402

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paper received ※ 19 May 2021 paper accepted ※ 28 July 2021 issue date ※ 24 August 2021

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TUPAB405

Design of High Energy Linac for Generation of Isotopes for Medical Applications

electron, target, gun, controls

2472

A.P. Deshpande, S.R. Bhat, T.S. Dixit, P.S. Jadhav, A.S. Kottawar, R. Krishnan, M.S. Kumbhare, J. Mishra, C.S. Nainwad, S.R. Name, R. Sandeep Kumar, A. Shaikh, K.A. Thakur, M.M. Vidwans, A. Waingankar
SAMEER, Mumbai, India
A.K. Mishra
INMAS, New Delhi, India
N. Upadhyay
University of Mumbai, Mumbai, India

Funding: Ministry of Electronics and Information Technology (MeitY), Govt. of India.
After successful implementation of 6 and 15 MeV electron linear accelerator (linac) technology for Cancer Therapy in India, we initiated the development of high energy high current accelerator for the production of radioisotopes for diagnostic applications. The accelerator will be of 30 MeV energy with 350 µA average current provided by a gridded gun. The linac is a side coupled standing wave accelerator operating at 2998 MHz frequency operating at p/2 mode. The choice of p/2 operating mode is particularly suitable for this case where the repetition rate will be around 400 Hz. Klystron with 7 MW peak power and 36 kW average power will be used as the RF source. The modulator will be a solid-state modulator. The control system is FPGA based setup developed in-house at SAMEER. A retractable target with tungsten will be used as a converter to generate X-rays via bremsstrahlung. The x-rays will then interact with enriched 100Mo target to produce 99Mo via (g, n) reaction. Eluted 99mTc will be used for diagnostic applications. The paper lists the challenges and novel schemes developed at SAMEER to make a compact, rugged, and easy to use system keeping in mind local conditions.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB405

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paper received ※ 19 May 2021 paper accepted ※ 23 June 2021 issue date ※ 02 September 2021

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TUPAB412

New 3 MeV and 7 MeV Accelerators for Cargo Screening and NDT

electron, target, gun, software

2491

S. Proskin, D. Fischer, A.V. Mishin
Varex Imaging, Salt Lake City, USA

For decades evaluating of cargo and non-destructive testing of objects have been utilizing high energy systems based on particle accelerators. End users wish for lower prices, better image quality, and convenience of utilization. In recent years Varex Imaging, world leader in innovation, development, and manufacture of X-ray imaging component solutions, has been developing a series of new accelerator products with improved parameters and a goal of replacing existing dated systems and growing of emerging markets. New S-band energy regulated 3 MeV and 7 MeV linear accelerators have been designed, tested at Varex Imaging and their customer sites. Novel linacs benefit is in dramatically increased output, reduced beam spot, longer operation, and improved versatility. Authors will outline recent progress and future endeavors in linear accelerator development with regards to improvement of accelerating structures, X-ray targets, and corresponding RF components*.
This work would have not been successful without outstanding contribution of the whole Linac Group of Varex Imaging and established partnerships with our customers

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB412

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paper received ※ 18 May 2021 paper accepted ※ 02 June 2021 issue date ※ 18 August 2021

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TUPAB416

Depth-Dose Distribution Dependence on the Energy Profile of Linear and Laser Wakefield Accelerator Electron Beams

electron, radiation, simulation, HOM

2502

T.A. Nguyen
VNUHCM, Ho Chi Minh, Viet Nam
C. Rangacharyulu
University of Saskatchewan, Saskatoon, Canada
C.V. Tao
HCMUS, Ho Chi Minh City, Viet Nam

The depth-dose distributions of 10 MeV electron beams used for food irradiation and sterilization purposes at Research and Development Center for Radiation Technology, HCMC, Vietnam are measured and the results are well reproduced by the MCNP simulations. We extend the simulations to predict the dose depth distribution for 10 MeV electron beams with the energy profiles of a model Laser Wake Field accelerator (LWFA). The dosimetry and simulation results show that the maximum dose of the depth-dose curve inside the product is 1.4 times surface dose with an area density limit of 8.6 g/cm² for two-sided irradiation with nearly mono-energetic beams from the linear accelerator and the corresponding parameters for LWFA are 1.2 times surface dose and 13.0 g/cm², respectively.

Poster TUPAB416 [1.506 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB416

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paper received ※ 17 May 2021 paper accepted ※ 11 June 2021 issue date ※ 31 August 2021

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WEXB05

Beam Commissioning SPIRAL2

MEBT, proton, rfq, MMI

2540

A.K. Orduz, M. Di Giacomo, R. Ferdinand, B. Jacquot, O. Kamalou, J.-M. Lagniel, G. Normand, A. Savalle
GANIL, Caen, France
D. Uriot
CEA-IRFU, Gif-sur-Yvette, France

The SPIRAL2 injector includes a 5 mA proton-deuteron ECR source, a 1 mA ECR heavy ion source (up to A/Q =3) and a CW 0.73 MeV/u RFQ. It has been successfully commissioned using a diagnostic-plate in parallel with the superconducting linac installation. The green light has been obtained for the LINAC commissioning in July of 2019, starting with the Medium Energy Beam Transport (MEBT) commissioning with protons then with helium in 2020. The MEBT line and tuning process are described. The main experimental results are given, including the emittance and profile measurements which are compared with TraceWin simulations. RFQ output energy variation has been found due to an input energy error, its correction optimizing the source platform voltage is presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEXB05

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paper received ※ 19 May 2021 paper accepted ※ 25 June 2021 issue date ※ 13 August 2021

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WEXB06

Development of an APF IH-DTL in the J-PARC Muon g-2/EDM Experiment

DTL, cavity, experiment, focusing

2544

Y. Nakazawa, H. Iinuma
Ibaraki University, Hitachi, Ibaraki, Japan
E. Cicek, N. Kawamura, T. Mibe, M. Yoshida
KEK, Ibaraki, Japan
N. Hayashizaki
RLNR, Tokyo, Japan
Y. Iwata
NIRS, Chiba-shi, Japan
R. Kitamura, Y. Kondo, T. Morishita
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
M. Otani, N. Saito
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
Y. Sue, K. Sumi, M. Yotsuzuka
Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan
Y. Takeuchi
Kyushu University, Fukuoka, Japan
T. Yamazaki
KEK, Tokai Branch, Tokai, Naka, Ibaraki, Japan
H.Y. Yasuda
University of Tokyo, Tokyo, Japan

An inter-digital H-mode drift-tube linac (IH-DTL) is under development in a muon linac at the J-PARC muon g-2/EDM experiment. It accelerates muons from 0.34 MeV to 4.3 MeV at an operating frequency of 324 MHz. The cavity can be miniaturized by introducing the alternative phase focusing (APF) method that enables transverse focusing only with an E-field. The APF IH-DTL cavity was modeled by a three-dimensional field analysis, and the beam dynamics were evaluated numerically. The beam emittance was calculated as 0.316pi and 0.189pi mm mrad in the horizontal and vertical directions, respectively. It satisfies the experimental requirement. Actually, the field error due to the fabrication errors and thermal expansion during operation causes an emittance growth. It was evaluated that the optimized tuners can suppress the emittance growth to less than 10%. In this paper, the detailed design of the APF IH-DTL including the tuner will be reported.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEXB06

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paper received ※ 19 May 2021 paper accepted ※ 29 July 2021 issue date ※ 20 August 2021

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WEPAB001

Accelerator Challenges of the LHeC Project

electron, emittance, optics, proton

2570

B.J. Holzer, K.D.J. André, O.S. Brüning
CERN, Geneva, Switzerland
S.A. Bogacz
JLab, Newport News, Virginia, USA
M. Klein
The University of Liverpool, Liverpool, United Kingdom

The LHeC project studies the design of a future electron-proton collider at CERN that will run in parallel to the standard LHC operation. For this purpose, the existing LHC storage ring will be combined with an Energy Recovery Linac (ERL), to accelerate electrons up to kinetic energy of 50 GeV. This concept - also applicable to the FCC-eh collider and studied at the PERLE project as prototype version - allows a peak luminosity of 10³⁴ cm^-2 s^-1. A sophisticated design of the RF structures, linacs, arcs, and interaction region is required. The electrons are accelerated and, after the interaction point, their energy is recovered through the same RF structures. While this energy recovery concept is a very promising approach, severe challenges are set by the layout of the interaction region, the beam separation concept and the design of the linac and arc lattice for the highest possible momentum acceptance. Emittance control and beam-beam effect of both, electron and proton beams, have been studied in front-to-end simulations and will be presented. We summarise the design principles of the ERL, the optimization of the arc lattice, and the main parameters of the project.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB001

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

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WEPAB012

Preliminary Investigation into Accelerators for In-Situ Cultural Heritage Research

rfq, proton, radiation, detector

2605

T.K. Charles
The University of Liverpool, Liverpool, United Kingdom
A. Castilla
CERN, Meyrin, Switzerland
A. Castilla
Lancaster University, Lancaster, United Kingdom

Ion Beam Analysis (IBA) centres have provided researchers with powerful techniques to analyse objects of cultural significance in a non-destructive and non-invasive manner. However, in some cases it is not be feasible to remove an object from the field or museum and transport it to the laboratory. In this conference proceedings, we report the initial results of an investigation into the feasibility of a compact accelerator that can be taken to sites of cultural significance, for PIXE analysis. In particular, we consider the application of a compact, robust accelerator that is capable to producing 2 MeV protons that can be taken into the field to perform PIXE measurements on rock art. We detail the main challenges and considerations for such a device, as well as highlighting the potential benefits of this new accelerator application.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB012

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paper received ※ 18 May 2021 paper accepted ※ 25 June 2021 issue date ※ 10 August 2021

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WEPAB013

A New Algorithm for Positron Source Parameter Optimisation

positron, target, electron, simulation

2609

Y. Zhao, L. Ma
SDU, Shandong, People’s Republic of China
S. Döbert, A. Latina
CERN, Geneva, Switzerland

In this report, we proposed a new simple and efficient algorithm for positron source parameter optimisation, which is based on iterations of scan of free parameters in the simulation. The new algorithm is fast, simple and convincing since the results can be visually drawn and flexibly tuned and it has an advantage that it can easily handle realistic parametric problems with more than one objective quantities to optimise. The optimisation of the main parameters of the CLIC positron source at the 380 GeV stage is presented as an example to demonstrate how the algorithm works.

Poster WEPAB013 [1.352 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB013

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paper received ※ 15 May 2021 paper accepted ※ 24 June 2021 issue date ※ 17 August 2021

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WEPAB014

Optimisation of the CLIC Positron Source

positron, target, simulation, electron

2613

Y. Zhao, L. Ma
SDU, Shandong, People’s Republic of China
H.M.A. Bajas, S. Döbert, A. Latina
CERN, Geneva, Switzerland

In this report, we reoptimised the CLIC positron source at all collision energy stages. Simulation, optimisation algorithm and results were all improved compared with previous studies. Two different target schemes were studied and compared in terms of the advantages and disadvantages. The spot size of the injected electron beam was also optimised to achieve a compromise between large positron yields and safe energy deposition. The matching device for the capture of positrons was simulated and optimised with both improved analytic and realistic field maps. Conical aperture and front and rear gaps of the matching device were also considered for the first time. The optimised positron source is expected to have the lowest cost.

Poster WEPAB014 [1.825 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB014

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paper received ※ 15 May 2021 paper accepted ※ 21 June 2021 issue date ※ 25 August 2021

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WEPAB015

Comparison of Different Matching Device Field Profiles for the FCC-ee Positron Source

positron, target, electron, simulation

2617

Y. Zhao, L. Ma
SDU, Shandong, People’s Republic of China
B. Auchmann, P. Craievich, J. Kosse, R. Zennaro
PSI, Villigen PSI, Switzerland
I. Chaikovska, R. Chehab
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
S. Döbert, A. Latina
CERN, Meyrin, Switzerland
P.V. Martyshkin
BINP SB RAS, Novosibirsk, Russia

In this report, we compared different matching device field profiles for the FCC-ee positron source. The matching device is used to capture positrons with magnetic field. A flux concentrator was designed with a conical inner chamber. A smaller aperture and a larger aperture were studied. An analytic field profile was also studied using an adiabatic formula. The peak field of the analytic profile as well as beam and target parameters was optimised to achieve a maximum positron yield. A safe energy deposition in the target was guaranteed by requiring a constraint on the deposited power and peak energy deposition density.

Poster WEPAB015 [3.066 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB015

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paper received ※ 15 May 2021 paper accepted ※ 23 June 2021 issue date ※ 30 August 2021

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WEPAB038

Commissioning of a New X-Band, Low-Noise LLRF System

klystron, LLRF, cavity, MMI

2683

A.V. Edwards, M. Boronat Arevalo, N. Catalán Lasheras, G. McMonagle
CERN, Meyrin, Switzerland
A.C. Dexter
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom

To increase beam energy in the CLEAR facility at CERN and study the CLIC accelerating structure prototype in operating conditions, the first X-band test facility at CERN was upgraded in 2020. Both, the acquisition and software systems at X-band test stand 1 (Xbox1) were upgraded to exhibit low phase noise which is relevant to klystron based CLIC and to the use of crab cavities in the beam delivery system. The new LLRF uses down-conversion which necessitates a local oscillator which can be produced by two different methods. The first is a PLL, a commonly used technique which has been previously employed at the other X-band facilities at CERN. The second is a novel application of a single sideband up-convertor. The up-convertor system has demonstrated reduced phase noise when compared with the PLL. The commissioning of the new system began in late 2020 with the conditioning of a 50 MW Klystron. Measurements of the quality of the new LLRF will be shown. These will compare the PLL and up-convertor with particular attention on the quality of the phase measurements. Also, a preliminary study of phase shifts in the waveguide network due to temperature changes will be presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB038

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paper received ※ 13 May 2021 paper accepted ※ 05 July 2021 issue date ※ 20 August 2021

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WEPAB039

Construction of a Compact Electron Injector Using a Gridded RF Thermionic Gun and a C-Band Accelerator

electron, injection, operation, emittance

2687

T. Inagaki, T. Asaka, T. Hara, T. Hiraiwa, N. Hosoda, E. Iwai, C. Kondo, H. Maesaka, T. Ohshima, H. Tanaka
RIKEN SPring-8 Center, Hyogo, Japan
H. Dewa, T. Magome, Y. Minagawa, T. Sakurai
JASRI/SPring-8, Hyogo-ken, Japan
T. Fukui
RIKEN SPring-8 Center, Innovative Light Sources Division, Hyogo, Japan
S. Hashimoto
LASTI, Hyogo, Japan
S.I. Inoue, K. Kajimoto, S. Nakata, T. Seno, H. Sumitomo, R. Takesako, S. Tanaka, R. Yamamoto, M. Yoshioka
SES, Hyogo-pref., Japan
K. Yanagida
JASRI, Hyogo, Japan

A compact and low-cost 1 GeV injector linac was designed and constructed to provide injection beams to the soft X-ray synchrotron radiation facility NewSUBARU instead of the SPring-8 injector system, which will be shutdown. The total length of the injector linac needs to be less than 70 m to fit into the existing tunnel. To this end, an RF electron gun with a gridded thermionic cathode directly attached to a 238 MHz RF cavity was developed and adopted. The 500 keV, 0.6 ns, 1 nC beam emitted from the cavity is compressed to 3 ps by velocity bunching driven by a 476 MHz RF cavity and a S-band RF structure. The short-pulsed beams are accelerated up to 1 GeV with 16 C-band RF structures. In the C-band accelerator section, the klystron output of 50 MW is multiplied 4 times by a pulse compressor and fed to the 4 RF structures to generate a high accelerating field of 31 MV/m. A low-level RF system consisting of a MTCA.4 based high-speed digitizers and RF frontend boards has been constructed. This injector system is used at the 3 GeV SR facility currently under construction in Sendai. In this paper, we report the design outline and the operational performance of the injector system.

Poster WEPAB039 [2.419 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB039

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paper received ※ 20 May 2021 paper accepted ※ 02 July 2021 issue date ※ 24 August 2021

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WEPAB041

Testing of the Milliampere Booster Prototype Cavity

cavity, vacuum, operation, solenoid

2693

R.G. Heine
KPH, Mainz, Germany

The Milliampere Booster (MAMBO) is the injector linac for the Mainz Energy-recovering Superconducting Accelerator MESA. MESA is a multi-turn energy recovery linac with beam energies in the 100 MeV regime currently designed and built at Institut für Kernphysik (KPH) of Johannes Gutenberg-Universität Mainz. The main accelerator consists of two superconducting Rossendorf type modules, while the injector MAMBO relies on normal conducting technolgy. The MAMBO RF cavities are bi-periodic pi/2 structures with 33 cells and 37 cells, respectively. In this paper we present the results of the commissioning and testing of a 13 cell prototype structure.

Poster WEPAB041 [2.824 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB041

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paper received ※ 18 May 2021 paper accepted ※ 23 June 2021 issue date ※ 21 August 2021

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WEPAB042

Linac-200: A New Electron Test Beam Facility at JINR

electron, controls, gun, klystron

2697

M.A. Nozdrin, M. Gostkin, V. Kobets, Y.A. Samofalova, G. Shirkov, A. Trifonov, K. Yunenko, A. Zhemchugov
JINR, Dubna, Moscow Region, Russia

Commissioning of a new electron test beam facility Linac-200 comes to the end at JINR (Dubna, Russia). The core of the facility is a refurbished MEA accelerator from NIKHEF. The key accelerator subsystems including controls, vacuum, precise temperature regulation were redesigned or deeply upgraded. The facility provides electron beams with energy up to 200 MeV while the beam current varying smoothly from 40 mA down to almost zero (single electrons in a bunch). The main goal of the facility is providing test beams for particle detector R&D, studies of novel approaches to the beam diagnostics, and education and training of graduate and postgraduate students. The current status and operation parameters of the facility will be reported.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB042

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

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WEPAB044

Status of VHEE Radiotherapy Related Studies at the CLEAR User Facility at CERN

electron, experiment, radiation, focusing

2704

R. Corsini, W. Farabolini, A. Gilardi
CERN, Geneva, Switzerland
L.A. Dyks, P. Korysko
Oxford University, Physics Department, Oxford, Oxon, United Kingdom
W. Farabolini
CEA-DRF-IRFU, France
A. Gilardi
University of Napoli Federico II, Napoli, Italy
K.N. Sjobak
University of Oslo, Oslo, Norway

Despite the increase in interest in using Very High Energy Electron (VHEE) beams for cancer radiotherapy many unanswered questions in its development remain. The use of test facilities will be an essential tool used to solve these issues. The 200 MeV electron beam from the CERN Linear Accelerator for Research (CLEAR) has been used extensively, in collaboration with several research institutes, to perform dosimetry studies and explore potential applications of VHEE beams to radiotherapy, including the exploitation of the so called FLASH effect. In this paper, we present an overview of past studies with emphasis on the more recent results. We describe methods, techniques and equipment developed at CERN in this framework, and give an outlook on future activities.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB044

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paper received ※ 18 May 2021 paper accepted ※ 23 June 2021 issue date ※ 27 August 2021

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WEPAB051

Beam Dynamics for a High Field C-Band Hybrid Photoinjector

electron, emittance, cathode, gun

2714

L. Faillace, F. Bosco, M. Carillo, L. Giuliano, M. Migliorati, A. Mostacci, L. Palumbo
Sapienza University of Rome, Rome, Italy
R.B. Agustsson, I.I. Gadjev, S.V. Kutsaev, A.Y. Murokh
RadiaBeam, Marina del Rey, California, USA
M. Behtouei, A. Giribono, B. Spataro, C. Vaccarezza
INFN/LNF, Frascati, Italy
A. Fukasawa, N. Majernik, J.B. Rosenzweig, O. Williams
UCLA, Los Angeles, California, USA
S.G. Tantawi
SLAC, Menlo Park, California, USA

Funding: This work supported by DARPA GRIT under contract no. 20204571 and partially by INFN National Committee V through the ARYA project.
In this paper, we present a new class of a hybrid photoinjector in C-Band. This project is the effort result of a UCLA/Sapienza/INFN-LNF/SLAC/RadiaBeam collaboration. This device is an integrated structure consisting of an initial standing-wave 2.5-cell gun connected to a traveling-wave section at the input coupler. Such a scheme nearly avoids power reflection back to the klystron, removing the need for a high-power circulator. It also introduces strong velocity bunching due to a 90° phase shift in the accelerating field. A relatively high cathode electric field of 120 MV/m produces a ~4 MeV beam with ~20 MW input RF power in a small foot-print. The beam transverse dynamics are controlled with a ~0.27 T focusing solenoid. We show the simulation results of the RF/magnetic design and the optimized beam dynamics that shows 6D phase space compensation at 250 pC. Proper beam shaping at the cathode yields a ~0.5 mm-mrad transverse emittance. A beam waist occurs simultaneously with a longitudinal focus of <400 fs rms and peak current >600 A. We discuss application of this injector to an Inverse-Compton Scattering system and present corresponding start-to-end beam dynamics simulations.

Poster WEPAB051 [0.827 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB051

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paper received ※ 18 May 2021 paper accepted ※ 01 July 2021 issue date ※ 15 August 2021

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WEPAB054

Electromagnetic and Beam Dynamics Studies of the ThomX LINAC

HOM, gun, electron, solenoid

2721

M. Alkadi, C. Bruni, M. El Khaldi, M. Jacquet
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
H. Monard
IJCLab, ORSAY, France

ThomX is a new generation compact Compton source. The machine is composed of a 50/70 MeV injector linac and a storage ring where an electron bunch collides with a laser pulse accumulated in a Fabry-Perot resonator. The compact source, built at Irene Joliot-Curie Laboratory (IJCLAB) in the Orsay campus of Paris-Saclay University, is designed to produce a total flux of 10¹³ ph/s and a brightness of 1011 ph / (s.mm2.mrad2) in 0.1% of bandwidth with a tunable energy ranging from 45 keV to 90 keV on the X-ray beam axis. The photo-injector is composed of a homemade 2.5 cell photocathode RF-gun, placed between two solenoids. An energy of 5 MeV is reached with a 80 MV/m electric field gradient. During the commissioning phase, a 4.8 m S-band LIL section will be used to achieve a 50 MeV corresponding to a 45 keV X-ray energy. The LIL accelerating section is a quasi-constant gradient traveling wave structure. The energy gain in the section is 45 MeV, corresponding to an average effective accelerating gradient of 10 MV/m for an input RF power of 9 MW. Here we present the electromagnetic and beam dynamics studies of the ThomX LINAC.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB054

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paper received ※ 19 May 2021 paper accepted ※ 01 July 2021 issue date ※ 29 August 2021

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WEPAB055

Development of a Linac for Injection of Ultrashort Electron Bunches Into Laser Plasma Electron Accelerators

electron, laser, plasma, acceleration

2725

S. Masuda, N. Kumagai, T. Masuda, Y. Otake
JASRI, Hyogo, Japan
Y. Koshiba, S. Otsuka
Waseda University, Tokyo, Japan
T. Sakai, T. Tanaka
LEBRA, Funabashi, Japan
K. Sakaue
The University of Tokyo, The School of Engineering, Tokyo, Japan

Funding: This work is supported by JST-Mirai Program Grant Number JPMJMI17A1, Japan.
We are developing a C-band linac that produces ultrashort electron bunches as an injector for laser plasma accelerators. A plasma wave excited by a high intense ultrashort laser pulse has a wavelength of the order of 10 to 100 fs and transverse dimensions of the order of 10 to 100 um. To inject the bunch into a proper phase of the plasma wave, a length and transverse sizes of the bunch must be much smaller than the plasma wave structure. A laser triggered photo cathode electron RF-gun and a 2pi/3 mode traveling wave buncher with 24 cells for ultrashort electron bunch production have been developed based on electron beam tracking simulations that show the bunch length is less than 10 fs with a charge of 100 fC at a focus on the plasma wave. The simulations also show that sufficiently small transverse sizes of the bunch at the focus can be obtained by a Q triplet. A highly accurate timing lower than the plasma wavelength (~10fs) is required for the synchronization between the electron bunch injection and the plasma wave excitation. An RF master oscillator with low SSB phase noise (-150dBc/Hz@10MHz) has been developed for the synchronization. We will report present development status.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB055

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paper received ※ 19 May 2021 paper accepted ※ 15 July 2021 issue date ※ 29 August 2021

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WEPAB056

Advanced Photoinjector Development at the UCLA SAMURAI Laboratory

FEL, emittance, gun, simulation

2728

A. Fukasawa, G. Andonian, O. Camacho, C.E. Hansel, G.E. Lawler, W.J. Lynn, N. Majernik, P. Manwani, B. Naranjo, J.B. Rosenzweig, Y. Sakai, O. Williams
UCLA, Los Angeles, California, USA
Z. Li, R. Robles, S.G. Tantawi
SLAC, Menlo Park, California, USA
J.I. Mann
PBPL, Los Angeles, USA
M. Yadav
The University of Liverpool, Liverpool, United Kingdom

Funding: This work was supported by the US Department of Energy under the contract No. DE-SC0017648, DE-SC0009914, and DE-SC0020409, and by National Science Foundation Grant No. PHY-1549132
UCLA has recently constructed SAMURAI, a new radiation bunker and laser infrastructure for advanced accelerator research. In its first phase, we will build a 30 MeV photoinjector with an S-band hybrid gun. The beam dynamics simulation for this beamline showed the generation of the beam with the emittance 2.4 um and the peak current 270 A. FIR-FEL experiments are planned in this beamline. The saturation peak power was expected at 170 MW.

Poster WEPAB056 [0.939 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB056

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paper received ※ 28 May 2021 paper accepted ※ 01 July 2021 issue date ※ 11 August 2021

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WEPAB064

Front-to-End Simulations of the Energy Recovery Linac for the LHeC Project

emittance, electron, proton, radiation

2740

K.D.J. André, B.J. Holzer
CERN, Geneva, Switzerland

The LHeC project aims to study the electron-proton deep inelastic scattering at the TeV energy scale with an innovative accelerator program. It exploits the promising energy recovery technology in order to collide an intense 50 GeV lepton beam with one hadron beam from the High Luminosity Large Hadron Collider (HL-LHC) in parallel to the hadron-hadron operation. The paper presents the studies that have been performed to assess the performance of the machine and the efficiency of the energy recovery process for different scalings of the ERL. The studies include emittance blow-up due to synchrotron radiation emission and beam-disruption created by the strong beam-beam force at the interaction point. The design principles of the ERL structure are discussed, including the particle detector bypass and the interaction region, and the results of the tracking simulations are presented, considering the complete multi-turn ERL process. Special attention is turned to the lepton beam emittance budget and the resulting energy recovery performance.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB064

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paper received ※ 18 May 2021 paper accepted ※ 24 June 2021 issue date ※ 28 August 2021

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WEPAB065

Studies of the Energy Recovery Performance of the PERLE Project

cavity, HOM, electron, radiation

2744

K.D.J. André, B.J. Holzer
CERN, Geneva, Switzerland
S.A. Bogacz
JLab, Newport News, Virginia, USA

The Powerful Energy Recovery Linac for Experiments (PERLE) is an accelerator facility for the development and application of the energy recovery technique for an intense 500 MeV electron beam. The paper presents the studies that have been performed to assess the quality of the ERL lattice design and beam optics. The studies include the Coherent Synchrotron Radiation (CSR) emission and wakefields in the superconducting radio-frequency structures of the linacs. The lattice design and optics principles of the ERL structure are discussed, involving the vertical deflection system and the 180° arcs. Finally, the results of the front-to-end tracking simulations that consider the complete multi-turn energy recovery process are presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB065

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paper received ※ 18 May 2021 paper accepted ※ 24 June 2021 issue date ※ 30 August 2021

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WEPAB110

Solid-State Driven X-Band Linac for Electron Microscopy

electron, cavity, simulation, gun

2853

A. Dhar, E.A. Nanni, M.A.K. Othman, S.G. Tantawi
SLAC, Menlo Park, California, USA

Funding: This work was supported by the Department of Energy Contract No. DE-AC02-76SF00515.
Microcrystal electron diffraction (MicroED) is a technique used by scientists to image molecular crystals with cryo-electron microscopy (cryo-EM)*. However, cryo-EMs remain expensive, limiting MicroED’s accessibility. Current cryo-EMs accelerate electrons to 200-300 keV using DC electron guns with a nA of current and low emittance. However at higher voltages these DC guns rapidly grow in size. Replacing these electron guns with a compact linac powered by solid-state sources could lower cost while maintaining beam quality, thereby increasing accessibility. Utilizing compact high shunt impedance X-band structures ensures that each RF cycle contains at most a few electrons, preserving beam coherence. CW operation of the RF linac is possible with distributed solid-state architectures** that use 100W solid-state amplifiers at X-band frequencies. We present an initial design for a prototype low-cost CW RF linac for high-throughput MicroED producing 200 keV electrons with a standing-wave architecture where each cell is individually powered by a solid-state amplifier. This design also provides an upgrade path for future compact MeV-scale sources on the order of 1 meter in size.
* Jones, C. G. et al. ACS central science 4, 1587-1592 (2018).
** D. C. Nguyen et al, Proc. 9th International Particle Accelerator Conference (IPAC’18), no. 9, pp. 520-523

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB110

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paper received ※ 19 May 2021 paper accepted ※ 24 June 2021 issue date ※ 10 August 2021

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WEPAB141

Preliminary Simulation of CERN’s Linac4 H⁻ Source Beam Formation

plasma, simulation, electron, extraction

2947

A. Vnuchenko, J. Lettry
CERN, Geneva, Switzerland
U. Fantz, S. Mochalskyy, D. Wünderlich
MPI/IPP, Garching, Germany
T. Minea, A. Revel
CNRS LPGP Univ Paris Sud, Orsay, France

Linac4 is the new (H⁻) linear injector of CERN’s accelerator complex. This contribution describes the modelling activities required to get insight into H⁻ beam formation processes and their impact on beam properties. The simulation region starts from a homogeneous hydrogen plasma, the plasma then expands through the magnetic filter field. H⁻ ions and electrons are electrostatically extracted through the meniscus (line of separation between the plasma and the extracted beam) and eventually accelerated. The physics is simulated via the 3D PIC code ONIX. This code, originally dedicated to ITER’s neutral injector sources, has been modified to match single aperture sources. A new type of boundary condition is described, as well as the field distribution and geometry of the standard IS03 and a dedicated proto-type of CERN’s Linac4 H⁻ source. A plasma electrode prototype designed to provide metallic boundary conditions was produced and tested. This plasma electrode geometry enables Optical Emission Spectroscopy in the region closest to meniscus. A set of plasma parameters was chosen as input characterizing the plasma. Preliminary simulation results of beam formation region are presented.

Poster WEPAB141 [0.710 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB141

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paper received ※ 18 May 2021 paper accepted ※ 02 June 2021 issue date ※ 31 August 2021

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WEPAB149

The RF Gun for the Siberian Circular Light Source "SKIF"

cavity, gun, cathode, electron

2965

V. Volkov, A.M. Batrakov, S.M. Gurov, S.E. Karnaev, A.A. Kondakov, S.A. Krutikhin, G.Y. Kurkin, A.E. Levichev, O.I. Meshkov, V.K. Ovchar, A.V. Pavlenko, O.A. Pavlov, A.G. Tribendis, N.G. Vasileva
BINP SB RAS, Novosibirsk, Russia
A.E. Levichev, A.V. Pavlenko
NSU, Novosibirsk, Russia
A.G. Tribendis
NSTU, Novosibirsk, Russia

The Siberian Circular Light Source is a new medium-energy high brightness synchrotron light facility that is under construction on the Budker Institute of Nuclear Physics (BINP) in Russia, Novosibirsk. The accelerator facility is divided for convenience into three components; a 3 GeV storage ring, a full-energy booster synchrotron, and a 200 MeV injector linac with a thermionic gridded RF gun electron source. This paper describes the RF gun design and plans for operations.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB149

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paper received ※ 19 May 2021 paper accepted ※ 07 June 2021 issue date ※ 02 September 2021

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WEPAB151

Regenerative Beam Break Up Instability Analysis

cavity, HOM, dipole, experiment

2971

V. Volkov, V.M. Petrov
BINP SB RAS, Novosibirsk, Russia

New features of regenerative beam break up (BBU) instability such as the typing of high order dipole modes (HOMs)in each cavity by two classes, one of them are stable and other ones are unstable, HOM effective quality factor depending on average beam current, and normalized invariable threshold current individually characterizes each HOM are investigated in this article in detail.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB151

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paper received ※ 19 May 2021 paper accepted ※ 22 June 2021 issue date ※ 01 September 2021

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WEPAB163

An X-Band Ultra-High Gradient Photoinjector

gun, experiment, emittance, solenoid

2986

S.V. Kuzikov, S.P. Antipov, P.V. Avrakhov, E. Dosov, C.-J. Jing, E.W. Knight
Euclid TechLabs, Solon, Ohio, USA
G. Ha, C.-J. Jing, W. Liu, P. Piot, J.G. Power, D.S. Scott, J.H. Shao, E.E. Wisniewski
ANL, Lemont, Illinois, USA
C.-J. Jing
Euclid Beamlabs, Bolingbrook, USA
X. Lu
MIT/PSFC, Cambridge, Massachusetts, USA
X. Lu
SLAC, Menlo Park, California, USA
P. Piot
Fermilab, Batavia, Illinois, USA
P. Piot, W.H. Tan
Northern Illinois University, DeKalb, Illinois, USA
E.E. Wisniewski
IIT, Chicago, Illinois, USA

Funding: This work was supported by DoE SBIR grant # DE-SC0018709.
High brightness beams appealing for XFELs and UEM essentially imply a high current and a low emittance. To obtain such beams we propose to raise the accelerating voltage in the gun mitigating repealing Coulomb forces. An ultra-high gradient is achieved utilizing a short-pulse technology. We have designed a room temperature X-band 1,5 cell gun that is able to inject 4 MeV, 100 pC bunches with as low as 0.15 mcm normalized transverse emittance. The gun is operated with as high gradients as 400 MV/m and fed by 200 MW, 10 ns RF pulses generated with Argonne Wakefield Accelerator (AWA) power extractor. We report results of low RF power tests, laser alignment test results, and successful gun conditioning results carried out at nominal RF power.

Poster WEPAB163 [5.427 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB163

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paper received ※ 18 May 2021 paper accepted ※ 02 June 2021 issue date ※ 19 August 2021

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WEPAB209

Review of Medical Accelerator Development at Sameer, India

electron, photon, cavity, acceleration

3113

T.S. Dixit, N. Bansode, A.P. Bhagwat, S.T. Chavan, A.P. Deshpande, G. Gaikwad, S. Ghosh, R. Krishnan, C.S. Nainwad, G.D. Panchal, S.N. Pethe, K.A. Thakur, V.B. Ukey, M.M. Vidwans
SAMEER, Mumbai, India

Funding: Ministry of Electronics and Information Technology (MeitY), Government of India
At the Medical Electronics Division of SAMEER, R&D for the development of a 4 MeV energy electron linac for Cancer therapy was taken up in the late ’80s. An S-band standing wave side coupled structure operating at pi/2 mode was developed for electron acceleration. The linac was integrated with other subsystems in collaboration with CSIO and PGIMER and the first machine was commissioned at PGI, Chandigarh in 1990. Thereafter, a lot of modifications like energy, dose rate, iso-center height etc. were made in the system, and later 4 more machines were commissioned in hospitals for treatment. More than 1,50,000 patients have been treated using SAMEER’s 6 MeV oncology system. Subsequently, development of dual-mode and variable energy electron and photon output machines was undertaken. Two-photon energies of 6 and 15 MV and multiple electron energies starting from 6 to 18 MeV for treatment was offered from the linac. The electron energy variation was done using plunger mechanism in the side coupling cavity. This linac was successfully baked and RF tested for various parameters. This paper describes the experimental parameters achieved for both low and high energy dual-mode linac.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB209

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paper received ※ 14 May 2021 paper accepted ※ 07 July 2021 issue date ※ 13 August 2021

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WEPAB238

Modeling Short Range Wakefield Effects in a High Gradient Linac

wakefield, alignment, space-charge, dipole

3185

F. Bosco, M. Carillo, L. Faillace, L. Giuliano, M. Migliorati, A. Mostacci, L. Palumbo
Sapienza University of Rome, Rome, Italy
M. Behtouei, L. Faillace, A. Giribono, B. Spataro, C. Vaccarezza
INFN/LNF, Frascati, Italy
F. Bosco, M. Migliorati
INFN-Roma1, Rome, Italy
L. Giuliano, A. Mostacci, L. Palumbo
INFN-Roma, Roma, Italy
J.B. Rosenzweig
UCLA, Los Angeles, California, USA

Funding: This work is supported by DARPA GRIT under contract no. 20204571 and partially by INFN National committee V through the ARYA project.
The interaction of charged beams with the surrounding accelerating structures requires a thorough investigation due to potential negative effects on the phase space quality. Indeed, the wakefields acting back on the beam are responsible for emittance dilution and instabilities, such as the beam break-up, which limit the performances of electron-based radiation sources and linear colliders. Here we introduce a new tracking code which is meant to investigate the effects of short-range transverse wakefields in linear accelerators. The tracking is based on quasi-analytical models for the beam dynamics which, in addition to the basic optics specified by the applied fields, include dipole wakefield forces and a simple approach to account for space-charge effects. Such features provide a reliable tool which easily allows to inspect the performances of a linac. To validate the model, a parallel analysis for a reference case is performed with well-known beam dynamics codes, and comparisons are shown. As an illustrative application, we discuss a study on alignment tolerances evaluating the emittance growth induced by misaligned accelerating sections.

Poster WEPAB238 [1.747 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB238

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paper received ※ 18 May 2021 paper accepted ※ 07 July 2021 issue date ※ 01 September 2021

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WEPAB259

Impact of the Magnet Alignment and Field Errors on the Output Uniform Beam at the DONES HEBT Line

target, neutron, multipole, octupole

3251

C. Oliver, A. Ibarra, J. Mollá, I. Podadera, R. Varela
CIEMAT, Madrid, Spain
H. Dzitko
F4E, Germany
O. Nomen, D. Sánchez-Herranz
IREC, Sant Adria del Besos, Spain

Funding: This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-2018 under grant agreement No 633053
IFMIF-DONES will be a facility devoted to study the degradation of advanced materials for operation of fusion reactors. Motivated by the need of optimizing the neutron irradiation to the materials samples, the HEBT line of the deuteron DONES (DEMO Oriented Neutron Source) accelerator is based on non-linear magnetic fields. By using octupoles and dodecapoles magnets, it is possible to shape the beam profile to achieve the demanded rectangular uniform distribution across the flat top of the beam profile, with high edge peaks in the horizontal direction. Special optics conditions are obtained with a proper setting of quadrupole magnets to minimize the x-y coupling. Additionally, the high beam power (5 MW, for a 125 mA, 40 MeV deuteron beam) in conjunction with the huge space charge makes challenging the HEBT line design to avoid non-controlled losses, except in the devoted scrapers. A comprehensive beam dynamics analysis has been made using TraceWin code. It includes extensive error studies to define tolerances and verify the robustness of the design with respect to magnet misalignment, power supply instabilities and injection parameters.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB259

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

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WEPAB278

Beam-Beam Simulations for Lepton-Hadron Colliders: ALOHEP Software

collider, luminosity, hadron, lepton

3293

B.B. Oner
Gazi University, Faculty of Arts and Sciences, Teknikokullar, Ankara, Turkey
B. Dagli, S. Sultansoy
TOBB ETU, Ankara, Turkey
B. Ketenoğlu
Ankara University, Faculty of Engineering, Tandogan, Ankara, Turkey

It is known that rough luminosity estimations for ll, lh, and hh colliders can be performed easily using nominal beam parameters. In principle, more precise results can be obtained by analytical solutions. However, beam dynamics is usually neglected in this case since it is almost impossible to cope with beam size fluctuations. In this respect, several beam-beam simulation programs for linear e⁺e⁻ and photon colliders have been proposed while no similar open-access simulation exists for all types of colliders (i.e. linac-ring ep colliders). Here, we present the software ALOHEP (A Luminosity Optimizer for High Energy Physics), a luminosity calculator for linac-ring and ring-ring lh colliders, which also computes IP parameters such as beam-beam tune shift, disruption arising out of electromagnetic interactions. In addition, the program allows taking crossing-angle effects on luminosity into account.
* Y.C. Acar et al., Nucl. Instrum. Meth. A, 871 (2017).

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB278

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paper received ※ 19 May 2021 paper accepted ※ 26 July 2021 issue date ※ 27 August 2021

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WEPAB284

Interlock System Upgrades at the CERN Accelerator Complex During Long Shutdown 2

injection, booster, extraction, operation

3316

J.A. Uythoven, A. Antoine, C. Martin, A. Mirana Fontan, R. Mompo, I. Romera, R. Secondo
CERN, Geneva, Switzerland

The CERN accelerator complex stopped operation at the end of 2018 for the Long Shutdown 2 (LS2), allowing for the LHC Injector Upgrade program (LIU) and consolidation work to be accomplished. A gradual restart of the different accelerators is ongoing in 2021, culminating with the LHC foreseen to be back in operation early 2022. During LS2 a very large range of systems was modified throughout the accelerator complex. This includes the so-called Machine Interlock systems, which are at the heart of the overall machine protection system. This paper gives an overview of the Machine Interlock systems changes during LS2. It includes the installation of a Beam Interlock System (BIS) at the new linear accelerator LINAC4, at the PS-Booster and the installation of a new Injection BIS for the SPS synchrotron. New Safe Machine Parameter flags to protect the SPS transfer line mobile beam dumps against high intensity beams were put in place. The new Warm Magnet Controller (WIC) installations at LINAC4 the PS Booster and the different transfer lines and experimental areas are presented together with the modifications to the Power Interlock Controller protecting the LHC superconducting magnets.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB284

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paper received ※ 17 May 2021 paper accepted ※ 02 July 2021 issue date ※ 17 August 2021

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WEPAB297

A Recent Upgrade on Phase Drift Compensation System for a Stable Beam Injection at J-PARC Linac

cavity, DTL, injection, controls

3357

E. Cicek, Z. Fang, Y. Fukui, K. Futatsukawa
KEK, Ibaraki, Japan
T. Hirane, S. Shinozaki
JAEA/J-PARC, Tokai-mura, Japan
Y. Sato
Nippon Advanced Technology Co., Ltd., Tokai, Japan

J-PARC linac, consisting of 324 MHz and 972 MHz acceleration sections, delivers H⁻ beam to the rapid cycling synchrotron (RCS). The drift in the beam injection momentum from linac to RCS was measured to be highly dependent on the humidity at the klystron gallery. Also, changes in both temperature and humidity strongly affect the rf field phase controlled within the digital feedback (DFB) system. To cope with this, a unique phase drift compensation system, namely the phase drift monitor (PDM) system, is implemented in the MEBT2B1 station as the first step at the linac. However, the compensation of the drift correction could not be achieved directly since two different frequencies were used. The new PDM, which adapts the direct sampling method using the Radio Frequency System-on-Chip (RFSoC), will pave the way to ensure rf phase stability at all stations simultaneously. Here we present the effects of temperature and humidity on the rf field phase, along with performance and preliminary test results concerning the phase drift compensation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB297

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paper received ※ 19 May 2021 paper accepted ※ 01 July 2021 issue date ※ 18 August 2021

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WEPAB300

Python Based Tools for FRIB LLRF Operation and Management

controls, LLRF, cavity, EPICS

3367

S.R. Kunjir, D.G. Morris, S. Zhao
FRIB, East Lansing, Michigan, USA

Funding: This work is supported by the US Department of Energy Office of Science under Cooperative Agreement DE-SC0000661, the State of Michigan and Michigan State University.
Some Python based tools have been developed at the Facility for Rare Isotope Beams (FRIB) for the ease of operation and management of the low level radio frequency (LLRF) controllers. Utilizing the rich features in Python, some tasks can be easily applied to a whole segment, one type of cryomodule (CM), a specific cryomodule or individual cavities grouped by a complex custom query. The tasks include, for example, 1) testing interface connections between various sub-systems prior to an operational run; 2) setting, checking and saving/restoring parameters during and after an operational run; 3) updating LLRF controller firmware and software during maintenance. With these tools, routine manual tasks are streamlined to achieve significantly greater efficiency in terms of scalability, time, memory and network resources. Considering channel access security, beam on/off status etc., the strategy of choosing either input/output controller (IOC) or Python for the implementation of certain tasks is also discussed in the paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB300

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paper received ※ 18 May 2021 paper accepted ※ 01 July 2021 issue date ※ 24 August 2021

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WEPAB370

Study of an L-Band CW Linac

electron, radiation, emittance, solenoid

3575

J. Gao, H.B. Chen, J.Y. Liu, J. Shi, H. Zha
TUB, Beijing, People’s Republic of China

We have studied an L-band linac based on a cheap industrial magnetron, which works at CW mode with 75kW averaged output-power. The designed energy-gain of electrons is 500keV. Low accelerating gradient was the dominant problem encountered during the structure design. We adopted a standing-wave structure with magnetically coupling and nose cones to increase the effective shunt impedance. A 7-cell design has been completed, of which the transverse dynamics and thermodynamics were simulated. Results showed that this accelerating structure could work stably at 59 C and 100 mA output beam current was achieved. This L-band design provided a cheap and efficient way to generate low-energy electrons for industrial irradiation processing.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB370

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

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WEPAB371

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

simulation, injection, GUI, gun

3578

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

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

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

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

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WEPAB383

An Evolutionary Algorithm Approach to Multi-Pass ERL Optics Design

optics, quadrupole, focusing, simulation

3610

I. Neththikumara, T. Satogata
ODU, Norfolk, Virginia, USA
R.M. Bodenstein, S.A. Bogacz, T. Satogata
JLab, Newport News, Virginia, USA
A. Vandenhoeke
ULB, Bruxelles, Belgium

Funding: This material is based upon work supported by the U.S. Department of Energy under contract DE-AC05-06OR23177.
An Energy Recovery Experiment at CEBAF (ER@CEBAF) is aimed at demonstrating high energy, low current, multi-pass energy recovery at the existing 12 GeV CEBAF accelerator. The beam break-up instability, limiting the maximum beam current, can be controlled through minimizing beta functions for the lowest energy pass, which gives a preference to strongly focusing optics, e.g. a semi-periodic FODO lattice. On the other hand, one needs to limit beta function excursions, caused by under focusing, at the higher energy passes, which in turn favors weakly focusing linac optics. Balancing both effects is the main objective of proposed multi-pass linac optics optimization. Here, we discuss an optics design process for ER@CEBAF transverse optics using a genetic algorithm.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB383

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paper received ※ 19 May 2021 paper accepted ※ 02 July 2021 issue date ※ 15 August 2021

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WEPAB385

Beam Dynamic Analysis of RF Modulated Electron Beam Produced by Gridded Thermionic Guns

electron, gun, cathode, emittance

3618

G. Adam
University of Strathclyde, Glasgow, United Kingdom
A.W. Cross, L. Zhang
USTRAT/SUPA, Glasgow, United Kingdom
B.L. Militsyn
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
B.L. Militsyn
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: Science and Technology Facilities Council (STFC) U.K training grant, industrial case with TMD Ltd, UK ST/R002141/1 "Accelerators for Security, healthcare and Environmental applications ".
A thermionic cathode gridded electron gun used in injectors for different types of circular and linear particle accelerators and for energy recovery configurations was studied. Both theory and numerical simulation were used to explore the relationship between the bunch charge and bunch length. The electron gun is based on a Pierce-type geometry. It was initially designed using Vaughan synthesis followed by optimization using a 2D electron trajectory solver TRAK. After optimization, the grid in front of the cathode was inserted and the RF field was introduced through a coaxial waveguide structure. The complete gun was simulated using the PIC code MAGIC. High duty cycle operations at frequencies 1.5 GHz and 3.0 GHz, were investigated using different combinations of both the bias and the RF voltage applied between the cathode and the grid. The beam dynamics results from the PIC showed that a minimum bunch length of 10⁶ ps could be achieved with a bunch charge of 33 pC when the driving RF frequency was 1.5 GHz. Operating at the higher RF frequency of 3GHz did not significantly reduce the bunch length. The normalized emittance of about 5.6 mm-mrad was demonstrated in PIC simulations.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB385

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paper received ※ 19 May 2021 paper accepted ※ 02 July 2021 issue date ※ 30 August 2021

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WEPAB387

Study of Failure Modes in Electron Linac-Based X-Ray Sources for Industrial Applications

gun, electron, operation, vacuum

3622

K.P. Dixit, G. Vinod
BARC, Mumbai, India

Electron linac-based X-ray sources (XRS) have an increased demand in industrial applications, mainly for their advantages of compactness and ease of use. In order to achieve reliable operation, it is necessary to have rugged components in the linac system. Hence, this study focusses on achieving high reliability design; also in formulating a preventive maintenance programme to optimise the availability and prognostic methods for performance monitoring of components. This paper investigates the failure modes in the important sub-systems of a 6 MeV electron linac, including electron gun, RF power source, vacuum system, x-ray target, control system, etc. Electron guns suffer from problems related to the filament heater damage and high voltage insulation failure. In the RF source, major components (line-type pulsed modulators, magnetrons, circulator and RF window) are studied to assess their life. Fault tree analysis of the individual sub-systems and the effect of individual failures on the linac down-time are studied. A few mitigation techniques used in practical systems are also discussed here.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB387

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paper received ※ 18 May 2021 paper accepted ※ 23 July 2021 issue date ※ 29 August 2021

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WEPAB398

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

quadrupole, network, GUI, brightness

3638

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

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

Poster WEPAB398 [1.799 MB]

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

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

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THXC05

Simulation of Imaging Using Accelerated Muon Beams

acceleration, simulation, radio-frequency, scattering

3740

M. Otani
KEK, Tokai, Ibaraki, Japan
H.M. Miyadera
LANL, Los Alamos, New Mexico, USA
T. Shiba
Japan Atomic Energy Agency, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

Muons are elementary particles with strong penetrating power and cosmic-ray muons have been utilized to see through large structures such as the pyramids. Recently, we have succeeded in accelerating muons using a radio-frequency accelerator, opening the door to new imaging techniques using accelerated muon beams. Currently, imaging with cosmic-ray muons is limited in imaging time and resolution by their intensity and energy fluctuations. The muon beams can have high intensity and monochromatic energy, allowing for better resolution imaging in less time. In this poster, imaging of spent nuclear fuel in casks using cosmic rays and muon beams, as well as imaging in other cases, will be evaluated and compared.

Poster THXC05 [2.560 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THXC05

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paper received ※ 16 May 2021 paper accepted ※ 19 July 2021 issue date ※ 15 August 2021

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THXC06

Design and Measurements of an X-Band 8 MeV Standing-Wave Electron Accelerator

electron, bunching, gun, experiment

3744

F. Liu, H.B. Chen, J. Shi, C.-X. Tang, H. Zha
TUB, Beijing, People’s Republic of China

X-band low-energy electron linear accelerators are attractive to industrial and medical applications due to the compact size. In this work we present tests of an 8 MeV X-band accelerator for industrial use. It adopts the coaxial coupling standing wave structure working at 9300 MHz. The accelerator length is 50 cm including the cavity, thermal gun, and electron window. Dedicated bunching cells are designed to reduce the energy spread. In the high power tests, the accelerator was able to generate the electron beam with RMS energy spread less than 1% (beam energy: 8.1 MeV, peak current: 45 mA). Combining features of compact size and the low energy spread, this X-band accelerator design is valuable for various applications.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THXC06

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paper received ※ 19 May 2021 paper accepted ※ 01 July 2021 issue date ※ 02 September 2021

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THPAB003

Application of Generalized Gaussian Distribution in the Processing the Wire Scanner Data

emittance, hadron, background, electron

3759

H. Geng, C. Meng, F. Yan, Y. Zhang, Y.L. Zhao
IHEP, Beijing, People’s Republic of China

Wire scanners are widely used for measuring beam emittance in both electron and hadron accelerators. Gaussian fitting is the most commonly used method in processing the wire scanner data. But in hadron machines, beams are normally not gaussian distribution due to the action of nonlinear forces such as space charge effect. Under these circumstances, there would be big deviations if the wire scanner data was still fitted with gaussian distributions. This paper introduces generalized Gaussian distribution in the processing the wire scanner data measured in the ADS injector-I. The results using different fitting method will be compared.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB003

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paper received ※ 14 May 2021 paper accepted ※ 18 June 2021 issue date ※ 30 August 2021

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THPAB007

Technology Spinoff and Lessons Learned from the 4-Turn ERL CBETA

permanent-magnet, cavity, radiation, SRF

3762

K.E. Deitrick, N. Banerjee, A.C. Bartnik, D.C. Burke, J.A. Crittenden, J. Dobbins, C.M. Gulliford, G.H. Hoffstaetter, Y. Li, W. Lou, P. Quigley, D. Sagan, K.W. Smolenski
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
J.S. Berg, S.J. Brooks, R.L. Hulsart, G.J. Mahler, F. Méot, R.J. Michnoff, S. Peggs, T. Roser, D. Trbojevic, N. Tsoupas
BNL, Upton, New York, USA
T. Miyajima
KEK, Ibaraki, Japan

The Cornell-BNL ERL Test Accelerator (CBETA) developed several energy-saving measures: multi-turn energy recovery, low-loss superconducting radiofrequency (SRF) cavities, and permanent magnets. With green technology becoming imperative for new high-power accelerators, the lessons learned will be important for projects like the FCC-ee or new light sources, where spinoffs and lessons learned from CBETA are already considered for modern designs.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB007

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paper received ※ 20 May 2021 paper accepted ※ 05 July 2021 issue date ※ 12 August 2021

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THPAB021

Status of VEPP-5 Injection Complex

injection, positron, damping, electron

3796

F.A. Emanov, A.V. Andrianov, K.V. Astrelina, V.V. Balakin, A.M. Barnyakov, A.M. Batrakov, O.V. Belikov, D.E. Berkaev, Y.M. Boimelshtain, D. Bolkhovityanov, A. Butakov, A.R. Frolov, G.V. Karpov, A.S. Kasaev, A.A. Kondakov, N.Kh. Kot, E.S. Kotov, G.Y. Kurkin, R.M. Lapik, N.N. Lebedev, A.E. Levichev, Yu.I. Maltseva, P.V. Martyshkin, S.V. Motygin, A.A. Murasev, V. Muslivets, D.A. Nikiforov, A.V. Pavlenko, A.M. Pilan, Yu.A. Rogovsky, S.L. Samoylov, A.G. Tribendis, S. Vasiliev, V.D. Yudin
BINP SB RAS, Novosibirsk, Russia

VEPP-5 injection complex is being put into operation as beam source of VEPP-2000 and VEPP-4 colliders at the end of 2016. Since then injection complex demonstrated maximum positron storage rate 1.7·10¹⁰ e+/s and stable operation at the energy of 430 MeV. Latest operation results and prospects are presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB021

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

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THPAB025

A Proposed Beam-Beam Test Facility COMBINE

collider, experiment, electron, beam-beam-effects

3802

E.A. Nissen, G.A. Krafft
JLab, Newport News, Virginia, USA
J.R. Delayen
ODU, Norfolk, Virginia, USA

Funding: Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The U.S. Government retains a non-exclusive, license to publish or reproduce this manuscript.
The COmpact Machine for Beam-beam Interactions in Non-Equilibrium systems (COMBINE) is a proposed, dedicated, beam-beam test facility. The base design would make use of a pair of identical octagonal rings (2.5 meters per side) one rotated 180 degrees from the other, meeting at their common interaction point. These would be fed by an electron gun producing up to 125 keV electrons. The low energy will allow for beam-beam tune shifts commensurate with existing colliders, some linac-ring type systems, and will also allow for an exploration of the predicted effects of gear-changing, which would be performed using a variable pathlength scheme. The low energy, and small size will allow for cost effective research, simulation code benchmarking, as well as training opportunities for students.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB025

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paper received ※ 20 May 2021 paper accepted ※ 01 September 2021 issue date ※ 16 August 2021

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THPAB069

Design Concepts for a High-Gradient C-Band Linac

cavity, FEL, electron, accelerating-gradient

3919

T.B. Bolin, S.I. Sosa Guitron
UNM-ECE, Albuquerque, USA
S. Biedron
UNM-ME, Albuquerque, New Mexico, USA
J.R. Cary
Tech-X, Boulder, Colorado, USA
M. Dal Forno
SLAC, Menlo Park, California, USA

Funding: This work was performed under Contract No. 89233218CNA000001, supported by the U.S. DOE’s National Nuclear Security Administration, for the operation of Los Alamos National Laboratory (LANL).
During the last decade, the production of soft to hard x-rays (up to 25 keV) at XFEL facilities has enabled new developments in a broad range of disciplines. One caveat is that these instruments can require a large amount of real estate. For example, the XFEL driver is typically an electron beam linear accelerator (LINAC) and the need for higher electron beam energies capable of generating higher energy X-rays can require longer linacs; costs quickly become prohibitive, requiring state of art methods. One cost-saving measure is to produce a high accelerating gradient while reducing cavity size. Compact accelerating structures are also high-frequency. Here, we describe design concepts for a high-gradient, cryo-cooled LINAC for XFEL facilities in the C-band regime (~4-8 GHz). We are also exploring C-band for different applications including drivers for security applications. We investigate 2 different traveling wave (TW) geometries optimized for high-gradient operation as modeled with VSim software.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB069

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paper received ※ 20 May 2021 paper accepted ※ 02 July 2021 issue date ※ 14 August 2021

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THPAB082

Recent Operational Experience with Thermionic RF Guns at the APS

gun, operation, cathode, injection

3959

Y. Sun, M. Borland, G.I. Fystro, X. Huang, H. Shang
ANL, Lemont, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357
The electron beam at the Argonne Advanced Photon Source (APS) is generated from an S-band thermionic RF gun. There are two locations at the frontend of the linac where thermionic RF guns are installed – RG1 and RG2. Three so-called generation-III guns are available, two are installed at RG1 and RG2, one is a spare. In recent years, these guns are showing signs of aging after over a couple of decades of operations. RF trips started to occur, and we had to reduce the nominal operating rf power to alleviate the problem. In addition, beam generated by RG1 suffers from low transportation efficiency from the gun to the linac, and beam trajectory is unstable which results in charge instabilities. Recently, APS obtained a new type of prototype gun and it was beam commissioned in the linac. In this paper, we report our operational experience with these thermionic rf guns including thermionic-cathode beam extraction, gun front-end optimization for maximum charge transmission through the linac, linac lattice setup to match beam for injection into the Particle Accumulator Ring (PAR) and optimization for maximum PAR injection efficiency.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB082

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paper received ※ 19 May 2021 paper accepted ※ 28 July 2021 issue date ※ 26 August 2021

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THPAB083

Measurement of the Longitudinal Phase-Space of the APS Photo-Injector Beam

cavity, gun, dipole, lattice

3963

Y. Sun
ANL, Lemont, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
An S-band photo-cathode RF gun (PCG) exists at the front of the linac. The high-brightness photoinjector beam is accelerated by the linac and and can be used for accelerator technology and beam physics R&D experiments in the Linac Extension Area (LEA). For some applications, the beam needs to be compressed by a magnetic bunch compressor in the middle of the linac. An S-band transverse-mode cavity (Tcav) is available at the end of the linac for beam longitudinal phase-space diagnostics. Beam commissioning experience of the Tcav is reported in this paper. The cavity rf conditioning and calibration was performed. There is a horizontally bending dipole magnet downstream of the Tcav, which kicks beam in the vertical plane. Beam image on a YAG screen downstream of the Tcav and dipole magnet contains the single-shot information of the longitudinal phase-space of the photo-injector beam. The first measurements of the longitudinal phase-space of the compressed and non-compressed photoinjector beam are discussed. Improvements of the measurement resolution are planned.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB083

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paper received ※ 25 May 2021 paper accepted ※ 12 July 2021 issue date ※ 21 August 2021

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THPAB106

Optimization of a High Bunch Charge ERL Injection Merger for PERLE

emittance, space-charge, booster, cavity

3983

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

Delivery of high charge electron bunches into the main loop of an ERL (energy recovery linac) while preserving the emittance is challenging. This is because at the typical injection momentum, space charge forces still have a significant effect on the beam dynamics. In this work we consider the design of the merger for PERLE, an ERL test facility to be based at IJCLab in France. Previous simulations have shown that the baseline DC gun based injector can achieve the required emittance at the booster linac exit. The quality of the 500 pC bunches must then be preserved with space charge through the merger at total beam energy of 7 MeV keeping the emittance below 6 mm mrad. The beam dynamics in the merger were simulated using the code OPAL and optimised using a genetic algorithm. Three possible merger schemes were investigated. The goal of the optimisation was to minimise the emittance growth while also achieving the required Twiss parameters to match onto the spreader at the main linac exit. A three dipole solution is then examined in more detail.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB106

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

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THPAB113

The Extended Operative Range of the LNF LINAC and BTF Facilities

experiment, positron, target, klystron

3987

L.G. Foggetta, M. Belli, B. Buonomo, F. Cardelli, R. Ceccarelli, A. Cecchinelli, R. Clementi, D. Di Giovenale, C. Di Giulio, G. Piermarini, L.A. Rossi, S. Strabioli, R. Zarlenga
INFN/LNF, Frascati, Italy

Funding: These activities has been partially supported by AIDA-2020 Grant Agreement 654168 and ERAD projects.
In 2020 the INFN-LNF LINAC and BTF have performed long-term runs for test beams and fixed-target experiments. The scientific needs of these items have been leading our groups to continuous improvements of the LINAC operative range both in pulse time at maximum energy and on the minimum transported energy, until the reset to DAΦNE injections at the beginning of 2021. We will also show the BTF recent developments in the transported beams and the second line installation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB113

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

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THPAB120

Beam on Demand for High-Repetition-Rate X-Ray Free-Electron Lasers

electron, laser, FEL, SRF

3995

Z. Zhang, Y. Ding, Z. Huang
SLAC, Menlo Park, California, USA

High-repetition-rate (HRR) free-electron lasers (FELs) with multiple undulator beamlines will advance the frontiers of X-ray science significantly from the remarkable success of existing X-ray FEL facilities. The wide-ranging requirements for the photon properties from multiple beamlines are extremely challenging to satisfy by the same electron beam from a single superconducting radio-frequency (SRF) accelerator. To realize the full potential of an HRR FEL facility, a new emerging concept of "beam on demand" is proposed here. The concept is based on advanced beam dynamics and radio-frequency (RF) techniques to provide beam properties tailored to each undulator line at the desired repetition rate. The beam properties that will be pursued in this proposal include, but are not limited to, beam energy, bunch charge, bunch length, beam current, and its profile. The realization of "beam on demand" will allow optimization of photon properties of individual beamlines to maximize their performance and drastically improve the multiplexing capabilities of Linac Coherent Light Source II and its high-energy upgrade.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB120

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paper received ※ 17 May 2021 paper accepted ※ 23 July 2021 issue date ※ 27 August 2021

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THPAB129

Beam Dynamics Simulations in a High-Gradient X-Band Photoinjector

gun, emittance, cathode, electron

4013

W.H. Tan, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
G. Chen, S.V. Kuzikov
Euclid TechLabs, Solon, Ohio, USA
G. Chen
IIT, Chicago, Illinois, USA
G. Ha, C.-J. Jing
ANL, Lemont, Illinois, USA
C.-J. Jing
Euclid Beamlabs, Bolingbrook, USA

A high-gradient X-band (11.7-GHz) photoinjector was recently developed by Euclid Techlabs and is in its commissioning phase at the Argonne Wakefield Accelerator (AWA). This contribution discuss the beam-dynamics modeling of the photoinjector system comprising an RF gun and linac section. We especially discuss beam-dynamics optimization of setup for an integrated proof-of-principle experiments. We also discuss the use of such a photoinjector as a witness-bunch source for a future high-gradient collinear-wakefield accelerator experiments at the AWA.
* S. V. Kuzikov, et al. these proceedings.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB129

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paper received ※ 20 May 2021 paper accepted ※ 14 July 2021 issue date ※ 31 August 2021

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THPAB158

BEAM COLLIMATION IN THE PIP-II LINAC TO BOOSTER TRANSFER LINE

injection, booster, collimation, proton

4068

D.E. Johnson, V.V. Kapin, J.-F. Ostiguy, V.I. Sidorov, M. Xiao
Fermilab, Batavia, Illinois, USA
D.G. Georgobiani
FRIB, East Lansing, Michigan, USA

Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
The new PIP-II superconducting linac will deliver a 2 mA average H^- beam to the existing Booster synchrotron. The injected beam is accumulated by charge exchange over approximately 300 turns; phase space painting is used to mitigate space charge effects. To limit the power load on the internal waste beam absorber from the transverse tails of the H⁻ distribution missing the foil, the beam will be collimated in both planes in the linac to Booster transfer line using compact collimators of a novel design. Both the number of parasitic hits and the fraction of the beam missing the foil are sensitive functions of the H⁻ beam centroid position with respect to the edge of the foil. The positioning of the collimation is constrained by the availability of suitable space in the transfer line lattice, by specifics of the collimator design, by the phase space orientation at the collimator, and by the betatron phase advance to the foil needed to achieve proper orientation of the spatial distribution at the injection point. In this contribution, we describe the procedure by which collimator positions were optimized. We then discuss the expected performance of the overall system.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB158

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paper received ※ 04 June 2021 paper accepted ※ 02 July 2021 issue date ※ 26 August 2021

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THPAB165

5 MW Beam Power in the ESSnuSB Accumulator: A Way to Manage Foil Stripping Injection at 14 Hz Linac Pulse Rate

emittance, injection, proton, space-charge

4072

H. Schönauer
CERN, Geneva, Switzerland
Y. Zou
Uppsala University, Uppsala, Sweden

Funding: This work is supported by the European Union’s Horizon 2020 research and innovation program under grant agreement No 777419.
In the past, the scenario for foil stripping consisted of splitting a linac pulse into 4 rings, or 3 or 4 intermediate pulses, and one ring. At present, the scenario, in view of laser stripping, consists of one ring, one pulse, split into four batches. Conventional stripping geometry would lead to foil evaporation under this beam load. One way out appears to be replacing the standard corner foil by a single-edge foil rotated to about 45deg. The tilted foil allows moving the injection point together with the painting bumps along the foil edge, distributing the deposited beam power over a larger foil area. Simulation results obtained with the same tools as in the past scenarios are presented. They show peak foil temperatures, which compare with the best results obtained from the past scenarios.

Poster THPAB165 [2.205 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB165

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paper received ※ 11 May 2021 paper accepted ※ 21 June 2021 issue date ※ 18 August 2021

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THPAB171

mm-Wave Linac Design for Next Generation VHEE Cancer Therapy Systems

electron, simulation, impedance, coupling

4090

E.J.C. Snively, K.C. Deering, E.A. Nanni
SLAC, Menlo Park, California, USA

Direct electron therapy offers an attractive method for providing the high dose rates necessary for FLASH radiation therapy, a new treatment modality with the potential for enhanced healthy tissue sparing. Direct electron therapy has been limited by the low beam energies, up to 20 MeV, provided by today’s medical linacs, restricting the achievable dose depth to superficial tumors. Very High Energy Electron (VHEE) therapy could reach deep-seated tumors throughout the body. A clinically viable VHEE system must provide electron energies of around 100 MeV in a compact footprint, roughly 1 to 2 meters, with modest power requirements. We investigate the development of mm-wave linacs to provide the necessary beam energies on the sub-meter scale, taking advantage of the favorable scaling of high-frequency operation to support gradients well above 100 MeV/m. We discuss the design parameters necessary for high-efficiency structures, with shunt impedance on the order of 1 GOhm/m, producing high gradients with only a few megawatts of power. We present simulations of cavity performance in the mm-wave operating regime, with an emphasis on compatibility with the requirements of VHEE therapy.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB171

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paper received ※ 19 May 2021 paper accepted ※ 26 July 2021 issue date ※ 15 August 2021

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THPAB173

Fundamental Study on Electromagnetic Characteristics of Half-Wave Resonator for 200 MeV Energy Upgrade of KOMAC Proton Linac

cavity, simulation, proton, SRF

4098

J.J. Dang, Y.-S. Cho, H.S. Kim, H.-J. Kwon, S. Lee
Korea Atomic Energy Research Institute (KAERI), Gyeongbuk, Republic of Korea

Funding: This work has been supported through KOMAC operation fund of KAERI by the Korea government (MSIT).
A superconducting linac has been developed at KOrea Multi-purpose Accelerator Complex (KOMAC). A goal of the SRF linac is to increase proton beam energy from 100 MeV to 200 MeV. 350 MHz medium beta half-wave resonator (HWR) should provide 3.6 MV accelerating voltage to achieve the energy upgrade. An electromagnetic (EM) analysis on the parametrically designed HWR cavity was conducted. The cavity design was optimized to reduce a peak electric field and a peak magnetic field while satisfying the required acerating voltage. In addition, a mechanical-EM coupled simulation was conducted to estimate a helium pressure sensitivity. Also, Lorentz force detuning was simulated. The design is being optimized to minimize the frequency detuning due to the helium pressure and Lorentz force.

Poster THPAB173 [0.800 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB173

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

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THPAB176

Studies on Beam Collimation System for the ESSnuSB Accumulator

collimation, scattering, proton, simulation

4107

Y. Zou, M. Olvegård
Uppsala University, Uppsala, Sweden

Funding: This work is supported by the European Union Horizon 2020 research and innovation program under grant agreement No 777419.
The ESSnuSB, a neutrino facility based on the European Spallation Source, aims at measuring, with precision, the charge-parity (CP) violating lepton phase at the 2nd oscillation maximum. The ESS linac will have to be upgraded to provide an additional 5 MW beam for the ESSnuSB to produce an unprecedented high-intensity neutrino beam. An accumulator ring is employed to compress the 2.86 ms long pulse from the linac to around 1.5 µs in order to satisfy the target requirements and improve the physics performance. In the operation of a high-intensity proton accumulator, the most important issue is to minimize the uncontrolled beam loss to reduce component activation to make hands-on maintenance possible. For this purpose, a two-stage collimation system is designed, which consists of a thin scraper to scatter halo particles and secondary collimators to absorb those scattered particles. Phase advances between scraper and secondary collimators, together with the material, the thickness of collimators, have been detailed studied and numerical simulations have been performed to evaluate the performance of the collimation system. This paper presents the design of the collimation system.

Poster THPAB176 [5.022 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB176

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paper received ※ 11 May 2021 paper accepted ※ 21 June 2021 issue date ※ 01 September 2021

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THPAB181

AI-ML Developments for the ATLAS Ion Linac Facility

rfq, operation, experiment, simulation

4122

B.M. Mustapha, B.R. Blomberg, C. Dickerson, J.L. Martinez Marin, C.E. Peters
ANL, Lemont, Illinois, USA

Funding: This work was supported by the U.S. Department of Energy, under Contract No. DE-AC02-06CH11357. This research used the ATLAS facility, which is a DOE Office of Nuclear Physics User Facility.
ATLAS is a DOE/NP User Facility for the study of low-energy nuclear physics with heavy ions. It operates ~6000 hours per year. In addition to delivering any stable beam from proton to uranium, the facility also provides radioactive beams from the CARIBU source or via the in-flight radioactive ion separator, RAISOR. The facility uses 3 ion sources and services 6 target areas at energies from ~1-15 MeV/u. To accommodate the large number and variety of approved experiments, ATLAS reconfigures once or twice per week over 40 weeks of operation per year. The startup time varies from ~12-48 hours depending on the complexity of the tuning, which will increase with the upcoming Multi-User Upgrade to deliver beam to two experimental stations simultaneously. DOE/NP has recently approved a project to use AI/ML to support ATLAS operations. The project aim is to significantly reduce the accelerator tuning time and improve machine performance by developing and deploying artificial intelligence methods. These improvements will increase the scientific throughput of the facility and the quality of the data collected. Our recent developments and future plans will be presented and discussed.

Poster THPAB181 [1.034 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB181

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paper received ※ 06 June 2021 paper accepted ※ 28 July 2021 issue date ※ 12 August 2021

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THPAB185

Solution to Beam Transmission Decline in the CSNS Linac Operation Using Measurements and Simulations

rfq, DTL, emittance, operation

4134

J. Peng, M.T. Li, X.H. Lu, X.B. Luo
IHEP CSNS, Guangdong Province, People’s Republic of China
Y.W. An, S. Fu, L. Huang, M.Y. Huang, Y. Li, Z.P. Li, S. Wang, S.Y. Xu, Y. Yuan
IHEP, Beijing, People’s Republic of China

The CSNS linac operation at its design average power currently. However, the beam transmission is declining and the beam loss is increasing during the operation. With simulations and experiments, we found there is a long longitudinal tail exist in the beam bunch output from the RFQ. And this tail caused the beam loss in the following linac. After inhibition of the longitudinal tail in the beam bunch, the beam transmission in operation can keep stable.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB185

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paper received ※ 19 May 2021 paper accepted ※ 01 July 2021 issue date ※ 02 September 2021

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THPAB186

Review of Proton Linac Beam Dynamic Simulation Code

simulation, proton, space-charge, software

4137

X.Y. Feng, J. Peng
IHEP CSNS, Guangdong Province, People’s Republic of China

CSNS-II project design a linac accelerates 40 mA H⁻ beam from 3.8 MeV to 300 MeV, which should not only overcome the space-charge effect at low energy but also have high efficiency at high energy. Therefore, lots of simulation studies should be done on a variety of codes. Each of them has its own characteristics. For example, MAD can easily match quadrupole fast while it couldn’t do the multiparticle calculation. This paper will introduce some common and efficient code used to design linac and study beam dynamic performance.

Poster THPAB186 [0.880 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB186

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paper received ※ 17 May 2021 paper accepted ※ 08 July 2021 issue date ※ 11 August 2021

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THPAB187

Determination of Required Tolerances and Stop Band Width for Cells Manufacturing and Tuning in Compensated High Energy Accelerating Structures

coupling, cavity, hadron, factory

4139

I.V. Rybakov, V.V. Paramonov
RAS/INR, Moscow, Russia

The required value of the spread for accelerating field distribution comes from the beam dynamics conditions and for cavities in high energy hadron linacs is ~1%. The standard deviation of the accelerating field distribution depends on the spread in frequencies of accelerating and coupling cells, stop bandwidth and deviations in coupling coefficients. The deviations in frequencies for accelerating, coupling cells, coupling coefficients, are directly related to tolerances manufacturing tolerances for cells. The stop bandwidth should be adjusted with cell tuning. Relations between the standard deviation of field distribution and deviations in cells parameters* are known. Together with the relation between deviations in cells dimensions and cells parameters** recommendations for cells manufacturing tolerances could be obtained. In relation to the coupling coefficient of compensated accelerating structures (ACS, SCS, CDS, DAW) for high-energy parts of linacs some recommendations for the determination of optimal manufacturing tolerances and acceptable stopband are presented.
* V.F. Vikulov and V.E. Kalyuzhny // Tech. Phys., v. 50, 1980, pp. 773-779
** I.V. Rybakov, V.V. Paramonov, A.K. Skassyrskaya // Proc. RuPAC 2016, pp. 291-293

Poster THPAB187 [0.649 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB187

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paper received ※ 18 May 2021 paper accepted ※ 25 June 2021 issue date ※ 24 August 2021

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THPAB204

End-to-End RMS Envelope Model of the ISAC-I Linac

ISAC, rfq, simulation, DTL

4183

O. Shelbaya, R.A. Baartman, O.K. Kester
TRIUMF, Vancouver, Canada

A full end-to-end simulation of the ISAC-I linear accelerator has been built in the first order envelope code TRANSOPTR. This enables the fast tracking of rms sizes and correlations for a 6-dimensional hyperellipsoidal beam distribution defined around a Frenet-Serret reference particle frame, for which the equations guiding envelope evolution are numerically solved through a model of the machine’s electromagnetic potentials. Further, the adopted formalism enables the direct integration of energy gain via time-dependent accelerating potentials, without resorting to transit-time factors.

Poster THPAB204 [0.627 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB204

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paper received ※ 18 May 2021 paper accepted ※ 08 July 2021 issue date ※ 31 August 2021

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THPAB219

Beam Dynamics in Coherent Electron Cooling Accelerator

electron, simulation, cavity, emittance

4216

Y.C. Jing, V. Litvinenko, I. Petrushina, I. Pinayev, K. Shih, Y.H. Wu
BNL, Upton, New York, USA
V. Litvinenko
Stony Brook University, Stony Brook, USA
I. Petrushina, Y.H. Wu
SUNY SB, Stony Brook, New York, USA
K. Shih
SBU, Stony Brook, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Coherent electron Cooling (CeC) has the potential to substantially reduce the cooling time of the high-energy hadrons and hence to boost luminosity in high-intensity hadron-hadron and electron-hadron colliders. Recent development in CeC cooling theory requires the accelerator to deliver high-quality electron bunches with low beam noise. In this paper, we present our design of the CeC accelerator to achieve the electron beam requirements and compare our findings with the experimental observations.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB219

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paper received ※ 27 May 2021 paper accepted ※ 27 July 2021 issue date ※ 11 August 2021

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THPAB220

Multibunch Studies for LCLS-II High Energy Upgrade

cavity, dipole, emittance, HOM

4219

R.J. England, K.L.F. Bane, Z. Li, T.O. Raubenheimer, M.D. Woodley
SLAC, Menlo Park, California, USA
M. Borland
ANL, Lemont, Illinois, USA
A. Lunin
Fermilab, Batavia, Illinois, USA

Funding: The work is supported in part by DOE Contract No. DE-AC02-76SF00515.
The Linac Coherent Light Source (LCLS) X-ray free-electron laser at SLAC is being upgraded to LCLS-II with a superconducting linac and 1 MHz bunch repetition rate. The proposed high-energy upgrade (LCLS-II-HE) will increase the beam energy from 4 to 8 GeV, extending the reach of accessible X-ray photon energies. With the increased repetition rate and longer linac of LCLS-II-HE, multi-bunch effects are of greater concern. We use recently introduced capabilities in the beam transport code ELEGANT to study dipole and monopole beam breakup effects for LCLS-II HE beam parameters. The results indicate that resonant dipole kicks have steady-state settle times on the order of 500 bunches or less and appear manageable. We also consider a statistical variation of the cavity frequencies and transverse offsets of cavities and quadrupoles. Resonant emittance growth driven by monopole kicks is found to be disrupted by frequency variation between cavities.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB220

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

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THPAB223

Energy Compression System Radio Frequency Design at the Canadian Light Source

impedance, GUI, simulation, RF-structure

4231

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

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

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

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

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THPAB296

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

DTL, cavity, GUI, klystron

4383

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

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

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

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

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THPAB310

Automatic Correction System for the TLS Booster Linac Klystron Modulator

klystron, electron, booster, acceleration

4396

S.J. Huang, Y.K. Lin
NSRRC, Hsinchu, Taiwan

The aim of this article is to analyse the performance output of the klystron modulator, which is based on the observation of the output voltage and current performance of the linear-accelerator klystron modulator; we modify the operating-point parameters based on those results or assess whether the klystron needs to be replaced. For this purpose, we collect the observation data of the klystron performance; we then develop a program to adjust automatically the high-voltage setting of the klystron to ensure that the storage current maintains beam current 360 mA in the top-up mode operation.

Poster THPAB310 [0.785 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB310

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paper received ※ 16 May 2021 paper accepted ※ 02 July 2021 issue date ※ 13 August 2021

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THPAB322

Transient Beam Loading in the CBETA Multi-Turn ERL

cavity, beam-loading, operation, SRF

4422

N. Banerjee
Enrico Fermi Institute, University of Chicago, Chicago, Illinois, USA
G.H. Hoffstaetter
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: This work was supported by NSF Grant No. DMR0807731, DOE Award No. DE-SC0012704, and NYSERDA Agreement No. 102192.
The Cornell-BNL ERL Test Accelerator (CBETA) is the first superconducting multi-turn ERL that has been commissioned at Cornell University in a low current mode. In this paper, we first discuss a new model of beam loading which is valid for the low injection energies used in CBETA. Using this model, we explore the effect of bunch patterns, beam turn-on, and turn-off transients on the fundamental mode of the 7-cell SRF cavities used in the main linac. In particular, we examine the operational constraints on the rf system at the design current of 40 mA.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB322

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paper received ※ 20 May 2021 paper accepted ※ 29 July 2021 issue date ※ 16 August 2021

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THPAB324

PIP-II 800 MeV Proton Linac Beam Pattern Generator

booster, injection, MEBT, kicker

4426

H. Maniar, B.E. Chase
Fermilab, Batavia, Illinois, USA
J.E. Dusatko
SLAC, Menlo Park, California, USA
S. Khole
BARC, Trombay, Mumbai, India
D. Sharma
RRCAT, Indore (M.P.), India

The PIP2 IT Beam Pattern Generator is the system that synchronizes beam injection and the RF systems between the PIP2 LINAC to the Booster. The RF frequencies of these two accelerator systems are not harmonically related. Synchronization is accomplished by controlling two MEBT Beam Choppers, which select 162.5MHz beam bunches from the LEBT and RFQ to produce an appropriate reduced beam bunch pattern that enables bucket-to-bucket transfer to the Booster RF at 46.46MHz (84th harmonic). This chopping pattern also reduces the beam current to an average of 2mA over the Booster injection, matching the Linac nominal beam current. The BPG also generates the RF frequency/phase reference which the Booster will phase lock to during injection. The BPG is fully programmable, allowing for arbitrary beam patterns with adjustable timing parameters, having a fine adjustment resolution of 38ps. The latter is accomplished using digital signal processing techniques. This paper discusses the design of the BPG, its construction, test results, and operational experience after being integrated into the PIP2 IT test accelerator and concludes with a discussion of the system’s performance and future plans.

Poster THPAB324 [0.676 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB324

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paper received ※ 18 May 2021 paper accepted ※ 01 July 2021 issue date ※ 13 August 2021

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THPAB348

INFN-LASA for the PIP-II LB650 Linac

cavity, SRF, experiment, cryogenics

4474

R. Paparella, M. Bertucci, M. Bonezzi, A. Bosotti, A. D’Ambros, A.T. Grimaldi, P. Michelato, L. Monaco, D. Sertore
INFN/LASA, Segrate (MI), Italy
C. Pagani
Università degli Studi di Milano & INFN, Segrate, Italy

INFN joined the international effort for the PIP-II project at Fermilab and it’s going to contribute to the low-beta section of the PIP-II proton linac. In particular, INFN-LASA is finalizing its commitment to deliver in kind the full set of the LB650 cavities, namely 36 plus spares 5-cell cavities at 650 MHz and geometrical beta 0.61. All cavities, designed by INFN-LASA, will be produced and surface treated in industry, qualified through vertical cold test, and delivered as ready for string installation. This paper reports the status of INFN’s contribution to PIP-II and of ongoing activities toward the experimental qualifications of infrastructures and prototypes.

Poster THPAB348 [4.076 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB348

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paper received ※ 16 May 2021 paper accepted ※ 01 July 2021 issue date ※ 12 August 2021

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THPAB369

Research and Design of an X-Band 100-MeV Compact Electron Accelerator for Very High Energy Electron Therapy in Tsinghua University

cavity, electron, gun, klystron

4502

X. Lin, H.B. Chen, J. Shi, C.-X. Tang, H. Zha, L.Y. Zhou
TUB, Beijing, People’s Republic of China

A 100-MeV Compact Electron Accelerator scheme based on the Tsinghua X-band (11.424 GHz) High Power Test stand (TPot-X) was proposed for Very High Energy Electron (VHEE) radiotherapy. A pulse compressor with correction cavity chain was designed to compress the 50 MW, 1500 ns microwave pulse from the X-band klystron to 120 MW, 300 ns. The acceleration system consists of 3 parts, a buncher which bunches and boosts the electron from a thermionic cathode gun to 8 MeV, and two accelerating structure which further boost the electron energy to 100MeV. The detailed design and consideration are presented in this article.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB369

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paper received ※ 19 May 2021 paper accepted ※ 01 July 2021 issue date ※ 14 August 2021

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FRXA01

Full Energy On-Demand Beam Injection from SACLA into the SPring-8 Storage Ring

injection, electron, FEL, operation

4508

H. Maesaka, T. Fukui, T. Hara, T. Hiraiwa, T. Inagaki, E. Iwai, H. Tanaka, K. Togawa
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
H. Dewa, T. Fujita, K. Fukami, N. Hosoda, A. Kiyomichi, M. Masaki, S. Matsubara, T. Ohshima, M. Oishi, K. Soutome, S. Takano, T. Watanabe
JASRI/SPring-8, Hyogo-ken, Japan
C. Kondo
JASRI, Hyogo, Japan

The beam injector for the SPring-8 storage ring (SR) was switched from the booster synchrotron to the SACLA linac, a driver for X-ray free-electron laser (XFEL). The low-emittance beam from SACLA (~100 pm rad, 8 GeV) is delivered to the SR through a 600m-long beam transport line. This low-emittance beam can be applied to the new low-emittance storage ring after the SPring-8 upgrade planed in the coming years. The shutdown of the booster synchrotron and 1-GeV linac saves energy consumption and operation cost. To provide the electron beam injected to the SR on demand for the top-up injection during the XFEL operation, the SACLA linac must be synchronized to the desired bucket of the SR, the beam energy and route must be switched shot-to-shot, and the XFEL performance must not be degraded. We developed a precise synchronization system, on-demand beam route and parameter switching system, a pulsed magnet for the switchyard, isolated bunch purification system, etc. In this presentation, we will show the design and performance of each component for the beam injection and the results from beam commissioning of the accelerator and transport line.

Slides FRXA01 [3.446 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-FRXA01

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paper received ※ 19 May 2021 paper accepted ※ 01 July 2021 issue date ※ 31 August 2021

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FRXB02

Development of 36 GHz RF Systems for RF Linearisers

cavity, klystron, HOM, impedance

4518

A. Castilla, G. Burt
Lancaster University, Lancaster, United Kingdom
M. Behtouei, B. Spataro
INFN/LNF, Frascati, Italy
G. Burt
Cockcroft Institute, Warrington, Cheshire, United Kingdom
J.C. Cai, A. Castilla, A. Latina, X. Liu, I. Syratchev, X.W. Wu, W. Wuensch
CERN, Geneva, Switzerland
J.C. Cai, A. Castilla
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
A.W. Cross, L. Zhang
USTRAT/SUPA, Glasgow, United Kingdom
L.J.R. Nix
University of Strathclyde, Glasgow, United Kingdom

Funding: This project has received funding from the European Union’s Horizon2020 research and innovation programme under grant agreement No 777431.
As part of the deign studies, the CompactLight project plans to use an injector in the C-band. Which constitutes a particular complication for the harmonic system in charge of linearising the beam’s phase space, since it means its operation frequency could be higher than the standard X-band RF technologies. In the present work, we investigated a 36 GHz (Ka-band) as the ideal frequency for the harmonic system. A set of structure designs are presented as candidates for the lineariser, based on different powering schemes and pulse compressor technologies. The comparison is made both in terms of beam dynamics and RF performance. Given the phase stability requirements for the MW class RF sources needed for this system, we performed careful studies of a Gyro-Klystron and a multi-beam klystron as potential RF sources, with both showing up to 3 MW available power using moderate modulator voltages. Alternatives for pulse compression at Ka-band are also discussed in this work.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-FRXB02

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paper received ※ 17 May 2021 paper accepted ※ 19 July 2021 issue date ※ 25 August 2021

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