IPAC2021 - List of Keywords (vacuum)

Paper	Title	Other Keywords	Page
MOXC02	Improved Lifetime of a High Spin Polarization Superlattice Photocathode	electron, cathode, polarization, gun	31
	L. Cultrera BNL, Upton, New York, USA
	Funding: Department of Energy under grant DE-SC0012704 Highly spin polarized electron beams are required for the operation of a wide range of accelerators and instruments. The production of such electrons requires the use of Negative Electron Affinity (NEA) activated GaAs-based cathodes operated in photoelectron guns. Because of their extreme sensitivity to poor vacuum conditions the degradation of the photoemission process is so strong that NEA activated GaAs-based photocathodes can only survive in the extreme vacuums typical of DC gun. State-of-the-art on photocathode technology for spin polarized beam productions are summarized. Recent results on the use of robust NEA coating based on the Cs-Te and Cs-Sb leading to improved operational lifetime of a high spin polarization photocathode are reviewed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOXC02
About •	paper received ※ 20 May 2021 paper accepted ※ 19 July 2021 issue date ※ 19 August 2021
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MOPAB030	Research and Development Progress of CEPC RF Shield Bellows	positron, impedance, electron, controls	142
	J.M. Liu, Y.H. Guan, S.M. Liu, B. Tan, P.C. Wang DNSC, Dongguan, People’s Republic of China H. Dong, Y. Ma IHEP, Beijing, People’s Republic of China H.Y. He, T. Huang IHEP CSNS, Guangdong Province, People’s Republic of China
	The circular electron positron collider (CEPC) is a candidate for the next-generation electron positron collider, which can be used to accurately measure the Higgs and electroweak bosons. The RF shield bellow is a vacuum component necessary for the construction of CEPC. Therefore, a RF shield bellow model machine with an elliptical cross-section was designed and processed for technical verification. Based on the traditional interdigital structure, a special contact force testing device was also designed to reduce measurement errors. The on-off status of the circuit was used by the device to determine whether the spring finger was pulled up, thus reducing the influences of human factors in the measurement process. It can be known from the measurement results of the model machine that the contact force of the spring finger is between 120g and 130g, which can satisfy the technical requirements.
	Poster MOPAB030 [1.467 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB030
About •	paper received ※ 19 May 2021 paper accepted ※ 20 May 2021 issue date ※ 13 August 2021
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MOPAB031	Development and Operation of Vacuum System for Rapid Cycling Synchrotron to Target Beam Transfer Line of China Spallation Neutron Source	target, neutron, operation, proton	145
	J.M. Liu, Y.H. Guan, S.M. Liu, B. Tan, P.C. Wang DNSC, Dongguan, People’s Republic of China H. Dong IHEP, Beijing, People’s Republic of China H.Y. He, T. Huang IHEP CSNS, Guangdong Province, People’s Republic of China
	China Spallation Neutron Source (CSNS) is a major scientific project during the National Eleventh Five-Year Plan. It consists of a negative hydrogen ion linear accelerator, a rapid cycling synchrotron ( RCS), a linac to RCS beam transfer line (LRBT), an RCS to target beam transfer line (RTBT), and a target station. As an important part of CSNS, the RTBT connects the rapid cycling synchrotron and the target window. This paper described the design requirements, technical solutions, and operating conditions of the vacuum system for the CSNS RCS to target beam transfer line. In addition, the fast valve protection system and its verification results were also expounded. The CSNS has been in operation for over three years, during this period, the beam power has been gradually improved from 10KW to 100KW, and the vacuum system for RTBT has been operating stably.
	Poster MOPAB031 [0.581 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB031
About •	paper received ※ 19 May 2021 paper accepted ※ 24 May 2021 issue date ※ 25 August 2021
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MOPAB079	Experience of the First Six Years Operations and Plans in NSlS-II	operation, cavity, MMI, feedback	308
	G.M. Wang BNL, Upton, New York, USA
	NSLS-II is a 3 GeV third-generation synchrotron light source at BNL. The storage ring was commissioned in 2014 and began its routine operations in the December of the same year. Since then, we have been continuously installing and commissioning new insertion devices, their front-ends, and beamlines. At this point, the facility hosts 28 operating beamlines from various radiation sources, including damping wiggler, IVU, EPU, 3PW, and bending magnets for infrared beamlines. Over the past six years, the storage ring performance continuously improved, including 500 mA with limited insertion devices close due to RF power limitation and routinely 400 mA top off operation, >95% operation reliability, maintenance of beam motion short- and long-term stability. In this paper, we report NSLS-II accelerator operations experience and plans for future facility developments.
	Poster MOPAB079 [2.064 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB079
About •	paper received ※ 17 May 2021 paper accepted ※ 21 June 2021 issue date ※ 25 August 2021
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MOPAB084	Acceptance Tests and Installation of the IVU and Front End for the XAIRA Beamline of ALBA	undulator, photon, experiment, insertion	318
	J. Campmany, J. Marcos, V. Massana ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
	XAIRA is a new beamline being built at ALBA synchrotron for macromolecular crystallography (MX) devoted to the study of small bio crystals. It aims at providing a full beam with a size of 3x1 µm² FWHM (hxv) and flux of >3·10¹² ph/s (250 mA in Storage Ring) at 1 Å wavelength (12.4 keV) to tackle MX projects for which only tiny (<10 μm) or imperfect crystals are obtained. Besides, XAIRA aims at providing photons at low energies, down to 4 keV, to support MX experiments exploiting the anomalous signal of the metals naturally occurring in proteins (native phasing), which is enhanced in the case of small crystals and long wavelengths. To this end, an in-vacuum undulator has been built by a consortium between Kyma and Research Instruments companies. In this paper, we present the results of the Site Acceptance Tests made at ALBA using a new bench developed to measure closed structures, and also the steps done for its installation in the ALBA tunnel.
	Poster MOPAB084 [1.715 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB084
About •	paper received ※ 11 May 2021 paper accepted ※ 20 May 2021 issue date ※ 25 August 2021
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MOPAB085	Design and Fabrication of a Short Multipole Wiggler and the Front End for the New ALBA Beamline FAXTOR	photon, wiggler, insertion, insertion-device	321
	J. Campmany, J. Marcos, V. Massana ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
	FAXTOR is a new hard XR tomography beam line that is being built at ALBA in order to fulfil the needs that cannot be currently covered by the MISTRAL VUV and soft XR beamline. This beam line needs a small source size as well higher than 10¹² Photons per second through an aperture of 4x1 mm2 in the whole range 5 to 60 keV, for a current of 250 mA in Storage Ring with source size maintained below 310 µm horizontal and 25 µm vertical. The contract was awarded to AVS-US Company. In this paper we present the design finally selected as well as the preliminary design carried out by manufacturer to implement the conceptual model designed by ALBA.
	Poster MOPAB085 [1.879 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB085
About •	paper received ※ 11 May 2021 paper accepted ※ 20 May 2021 issue date ※ 31 August 2021
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MOPAB086	Design of Front End and a 3-Pole-Wiggler as a Photon Source for BEATS Beamline at SESAME	photon, wiggler, synchrotron, insertion	324
	J. Campmany, J. Marcos ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain M. Al Nadjawi, M. Attal, G. Lori SESAME, Allan, Jordan I. Cudin Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy S. Guiducci INFN/LNF, Frascati, Italy P. Van Vaerenbergh ESRF, Grenoble, France
	BEATS is an international collaboration funded by EU in order to design and implement an XR tomography beam line in SESAME Jordanian synchrotron. ALBA contribution consists in the design of the photon source and the Front End elements. In this paper we present the conceptual designs of both the 3-pole wiggler uses as photon source as well as the Front End elements designed for the beamline.
	Poster MOPAB086 [2.306 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB086
About •	paper received ※ 11 May 2021 paper accepted ※ 21 May 2021 issue date ※ 17 August 2021
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MOPAB088	Beam-Based Measurement on the Performance of Ferrite Dampers in an In-Vacuum Undulator	damping, HOM, feedback, radiation	331
	K. Tian, A. Ringwall, J.J. Sebek SLAC, Menlo Park, California, USA
	In this paper, we first present the tracking studies for SPEAR3 with the new BL17 ID and estimate its impact on the dynamic aperture of the low emittance lattice. Then the ferrite dampers installations in the device is briefly reviewed. After that, we will show that, based on beam-based measurements, the performance of the dampers is as being expected from earlier numerical studies.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB088
About •	paper received ※ 19 May 2021 paper accepted ※ 18 June 2021 issue date ※ 24 August 2021
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MOPAB091	Injection Section Upgrading with the Septum-Magnet Replacement in KEK-PF Ring	injection, septum, storage-ring, operation	342
	C. Mitsuda, K. Harada, N. Higashi, T. Honda, Y. Kobayashi, H. Miyauchi, S. Nagahashi, N. Nakamura, T. Nogami, T. Obina, M. Tadano, R. Takai, H. Takaki, Y. Tanimoto, T. Uchiyama, A. Ueda KEK, Ibaraki, Japan
	In 2015, the water leakage happened at the cooling pipe of the in-vacuum septum magnet installed into the injection point. Because the maintenance of the leakage needed the total replacement of the magnet, the water circulation was stopped permanently, and accordingly, the light absorber was installed upstream in the storage ring to prevent the synchrotron light of the bending magnet from coming to the septum wall. This treatment temporally worked well, but the beam injection efficiency was decreased to about 30% due to the physical aperture narrowed by the absorber. With the desired replacement of septum magnet to maintainable out-vacuum type, the injection section upgrading was simultaneously planned to recover and improve the injection efficiency. In this upgrade, the injection beam is closed to the stored beam more than before by adapting the thinner septum structure as a way to improve the injection efficiency. And some new ideas are introduced in the part of monitor and beam duct, for example, realtime beam monitor, thinner Inconel duct. The detailed design of the upgraded injection section and technical points will be reviewed in this conference.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB091
About •	paper received ※ 19 May 2021 paper accepted ※ 26 May 2021 issue date ※ 02 September 2021
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MOPAB093	Operational Status of Photon Factory Light Sources	injection, operation, radiation, electron	350
	T. Honda, Y. Kobayashi, C. Mitsuda, S. Nagahashi, R. Takai, H. Takaki KEK, Ibaraki, Japan
	One of the recent topics of Photon Factory light sources, PF-ring and PF-AR, is a construction of a GeV-class beamline for testing detectors at the PF-AR. The bremsstrahlung photons generated by a thin carbon wire are brought to a copper target to generate e⁺e⁻ pairs. Sufficient count rates can be expected when the thin wire touching halo of the stored beam, and the test beamline can be used without disturbing the synchrotron radiation experiments. In addition to the usual 6.5-GeV operation, a low-energy operation at 5-GeV was started recently at PF-AR to secure operation time by saving electricity costs. At the PF-ring, the injection section has been upgraded with the septum-magnet replacement. By the top-up injection and improved bunch feedback, the hybrid-fill mode operation has become convenient for both single-bunch users and multi-bunch users, and about 30% or 40% of the user time is scheduled as the hybrid-fill mode now.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB093
About •	paper received ※ 21 May 2021 paper accepted ※ 25 May 2021 issue date ※ 13 August 2021
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MOPAB102	CSR Impedance in HEPS Storage Ring	impedance, storage-ring, lattice, synchrotron	379
	H.S. Xu, X.Y. Li, N. Wang IHEP, Beijing, People’s Republic of China
	High Energy Photon Source (HEPS) is under construction in Beijing, China. The relatively complete impedance model has been built up based on the element-by-element impedance calculation. However, Coherent Synchrotron Radiation (CSR) impedance, which might affect the longitudinal performance of the beam, was not included in the impedance model of the HEPS storage ring in the preliminary design stage. For completeness, we would like to take the CSR impedance into consideration. The most important contributions to the total CSR impedance come from the bending magnets and insertion devices. We therefore calculate the CSR impedance from both above mentioned elements in HEPS storage ring. The influence of the CSR impedance on the microwave instability threshold is studied and presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB102
About •	paper received ※ 17 May 2021 paper accepted ※ 18 June 2021 issue date ※ 27 August 2021
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MOPAB114	Development of a Decoherence Kicker for the ALS Upgrade Project (ALS-U)	kicker, storage-ring, extraction, injection	414
	C. Sun, S. De Santis, M.P. Ehrlichman, T. Hellert, T. Oliver, G. Penn, C. Steier, M. Venturini, W.L. Waldron LBNL, Berkeley, California, USA
	The Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory is upgrading the existing storage-ring lattice to a nine-bend-achromat lattice with on-axis swap-out injection. The upgraded storage ring will provide a highly focused beam of about 10 um in both horizontal and vertical directions with a single bunch train energy of about 60 J at 2.0 GeV. Such a small and intense beam could cause damage to the transfer line vacuum chambers in case of extraction element failures or damage to the storage ring vacuum chamber in case of RF failures. To mitigate these potential damages, a fast kicker magnet (so-called decoherence kicker) will be installed in the ALS-U storage ring and activated to dilute the beam charge density either on a train to be swapped out a few 100s turns before extraction or on the whole beam after RF failures. In this paper, we will present both physics and engineering designs of this decoherence kicker.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB114
About •	paper received ※ 19 May 2021 paper accepted ※ 27 May 2021 issue date ※ 20 August 2021
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MOPAB117	Single Bunch Collective Effects in the EBS Storage Ring	impedance, simulation, SRF, synchrotron	425
	L.R. Carver, E. Buratin, N. Carmignani, F. Ewald, L. Hoummi, S.M. Liuzzo, T.P. Perron, B. Roche, S.M. White ESRF, Grenoble, France
	The ESRF storage ring (SR) has been dismantled and replaced by the Extremely Brilliant Source (EBS) which has now been commissioned. Beam based measurements have been performed to characterise the impedance of the new machine and to make a first comparison with predictions. The results from instability threshold scans and tune shift measurements will be presented, as well as bunch length and position variation with current and microwave threshold measurements.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB117
About •	paper received ※ 11 May 2021 paper accepted ※ 31 May 2021 issue date ※ 25 August 2021
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MOPAB131	Synchrotron SOLEIL Upgrade Project	lattice, emittance, photon, injection	463
	A. Nadji SOLEIL, Gif-sur-Yvette, France
	To remain competitive in the future, SOLEIL is also working on an upgrade project plan based on Multi-Bend Achromat (MBA) lattices. The Technical Design Report of the project is expected to start in early 2021 immediately after the completion of the Conceptual Design Report (CDR) phase. The achieved equilibrium emittance in the CDR reference lattice (80 pm-rad) is about 50 times smaller than that of the existing storage ring (4000 pm-rad). By operating on a linear coupling resonance, round beam sizes in Insertion Devices straight sections of less than 10 microns RMS in both planes can be produced. These performances rely on the use of a 10 mm inner diameter circular copper vacuum chamber with NEG-coating allowing reaching strong quadrupole gradients and very strong sextupole and octupole strengths. As all these technical challenges are pushing the engineering technology to the limits, they are being investigated through an intensive R&D program based on extensive numerical simulations, prototyping, and measurement with the beam. Extensive use of the pure permanent magnet technology beyond what has been done so far in the other similar projects is considered in this project.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB131
About •	paper received ※ 22 May 2021 paper accepted ※ 27 July 2021 issue date ※ 30 August 2021
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MOPAB140	Gas Sheet Ionization Diagnostic for High Intensity Electron Beams	diagnostics, electron, detector, operation	489
	N.P. Norvell, G. Andonian, T.J. Campese, A.-L.M.S. Lamure, M. Ruelas, A.Yu. Smirnov RadiaBeam, Santa Monica, California, USA N.M. Cook RadiaSoft LLC, Boulder, Colorado, USA J.K. Penney UCLA, Los Angeles, California, USA C.P. Welsch The University of Liverpool, Liverpool, United Kingdom
	Funding: Work supported by DOE grant DE-SC0019717 The characterization of high intensity charged particle beams in a minimally interceptive, and non-destructive manner is performed using an ionization diagnostic. In this application, a neutral gas is tailored into a thin sheet, or curtain-like, distribution at the interaction point with an electron beam. The electron beam ionizes the neutral gas in localized space, leaving a footprint of the beam transverse distribution. The ion cloud is subseqeuntly imaged with a series of electrostatic lenses to a detector plane. The resultant image is used in a reconstruction algorithm to reconstruct the beam profile at the interaction point. In this paper, we present progress on the development of this diagnostic for the characterization of high charge, 10GeV electron beams with small transverse distributions.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB140
About •	paper received ※ 20 May 2021 paper accepted ※ 10 June 2021 issue date ※ 01 September 2021
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MOPAB142	A Compact, Low-Field, Broadband Matching Section for Externally-Powered X-Band Dielectric-Loaded Accelerating Structures	coupling, GUI, simulation, linac	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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MOPAB143	Simulations for MeV Energy Gain in Multi-Micron Vacuum Channel Dielectric Structures Driven by a CO₂ Laser	laser, electron, simulation, acceleration	499
	G. Yadav, O. Apsimon, Y. Wei, C.P. Welsch The University of Liverpool, Liverpool, United Kingdom O. Apsimon, C.P. Welsch, G.X. Xia Cockcroft Institute, Warrington, Cheshire, United Kingdom G.X. Xia The University of Manchester, Manchester, United Kingdom
	Funding: This work was supported by STFC LIV. DAT under grant agreement ST/P006752/1. This research used the resources of the Supercomputing Laboratory at KAUST in Thuwal, Saudi Arabia. Dielectric Laser Accelerators (DLAs) have been demonstrated as a novel scheme for producing high acceleration gradients (~1 GV/m) within the damage threshold of the dielectric. The compactness of the DLAs and the low emittance of the output electron beam make it an attractive candidate for future endoscopic devices to be used in tumor irradiation. However, due to the small accelerating distances(sub-mm), the total energy gain is limited to sub-MeV which remains an obstacle for its realistic applications. Also, these DLAs operate under solid-state lasers with wavelengths near IR (800 nm to 2 um), where required sub-micron vacuum channel at such wavelengths imposes major aperture restrictions for the amount of charge to be accelerated. Here, we present numerical simulation results for a dielectric structure excited by a CO₂ laser with a wavelength of 10.6 um. Upon injecting a 50 MeV electron bunch through a 5.3 um diameter of vacuum channel width, our simulation suggests an energy gain beyond 1 MeV. These results are the initial steps for the realization of an mm-scale DLA capable of producing MeV energy electron beams.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB143
About •	paper received ※ 18 May 2021 paper accepted ※ 02 June 2021 issue date ※ 11 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, cyclotron, experiment, linac	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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MOPAB208	LLRF Measurements and Cu-plating at the First-of-Series Cavity Section of the Alvarez 2.0 at GSI	cavity, DTL, operation, simulation	686
	M. Heilmann, T. Dettinger, X. Du, L. Groening, S. Mickat, A. Rubin GSI, Darmstadt, Germany
	The Alvarez 2.0 will replace the existing post-stripper DTL of the GSI UNILAC. Today’s GSI comprises the UNILAC and the synchrotron SIS18 and is going to serve as the injector chain for the Facility of Antiproton and Ion Research (FAIR). The new Alvarez-type DTL is operated at 10⁸.4 MHz providing acceleration from 1.4 MeV/u to 11.4 MeV/u along a total length of 55 meters. The first-of-series (FoS) cavity section has 12 RF-gaps along a total length of 1.9 m. It is the first cavity section of the new DTL. All main components were delivered in 2019, followed by successful SAT and installation of the 11 drift tubes and copper-plating. Completion of first low level RF-measurements prior to copper plating and the subsequent plating are major project milestones. These proceedings report on the results and compares them to simulation using CST Microwave Studio.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB208
About •	paper received ※ 18 May 2021 paper accepted ※ 31 May 2021 issue date ※ 22 August 2021
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MOPAB209	Commissioning of SANAEM RFQ Accelerator	rfq, cavity, plasma, proton	690
	B. Yasatekin, A. Alacakir, A.S. Bolukdemir, I. Kilic, Y. Olgac TENMAK-NUKEN, Ankara, Turkey E. Cicek KEK, Ibaraki, Japan E. Cosgun UNIST, Ulsan, Republic of Korea
	The former SANAEM RFQ is upgraded with a newly manufactured cavity, made of oxygen-free copper (OFC), having the capability of accelerating protons from 20 keV to 1.3 MeV. In the assembling of cavity vanes, flanges, etc., indium wire is preferred over the brazing process providing a more flexible and easy method for vacuum sealing. After assembling the cavity, argon plasma cleaning is performed for the final cleaning and RF pre-conditioning. Vacuum tests revealed that levels of 2·10^-7 mbar could be achieved quite easily. RF power conditioning of the RFQ cavity is successfully completed with the observation of quite few sparks. In the commissioning tests with the proton beam, a magnetic analyzer is used to measure the energy of the particles. This paper presents the strategy and the results concerning the commissioning of the proton beam with special emphasis on the RFQ cavity.
	Poster MOPAB209 [5.076 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB209
About •	paper received ※ 19 May 2021 paper accepted ※ 14 June 2021 issue date ※ 22 August 2021
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MOPAB282	Development of a Multi-Camera System for Non-Invasive Intense Ion Beam Investigations	diagnostics, ion-source, solenoid, experiment	895
	A. Ateş, H. Hähnel, U. Ratzinger, K. Volk, C. Wagner IAP, Frankfurt am Main, Germany
	The continued popularity of miniaturized cameras integrated into smartphones is leading to further research for more advanced CMOS camera sensors. This made CMOS technology even superior to scientific CCD cameras. Due to the lower power consumption and high flexibility, a multicamera system can be developed more effectively. At the Institute of Applied Physics at Goethe University Frankfurt (IAP) a prototype of a beam induced rest gas fluorescence monitor (BIF) was developed and tested successfully. The BIF consists of x and y single board cameras integrated into the vacuum chamber. A multi-camera system was installed in the LEBT area of the FRANZ project at the IAP within the first diagnostic chamber. This system consists of six cameras. With this equipment it is possible to investigate the beam along a 484 mm path in x and y direction. The developments on the reconstruction and image processing methods are in progress.
	Poster MOPAB282 [1.139 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB282
About •	paper received ※ 12 May 2021 paper accepted ※ 08 June 2021 issue date ※ 24 August 2021
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MOPAB321	Schlieren Imaging for Flow Visualisation of Gas Jet in Vacuum for Accelerator Applications	controls, laser, solenoid, linac	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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MOPAB324	High Voltage Design and Evaluation of Wien Filters for the CEBAF 200 keV Injector Upgrade	electron, high-voltage, GUI, simulation	1000
	G.G. Palacios Serrano, P.A. Adderley, J.F. Benesch, D.B. Bullard, J.M. Grames, C. Hernandez-Garcia, A.S. Hofler, D. Machie, M. Poelker, M.L. Stutzman, R. Suleiman JLab, Newport News, Virginia, USA H. Baumgart, G.G. Palacios Serrano ODU, Norfolk, Virginia, 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. High-energy nuclear physics experiments at the Jefferson Lab Continuous Electron Beam Accelerator Facility (CEBAF) require highly spin-polarization electron beams, produced from strained super-lattice GaAs photocathodes, activated to negative electron affinity in a photogun operating at 130 kV dc. A pair of Wien filter spin rotators in the injector defines the orientation of the electron beam polarization at the end station target. An upgrade of the CEBAF injector to better support the upcoming MOLLER experiment requires increasing the electron beam energy to 200 keV, to reduce unwanted helicity correlated intensity and position systematics and provide precise control of the polarization orientation. Our contribution describes design, fabrication and testing of the high voltage system to upgrade the Wien spin rotator to be compatible with the 200 keV beam. This required Solidworks modeling, CST and Opera electro- and magnetostatic simulations, upgrading HV vacuum feedthroughs, and assembly techniques for improving electrode alignment. The electric and magnetic fields required by the Wien condition and the successful HV characterization under vacuum conditions are also presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB324
About •	paper received ※ 19 May 2021 paper accepted ※ 24 May 2021 issue date ※ 29 August 2021
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MOPAB330	Production and Performance Evaluation of a Compact Deflecting Cavity to Measure the Bunch Length in the cERL	cavity, resonance, coupling, impedance	1023
	D. Naito, Y. Honda, T. Miyajima, N. Yamamoto KEK, Ibaraki, Japan
	At the KEK compact energy recovery linac, we try to generate an infrared free-electron laser (FEL). To generate the FEL, an electron bunch should be compressed along the longitudinal direction. The measurement of the bunch length is key to optimize the bunch compression. We plan to measure the bunch length by deflecting cavities in the burst mode. The deflecting cavities are required to be a time resolution of 33 fs in order to not only measure the bunch length but also resolve the structure inside the electron bunch. To achieve the requirement, we developed a c-band cavity whose RF input port is compact. The deflecting cavity is a single cell and normal conducting cavity. The deflection mode of the cavity is TM110. The 12 cavities will be located at the exit of undulators. In this presentation, we explain the design of our cavity and report the production of the first cavity. We also report the evaluation of the resonance frequency, the unloaded Q and the external Q of the cavity. From the measurements and simulations, the R/Q is estimated to be 1 mega orms. The time resolution of the cavity is expected to be 400 fs when the input RF power is 1 kW and the beam energy is 20 MeV.
	Poster MOPAB330 [12.920 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB330
About •	paper received ※ 12 May 2021 paper accepted ※ 08 June 2021 issue date ※ 28 August 2021
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MOPAB336	Multipacting Analysis of Warm Linac RF Vacuum Windows	simulation, multipactoring, GUI, Windows	1044
	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 with 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 that 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. Possible techniques for reducing and eliminating multipacting activities in these structures are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB336
About •	paper received ※ 17 May 2021 paper accepted ※ 28 May 2021 issue date ※ 29 August 2021
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MOPAB340	Experimental Tests with the First Segment of ESS-Bilbao RFQ Linac	rfq, simulation, experiment, operation	1054
	J.L. Muñoz, I. Bustinduy, A. Conde, N. Garmendia, P.J. González, J. Martin, A. Zugazaga ESS Bilbao, Zamudio, Spain
	The ESS-Bilbao RFQ is an assembly of four segments, each one about 800 mm in length. The first segment has been manufactured before the others, so it could be thoroughly tested in order to validate the chosen technological approach for the RFQ, as it uses polymeric vacuum gaskets and bolts instead of brazing. In this paper we report on the tests run with the segment and their results. Vacuum tests, metrology measurements, low power RF tests as well as extensive tuning tests measuring the cavity resonant quadrupolar frequency as a function of cooling water temperature have been done. Experimental results are compared to the expected values obtained from numerical simulations. We describe the experimental set-ups for the measurements and the simulations. Results are analyzed with the aim of validating the design, and also to provide predictions for tuning and operation of the whole RFQ. As a consequence of the positive results of the tests reported here, the remaining segments have already been tendered.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB340
About •	paper received ※ 19 May 2021 paper accepted ※ 25 May 2021 issue date ※ 20 August 2021
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MOPAB344	Machine Learning Models for Breakdown Prediction in RF Cavities for Accelerators	cavity, operation, network, linac	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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MOPAB346	Broadband Frequency Electromagnetic Characterisation of Coating Materials	GUI, experiment, electron, site	1076
	A. Passarelli, C. Koral, M.R. Masullo INFN-Napoli, Napoli, Italy A. Andreone Naples University Federico II, Napoli, Italy M. De Stefano University of Naples, Naples, Italy V.G. Vaccaro Naples University Federico II and INFN, Napoli, Italy
	In the new generation of particle accelerators and storage rings, collective effects have to be carefully analyzed. In particular, the finite conductivity of the beam pipe walls is a major source of impedance and instabilities. A reliable electromagnetic (EM) characterisation of different coating materials is required up to hundreds of GHz due to very short bunches. We propose two different measurement techniques for an extended frequency characterization: (i) a THz time domain setup based on the signal transmission response of a tailored waveguide to infer the coating EM properties from 100 to 300 GHz or even further.. This technique has been tested both on NEG and amorphous Carbon films. (ii) a resonant method, based on dielectric cavities, to evaluate the surface resistance Rs of thin conducting samples at low (GHz) frequencies*. Due to its high sensitivity, Rs values can be obtained for very thin (nanometric) coatings or for copper samples with a laser treated surface, since they have an expected conductivity very close to bulk copper. A. Passarelli et al., Phys. Rev. Accel. Beams, v.21, p.103101, 2018 A. Passarelli et al., Cond. Matter, v.5, p.9, 2020 *A. Andreone et al., Applied Physics Letters, v.91, n.7, p.072512, 2007
	Poster MOPAB346 [2.613 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB346
About •	paper received ※ 18 May 2021 paper accepted ※ 09 June 2021 issue date ※ 26 August 2021
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MOPAB347	High Power Coupler Conditioning for bERLinPro Energy Recovery Linac Injector	booster, cavity, SRF, MMI	1080
	A. Neumann, W. Anders, F. Göbel, A. Heugel, S. Klauke, J. Knobloch, M. Schuster, Y. Tamashevich HZB, Berlin, Germany
	Funding: The work is funded by the Helmholtz-Association, BMBF, the state of Berlin and HZB. Helmholtz Zentrum Berlin is currently finalizing the construction of the demonstrator Energy Recovery Linac bERLinPro . The first part, which will be commissioned, will be the injector consisting of a superconducting RF (SRF) photo-injector (Gun) and a Booster module made up of three two cell SRF cavities. For the latter the 2.3 MeV beam from the gun needs to be accelerated to 6.5 MeV, whereas one Booster cavity will be operated in zero-crossing mode for bunch-shortening. Thus, for the final stage with a 100 mA beam, the twin power couplers of the Booster cavity need to deliver up to 120 kW in travelling continous wave (CW) mode at 1.3 GHz each. To achieve that, a dedicated coupler conditioning setup was installed and commissioned. Here, we will present the first conditioning results with the bERLinPro Booster fundamental power couplers in pulsed and CW regime. M. Abo-Bakr et al., in Proc. 9th Int. Particle Accelerator Conf. (IPAC’18), Vancouver, BC, Canada, Apr. 4,, pp. 4127-4130, doi:10.18429/JACoW-IPAC2018-THPMF034
	Poster MOPAB347 [3.256 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB347
About •	paper received ※ 18 May 2021 paper accepted ※ 08 June 2021 issue date ※ 14 August 2021
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MOPAB356	The ESS MEBT RF Buncher Cavities Conditioning Process	cavity, controls, MEBT, EPICS	1107
	I. Bustinduy, N. Garmendia, P.J. González, A. Kaftoosian, S. Masa, I. Mazkiaran, L.C. Medina, J.L. Muñoz ESS Bilbao, Zamudio, Spain J. Etxeberria, J.P.S. Martins ESS, Lund, Sweden
	Funding: This work is part of FEDER-TRACKS project, co-funded by the European Regional Development Fund (ERDF) . As part of the 5 MW European Spallation Source (ESS), the Medium Energy Beam Transport (MEBT) was designed, assembled, and installed in the tunnel since May 2020 by ESS-Bilbao. This section of the accelerator is located between the Radio Frequency Quadrupole (RFQ) and the Drift Tube Linac (DTL). The main purpose of the MEBT is to match the incoming beam from the RFQ both transversely and longitudinally into the DTL. The longitudinal matching is achieved by three 352.209 MHz RF buncher cavities. In this paper, we focus on the RF conditioning process for each set of power coupler and buncher cavity. For this purpose, different tools were developed on EPICS and Python as well as electronics hardware such as Fast Interlock Module (FIM) and timing system. These tools served to automatize both the cavity frequency tuning and the power ramp-up process and will be described in detail in the following sections.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB356
About •	paper received ※ 18 May 2021 paper accepted ※ 09 June 2021 issue date ※ 25 August 2021
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MOPAB359	Operational Experience and Redesign of the Tuner without Spring Fingers for the LEReC Warm Cavity	cavity, operation, SRF, electron	1116
	B.P. Xiao, J.M. Brennan, J.C. Brutus, K. Mernick, S. Polizzo, S.K. Seberg, F. Severino, K.S. Smith, A. Zaltsman BNL, Upton, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. A folded coaxial tuner without spring fingers was designed for the Low Energy RHIC electron Cooler (LEReC) 2.1 GHz warm cavity. During RHIC run 2019, this tuner was found to cause cavity trips via different failure modes. After analyzing these failure modes, a new straight coaxial tuner without spring fingers was proposed and was installed. We show the operational experience of the new tuner in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB359
About •	paper received ※ 17 May 2021 paper accepted ※ 25 June 2021 issue date ※ 29 August 2021
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MOPAB360	Anomalous Skin Effect Study of Normal Conducting Film	impedance, plasma, ECR, interface	1119
	B.P. Xiao, M. Blaskiewicz, T. Xin BNL, Upton, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. For the radiofrequency (RF) applications of normal conducting film with large mean free path at high frequency and low temperature, the anomalous skin effect differs considerably from the normal skin effect with field decaying exponentially in the film. Starting from the relationship between the current and the electric field (E field) in the film, the amplitude of E field along the film depth is calculated, and is found to be non-monotonic. The surface impedance is found to have a minimum value at certain film thickness.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB360
About •	paper received ※ 17 May 2021 paper accepted ※ 25 June 2021 issue date ※ 17 August 2021
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MOPAB365	Construction and First Test Results of the Barrier and Harmonic RF Systems for the NICA Collider	cavity, collider, injection, electron	1136
	A.G. Tribendis, Y.A. Biryuchevsky, K.N. Chernov, A.N. Dranitchnikov, E. Kenzhebulatov, A.A. Kondakov, A.A. Krasnov, Ya.G. Kruchkov, S.A. Krutikhin, G.Y. Kurkin, A.M. Malyshev, A.Yu. Martynovsky, N.V. Mityanina, S.V. Motygin, A.A. Murasev, V.N. Osipov, V.M. Petrov, E. Pyata, E. Rotov, V.V. Tarnetsky, I.A. Zapryagaev, A.A. Zhukov BINP SB RAS, Novosibirsk, Russia O.I. Brovko, A.M. Malyshev, I.N. Meshkov, E. Syresin JINR, Dubna, Moscow Region, Russia I.N. Meshkov Saint Petersburg State University, Saint Petersburg, Russia E. Rotov NSU, Novosibirsk, Russia A.G. Tribendis NSTU, Novosibirsk, Russia A.V. Zinkevich Triada-TV, Novosibirsk, Russia
	This paper reports on the design features and construction progress of the three RF systems for the NICA collider being built at JINR, Dubna. Each of the two collider rings has three RF systems named RF1 to 3. RF1 is a barrier bucket system used for particles capturing and accumulation during injection, RF2 and 3 are resonant systems operating at 22nd and 66th harmonics of the revolution frequency and used for the 22 bunches formation. The RF systems are designed and produced by Budker INP. Solid state RF power amplifiers developed by the Triada-TV company, Novosibirsk, are used for driving the RF2 and three cavities. Two RF1 stations were already delivered to JINR, the prototypes of the RF2 and 3 stations were built and successfully tested at BINP. Series production of all eight RF2 and sixteen RF3 stations is in progress. The design modifications and test results are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB365
About •	paper received ※ 18 May 2021 paper accepted ※ 24 May 2021 issue date ※ 14 August 2021
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MOPAB370	X-Band RF Spiral Load Optimization for Additive Manufacturing Mass Production	GUI, simulation, ECR, linac	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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MOPAB371	A Coupon Tester for Normal Conducting High-Gradient Materials	cavity, coupling, RF-structure, klystron	1147
	J.W. Lewellen, D. Gorelov, D. Perez, E.I. Simakov LANL, Los Alamos, New Mexico, USA M.E. Schneider Michigan State University, East Lansing, Michigan, USA
	Funding: Los Alamos National Laboratory LDRD Program A coupon tester is an RF structure used to subject a material sample to very high RF fields, with the fields on the sample, or coupon, being higher than elsewhere in the cavity. To date, most such cavities were originally intended to explore the RF properties of superconducting materials, and can expose the sample to strong magnetic fields, but weak to no electric fields. As part of a program to develop materials and structures for high-gradient (> 100 MV/m), low-breakdown-rate normal-conducting accelerators, we have designed a C-band (5.712 GHz) cavity intended to subject samples to both magnetic and electric fields comparable to those experienced in high-gradient structure designs, using a TM-mode cavity; the electric and magnetic fields along the sample coupon can be directly compared to the fields on the iris of high-gradient structures. This poster will present the design criteria for our coupon tester cavity, nominal operating parameters, and our structure concept. The cavity design will be refined over the next several months, and will be constructed and in service near the start of 2022.
	Poster MOPAB371 [0.764 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB371
About •	paper received ※ 17 May 2021 paper accepted ※ 26 May 2021 issue date ※ 30 August 2021
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MOPAB388	Status of the High Power Couplers for ESS Elliptical Cavities	cavity, cryomodule, simulation, SRF	1186
	C. Arcambal, P. Bosland, G. Devanz, T. Hamelin, C. Madec, C. Marchand, M. Oublaid, G. Perreu, C. Servouin, C. Simon CEA-IRFU, Gif-sur-Yvette, France M. Baudrier, C. Mayri, S. Regnaud, T.V. Vacher CEA-DRF-IRFU, France
	In the framework of the European Spallation Source (ESS), CEA Paris-Saclay is responsible for the delivery of 30 cryomodules (9 medium beta (β = 0.67) and 21 high beta (β = 0.86) ones). Each cryomodule contains 4 elliptical cavities equipped with a radio frequency power coupler. The ESS nominal pulse is 1.1 MW maximum peak power over a width of 3.6 ms at a repetition rate of 14 Hz. The design of the couplers for medium beta and for high beta cavities is the same, except a small difference of the antenna penetration to adjust the Q_ext. The mass production of the 120 couplers started and all the medium beta couplers have been conditioned at room temperature. The first cryomodules equipped with the power couplers were successfully tested at high RF power and with cavities at 2K reaching the ESS nominal pulse. The main issue at the start of the series production could be fixed and it was due to bad TiN coatings that caused abnormal dielectric losses in the window. Thus, this paper deals with the TiN coating defect, presents the conditioning procedure and gives a conditioning report of these 36 couplers.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB388
About •	paper received ※ 19 May 2021 paper accepted ※ 24 May 2021 issue date ※ 18 August 2021
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MOPAB401	In-Situ EXAFS Investigations of Nb-Treatments in N₂, O₂ and N₂-O₂ Mixtures at Elevated Temperatures	site, experiment, niobium, cavity	1214
	P. Rothweiler, B. Bornmann, J. Klaes, D. Lützenkirchen-Hecht, R. Wagner University of Wuppertal, Wuppertal, Germany
	Funding: We gratefully acknowledge financial support by the German Federal Ministry of Education and Research (BMBF) under project No. 05H18PXRB1. Smooth polycrystalline Nb metal foils were treated in dilute gas atmospheres using a temperature of 900 °C. Transmission mode X-ray absorption spectroscopy (EX-AFS) at the Nb K-edge was used to investigate changes in the atomic short-range order structure of the bulk Nb-material in-situ. The experiments were performed in a dedicated high-vacuum cell that allows treatments in a dilute gas atmosphere and temperatures of up to 1200 °C. Typical treatments include (i) pre-heating at 900 °C under high-vacuum, (ii) gas exposure at the desired pressure and temperature, and (iii) cooldown to room temperature under vacuum. EXAFS data were collected during the entire procedure with a time resolution of 1 s. For the treatments in N₂ at T = 900°C, the data show subtle changes in the Nb-EXAFS, that are compatible with N-doping of the bulk Nb, and the results suggest Nb uptake on octahedral interstitial sites. However, even a small O2-partial pressure leads to distinct oxidation of the Nb. The results will be discussed in more detail in the presentation.
	Poster MOPAB401 [2.032 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB401
About •	paper received ※ 19 May 2021 paper accepted ※ 26 May 2021 issue date ※ 27 August 2021
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MOPAB419	Acceleration and Measurement of Alpha Particles and Hydrogen Molecular Ions with the HZB Cyclotron	cyclotron, radiation, proton, scattering	1264
	G. Kourkafas, J. Bundesmann, A. Denker, T. Fanselow, J. Röhrich HZB, Berlin, Germany J. Heufelder, A. Weber Charite, Berlin, Germany
	The HZB cyclotron has treated more than 4000 patients with eye tumors using protons. The accelerator can also provide heavier ions which could be suitable for ocular radiation therapy. Helium ions exhibit less lateral spread, increased relative biological effectiveness and a sharper Bragg-Peak compared to protons of the same range, while minimizing nuclear fragmentation and thus excessive dose downstream the irradiated volume compared to more heavy ions. When accelerating fully stripped helium ions (alpha particles), hydrogen molecular ions can also be accelerated to the same energy with a small tuning of the machine due to having almost the same mass-to-charge ratio, yielding a proton beam of double current after the beam exits the vacuum window towards the target. The acceleration and characterization of these two ion species are described in this paper, suggesting the feasibility of a corresponding clinical cyclotron for ocular or even deep-seated tumors.
	Poster MOPAB419 [0.806 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB419
About •	paper received ※ 19 May 2021 paper accepted ※ 09 June 2021 issue date ※ 13 August 2021
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TUPAB031	Construction and Installation of the New CERN Proton Synchrotron Internal Beam Dumps	MMI, shielding, interface, proton	1409
	K.G. Andersen, M. Calviani, A. Cherif, T. Coiffet, A. De Macedo, S. Devidal, J.-M. Geisser, S.S. Gilardoni, M.M.J. Gillet, E. Grenier-Boley, J.M. Heredia, A. Majbour, F. Monnet, M.R. Monteserin, F.-X. Nuiry, D. Pugnat, G. Romagnoli, Y.D.R. Seraphin, J.A.F. Somoza, N. Thaus CERN, Geneva 23, Switzerland
	In the framework of the CERN Large Hadron Collider Injectors Upgrade (LIU) Project, the Proton Synchrotron (PS) has been equipped with two new movable Internal Dumps (PSID), each of them capable of absorbing particle beams of an energy of up to 100 kJ. These dumps replace the old Internal Dumps, which have been operated in the accelerator complex since their installation in 1975 until their decommissioning and removal from the machine during the second LHC Long Shut down (LS2). This contribution will address the construction and testing phases of the new PSIDs, including the assembly of the dump core, its actuation system and the respective shielding, mechanical running-in tests, metrology adjustments, Ultra-High Vacuum (UHV) and impedance acceptance tests. The described installation work was completed successfully, and the new generation Dumps are currently operational in the PS machine.
	Poster TUPAB031 [3.146 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB031
About •	paper received ※ 18 May 2021 paper accepted ※ 27 May 2021 issue date ※ 26 August 2021
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TUPAB065	Solaris Storage Ring Performance After 6 Years of Operation	storage-ring, operation, MMI, synchrotron	1515
	A.I. Wawrzyniak, A. Curcio, K. Gula, M.A. Knafel, G.W. Kowalski, A.M. Marendziak, R. Panaś, M. Waniczek, M. Wiśniowski NSRC SOLARIS, Kraków, Poland
	Solaris is a third generation light source operating since 2015 in Kraków, Poland. Between 2015 and 2018 the synchrotron as well as two beamlines were commissioned. During commissioning phases, the good performance of Solaris storage ring has been reached. The beam optics was brought close to the design one. Since October 2018 Solaris storage ring is in the user operation mode. Moreover, two other beamlines with the elliptically polarized undulators used as source were installed and are under commissioning now. In 2020 the total beam availability of 93% was reached with the average circulating current of 400 mA and the total lifetime of 15 h. Over last two years few improvements of the storage ring were done to optimize the storage ring performance. The Landau cavities were tuned to improve the Touschek lifetime and suppress the instabilities. Two diagnostics beamlines were installed and commissioned allowing for the beam sizes in three planes and emittance measurements. The storage ring optics was fine-tuned to increase the dynamic aperture.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB065
About •	paper received ※ 19 May 2021 paper accepted ※ 26 May 2021 issue date ※ 16 August 2021
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TUPAB102	A New 2nd Bunch Compression Chicane for the FLASH2020+ Project	quadrupole, dipole, focusing, FEL	1618
	M. Vogt, J. Zemella DESY, Hamburg, Germany
	The first stage of the FLASH2020+ project is an upgrade of the FLASH injector beamline. Within this framework, the 2nd bunch compression chicane (BCC) will be completely redesigned. The old S-chicane will be replaced with a new C-chicane which is 3.5m shorter thereby generating space a new section for re-matching the beam from the injector into the linac. The new BCC will be equipped with quad/skew-quad units in both legs of the chicane to compensate correlations of the transverse degrees of freedom with the longitudinal ones. Since quadrupoles tend to have a circular bore, the chicane is designed with movable round vacuum chambers and movable dipoles for maintaining full flexibility in choosing the compression parameters. This article describes the technical details and introduces a thin-lens model of BCCs which allows analytical estimates on the effects of powering the quad/skew-quad units on optics parameters as well as estimates on the required strengths of these magnets in order to remove correlations of the magnitudes typically observed at FLASH.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB102
About •	paper received ※ 19 May 2021 paper accepted ※ 14 June 2021 issue date ※ 29 August 2021
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TUPAB122	SASE3 Variable Polarization Project at the European XFEL	undulator, polarization, FEL, electron	1678
	S.K. Karabekyan, S. Abeghyan, M. Bagha-Shanjani, S. Casalbuoni, U. Englisch, G. Geloni, J. Grünert, S. Hauf, C. Holz, D. La Civita, J. Laksman, D. Mamchyk, M.P. Planas, F. Preisskorn, S. Serkez, H. Sinn, A. Violante, G. Wellenreuther, M. Wuenschel, M. Yakopov, C. Youngman EuXFEL, Schenefeld, Germany A. Block, W. Decking, N. Golubeva, K. Knebel, T. Ladwig, D.L. Lenz, D. Lipka, R. Mattusch, N. Mildner, E. Negodin, D. Nölle, J. Prenting, F. Saretzki, M. Schlösser, F. Schmidt-Föhre, E. Schneidmiller, D. Thoden, T. Wamsat, S. Wendt, T. Wilksen, T. Wohlenberg, M.V. Yurkov DESY, Hamburg, Germany M. Brügger, M. Calvi, S. Danner, R. Ganter, L. Huber, A. Keller, M.S. Schmidt, T. Schmidt PSI, Villigen PSI, Switzerland D.E. Kim PAL, Pohang, Republic of Korea Y. Li IHEP, People’s Republic of China
	At the European XFEL, two undulator systems for hard and one for soft X-rays have been successfully put into operation. The SASE3 soft X-ray undulator system generates linearly polarized radiation in the horizontal plane. One of the requirements for extending the radiation characteristics is the ability to obtain different polarization modes. These include both right and left circular, elliptical polarization, or linear polarization at an arbitrary angle. For this purpose, a system consisting of four APPLE X helical undulators developed at the Paul Scherrer Institute (PSI) is used. This paper presents the design parameters of the SASE3 undulator system after modifying it with the helical afterburner. It also describes the methods and the design solutions different from those used at PSI. The status and schedule of the project are introduced.
	Poster TUPAB122 [0.553 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB122
About •	paper received ※ 19 May 2021 paper accepted ※ 31 May 2021 issue date ※ 27 August 2021
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TUPAB133	Brazing free RF Pulse Compressor for High Gradient Accelerators	GUI, cavity, coupling, simulation	1700
	L. Kankadze, D. Alesini, F. Cardelli, G. Di Raddo, M. Diomede INFN/LNF, Frascati, Italy
	EURPRAXIA@SPARC\_LAB, is a proposal to upgrade the SPARC\_LAB test facility (at LNF, Frascati) to a soft X-ray user facility based on plasma acceleration and high-gradient X-band (11.9942 GHz) accelerating modules. Each module is made up of a group of 4 TW sections assembled on a single girder and fed by one klystron by means of one rf pulse compressor system and a low attenuation circular waveguide network that transports the rf power to the input hybrids of the sections. The pulse compressor is based on a single Barrel Open Cavity (BOC). The BOC use a ’whispering gallery’ mode which has an intrinsically high quality factor and operates in a resonant rotating wave regime. Compared to the conventional SLED scheme it requires a single cavity instead of two cavities and a 3-dB hybrid. A new brazeless mechanical design has been proposed and is described in the present paper together with the electro-magnetic and thermo-mechanical simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB133
About •	paper received ※ 21 May 2021 paper accepted ※ 15 June 2021 issue date ※ 10 August 2021
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TUPAB201	Vacuum Tube Operation Tuning for a High Intensity Beam Acceleration in J-PARC RCS	acceleration, operation, electron, controls	1884
	M. Yamamoto, M. Nomura, H. Okita, T. Shimada, F. Tamura JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan M. Furusawa, K. Hara, K. Hasegawa, C. Ohmori, Y. Sugiyama, M. Yoshii KEK, Tokai, Ibaraki, Japan
	Tetrode vacuum tubes in the J-PARC RCS are used under a reduced filament voltage condition compared with the rating value to prolong the tube life time. One tube reached the end of life in 2020; it was the first case in the RCS after 60,000 hours operation time. This means the reduced filament voltage works well because the tube has been running beyond an expected life time suggested by the tube manufacturer. However, an electron emission from the filament is decreased by the reduced filament voltage. Although the large amplitude of the anode current is necessary for the high intensity beam acceleration to compensate an wake voltage, a solid-state amplifier to drive a control grid circuit almost reaches the output power limit because of the poor electron emission. We changed the filament voltage reduction rate from 15 % to 5 %; the required power of the solid-state amplifier was fairly reduced, whereas the accelerated beam power was same. We will describe the measurement results of the vacuum tube parameters in terms of the filament voltage tuning.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB201
About •	paper received ※ 17 May 2021 paper accepted ※ 17 June 2021 issue date ※ 02 September 2021
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TUPAB244	THE WAKEFIELD STUDY OF THE RF-SHIELDED BELLOWS AT THE ILSF STORAGE RING	impedance, wakefield, factory, simulation	2015
	N. Khosravi, E. Ahmadi, M. Akhyani ILSF, Tehran, Iran M. Akhyani EPFL, Lausanne, Switzerland A. Khosravi LAPRI, Tehran, Iran
	The corrugated geometry of the bellows made it critical to be shielded with an RF-Shield. Different types of RF shields can be applied to the ILSF vacuum chamber to cover this component’s destructive impedance peaks. Then, the Impedance study and optimization of the RF shields can improve the impedance budget. In this article, two common types of RF shields are simulated in CST software.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB244
About •	paper received ※ 16 May 2021 paper accepted ※ 02 June 2021 issue date ※ 14 August 2021
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TUPAB260	A Beam Screen to Prepare the RHIC Vacuum Chamber for EIC Hadron Beams: Conceptual Design and Requirements	electron, hadron, dipole, collider	2066
	S. Verdú-Andrés, M. Blaskiewicz, J.M. Brennan, X. Gu, R.C. Gupta, A. Hershcovitch, M. Mapes, G.T. McIntyre, J.F. Muratore, S.K. Nayak, S. Peggs, V. Ptitsyn, R. Than, J.E. Tuozzolo, D. Weiss BNL, Upton, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. The Electon Ion Collider (EIC) hadron ring will use the existing Relativistic Heavy Ion Collider storage rings, including the superconducting magnet arcs. The vacuum chambers in the superconducting magnets and the cold mass interconnects were not designed for EIC beams and so must be updated to reduce its resistive-wall heating and to suppress electron clouds. To do so without compromising the EIC luminosity goal, a stainless steel beam screen with co-laminated copper and a thin layer of amorphous carbon will be installed. This paper describes the main requirements that our solution for the hadron ring vacuum chamber needs to satisfy, including impedance, aperture limitations, vacuum, thermal and structural stability, mechanical design, installation and operation. The conceptual design of the beam screen currently under development is introduced.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB260
About •	paper received ※ 19 May 2021 paper accepted ※ 25 August 2021 issue date ※ 12 August 2021
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TUPAB270	Thermal Transition Design and Beam Heat-load Estimation for the COLDDIAG Refurbishment	operation, cryogenics, diagnostics, simulation	2097
	H.J. Cha, N. Glamann, A.W. Grau, A.-S. Müller, D. Saez de Jauregui KIT, Eggenstein-Leopoldshafen, Germany
	Funding: This work is supported by the BMBF project 05H18VKRB1 HIRING (Federal Ministry of Education and Research). The COLDDIAG (cold vacuum chamber for beam heat load diagnostics) developed at Karlsruhe Institute of Technology has been modified for more studies at cryogenic temperatures different from the previous operations at 4 K in a cold bore and at 50 K in a thermal shield. The key components in this campaign are two thermal transitions connecting both ends of the bore at 50 K with the shield at the same or higher temperature. In this paper, we present design efforts for the compact transitions, allowed heat intakes to the cooling power margin and mechanical robustness in the cryogenic environment. A manufacture scheme for the transition and its peripheral is also given. In addition, the beam heat loads in the refurbished COLDDIAG are estimated in terms of the accelerator beam parameters.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB270
About •	paper received ※ 12 May 2021 paper accepted ※ 02 June 2021 issue date ※ 12 August 2021
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TUPAB281	Gas-Mixing to Improve the Resolution of Non-Invasive Gas Jet-Based Ionization Profile Monitors	injection, electron, simulation, background	2132
	N. Kumar, A. Salehilashkajani, C.P. Welsch, H.D. Zhang Cockcroft Institute, Warrington, Cheshire, United Kingdom N. Kumar, A. Salehilashkajani, C.P. Welsch, H.D. Zhang The University of Liverpool, Liverpool, United Kingdom
	Funding: This work is supported by the HL-LHC-UK project funded by STFC and CERN and the STFC Cockcroft core grant No. ST/G008248/1. Ionization beam profile monitor using a supersonic gas jet is an attractive option for the characterization of low and medium energy beams. In this scheme, a primary beam crosses a 45-degree tilted thin gas curtain which causes ionization of gas molecules in the jet. The generated ions are then collected using an electrostatic extraction system to determine the 2D transverse profile of the primary beam. The most commonly used gases for the jet are neon and nitrogen. The signal from the gas jet is always super-imposed with the signal resulting from residual gases in the interaction chamber. CST simulations indicate that the gas jet speed is a key factor for the separation of the jet and the residual gas signals. To obtain a good signal separation, one can increase the velocity of the gas jet. This can be accomplished by generating a gas jet that mixes heavier and lighter gases. This contribution gives a general overview of the monitor design, discusses the effects of gas mixing and CST simulation results. It also presents experimental results obtained with Helium, and Nitrogen, as well as a mixture of them using different percentages and the impact on measurement resolution.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB281
About •	paper received ※ 19 May 2021 paper accepted ※ 02 June 2021 issue date ※ 13 August 2021
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TUPAB308	Mechanical Consolidation of the LHC Inner Triplet Magnet Supporting System for Remote Alignment	alignment, GUI, quadrupole, ECR	2207
	F. Micolon, N. Bourcey, J-B. Deschamps, A. Herty, S. Le Naour, T. Mikkola, V. Parma, D. Ramos, V. Rude, M. Sosin CERN, Meyrin, Switzerland
	Given the high radiation area and the tight alignment tolerances, the LHC inner triplet magnets were designed to be realigned remotely using motorized supporting jacks. However, during run 2 the LHC triplet realignment system started to show an unexpected behavior with erratic load variations on the magnet supporting jacks when operated. It was then decided to freeze any further realignment of the LHC triplet magnet for the remainder of the run. Subsequently, a project team was set up at CERN to understand better the conditions leading to such unexpected behavior and to study and propose a technical consolidation for the realignment system of the LHC triplet magnet. A fully instrumented magnet string using LHC triplet spare magnets was assembled and used at CERN to provide a realistic test bench for this study. This paper reports on the work undertaken to study the triplet magnet overall realignment kinematic, the findings on the readjustment system malfunction and details the consolidation solution implemented for the next LHC run
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB308
About •	paper received ※ 18 May 2021 paper accepted ※ 07 June 2021 issue date ※ 18 August 2021
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TUPAB318	The Beamline Safety Interlock System of Taiwan Photon Source	radiation, photon, controls, synchrotron-radiation	2239
	C.F. Chang, C.Y. Chang, C.Y. Liu, H.Y. Yan NSRRC, Hsinchu, Taiwan
	The energy of synchrotron radiation generated by bremsstrahlung radiation and magnet is rather high, which may cause serious radiation damage to human body or even imperil people’s life. The beamline therefore must be equipped with radiation-protection system; in addition, the overheat of optical components exposed to synchrotron radiation will lead to the damage of optical components and devices. In consequence, the beamline should be furnished with the cooling-protection system to cool down optical components and devices. The Beamline Safety Interlock System targets at protecting the personnel and the safety of devices, limiting the radiation dose to a security value for experimental personnel or staffs exposing to radiation on the site as well as preventing beamline components from being exposed to overheat or vacuum damages to improve the effectiveness of beamline.
	Poster TUPAB318 [3.440 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB318
About •	paper received ※ 09 May 2021 paper accepted ※ 10 June 2021 issue date ※ 31 August 2021
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TUPAB339	High Power Test of the Antenna Adjustable Power Coupler for 325 MHz Superconducting Cavities	cavity, multipactoring, electron, pick-up	2286
	J.Y. Yoon, E.-S. Kim, C.S. Park, S.H. Park KUS, Sejong, Republic of Korea J. Bahng Korea University Sejong Campus, Sejong, Republic of Korea E. Kako KEK, Ibaraki, Japan K.R. Kim PAL, Pohang, Republic of Korea
	Funding: The Ministry of Education (South Korea) The power coupler is development at Korea University for a Single Spoke Resonator (SSR) of heavy ion accelerator. Our power coupler is a coaxial capacitive type based on a conventional 3-1/8 inch electronic industries alliance (EIA) 50 Ω coaxial transmission line with a titanium nitride (TiN) coated single ceramic window. A high power test is rectangular test cavity with high vacuum and various measuring equipment, such as an arc detector, a power meter, and an electron pick-up probe. The interlock system under vacuum and arc instrumentations prevent the RF window from breaking the power coupler window during the high power test. We conduct high power tests for more than 12 hrs at 12 kW in a 325 MHz continous wave (CW) mode to verify the performance of the designed power coupler. Superconducting, Power Coupler
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB339
About •	paper received ※ 12 May 2021 paper accepted ※ 21 June 2021 issue date ※ 24 August 2021
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TUPAB359	Magnetic Field Measurement and Beam Performance Test of Ceramics Chamber with Integrated Pulsed Magnet at KEK-PF	experiment, survey, kicker, dipole	2352
	Y. Lu Sokendai, Ibaraki, Japan K. Harada, Y. Kobayashi, C. Mitsuda, S. Nagahashi, T. Nogami, T. Obina, R. Takai, H. Takaki, T. Uchiyama, A. Ueda KEK, Ibaraki, Japan
	An air-core magnet named Ceramics Chamber with integrated Pulsed Magnet(CCiPM) is being developed at the photon factory of KEK(KEK-PF), which will have several applications for the future light source. One prototype has been developed as a dipole kicker, whose bore is only 30mm. Due to the type and structure, it’s expected to have strong magnetic field and high repetition rate. After finishing the offline measurement of magnetic field and evaluation of vacuum tightness, the CCiPM was installed in the beam transport-dump line of PF to have an online beam performance and durability test. The results of the magnetic field measurement and beam performance test will be reviewed.
	Poster TUPAB359 [1.164 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB359
About •	paper received ※ 19 May 2021 paper accepted ※ 02 June 2021 issue date ※ 16 August 2021
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TUPAB365	Demonstration of ‘ZEPTO’ Permanent Magnet Technology on Diamond Light Source	quadrupole, permanent-magnet, lattice, radiation	2370
	A.R. Bainbridge, B.J.A. Shepherd STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom N. Krumpa STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom I.P.S. Martin, W. Tizzano DLS, Oxfordshire, United Kingdom
	The use of permanent magnets (PM’s) in place of traditional electromagnets is becoming more common in accelerator systems around the world. This change is being driven by the desire to reduce both the energy costs and carbon footprint of accelerators. However, the problem remains that it is difficult to adjust the field strength of PM systems. STFC and CERN have a longstanding collaboration in the Zero-Power Tuneable Optics (ZEPTO) project which aims to develop PM systems that are tuneable via moving the PM blocks within a static pole structure. This collaboration has previously produced 3 prototype magnets (2 quadrupoles and 1 dipole) for the proposed CLIC accelerator and aims to expand suitability to a variety of accelerators. We are now demonstrating this technology on a real machine by installing a ZEPTO magnet on Diamond Light Source. We outline the design, construction, and improvement of this technology demonstrator, highlighting the innovations over previous generations of ZEPTO technology that account for previously observed drawbacks.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB365
About •	paper received ※ 18 May 2021 paper accepted ※ 22 June 2021 issue date ※ 12 August 2021
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TUPAB381	Thermal Analysis of the RHIC Arc Dipole Magnet Cold Mass with the EIC Beam Screen	dipole, electron, hadron, cryogenics	2413
	S.K. Nayak, M. Anerella, M. Blaskiewicz, J.M. Brennan, R.C. Gupta, M. Mapes, G.T. McIntyre, S. Peggs, R. Than, J.E. Tuozzolo, S. Verdú-Andrés, D. Weiss BNL, Upton, New York, USA
	Funding: Funding agency Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. The EIC will make use of the existing RHIC storage rings with their superconducting (SC) magnet arcs. A stainless-steel beam screen with co-laminated copper and a thin amorphous carbon (aC) film on the inner surface will be installed in the beam pipe of the SC magnets. The copper will reduce the beam-induced resistive-wall (RW) heating from operation with the higher intensity EIC beams, that if not addressed would make the magnets quench. Limiting the RW heating is also important to achieve an adequately low vacuum level. The aC coating will reduce secondary electron yield which could also cause heating and limit intensity. Among all the RHIC SC magnets, the arc dipoles present the biggest challenge to the design and installation of beam screens. The arc dipoles, which make up for 78% (2.5 km) length of all SC magnets in RHIC, expect the largest RW heating due to their smallest aperture. These magnets are also the longest (9.45 m each), thus experiencing the largest temperature rise over their length, and have a large sagitta (48.5 mm) that increases the difficulty to install the beam screen in place. This paper presents a detailed thermal analysis of the magnet-screen system.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB381
About •	paper received ※ 19 May 2021 paper accepted ※ 20 July 2021 issue date ※ 23 August 2021
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TUPAB391	Cryopanels in the Room Temperature Heavy Ion Synchrotron SIS18	simulation, cryogenics, quadrupole, heavy-ion	2435
	S. Aumüller, L.H.J. Bozyk, P.J. Spiller GSI, Darmstadt, Germany K. Blaum MPI-K, Heidelberg, Germany
	The FAIR complex at the GSI Helmholtzzentrum will generate heavy ion beams of ultimate intensities. To achieve this goal, medium charge states have to be used. However, the probability for charge exchange in collisions with residual gas particles of such ions is much higher than for higher charge states. In order to lower the residual gas density to extreme high vacuum conditions, 65% of the circumference of SIS18 are already coated with NEG, which provides high and distributed pumping speed. Nevertheless, nobel and nobel-like components, which have very high ionization cross sections, do not get pumped by this coating. A cryogenic environment at moderate temperatures, i.e. at 50-80K, provides high pumping speed for all heavy residual gas particles. The only typical residual gas species, that cannot be pumped at this temperature is hydrogen. With an additional NEG coating the pumping will be optimized for all residual gas particles. The installation of cryogenic surfaces in the existing room temperature synchrotron SIS18 at GSI has been investigated. A prototype quadrupole chamber with cryogenic surfaces, first measurements, and simulations of the adapted accelerator are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB391
About •	paper received ※ 19 May 2021 paper accepted ※ 31 August 2021 issue date ※ 25 August 2021
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TUPAB392	Conceptual Design of the Vacuum System for the Future Circular Collider FCC-ee Main Rings	photon, collider, quadrupole, scattering	2438
	R. Kersevan, C. Garion CERN, Geneva, Switzerland
	The Future Circular Collider study program comprises several machine concepts for the future of high-energy particle physics. Among them there is a twin-ring e⁻e⁺ collider capable to run at beam energies between 45.6 and 182.5 GeV, i.e. the energies corresponding to the resonances of the Z, W, H bosons and the top quark. The conceptual design of the two 100-km rings has advanced to what is believed to be a working solution, i.e. capability to deal with low-energy (45.6 GeV) high-current (1390 mA) version as well as the high-energy (182.5 GeV) low-current (5.4 mA) one, with intermediate energy and current steps for the other 2 resonances. The limit for all of the versions is given by the 50 MW/beam allotted to the synchrotron radiation (SR) losses. The paper will outline the main beam/machine parameters, the vacuum requirements, and the choices made concerning the vacuum chamber geometry, material, surface treatments, pumping system, and the related pressure profiles. The location of lumped SR photon absorbers for the generic arc cell has been determined. An outline of the studies needed and envisaged for the near future will also be given.
	Poster TUPAB392 [3.036 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB392
About •	paper received ※ 19 May 2021 paper accepted ※ 31 May 2021 issue date ※ 25 August 2021
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TUPAB393	Study of Remote Helium Mass Spectrometer Leak Detection in Accelerator	gun, detector, operation, controls	2441
	H.Y. He, D.H. Zhu IHEP CSNS, Guangdong Province, People’s Republic of China J.M. Liu DNSC, Dongguan, People’s Republic of China
	In order to solve the problem that the vacuum system of the accelerator can’t be close to the operation for a long time, a long-distance helium mass spectrometer leak detection system is explored by studying the structure of the conventional round tube vacuum box of the vacuum system, which integrates the online vacuum leak detection, defect diagnosis and process design, improves the digital operation, realizes the accurate and effective detection of the leak location range and leak rate, and provides the technology for the remote leak detection of the vacuum system. Support.
	Poster TUPAB393 [0.666 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB393
About •	paper received ※ 13 May 2021 paper accepted ※ 31 May 2021 issue date ※ 10 August 2021
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TUPAB395	Vacuum System Models for Minerva Linac Design	linac, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB395
About •	paper received ※ 19 May 2021 paper accepted ※ 01 June 2021 issue date ※ 28 August 2021
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TUPAB396	The Thermal Outgassing Rate of Materials Used in Vacuum Systems	experiment, diagnostics, cathode, radiation	2447
	A.M. Semenov BINP & NSTU, Novosibirsk, Russia A. Burdakov, A.A. Krasnov, B.P. Tolochko, A.V. Varand BINP SB RAS, Novosibirsk, Russia S.R. Ivanova GPI, Moscow, Russia A.A. Krasnov NSU, Novosibirsk, Russia M.A. Mikhailenko ISSCM SB RAS, Novosibirsk, Russia A.A. Shoshin Budker INP & NSU, Novosibirsk, Russia
	There are many rarely used materials in vacuum systems that are poorly investigated in terms of vacuum properties. For example, phosphors, scintillating materials, ferrites, various adhesives, etc. In addition, new organic materials are being developed with mechanical properties similar to those of conventional steel. The use of such materials is very promising in vacuum technology. This article presents the thermal degassing performance of several rarely used materials and promising materials for vacuum applications.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB396
About •	paper received ※ 18 May 2021 paper accepted ※ 31 August 2021 issue date ※ 20 August 2021
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TUPAB398	Vacuum Issues with Argon Gas in the LANSCE Accelerator	neutron, linac, 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]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB398
About •	paper received ※ 19 May 2021 paper accepted ※ 01 June 2021 issue date ※ 28 August 2021
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TUPAB400	Manufacturing of Ceramic Vacuum Chambers for Sirius On-Axis Kicker	kicker, HOM, niobium, target	2457
	R. Defavari, O.R. Bagnato, M.W.A. Feitosa, F.R. Francisco, D.Y. Kakizaki, R.L. Parise, R.D. Ribeiro LNLS, Campinas, Brazil
	Ceramic vacuum chambers were produced by LNLS for the Sirius kickers. Alumina tubes with an elliptical inner shape of 9.5 mm (V) x 29 mm (H) and 500 mm long were successfully manufactured by a Brazilian company. Metallic F136 titanium flanges were brazed to Nb inserts using Ag-58.5Cu-31.5Pd wt% alloy, these inserts were brazed to the ceramic using Ag-26.7Cu-4.5Ti wt% active filler metal. A titanium film was coated inside the chamber using argon plasma by RF Magnetron Sputtering technique. Samples have been investigated by Scanning Electron Microscopy (SEM) to measure film thickness along the inner section of the tube, coating morphology, chemical composition and homogeneity. The total electrical resistance of the tube was also monitored during the sputtering process to achieve the desired value (0.2 ohms/square). In this contribution, we present the results of an On-Axis kicker manufacturing process developed by LNLS.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB400
About •	paper received ※ 18 May 2021 paper accepted ※ 31 May 2021 issue date ※ 29 August 2021
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TUPAB401	Mechanical Design, Fabrication and Characterization of Electron Beam Position Monitors for Sirius	pick-up, operation, impedance, storage-ring	2461
	R. Defavari, O.R. Bagnato, M.W.A. Feitosa, F.R. Francisco, G.R. Gomes, D.Y. Kakizaki, R.L. Parise, R.D. Ribeiro LNLS, Campinas, Brazil
	Beam Position Monitors were designed and manufactured to meet Sirius operation requirements. Final dimensional accuracy and stability of the BPM were achieved by careful specification of its components’ manufacturing tolerances and materials. AISI-305 Stainless Steel was used for the BPM support fabrication due to magnetic and thermal expansion constraints. High purity molybdenum for the electrode pin and Ti6Al4V F136 G23 alloy for housing was used to manufacture the sensor components for their thermal characteristics. The electrical insulator was made of high alumina. The materials were joined by an active metal brazing process using 0,01mm accurate fixtures. The brazed sensors were subjected to dimensional, mechanical, and metallurgical testing, as well as leak detection and optical microscopy inspection at each stage. The sensors were joined in Ti6Al4V F136 BPM bodies using TIG welding. Dimensional sorting was used to choose groups of sensors-to-body, and body-to-support pairs during the final assembly. 160 BPMs are currently in operation on Sirius storage ring. In this contribution, we present the results of BPM manufacturing and testing processes developed for Sirius.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB401
About •	paper received ※ 18 May 2021 paper accepted ※ 31 May 2021 issue date ※ 29 August 2021
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WEXB01	The ESS Elliptical Cavity Cryomodules Production at CEA	cryomodule, cavity, status, site	2536
	C. Madec CEA, Gif-sur-Yvette, France C. Arcambal, S. Berry, A. Bouygues, G. Devanz, C. Mayri, P. Sahuquet, T. Trublet CEA-DRF-IRFU, France P. Bosland, E. Cenni, C. Cloué, T. Hamelin, O. Piquet CEA-IRFU, Gif-sur-Yvette, France P. Pierini ESS, Lund, Sweden
	CEA in Kind contribution to the ESS superconducting LINAC includes 30 elliptical medium and high-beta cryomodules. CEA is in charge of the production of all the components (except the cavities delivered by LASA and STFC) as well as the assembly of the cryomodules and a few cryogenic and RF tests. The power couplers operating at a maximum power of 1.1MW on a 3.6ms pulse at 14Hz are conditioned at high RF power on a dedicated stand. The assembly of the cryomodules is performed at CEA by a private Company under the supervision of CEA. This paper presents the status of the cryomodules production and the infrastructure dedicated to this project at CEA Saclay.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEXB01
About •	paper received ※ 18 May 2021 paper accepted ※ 19 July 2021 issue date ※ 30 August 2021
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WEPAB032	Studies of the Short-Range Wakefields for the Electron Storage Ring in the Electron Ion Collider	simulation, electron, wakefield, dipole	2675
	G. Wang, M. Blaskiewicz, A. Blednykh, M.P. Sangroula BNL, Upton, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. During the estimates of impedance budget for the Electron Storage Ring (ESR) of Electron-Ion Collider (EIC), various codes, including GdfidL, CST and ECHO3D, have been used to calculate the short-range wake-fields due to the vacuum components. The ECHO 3D code demonstrates more reliable results for the tapered type of structures rather than the GdfidL code, where the stepsize needs to be dramatically decreased to achieve a high-performance calculation. Impedance of the following components are discussed and compared in details: Interaction Region (IR) chamber, bellows, and synchrotron radiation mask (flange absorber).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB032
About •	paper received ※ 19 May 2021 paper accepted ※ 10 June 2021 issue date ※ 24 August 2021
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WEPAB041	Testing of the Milliampere Booster Prototype Cavity	cavity, linac, 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
About •	paper received ※ 18 May 2021 paper accepted ※ 23 June 2021 issue date ※ 21 August 2021
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WEPAB081	The Broad-Band Impedance Budget in the Storage Ring of the ALS-U Project	impedance, cavity, wakefield, storage-ring	2779
	D. Wang, K.L.F. Bane, R. Bereguer, T. Cui, S. De Santis, P. Gach, D. Li, T.H. Luo, T. Miller, T. Oliver, O. Omolayo, C. Steier, T.L. Swain, M. Venturini, G. Wang LBNL, Berkeley, California, USA
	Design work is underway for the upgrade of the Advanced Light Source (ALS-U) to a diffraction-limited soft x-rays radiation source. Like other 4th-generation light source machines, the ALS-U multiple-bend achromat storage-ring (SR) is potentially sensitive to beam-coupling impedance effects. This paper presents the SR broad-band impedance budget in both the longitudinal and transverse planes. In our modeling we follow the commonly accepted approach of separating the resistive-wall and the geometric parts of the impedance, the former being described by analytical formulas and the latter obtained by numerical electromagnetic codes (primarily CST Studio software) assuming perfectly conducting materials. We discuss the main sources of impedance. Results of our analysis are the basis for the single bunch instability study and would feedback on the design of critical vacuum components.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB081
About •	paper received ※ 20 May 2021 paper accepted ※ 01 July 2021 issue date ※ 20 August 2021
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WEPAB131	Magnetic Tuning and Installation Modifications of U48 Undulator for the Delhi Light Source (DLS)	undulator, electron, controls, focusing	2918
	M. Tischer, P. Neumann, A. Schöps, P. Vagin, T. Vielitz, T. Wohlenberg DESY, Hamburg, Germany M. Aggarwal, R.N. Dutt, S. Ghosh, J. Karmakar, S. Sahu IUAC, New Delhi, India J. Bahrdt, E.C.M. Rial HZB, Berlin, Germany
	A compact THz radiation facility based on the principle of a pre-bunched Free Electron Laser, called Delhi Light Source (DLS) is at the final stage of commissioning at IUAC, New Delhi, India. For generation of THz radiation in DLS, an undulator with period length of 48 mm (U48), built by HZB and refurbished at DESY will be used. The magnetic tuning and the field measurements have been done on the U48 along with the design and installation of correction coils at the entrance/exit of the U48. In addition, horizontal and vertical ambient field correction coils were integrated into the magnet girders. A quadrupole correction coil along the vacuum chamber in order to mitigate the defocusing effect of the U48 on the electron beam has been designed. The current through all coils has been adjusted as a function of the gap by the new control system designed for the U48. In addition, an extruded aluminium vacuum chamber was designed and fabricated and will be aligned with the the undulator soon.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB131
About •	paper received ※ 19 May 2021 paper accepted ※ 05 July 2021 issue date ※ 11 August 2021
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WEPAB132	Towards a Superconducting Undulator Afterburner for the European XFEL	FEL, photon, undulator, electron	2921
	S. Casalbuoni, J.E. Baader, G. Geloni, V. Grattoni, D. La Civita, C. Lechner, B. Marchetti, S. Serkez, H. Sinn EuXFEL, Schenefeld, Germany W. Decking, L. Lilje, S. Liu, T. Wohlenberg, I. Zagorodnov DESY, Hamburg, Germany
	We propose to develop, characterize and operate a superconducting undulator (SCU) afterburner consisting of 5 undulator modules (1 module = 2 times SCU coil of 2 m length and 1 phase shifter) at the SASE2 hard X-ray beamline of European XFEL. This afterburner has the potential to produce an output of more than 10¹⁰ ph/pulse at photon energies above 30 keV. The project is divided into the production of a pre-series prototype module and a small-series production of 5 modules. Central goals of this R&D activity are: the demonstration of the functionality of SCUs at an X-ray FEL, the set up of the needed infrastructure to characterize and operate SCUs, the industrialization of such undulators, and the reduction of the price per module. In this contribution, the main parameters and specifications of the pre-series prototype module (S-PRESSO) are described.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB132
About •	paper received ※ 15 May 2021 paper accepted ※ 05 July 2021 issue date ※ 14 August 2021
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WEPAB133	First Numerical Wakefield Studies of New In-Vacuum Cryogenic and APPLE II Undulators for BESSY II	impedance, simulation, undulator, factory	2925

Paper

Title

Other Keywords

Page

MOXC02

Improved Lifetime of a High Spin Polarization Superlattice Photocathode

electron, cathode, polarization, gun

31

L. Cultrera
BNL, Upton, New York, USA

Funding: Department of Energy under grant DE-SC0012704
Highly spin polarized electron beams are required for the operation of a wide range of accelerators and instruments. The production of such electrons requires the use of Negative Electron Affinity (NEA) activated GaAs-based cathodes operated in photoelectron guns. Because of their extreme sensitivity to poor vacuum conditions the degradation of the photoemission process is so strong that NEA activated GaAs-based photocathodes can only survive in the extreme vacuums typical of DC gun. State-of-the-art on photocathode technology for spin polarized beam productions are summarized. Recent results on the use of robust NEA coating based on the Cs-Te and Cs-Sb leading to improved operational lifetime of a high spin polarization photocathode are reviewed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOXC02

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

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MOPAB030

Research and Development Progress of CEPC RF Shield Bellows

positron, impedance, electron, controls

142

J.M. Liu, Y.H. Guan, S.M. Liu, B. Tan, P.C. Wang
DNSC, Dongguan, People’s Republic of China
H. Dong, Y. Ma
IHEP, Beijing, People’s Republic of China
H.Y. He, T. Huang
IHEP CSNS, Guangdong Province, People’s Republic of China

The circular electron positron collider (CEPC) is a candidate for the next-generation electron positron collider, which can be used to accurately measure the Higgs and electroweak bosons. The RF shield bellow is a vacuum component necessary for the construction of CEPC. Therefore, a RF shield bellow model machine with an elliptical cross-section was designed and processed for technical verification. Based on the traditional interdigital structure, a special contact force testing device was also designed to reduce measurement errors. The on-off status of the circuit was used by the device to determine whether the spring finger was pulled up, thus reducing the influences of human factors in the measurement process. It can be known from the measurement results of the model machine that the contact force of the spring finger is between 120g and 130g, which can satisfy the technical requirements.

Poster MOPAB030 [1.467 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB030

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paper received ※ 19 May 2021 paper accepted ※ 20 May 2021 issue date ※ 13 August 2021

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MOPAB031

Development and Operation of Vacuum System for Rapid Cycling Synchrotron to Target Beam Transfer Line of China Spallation Neutron Source

target, neutron, operation, proton

145

J.M. Liu, Y.H. Guan, S.M. Liu, B. Tan, P.C. Wang
DNSC, Dongguan, People’s Republic of China
H. Dong
IHEP, Beijing, People’s Republic of China
H.Y. He, T. Huang
IHEP CSNS, Guangdong Province, People’s Republic of China

China Spallation Neutron Source (CSNS) is a major scientific project during the National Eleventh Five-Year Plan. It consists of a negative hydrogen ion linear accelerator, a rapid cycling synchrotron ( RCS), a linac to RCS beam transfer line (LRBT), an RCS to target beam transfer line (RTBT), and a target station. As an important part of CSNS, the RTBT connects the rapid cycling synchrotron and the target window. This paper described the design requirements, technical solutions, and operating conditions of the vacuum system for the CSNS RCS to target beam transfer line. In addition, the fast valve protection system and its verification results were also expounded. The CSNS has been in operation for over three years, during this period, the beam power has been gradually improved from 10KW to 100KW, and the vacuum system for RTBT has been operating stably.

Poster MOPAB031 [0.581 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB031

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paper received ※ 19 May 2021 paper accepted ※ 24 May 2021 issue date ※ 25 August 2021

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MOPAB079

Experience of the First Six Years Operations and Plans in NSlS-II

operation, cavity, MMI, feedback

308

G.M. Wang
BNL, Upton, New York, USA

NSLS-II is a 3 GeV third-generation synchrotron light source at BNL. The storage ring was commissioned in 2014 and began its routine operations in the December of the same year. Since then, we have been continuously installing and commissioning new insertion devices, their front-ends, and beamlines. At this point, the facility hosts 28 operating beamlines from various radiation sources, including damping wiggler, IVU, EPU, 3PW, and bending magnets for infrared beamlines. Over the past six years, the storage ring performance continuously improved, including 500 mA with limited insertion devices close due to RF power limitation and routinely 400 mA top off operation, >95% operation reliability, maintenance of beam motion short- and long-term stability. In this paper, we report NSLS-II accelerator operations experience and plans for future facility developments.

Poster MOPAB079 [2.064 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB079

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paper received ※ 17 May 2021 paper accepted ※ 21 June 2021 issue date ※ 25 August 2021

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MOPAB084

Acceptance Tests and Installation of the IVU and Front End for the XAIRA Beamline of ALBA

undulator, photon, experiment, insertion

318

J. Campmany, J. Marcos, V. Massana
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain

XAIRA is a new beamline being built at ALBA synchrotron for macromolecular crystallography (MX) devoted to the study of small bio crystals. It aims at providing a full beam with a size of 3x1 µm² FWHM (hxv) and flux of >3·10¹² ph/s (250 mA in Storage Ring) at 1 Å wavelength (12.4 keV) to tackle MX projects for which only tiny (<10 μm) or imperfect crystals are obtained. Besides, XAIRA aims at providing photons at low energies, down to 4 keV, to support MX experiments exploiting the anomalous signal of the metals naturally occurring in proteins (native phasing), which is enhanced in the case of small crystals and long wavelengths. To this end, an in-vacuum undulator has been built by a consortium between Kyma and Research Instruments companies. In this paper, we present the results of the Site Acceptance Tests made at ALBA using a new bench developed to measure closed structures, and also the steps done for its installation in the ALBA tunnel.

Poster MOPAB084 [1.715 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB084

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paper received ※ 11 May 2021 paper accepted ※ 20 May 2021 issue date ※ 25 August 2021

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MOPAB085

Design and Fabrication of a Short Multipole Wiggler and the Front End for the New ALBA Beamline FAXTOR

photon, wiggler, insertion, insertion-device

321

J. Campmany, J. Marcos, V. Massana
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain

FAXTOR is a new hard XR tomography beam line that is being built at ALBA in order to fulfil the needs that cannot be currently covered by the MISTRAL VUV and soft XR beamline. This beam line needs a small source size as well higher than 10¹² Photons per second through an aperture of 4x1 mm2 in the whole range 5 to 60 keV, for a current of 250 mA in Storage Ring with source size maintained below 310 µm horizontal and 25 µm vertical. The contract was awarded to AVS-US Company. In this paper we present the design finally selected as well as the preliminary design carried out by manufacturer to implement the conceptual model designed by ALBA.

Poster MOPAB085 [1.879 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB085

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

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MOPAB086

Design of Front End and a 3-Pole-Wiggler as a Photon Source for BEATS Beamline at SESAME

photon, wiggler, synchrotron, insertion

324

J. Campmany, J. Marcos
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
M. Al Nadjawi, M. Attal, G. Lori
SESAME, Allan, Jordan
I. Cudin
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
S. Guiducci
INFN/LNF, Frascati, Italy
P. Van Vaerenbergh
ESRF, Grenoble, France

BEATS is an international collaboration funded by EU in order to design and implement an XR tomography beam line in SESAME Jordanian synchrotron. ALBA contribution consists in the design of the photon source and the Front End elements. In this paper we present the conceptual designs of both the 3-pole wiggler uses as photon source as well as the Front End elements designed for the beamline.

Poster MOPAB086 [2.306 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB086

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paper received ※ 11 May 2021 paper accepted ※ 21 May 2021 issue date ※ 17 August 2021

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MOPAB088

Beam-Based Measurement on the Performance of Ferrite Dampers in an In-Vacuum Undulator

damping, HOM, feedback, radiation

331

K. Tian, A. Ringwall, J.J. Sebek
SLAC, Menlo Park, California, USA

In this paper, we first present the tracking studies for SPEAR3 with the new BL17 ID and estimate its impact on the dynamic aperture of the low emittance lattice. Then the ferrite dampers installations in the device is briefly reviewed. After that, we will show that, based on beam-based measurements, the performance of the dampers is as being expected from earlier numerical studies.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB088

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paper received ※ 19 May 2021 paper accepted ※ 18 June 2021 issue date ※ 24 August 2021

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MOPAB091

Injection Section Upgrading with the Septum-Magnet Replacement in KEK-PF Ring

injection, septum, storage-ring, operation

342

C. Mitsuda, K. Harada, N. Higashi, T. Honda, Y. Kobayashi, H. Miyauchi, S. Nagahashi, N. Nakamura, T. Nogami, T. Obina, M. Tadano, R. Takai, H. Takaki, Y. Tanimoto, T. Uchiyama, A. Ueda
KEK, Ibaraki, Japan

In 2015, the water leakage happened at the cooling pipe of the in-vacuum septum magnet installed into the injection point. Because the maintenance of the leakage needed the total replacement of the magnet, the water circulation was stopped permanently, and accordingly, the light absorber was installed upstream in the storage ring to prevent the synchrotron light of the bending magnet from coming to the septum wall. This treatment temporally worked well, but the beam injection efficiency was decreased to about 30% due to the physical aperture narrowed by the absorber. With the desired replacement of septum magnet to maintainable out-vacuum type, the injection section upgrading was simultaneously planned to recover and improve the injection efficiency. In this upgrade, the injection beam is closed to the stored beam more than before by adapting the thinner septum structure as a way to improve the injection efficiency. And some new ideas are introduced in the part of monitor and beam duct, for example, realtime beam monitor, thinner Inconel duct. The detailed design of the upgraded injection section and technical points will be reviewed in this conference.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB091

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paper received ※ 19 May 2021 paper accepted ※ 26 May 2021 issue date ※ 02 September 2021

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MOPAB093

Operational Status of Photon Factory Light Sources

injection, operation, radiation, electron

350

T. Honda, Y. Kobayashi, C. Mitsuda, S. Nagahashi, R. Takai, H. Takaki
KEK, Ibaraki, Japan

One of the recent topics of Photon Factory light sources, PF-ring and PF-AR, is a construction of a GeV-class beamline for testing detectors at the PF-AR. The bremsstrahlung photons generated by a thin carbon wire are brought to a copper target to generate e⁺e⁻ pairs. Sufficient count rates can be expected when the thin wire touching halo of the stored beam, and the test beamline can be used without disturbing the synchrotron radiation experiments. In addition to the usual 6.5-GeV operation, a low-energy operation at 5-GeV was started recently at PF-AR to secure operation time by saving electricity costs. At the PF-ring, the injection section has been upgraded with the septum-magnet replacement. By the top-up injection and improved bunch feedback, the hybrid-fill mode operation has become convenient for both single-bunch users and multi-bunch users, and about 30% or 40% of the user time is scheduled as the hybrid-fill mode now.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB093

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paper received ※ 21 May 2021 paper accepted ※ 25 May 2021 issue date ※ 13 August 2021

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MOPAB102

CSR Impedance in HEPS Storage Ring

impedance, storage-ring, lattice, synchrotron

379

H.S. Xu, X.Y. Li, N. Wang
IHEP, Beijing, People’s Republic of China

High Energy Photon Source (HEPS) is under construction in Beijing, China. The relatively complete impedance model has been built up based on the element-by-element impedance calculation. However, Coherent Synchrotron Radiation (CSR) impedance, which might affect the longitudinal performance of the beam, was not included in the impedance model of the HEPS storage ring in the preliminary design stage. For completeness, we would like to take the CSR impedance into consideration. The most important contributions to the total CSR impedance come from the bending magnets and insertion devices. We therefore calculate the CSR impedance from both above mentioned elements in HEPS storage ring. The influence of the CSR impedance on the microwave instability threshold is studied and presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB102

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

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MOPAB114

Development of a Decoherence Kicker for the ALS Upgrade Project (ALS-U)

kicker, storage-ring, extraction, injection

414

C. Sun, S. De Santis, M.P. Ehrlichman, T. Hellert, T. Oliver, G. Penn, C. Steier, M. Venturini, W.L. Waldron
LBNL, Berkeley, California, USA

The Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory is upgrading the existing storage-ring lattice to a nine-bend-achromat lattice with on-axis swap-out injection. The upgraded storage ring will provide a highly focused beam of about 10 um in both horizontal and vertical directions with a single bunch train energy of about 60 J at 2.0 GeV. Such a small and intense beam could cause damage to the transfer line vacuum chambers in case of extraction element failures or damage to the storage ring vacuum chamber in case of RF failures. To mitigate these potential damages, a fast kicker magnet (so-called decoherence kicker) will be installed in the ALS-U storage ring and activated to dilute the beam charge density either on a train to be swapped out a few 100s turns before extraction or on the whole beam after RF failures. In this paper, we will present both physics and engineering designs of this decoherence kicker.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB114

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

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MOPAB117

Single Bunch Collective Effects in the EBS Storage Ring

impedance, simulation, SRF, synchrotron

425

L.R. Carver, E. Buratin, N. Carmignani, F. Ewald, L. Hoummi, S.M. Liuzzo, T.P. Perron, B. Roche, S.M. White
ESRF, Grenoble, France

The ESRF storage ring (SR) has been dismantled and replaced by the Extremely Brilliant Source (EBS) which has now been commissioned. Beam based measurements have been performed to characterise the impedance of the new machine and to make a first comparison with predictions. The results from instability threshold scans and tune shift measurements will be presented, as well as bunch length and position variation with current and microwave threshold measurements.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB117

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paper received ※ 11 May 2021 paper accepted ※ 31 May 2021 issue date ※ 25 August 2021

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MOPAB131

Synchrotron SOLEIL Upgrade Project

lattice, emittance, photon, injection

463

A. Nadji
SOLEIL, Gif-sur-Yvette, France

To remain competitive in the future, SOLEIL is also working on an upgrade project plan based on Multi-Bend Achromat (MBA) lattices. The Technical Design Report of the project is expected to start in early 2021 immediately after the completion of the Conceptual Design Report (CDR) phase. The achieved equilibrium emittance in the CDR reference lattice (80 pm-rad) is about 50 times smaller than that of the existing storage ring (4000 pm-rad). By operating on a linear coupling resonance, round beam sizes in Insertion Devices straight sections of less than 10 microns RMS in both planes can be produced. These performances rely on the use of a 10 mm inner diameter circular copper vacuum chamber with NEG-coating allowing reaching strong quadrupole gradients and very strong sextupole and octupole strengths. As all these technical challenges are pushing the engineering technology to the limits, they are being investigated through an intensive R&D program based on extensive numerical simulations, prototyping, and measurement with the beam. Extensive use of the pure permanent magnet technology beyond what has been done so far in the other similar projects is considered in this project.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB131

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paper received ※ 22 May 2021 paper accepted ※ 27 July 2021 issue date ※ 30 August 2021

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MOPAB140

Gas Sheet Ionization Diagnostic for High Intensity Electron Beams

diagnostics, electron, detector, operation

489

N.P. Norvell, G. Andonian, T.J. Campese, A.-L.M.S. Lamure, M. Ruelas, A.Yu. Smirnov
RadiaBeam, Santa Monica, California, USA
N.M. Cook
RadiaSoft LLC, Boulder, Colorado, USA
J.K. Penney
UCLA, Los Angeles, California, USA
C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom

Funding: Work supported by DOE grant DE-SC0019717
The characterization of high intensity charged particle beams in a minimally interceptive, and non-destructive manner is performed using an ionization diagnostic. In this application, a neutral gas is tailored into a thin sheet, or curtain-like, distribution at the interaction point with an electron beam. The electron beam ionizes the neutral gas in localized space, leaving a footprint of the beam transverse distribution. The ion cloud is subseqeuntly imaged with a series of electrostatic lenses to a detector plane. The resultant image is used in a reconstruction algorithm to reconstruct the beam profile at the interaction point. In this paper, we present progress on the development of this diagnostic for the characterization of high charge, 10GeV electron beams with small transverse distributions.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB140

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paper received ※ 20 May 2021 paper accepted ※ 10 June 2021 issue date ※ 01 September 2021

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MOPAB142

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

coupling, GUI, simulation, linac

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]

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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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MOPAB143

Simulations for MeV Energy Gain in Multi-Micron Vacuum Channel Dielectric Structures Driven by a CO₂ Laser

laser, electron, simulation, acceleration

499

G. Yadav, O. Apsimon, Y. Wei, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
O. Apsimon, C.P. Welsch, G.X. Xia
Cockcroft Institute, Warrington, Cheshire, United Kingdom
G.X. Xia
The University of Manchester, Manchester, United Kingdom

Funding: This work was supported by STFC LIV. DAT under grant agreement ST/P006752/1. This research used the resources of the Supercomputing Laboratory at KAUST in Thuwal, Saudi Arabia.
Dielectric Laser Accelerators (DLAs) have been demonstrated as a novel scheme for producing high acceleration gradients (~1 GV/m) within the damage threshold of the dielectric. The compactness of the DLAs and the low emittance of the output electron beam make it an attractive candidate for future endoscopic devices to be used in tumor irradiation. However, due to the small accelerating distances(sub-mm), the total energy gain is limited to sub-MeV which remains an obstacle for its realistic applications. Also, these DLAs operate under solid-state lasers with wavelengths near IR (800 nm to 2 um), where required sub-micron vacuum channel at such wavelengths imposes major aperture restrictions for the amount of charge to be accelerated. Here, we present numerical simulation results for a dielectric structure excited by a CO₂ laser with a wavelength of 10.6 um. Upon injecting a 50 MeV electron bunch through a 5.3 um diameter of vacuum channel width, our simulation suggests an energy gain beyond 1 MeV. These results are the initial steps for the realization of an mm-scale DLA capable of producing MeV energy electron beams.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB143

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paper received ※ 18 May 2021 paper accepted ※ 02 June 2021 issue date ※ 11 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, cyclotron, experiment, linac

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.

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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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MOPAB208

LLRF Measurements and Cu-plating at the First-of-Series Cavity Section of the Alvarez 2.0 at GSI

cavity, DTL, operation, simulation

686

M. Heilmann, T. Dettinger, X. Du, L. Groening, S. Mickat, A. Rubin
GSI, Darmstadt, Germany

The Alvarez 2.0 will replace the existing post-stripper DTL of the GSI UNILAC. Today’s GSI comprises the UNILAC and the synchrotron SIS18 and is going to serve as the injector chain for the Facility of Antiproton and Ion Research (FAIR). The new Alvarez-type DTL is operated at 10⁸.4 MHz providing acceleration from 1.4 MeV/u to 11.4 MeV/u along a total length of 55 meters. The first-of-series (FoS) cavity section has 12 RF-gaps along a total length of 1.9 m. It is the first cavity section of the new DTL. All main components were delivered in 2019, followed by successful SAT and installation of the 11 drift tubes and copper-plating. Completion of first low level RF-measurements prior to copper plating and the subsequent plating are major project milestones. These proceedings report on the results and compares them to simulation using CST Microwave Studio.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB208

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paper received ※ 18 May 2021 paper accepted ※ 31 May 2021 issue date ※ 22 August 2021

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MOPAB209

Commissioning of SANAEM RFQ Accelerator

rfq, cavity, plasma, proton

690

B. Yasatekin, A. Alacakir, A.S. Bolukdemir, I. Kilic, Y. Olgac
TENMAK-NUKEN, Ankara, Turkey
E. Cicek
KEK, Ibaraki, Japan
E. Cosgun
UNIST, Ulsan, Republic of Korea

The former SANAEM RFQ is upgraded with a newly manufactured cavity, made of oxygen-free copper (OFC), having the capability of accelerating protons from 20 keV to 1.3 MeV. In the assembling of cavity vanes, flanges, etc., indium wire is preferred over the brazing process providing a more flexible and easy method for vacuum sealing. After assembling the cavity, argon plasma cleaning is performed for the final cleaning and RF pre-conditioning. Vacuum tests revealed that levels of 2·10^-7 mbar could be achieved quite easily. RF power conditioning of the RFQ cavity is successfully completed with the observation of quite few sparks. In the commissioning tests with the proton beam, a magnetic analyzer is used to measure the energy of the particles. This paper presents the strategy and the results concerning the commissioning of the proton beam with special emphasis on the RFQ cavity.

Poster MOPAB209 [5.076 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB209

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

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MOPAB282

Development of a Multi-Camera System for Non-Invasive Intense Ion Beam Investigations

diagnostics, ion-source, solenoid, experiment

895

A. Ateş, H. Hähnel, U. Ratzinger, K. Volk, C. Wagner
IAP, Frankfurt am Main, Germany

The continued popularity of miniaturized cameras integrated into smartphones is leading to further research for more advanced CMOS camera sensors. This made CMOS technology even superior to scientific CCD cameras. Due to the lower power consumption and high flexibility, a multicamera system can be developed more effectively. At the Institute of Applied Physics at Goethe University Frankfurt (IAP) a prototype of a beam induced rest gas fluorescence monitor (BIF) was developed and tested successfully. The BIF consists of x and y single board cameras integrated into the vacuum chamber. A multi-camera system was installed in the LEBT area of the FRANZ project at the IAP within the first diagnostic chamber. This system consists of six cameras. With this equipment it is possible to investigate the beam along a 484 mm path in x and y direction. The developments on the reconstruction and image processing methods are in progress.

Poster MOPAB282 [1.139 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB282

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paper received ※ 12 May 2021 paper accepted ※ 08 June 2021 issue date ※ 24 August 2021

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MOPAB321

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

controls, laser, solenoid, linac

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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MOPAB324

High Voltage Design and Evaluation of Wien Filters for the CEBAF 200 keV Injector Upgrade

electron, high-voltage, GUI, simulation

1000

G.G. Palacios Serrano, P.A. Adderley, J.F. Benesch, D.B. Bullard, J.M. Grames, C. Hernandez-Garcia, A.S. Hofler, D. Machie, M. Poelker, M.L. Stutzman, R. Suleiman
JLab, Newport News, Virginia, USA
H. Baumgart, G.G. Palacios Serrano
ODU, Norfolk, Virginia, 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.
High-energy nuclear physics experiments at the Jefferson Lab Continuous Electron Beam Accelerator Facility (CEBAF) require highly spin-polarization electron beams, produced from strained super-lattice GaAs photocathodes, activated to negative electron affinity in a photogun operating at 130 kV dc. A pair of Wien filter spin rotators in the injector defines the orientation of the electron beam polarization at the end station target. An upgrade of the CEBAF injector to better support the upcoming MOLLER experiment requires increasing the electron beam energy to 200 keV, to reduce unwanted helicity correlated intensity and position systematics and provide precise control of the polarization orientation. Our contribution describes design, fabrication and testing of the high voltage system to upgrade the Wien spin rotator to be compatible with the 200 keV beam. This required Solidworks modeling, CST and Opera electro- and magnetostatic simulations, upgrading HV vacuum feedthroughs, and assembly techniques for improving electrode alignment. The electric and magnetic fields required by the Wien condition and the successful HV characterization under vacuum conditions are also presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB324

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paper received ※ 19 May 2021 paper accepted ※ 24 May 2021 issue date ※ 29 August 2021

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MOPAB330

Production and Performance Evaluation of a Compact Deflecting Cavity to Measure the Bunch Length in the cERL

cavity, resonance, coupling, impedance

1023

D. Naito, Y. Honda, T. Miyajima, N. Yamamoto
KEK, Ibaraki, Japan

At the KEK compact energy recovery linac, we try to generate an infrared free-electron laser (FEL). To generate the FEL, an electron bunch should be compressed along the longitudinal direction. The measurement of the bunch length is key to optimize the bunch compression. We plan to measure the bunch length by deflecting cavities in the burst mode. The deflecting cavities are required to be a time resolution of 33 fs in order to not only measure the bunch length but also resolve the structure inside the electron bunch. To achieve the requirement, we developed a c-band cavity whose RF input port is compact. The deflecting cavity is a single cell and normal conducting cavity. The deflection mode of the cavity is TM110. The 12 cavities will be located at the exit of undulators. In this presentation, we explain the design of our cavity and report the production of the first cavity. We also report the evaluation of the resonance frequency, the unloaded Q and the external Q of the cavity. From the measurements and simulations, the R/Q is estimated to be 1 mega orms. The time resolution of the cavity is expected to be 400 fs when the input RF power is 1 kW and the beam energy is 20 MeV.

Poster MOPAB330 [12.920 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB330

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paper received ※ 12 May 2021 paper accepted ※ 08 June 2021 issue date ※ 28 August 2021

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MOPAB336

Multipacting Analysis of Warm Linac RF Vacuum Windows

simulation, multipactoring, GUI, Windows

1044

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 with 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 that 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. Possible techniques for reducing and eliminating multipacting activities in these structures are discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB336

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paper received ※ 17 May 2021 paper accepted ※ 28 May 2021 issue date ※ 29 August 2021

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MOPAB340

Experimental Tests with the First Segment of ESS-Bilbao RFQ Linac

rfq, simulation, experiment, operation

1054

J.L. Muñoz, I. Bustinduy, A. Conde, N. Garmendia, P.J. González, J. Martin, A. Zugazaga
ESS Bilbao, Zamudio, Spain

The ESS-Bilbao RFQ is an assembly of four segments, each one about 800 mm in length. The first segment has been manufactured before the others, so it could be thoroughly tested in order to validate the chosen technological approach for the RFQ, as it uses polymeric vacuum gaskets and bolts instead of brazing. In this paper we report on the tests run with the segment and their results. Vacuum tests, metrology measurements, low power RF tests as well as extensive tuning tests measuring the cavity resonant quadrupolar frequency as a function of cooling water temperature have been done. Experimental results are compared to the expected values obtained from numerical simulations. We describe the experimental set-ups for the measurements and the simulations. Results are analyzed with the aim of validating the design, and also to provide predictions for tuning and operation of the whole RFQ. As a consequence of the positive results of the tests reported here, the remaining segments have already been tendered.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB340

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paper received ※ 19 May 2021 paper accepted ※ 25 May 2021 issue date ※ 20 August 2021

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MOPAB344

Machine Learning Models for Breakdown Prediction in RF Cavities for Accelerators

cavity, operation, network, linac

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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MOPAB346

Broadband Frequency Electromagnetic Characterisation of Coating Materials

GUI, experiment, electron, site

1076

A. Passarelli, C. Koral, M.R. Masullo
INFN-Napoli, Napoli, Italy
A. Andreone
Naples University Federico II, Napoli, Italy
M. De Stefano
University of Naples, Naples, Italy
V.G. Vaccaro
Naples University Federico II and INFN, Napoli, Italy

In the new generation of particle accelerators and storage rings, collective effects have to be carefully analyzed. In particular, the finite conductivity of the beam pipe walls is a major source of impedance and instabilities. A reliable electromagnetic (EM) characterisation of different coating materials is required up to hundreds of GHz due to very short bunches. We propose two different measurement techniques for an extended frequency characterization: (i) a THz time domain setup based on the signal transmission response of a tailored waveguide to infer the coating EM properties from 100 to 300 GHz or even further*.**. This technique has been tested both on NEG and amorphous Carbon films. (ii) a resonant method, based on dielectric cavities, to evaluate the surface resistance Rs of thin conducting samples at low (GHz) frequencies***. Due to its high sensitivity, Rs values can be obtained for very thin (nanometric) coatings or for copper samples with a laser treated surface, since they have an expected conductivity very close to bulk copper.
*A. Passarelli et al., Phys. Rev. Accel. Beams, v.21, p.103101, 2018
**A. Passarelli et al., Cond. Matter, v.5, p.9, 2020
***A. Andreone et al., Applied Physics Letters, v.91, n.7, p.072512, 2007

Poster MOPAB346 [2.613 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB346

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paper received ※ 18 May 2021 paper accepted ※ 09 June 2021 issue date ※ 26 August 2021

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MOPAB347

High Power Coupler Conditioning for bERLinPro Energy Recovery Linac Injector

booster, cavity, SRF, MMI

1080

A. Neumann, W. Anders, F. Göbel, A. Heugel, S. Klauke, J. Knobloch, M. Schuster, Y. Tamashevich
HZB, Berlin, Germany

Funding: The work is funded by the Helmholtz-Association, BMBF, the state of Berlin and HZB.
Helmholtz Zentrum Berlin is currently finalizing the construction of the demonstrator Energy Recovery Linac bERLinPro *. The first part, which will be commissioned, will be the injector consisting of a superconducting RF (SRF) photo-injector (Gun) and a Booster module made up of three two cell SRF cavities. For the latter the 2.3 MeV beam from the gun needs to be accelerated to 6.5 MeV, whereas one Booster cavity will be operated in zero-crossing mode for bunch-shortening. Thus, for the final stage with a 100 mA beam, the twin power couplers of the Booster cavity need to deliver up to 120 kW in travelling continous wave (CW) mode at 1.3 GHz each. To achieve that, a dedicated coupler conditioning setup was installed and commissioned. Here, we will present the first conditioning results with the bERLinPro Booster fundamental power couplers in pulsed and CW regime.
* M. Abo-Bakr et al., in Proc. 9th Int. Particle Accelerator Conf. (IPAC’18), Vancouver, BC, Canada, Apr. 4,, pp. 4127-4130, doi:10.18429/JACoW-IPAC2018-THPMF034

Poster MOPAB347 [3.256 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB347

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paper received ※ 18 May 2021 paper accepted ※ 08 June 2021 issue date ※ 14 August 2021

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MOPAB356

The ESS MEBT RF Buncher Cavities Conditioning Process

cavity, controls, MEBT, EPICS

1107

I. Bustinduy, N. Garmendia, P.J. González, A. Kaftoosian, S. Masa, I. Mazkiaran, L.C. Medina, J.L. Muñoz
ESS Bilbao, Zamudio, Spain
J. Etxeberria, J.P.S. Martins
ESS, Lund, Sweden

Funding: This work is part of FEDER-TRACKS project, co-funded by the European Regional Development Fund (ERDF) .
As part of the 5 MW European Spallation Source (ESS), the Medium Energy Beam Transport (MEBT) was designed, assembled, and installed in the tunnel since May 2020 by ESS-Bilbao. This section of the accelerator is located between the Radio Frequency Quadrupole (RFQ) and the Drift Tube Linac (DTL). The main purpose of the MEBT is to match the incoming beam from the RFQ both transversely and longitudinally into the DTL. The longitudinal matching is achieved by three 352.209 MHz RF buncher cavities. In this paper, we focus on the RF conditioning process for each set of power coupler and buncher cavity. For this purpose, different tools were developed on EPICS and Python as well as electronics hardware such as Fast Interlock Module (FIM) and timing system. These tools served to automatize both the cavity frequency tuning and the power ramp-up process and will be described in detail in the following sections.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB356

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paper received ※ 18 May 2021 paper accepted ※ 09 June 2021 issue date ※ 25 August 2021

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MOPAB359

Operational Experience and Redesign of the Tuner without Spring Fingers for the LEReC Warm Cavity

cavity, operation, SRF, electron

1116

B.P. Xiao, J.M. Brennan, J.C. Brutus, K. Mernick, S. Polizzo, S.K. Seberg, F. Severino, K.S. Smith, A. Zaltsman
BNL, Upton, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
A folded coaxial tuner without spring fingers was designed for the Low Energy RHIC electron Cooler (LEReC) 2.1 GHz warm cavity. During RHIC run 2019, this tuner was found to cause cavity trips via different failure modes. After analyzing these failure modes, a new straight coaxial tuner without spring fingers was proposed and was installed. We show the operational experience of the new tuner in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB359

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paper received ※ 17 May 2021 paper accepted ※ 25 June 2021 issue date ※ 29 August 2021

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MOPAB360

Anomalous Skin Effect Study of Normal Conducting Film

impedance, plasma, ECR, interface

1119

B.P. Xiao, M. Blaskiewicz, T. Xin
BNL, Upton, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
For the radiofrequency (RF) applications of normal conducting film with large mean free path at high frequency and low temperature, the anomalous skin effect differs considerably from the normal skin effect with field decaying exponentially in the film. Starting from the relationship between the current and the electric field (E field) in the film, the amplitude of E field along the film depth is calculated, and is found to be non-monotonic. The surface impedance is found to have a minimum value at certain film thickness.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB360

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paper received ※ 17 May 2021 paper accepted ※ 25 June 2021 issue date ※ 17 August 2021

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MOPAB365

Construction and First Test Results of the Barrier and Harmonic RF Systems for the NICA Collider

cavity, collider, injection, electron

1136

A.G. Tribendis, Y.A. Biryuchevsky, K.N. Chernov, A.N. Dranitchnikov, E. Kenzhebulatov, A.A. Kondakov, A.A. Krasnov, Ya.G. Kruchkov, S.A. Krutikhin, G.Y. Kurkin, A.M. Malyshev, A.Yu. Martynovsky, N.V. Mityanina, S.V. Motygin, A.A. Murasev, V.N. Osipov, V.M. Petrov, E. Pyata, E. Rotov, V.V. Tarnetsky, I.A. Zapryagaev, A.A. Zhukov
BINP SB RAS, Novosibirsk, Russia
O.I. Brovko, A.M. Malyshev, I.N. Meshkov, E. Syresin
JINR, Dubna, Moscow Region, Russia
I.N. Meshkov
Saint Petersburg State University, Saint Petersburg, Russia
E. Rotov
NSU, Novosibirsk, Russia
A.G. Tribendis
NSTU, Novosibirsk, Russia
A.V. Zinkevich
Triada-TV, Novosibirsk, Russia

This paper reports on the design features and construction progress of the three RF systems for the NICA collider being built at JINR, Dubna. Each of the two collider rings has three RF systems named RF1 to 3. RF1 is a barrier bucket system used for particles capturing and accumulation during injection, RF2 and 3 are resonant systems operating at 22nd and 66th harmonics of the revolution frequency and used for the 22 bunches formation. The RF systems are designed and produced by Budker INP. Solid state RF power amplifiers developed by the Triada-TV company, Novosibirsk, are used for driving the RF2 and three cavities. Two RF1 stations were already delivered to JINR, the prototypes of the RF2 and 3 stations were built and successfully tested at BINP. Series production of all eight RF2 and sixteen RF3 stations is in progress. The design modifications and test results are presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB365

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paper received ※ 18 May 2021 paper accepted ※ 24 May 2021 issue date ※ 14 August 2021

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MOPAB370

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

GUI, simulation, ECR, linac

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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MOPAB371

A Coupon Tester for Normal Conducting High-Gradient Materials

cavity, coupling, RF-structure, klystron

1147

J.W. Lewellen, D. Gorelov, D. Perez, E.I. Simakov
LANL, Los Alamos, New Mexico, USA
M.E. Schneider
Michigan State University, East Lansing, Michigan, USA

Funding: Los Alamos National Laboratory LDRD Program
A coupon tester is an RF structure used to subject a material sample to very high RF fields, with the fields on the sample, or coupon, being higher than elsewhere in the cavity. To date, most such cavities were originally intended to explore the RF properties of superconducting materials, and can expose the sample to strong magnetic fields, but weak to no electric fields. As part of a program to develop materials and structures for high-gradient (> 100 MV/m), low-breakdown-rate normal-conducting accelerators, we have designed a C-band (5.712 GHz) cavity intended to subject samples to both magnetic and electric fields comparable to those experienced in high-gradient structure designs, using a TM-mode cavity; the electric and magnetic fields along the sample coupon can be directly compared to the fields on the iris of high-gradient structures. This poster will present the design criteria for our coupon tester cavity, nominal operating parameters, and our structure concept. The cavity design will be refined over the next several months, and will be constructed and in service near the start of 2022.

Poster MOPAB371 [0.764 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB371

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paper received ※ 17 May 2021 paper accepted ※ 26 May 2021 issue date ※ 30 August 2021

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MOPAB388

Status of the High Power Couplers for ESS Elliptical Cavities

cavity, cryomodule, simulation, SRF

1186

C. Arcambal, P. Bosland, G. Devanz, T. Hamelin, C. Madec, C. Marchand, M. Oublaid, G. Perreu, C. Servouin, C. Simon
CEA-IRFU, Gif-sur-Yvette, France
M. Baudrier, C. Mayri, S. Regnaud, T.V. Vacher
CEA-DRF-IRFU, France

In the framework of the European Spallation Source (ESS), CEA Paris-Saclay is responsible for the delivery of 30 cryomodules (9 medium beta (β = 0.67) and 21 high beta (β = 0.86) ones). Each cryomodule contains 4 elliptical cavities equipped with a radio frequency power coupler. The ESS nominal pulse is 1.1 MW maximum peak power over a width of 3.6 ms at a repetition rate of 14 Hz. The design of the couplers for medium beta and for high beta cavities is the same, except a small difference of the antenna penetration to adjust the Q_ext. The mass production of the 120 couplers started and all the medium beta couplers have been conditioned at room temperature. The first cryomodules equipped with the power couplers were successfully tested at high RF power and with cavities at 2K reaching the ESS nominal pulse. The main issue at the start of the series production could be fixed and it was due to bad TiN coatings that caused abnormal dielectric losses in the window. Thus, this paper deals with the TiN coating defect, presents the conditioning procedure and gives a conditioning report of these 36 couplers.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB388

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paper received ※ 19 May 2021 paper accepted ※ 24 May 2021 issue date ※ 18 August 2021

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MOPAB401

In-Situ EXAFS Investigations of Nb-Treatments in N₂, O₂ and N₂-O₂ Mixtures at Elevated Temperatures

site, experiment, niobium, cavity

1214

P. Rothweiler, B. Bornmann, J. Klaes, D. Lützenkirchen-Hecht, R. Wagner
University of Wuppertal, Wuppertal, Germany

Funding: We gratefully acknowledge financial support by the German Federal Ministry of Education and Research (BMBF) under project No. 05H18PXRB1.
Smooth polycrystalline Nb metal foils were treated in dilute gas atmospheres using a temperature of 900 °C. Transmission mode X-ray absorption spectroscopy (EX-AFS) at the Nb K-edge was used to investigate changes in the atomic short-range order structure of the bulk Nb-material in-situ. The experiments were performed in a dedicated high-vacuum cell that allows treatments in a dilute gas atmosphere and temperatures of up to 1200 °C. Typical treatments include (i) pre-heating at 900 °C under high-vacuum, (ii) gas exposure at the desired pressure and temperature, and (iii) cooldown to room temperature under vacuum. EXAFS data were collected during the entire procedure with a time resolution of 1 s. For the treatments in N₂ at T = 900°C, the data show subtle changes in the Nb-EXAFS, that are compatible with N-doping of the bulk Nb, and the results suggest Nb uptake on octahedral interstitial sites. However, even a small O2-partial pressure leads to distinct oxidation of the Nb. The results will be discussed in more detail in the presentation.

Poster MOPAB401 [2.032 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB401

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

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MOPAB419

Acceleration and Measurement of Alpha Particles and Hydrogen Molecular Ions with the HZB Cyclotron

cyclotron, radiation, proton, scattering

1264

G. Kourkafas, J. Bundesmann, A. Denker, T. Fanselow, J. Röhrich
HZB, Berlin, Germany
J. Heufelder, A. Weber
Charite, Berlin, Germany

The HZB cyclotron has treated more than 4000 patients with eye tumors using protons. The accelerator can also provide heavier ions which could be suitable for ocular radiation therapy. Helium ions exhibit less lateral spread, increased relative biological effectiveness and a sharper Bragg-Peak compared to protons of the same range, while minimizing nuclear fragmentation and thus excessive dose downstream the irradiated volume compared to more heavy ions. When accelerating fully stripped helium ions (alpha particles), hydrogen molecular ions can also be accelerated to the same energy with a small tuning of the machine due to having almost the same mass-to-charge ratio, yielding a proton beam of double current after the beam exits the vacuum window towards the target. The acceleration and characterization of these two ion species are described in this paper, suggesting the feasibility of a corresponding clinical cyclotron for ocular or even deep-seated tumors.

Poster MOPAB419 [0.806 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB419

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paper received ※ 19 May 2021 paper accepted ※ 09 June 2021 issue date ※ 13 August 2021

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TUPAB031

Construction and Installation of the New CERN Proton Synchrotron Internal Beam Dumps

MMI, shielding, interface, proton

1409

K.G. Andersen, M. Calviani, A. Cherif, T. Coiffet, A. De Macedo, S. Devidal, J.-M. Geisser, S.S. Gilardoni, M.M.J. Gillet, E. Grenier-Boley, J.M. Heredia, A. Majbour, F. Monnet, M.R. Monteserin, F.-X. Nuiry, D. Pugnat, G. Romagnoli, Y.D.R. Seraphin, J.A.F. Somoza, N. Thaus
CERN, Geneva 23, Switzerland

In the framework of the CERN Large Hadron Collider Injectors Upgrade (LIU) Project, the Proton Synchrotron (PS) has been equipped with two new movable Internal Dumps (PSID), each of them capable of absorbing particle beams of an energy of up to 100 kJ. These dumps replace the old Internal Dumps, which have been operated in the accelerator complex since their installation in 1975 until their decommissioning and removal from the machine during the second LHC Long Shut down (LS2). This contribution will address the construction and testing phases of the new PSIDs, including the assembly of the dump core, its actuation system and the respective shielding, mechanical running-in tests, metrology adjustments, Ultra-High Vacuum (UHV) and impedance acceptance tests. The described installation work was completed successfully, and the new generation Dumps are currently operational in the PS machine.

Poster TUPAB031 [3.146 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB031

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paper received ※ 18 May 2021 paper accepted ※ 27 May 2021 issue date ※ 26 August 2021

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TUPAB065

Solaris Storage Ring Performance After 6 Years of Operation

storage-ring, operation, MMI, synchrotron

1515

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

Solaris is a third generation light source operating since 2015 in Kraków, Poland. Between 2015 and 2018 the synchrotron as well as two beamlines were commissioned. During commissioning phases, the good performance of Solaris storage ring has been reached. The beam optics was brought close to the design one. Since October 2018 Solaris storage ring is in the user operation mode. Moreover, two other beamlines with the elliptically polarized undulators used as source were installed and are under commissioning now. In 2020 the total beam availability of 93% was reached with the average circulating current of 400 mA and the total lifetime of 15 h. Over last two years few improvements of the storage ring were done to optimize the storage ring performance. The Landau cavities were tuned to improve the Touschek lifetime and suppress the instabilities. Two diagnostics beamlines were installed and commissioned allowing for the beam sizes in three planes and emittance measurements. The storage ring optics was fine-tuned to increase the dynamic aperture.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB065

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paper received ※ 19 May 2021 paper accepted ※ 26 May 2021 issue date ※ 16 August 2021

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TUPAB102

A New 2nd Bunch Compression Chicane for the FLASH2020+ Project

quadrupole, dipole, focusing, FEL

1618

M. Vogt, J. Zemella
DESY, Hamburg, Germany

The first stage of the FLASH2020+ project is an upgrade of the FLASH injector beamline. Within this framework, the 2nd bunch compression chicane (BCC) will be completely redesigned. The old S-chicane will be replaced with a new C-chicane which is 3.5m shorter thereby generating space a new section for re-matching the beam from the injector into the linac. The new BCC will be equipped with quad/skew-quad units in both legs of the chicane to compensate correlations of the transverse degrees of freedom with the longitudinal ones. Since quadrupoles tend to have a circular bore, the chicane is designed with movable round vacuum chambers and movable dipoles for maintaining full flexibility in choosing the compression parameters. This article describes the technical details and introduces a thin-lens model of BCCs which allows analytical estimates on the effects of powering the quad/skew-quad units on optics parameters as well as estimates on the required strengths of these magnets in order to remove correlations of the magnitudes typically observed at FLASH.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB102

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paper received ※ 19 May 2021 paper accepted ※ 14 June 2021 issue date ※ 29 August 2021

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TUPAB122

SASE3 Variable Polarization Project at the European XFEL

undulator, polarization, FEL, electron

1678

S.K. Karabekyan, S. Abeghyan, M. Bagha-Shanjani, S. Casalbuoni, U. Englisch, G. Geloni, J. Grünert, S. Hauf, C. Holz, D. La Civita, J. Laksman, D. Mamchyk, M.P. Planas, F. Preisskorn, S. Serkez, H. Sinn, A. Violante, G. Wellenreuther, M. Wuenschel, M. Yakopov, C. Youngman
EuXFEL, Schenefeld, Germany
A. Block, W. Decking, N. Golubeva, K. Knebel, T. Ladwig, D.L. Lenz, D. Lipka, R. Mattusch, N. Mildner, E. Negodin, D. Nölle, J. Prenting, F. Saretzki, M. Schlösser, F. Schmidt-Föhre, E. Schneidmiller, D. Thoden, T. Wamsat, S. Wendt, T. Wilksen, T. Wohlenberg, M.V. Yurkov
DESY, Hamburg, Germany
M. Brügger, M. Calvi, S. Danner, R. Ganter, L. Huber, A. Keller, M.S. Schmidt, T. Schmidt
PSI, Villigen PSI, Switzerland
D.E. Kim
PAL, Pohang, Republic of Korea
Y. Li
IHEP, People’s Republic of China

At the European XFEL, two undulator systems for hard and one for soft X-rays have been successfully put into operation. The SASE3 soft X-ray undulator system generates linearly polarized radiation in the horizontal plane. One of the requirements for extending the radiation characteristics is the ability to obtain different polarization modes. These include both right and left circular, elliptical polarization, or linear polarization at an arbitrary angle. For this purpose, a system consisting of four APPLE X helical undulators developed at the Paul Scherrer Institute (PSI) is used. This paper presents the design parameters of the SASE3 undulator system after modifying it with the helical afterburner. It also describes the methods and the design solutions different from those used at PSI. The status and schedule of the project are introduced.

Poster TUPAB122 [0.553 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB122

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paper received ※ 19 May 2021 paper accepted ※ 31 May 2021 issue date ※ 27 August 2021

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TUPAB133

Brazing free RF Pulse Compressor for High Gradient Accelerators

GUI, cavity, coupling, simulation

1700

L. Kankadze, D. Alesini, F. Cardelli, G. Di Raddo, M. Diomede
INFN/LNF, Frascati, Italy

EURPRAXIA@SPARC\_LAB, is a proposal to upgrade the SPARC\_LAB test facility (at LNF, Frascati) to a soft X-ray user facility based on plasma acceleration and high-gradient X-band (11.9942 GHz) accelerating modules. Each module is made up of a group of 4 TW sections assembled on a single girder and fed by one klystron by means of one rf pulse compressor system and a low attenuation circular waveguide network that transports the rf power to the input hybrids of the sections. The pulse compressor is based on a single Barrel Open Cavity (BOC). The BOC use a ’whispering gallery’ mode which has an intrinsically high quality factor and operates in a resonant rotating wave regime. Compared to the conventional SLED scheme it requires a single cavity instead of two cavities and a 3-dB hybrid. A new brazeless mechanical design has been proposed and is described in the present paper together with the electro-magnetic and thermo-mechanical simulations.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB133

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paper received ※ 21 May 2021 paper accepted ※ 15 June 2021 issue date ※ 10 August 2021

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TUPAB201

Vacuum Tube Operation Tuning for a High Intensity Beam Acceleration in J-PARC RCS

acceleration, operation, electron, controls

1884

M. Yamamoto, M. Nomura, H. Okita, T. Shimada, F. Tamura
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
M. Furusawa, K. Hara, K. Hasegawa, C. Ohmori, Y. Sugiyama, M. Yoshii
KEK, Tokai, Ibaraki, Japan

Tetrode vacuum tubes in the J-PARC RCS are used under a reduced filament voltage condition compared with the rating value to prolong the tube life time. One tube reached the end of life in 2020; it was the first case in the RCS after 60,000 hours operation time. This means the reduced filament voltage works well because the tube has been running beyond an expected life time suggested by the tube manufacturer. However, an electron emission from the filament is decreased by the reduced filament voltage. Although the large amplitude of the anode current is necessary for the high intensity beam acceleration to compensate an wake voltage, a solid-state amplifier to drive a control grid circuit almost reaches the output power limit because of the poor electron emission. We changed the filament voltage reduction rate from 15 % to 5 %; the required power of the solid-state amplifier was fairly reduced, whereas the accelerated beam power was same. We will describe the measurement results of the vacuum tube parameters in terms of the filament voltage tuning.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB201

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paper received ※ 17 May 2021 paper accepted ※ 17 June 2021 issue date ※ 02 September 2021

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TUPAB244

THE WAKEFIELD STUDY OF THE RF-SHIELDED BELLOWS AT THE ILSF STORAGE RING

impedance, wakefield, factory, simulation

2015

N. Khosravi, E. Ahmadi, M. Akhyani
ILSF, Tehran, Iran
M. Akhyani
EPFL, Lausanne, Switzerland
A. Khosravi
LAPRI, Tehran, Iran

The corrugated geometry of the bellows made it critical to be shielded with an RF-Shield. Different types of RF shields can be applied to the ILSF vacuum chamber to cover this component’s destructive impedance peaks. Then, the Impedance study and optimization of the RF shields can improve the impedance budget. In this article, two common types of RF shields are simulated in CST software.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB244

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paper received ※ 16 May 2021 paper accepted ※ 02 June 2021 issue date ※ 14 August 2021

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TUPAB260

A Beam Screen to Prepare the RHIC Vacuum Chamber for EIC Hadron Beams: Conceptual Design and Requirements

electron, hadron, dipole, collider

2066

S. Verdú-Andrés, M. Blaskiewicz, J.M. Brennan, X. Gu, R.C. Gupta, A. Hershcovitch, M. Mapes, G.T. McIntyre, J.F. Muratore, S.K. Nayak, S. Peggs, V. Ptitsyn, R. Than, J.E. Tuozzolo, D. Weiss
BNL, Upton, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
The Electon Ion Collider (EIC) hadron ring will use the existing Relativistic Heavy Ion Collider storage rings, including the superconducting magnet arcs. The vacuum chambers in the superconducting magnets and the cold mass interconnects were not designed for EIC beams and so must be updated to reduce its resistive-wall heating and to suppress electron clouds. To do so without compromising the EIC luminosity goal, a stainless steel beam screen with co-laminated copper and a thin layer of amorphous carbon will be installed. This paper describes the main requirements that our solution for the hadron ring vacuum chamber needs to satisfy, including impedance, aperture limitations, vacuum, thermal and structural stability, mechanical design, installation and operation. The conceptual design of the beam screen currently under development is introduced.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB260

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paper received ※ 19 May 2021 paper accepted ※ 25 August 2021 issue date ※ 12 August 2021

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TUPAB270

Thermal Transition Design and Beam Heat-load Estimation for the COLDDIAG Refurbishment

operation, cryogenics, diagnostics, simulation

2097

H.J. Cha, N. Glamann, A.W. Grau, A.-S. Müller, D. Saez de Jauregui
KIT, Eggenstein-Leopoldshafen, Germany

Funding: This work is supported by the BMBF project 05H18VKRB1 HIRING (Federal Ministry of Education and Research).
The COLDDIAG (cold vacuum chamber for beam heat load diagnostics) developed at Karlsruhe Institute of Technology has been modified for more studies at cryogenic temperatures different from the previous operations at 4 K in a cold bore and at 50 K in a thermal shield. The key components in this campaign are two thermal transitions connecting both ends of the bore at 50 K with the shield at the same or higher temperature. In this paper, we present design efforts for the compact transitions, allowed heat intakes to the cooling power margin and mechanical robustness in the cryogenic environment. A manufacture scheme for the transition and its peripheral is also given. In addition, the beam heat loads in the refurbished COLDDIAG are estimated in terms of the accelerator beam parameters.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB270

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paper received ※ 12 May 2021 paper accepted ※ 02 June 2021 issue date ※ 12 August 2021

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TUPAB281

Gas-Mixing to Improve the Resolution of Non-Invasive Gas Jet-Based Ionization Profile Monitors

injection, electron, simulation, background

2132

N. Kumar, A. Salehilashkajani, C.P. Welsch, H.D. Zhang
Cockcroft Institute, Warrington, Cheshire, United Kingdom
N. Kumar, A. Salehilashkajani, C.P. Welsch, H.D. Zhang
The University of Liverpool, Liverpool, United Kingdom

Funding: This work is supported by the HL-LHC-UK project funded by STFC and CERN and the STFC Cockcroft core grant No. ST/G008248/1.
Ionization beam profile monitor using a supersonic gas jet is an attractive option for the characterization of low and medium energy beams. In this scheme, a primary beam crosses a 45-degree tilted thin gas curtain which causes ionization of gas molecules in the jet. The generated ions are then collected using an electrostatic extraction system to determine the 2D transverse profile of the primary beam. The most commonly used gases for the jet are neon and nitrogen. The signal from the gas jet is always super-imposed with the signal resulting from residual gases in the interaction chamber. CST simulations indicate that the gas jet speed is a key factor for the separation of the jet and the residual gas signals. To obtain a good signal separation, one can increase the velocity of the gas jet. This can be accomplished by generating a gas jet that mixes heavier and lighter gases. This contribution gives a general overview of the monitor design, discusses the effects of gas mixing and CST simulation results. It also presents experimental results obtained with Helium, and Nitrogen, as well as a mixture of them using different percentages and the impact on measurement resolution.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB281

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paper received ※ 19 May 2021 paper accepted ※ 02 June 2021 issue date ※ 13 August 2021

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TUPAB308

Mechanical Consolidation of the LHC Inner Triplet Magnet Supporting System for Remote Alignment

alignment, GUI, quadrupole, ECR

2207

F. Micolon, N. Bourcey, J-B. Deschamps, A. Herty, S. Le Naour, T. Mikkola, V. Parma, D. Ramos, V. Rude, M. Sosin
CERN, Meyrin, Switzerland

Given the high radiation area and the tight alignment tolerances, the LHC inner triplet magnets were designed to be realigned remotely using motorized supporting jacks. However, during run 2 the LHC triplet realignment system started to show an unexpected behavior with erratic load variations on the magnet supporting jacks when operated. It was then decided to freeze any further realignment of the LHC triplet magnet for the remainder of the run. Subsequently, a project team was set up at CERN to understand better the conditions leading to such unexpected behavior and to study and propose a technical consolidation for the realignment system of the LHC triplet magnet. A fully instrumented magnet string using LHC triplet spare magnets was assembled and used at CERN to provide a realistic test bench for this study. This paper reports on the work undertaken to study the triplet magnet overall realignment kinematic, the findings on the readjustment system malfunction and details the consolidation solution implemented for the next LHC run

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB308

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paper received ※ 18 May 2021 paper accepted ※ 07 June 2021 issue date ※ 18 August 2021

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TUPAB318

The Beamline Safety Interlock System of Taiwan Photon Source

radiation, photon, controls, synchrotron-radiation

2239

C.F. Chang, C.Y. Chang, C.Y. Liu, H.Y. Yan
NSRRC, Hsinchu, Taiwan

The energy of synchrotron radiation generated by bremsstrahlung radiation and magnet is rather high, which may cause serious radiation damage to human body or even imperil people’s life. The beamline therefore must be equipped with radiation-protection system; in addition, the overheat of optical components exposed to synchrotron radiation will lead to the damage of optical components and devices. In consequence, the beamline should be furnished with the cooling-protection system to cool down optical components and devices. The Beamline Safety Interlock System targets at protecting the personnel and the safety of devices, limiting the radiation dose to a security value for experimental personnel or staffs exposing to radiation on the site as well as preventing beamline components from being exposed to overheat or vacuum damages to improve the effectiveness of beamline.

Poster TUPAB318 [3.440 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB318

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paper received ※ 09 May 2021 paper accepted ※ 10 June 2021 issue date ※ 31 August 2021

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TUPAB339

High Power Test of the Antenna Adjustable Power Coupler for 325 MHz Superconducting Cavities

cavity, multipactoring, electron, pick-up

2286

J.Y. Yoon, E.-S. Kim, C.S. Park, S.H. Park
KUS, Sejong, Republic of Korea
J. Bahng
Korea University Sejong Campus, Sejong, Republic of Korea
E. Kako
KEK, Ibaraki, Japan
K.R. Kim
PAL, Pohang, Republic of Korea

Funding: The Ministry of Education (South Korea)
The power coupler is development at Korea University for a Single Spoke Resonator (SSR) of heavy ion accelerator. Our power coupler is a coaxial capacitive type based on a conventional 3-1/8 inch electronic industries alliance (EIA) 50 Ω coaxial transmission line with a titanium nitride (TiN) coated single ceramic window. A high power test is rectangular test cavity with high vacuum and various measuring equipment, such as an arc detector, a power meter, and an electron pick-up probe. The interlock system under vacuum and arc instrumentations prevent the RF window from breaking the power coupler window during the high power test. We conduct high power tests for more than 12 hrs at 12 kW in a 325 MHz continous wave (CW) mode to verify the performance of the designed power coupler.
*Superconducting, *Power Coupler

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB339

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paper received ※ 12 May 2021 paper accepted ※ 21 June 2021 issue date ※ 24 August 2021

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TUPAB359

Magnetic Field Measurement and Beam Performance Test of Ceramics Chamber with Integrated Pulsed Magnet at KEK-PF

experiment, survey, kicker, dipole

2352

Y. Lu
Sokendai, Ibaraki, Japan
K. Harada, Y. Kobayashi, C. Mitsuda, S. Nagahashi, T. Nogami, T. Obina, R. Takai, H. Takaki, T. Uchiyama, A. Ueda
KEK, Ibaraki, Japan

An air-core magnet named Ceramics Chamber with integrated Pulsed Magnet(CCiPM) is being developed at the photon factory of KEK(KEK-PF), which will have several applications for the future light source. One prototype has been developed as a dipole kicker, whose bore is only 30mm. Due to the type and structure, it’s expected to have strong magnetic field and high repetition rate. After finishing the offline measurement of magnetic field and evaluation of vacuum tightness, the CCiPM was installed in the beam transport-dump line of PF to have an online beam performance and durability test. The results of the magnetic field measurement and beam performance test will be reviewed.

Poster TUPAB359 [1.164 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB359

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paper received ※ 19 May 2021 paper accepted ※ 02 June 2021 issue date ※ 16 August 2021

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TUPAB365

Demonstration of ‘ZEPTO’ Permanent Magnet Technology on Diamond Light Source

quadrupole, permanent-magnet, lattice, radiation

2370

A.R. Bainbridge, B.J.A. Shepherd
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
N. Krumpa
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
I.P.S. Martin, W. Tizzano
DLS, Oxfordshire, United Kingdom

The use of permanent magnets (PM’s) in place of traditional electromagnets is becoming more common in accelerator systems around the world. This change is being driven by the desire to reduce both the energy costs and carbon footprint of accelerators. However, the problem remains that it is difficult to adjust the field strength of PM systems. STFC and CERN have a longstanding collaboration in the Zero-Power Tuneable Optics (ZEPTO) project which aims to develop PM systems that are tuneable via moving the PM blocks within a static pole structure. This collaboration has previously produced 3 prototype magnets (2 quadrupoles and 1 dipole) for the proposed CLIC accelerator and aims to expand suitability to a variety of accelerators. We are now demonstrating this technology on a real machine by installing a ZEPTO magnet on Diamond Light Source. We outline the design, construction, and improvement of this technology demonstrator, highlighting the innovations over previous generations of ZEPTO technology that account for previously observed drawbacks.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB365

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paper received ※ 18 May 2021 paper accepted ※ 22 June 2021 issue date ※ 12 August 2021

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TUPAB381

Thermal Analysis of the RHIC Arc Dipole Magnet Cold Mass with the EIC Beam Screen

dipole, electron, hadron, cryogenics

2413

S.K. Nayak, M. Anerella, M. Blaskiewicz, J.M. Brennan, R.C. Gupta, M. Mapes, G.T. McIntyre, S. Peggs, R. Than, J.E. Tuozzolo, S. Verdú-Andrés, D. Weiss
BNL, Upton, New York, USA

Funding: Funding agency Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
The EIC will make use of the existing RHIC storage rings with their superconducting (SC) magnet arcs. A stainless-steel beam screen with co-laminated copper and a thin amorphous carbon (aC) film on the inner surface will be installed in the beam pipe of the SC magnets. The copper will reduce the beam-induced resistive-wall (RW) heating from operation with the higher intensity EIC beams, that if not addressed would make the magnets quench. Limiting the RW heating is also important to achieve an adequately low vacuum level. The aC coating will reduce secondary electron yield which could also cause heating and limit intensity. Among all the RHIC SC magnets, the arc dipoles present the biggest challenge to the design and installation of beam screens. The arc dipoles, which make up for 78% (2.5 km) length of all SC magnets in RHIC, expect the largest RW heating due to their smallest aperture. These magnets are also the longest (9.45 m each), thus experiencing the largest temperature rise over their length, and have a large sagitta (48.5 mm) that increases the difficulty to install the beam screen in place. This paper presents a detailed thermal analysis of the magnet-screen system.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB381

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paper received ※ 19 May 2021 paper accepted ※ 20 July 2021 issue date ※ 23 August 2021

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TUPAB391

Cryopanels in the Room Temperature Heavy Ion Synchrotron SIS18

simulation, cryogenics, quadrupole, heavy-ion

2435

S. Aumüller, L.H.J. Bozyk, P.J. Spiller
GSI, Darmstadt, Germany
K. Blaum
MPI-K, Heidelberg, Germany

The FAIR complex at the GSI Helmholtzzentrum will generate heavy ion beams of ultimate intensities. To achieve this goal, medium charge states have to be used. However, the probability for charge exchange in collisions with residual gas particles of such ions is much higher than for higher charge states. In order to lower the residual gas density to extreme high vacuum conditions, 65% of the circumference of SIS18 are already coated with NEG, which provides high and distributed pumping speed. Nevertheless, nobel and nobel-like components, which have very high ionization cross sections, do not get pumped by this coating. A cryogenic environment at moderate temperatures, i.e. at 50-80K, provides high pumping speed for all heavy residual gas particles. The only typical residual gas species, that cannot be pumped at this temperature is hydrogen. With an additional NEG coating the pumping will be optimized for all residual gas particles. The installation of cryogenic surfaces in the existing room temperature synchrotron SIS18 at GSI has been investigated. A prototype quadrupole chamber with cryogenic surfaces, first measurements, and simulations of the adapted accelerator are presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB391

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paper received ※ 19 May 2021 paper accepted ※ 31 August 2021 issue date ※ 25 August 2021

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TUPAB392

Conceptual Design of the Vacuum System for the Future Circular Collider FCC-ee Main Rings

photon, collider, quadrupole, scattering

2438

R. Kersevan, C. Garion
CERN, Geneva, Switzerland

The Future Circular Collider study program comprises several machine concepts for the future of high-energy particle physics. Among them there is a twin-ring e⁻e⁺ collider capable to run at beam energies between 45.6 and 182.5 GeV, i.e. the energies corresponding to the resonances of the Z, W, H bosons and the top quark. The conceptual design of the two 100-km rings has advanced to what is believed to be a working solution, i.e. capability to deal with low-energy (45.6 GeV) high-current (1390 mA) version as well as the high-energy (182.5 GeV) low-current (5.4 mA) one, with intermediate energy and current steps for the other 2 resonances. The limit for all of the versions is given by the 50 MW/beam allotted to the synchrotron radiation (SR) losses. The paper will outline the main beam/machine parameters, the vacuum requirements, and the choices made concerning the vacuum chamber geometry, material, surface treatments, pumping system, and the related pressure profiles. The location of lumped SR photon absorbers for the generic arc cell has been determined. An outline of the studies needed and envisaged for the near future will also be given.

Poster TUPAB392 [3.036 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB392

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paper received ※ 19 May 2021 paper accepted ※ 31 May 2021 issue date ※ 25 August 2021

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TUPAB393

Study of Remote Helium Mass Spectrometer Leak Detection in Accelerator

gun, detector, operation, controls

2441

H.Y. He, D.H. Zhu
IHEP CSNS, Guangdong Province, People’s Republic of China
J.M. Liu
DNSC, Dongguan, People’s Republic of China

In order to solve the problem that the vacuum system of the accelerator can’t be close to the operation for a long time, a long-distance helium mass spectrometer leak detection system is explored by studying the structure of the conventional round tube vacuum box of the vacuum system, which integrates the online vacuum leak detection, defect diagnosis and process design, improves the digital operation, realizes the accurate and effective detection of the leak location range and leak rate, and provides the technology for the remote leak detection of the vacuum system. Support.

Poster TUPAB393 [0.666 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB393

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paper received ※ 13 May 2021 paper accepted ※ 31 May 2021 issue date ※ 10 August 2021

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TUPAB395

Vacuum System Models for Minerva Linac Design

linac, 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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TUPAB396

The Thermal Outgassing Rate of Materials Used in Vacuum Systems

experiment, diagnostics, cathode, radiation

2447

A.M. Semenov
BINP & NSTU, Novosibirsk, Russia
A. Burdakov, A.A. Krasnov, B.P. Tolochko, A.V. Varand
BINP SB RAS, Novosibirsk, Russia
S.R. Ivanova
GPI, Moscow, Russia
A.A. Krasnov
NSU, Novosibirsk, Russia
M.A. Mikhailenko
ISSCM SB RAS, Novosibirsk, Russia
A.A. Shoshin
Budker INP & NSU, Novosibirsk, Russia

There are many rarely used materials in vacuum systems that are poorly investigated in terms of vacuum properties. For example, phosphors, scintillating materials, ferrites, various adhesives, etc. In addition, new organic materials are being developed with mechanical properties similar to those of conventional steel. The use of such materials is very promising in vacuum technology. This article presents the thermal degassing performance of several rarely used materials and promising materials for vacuum applications.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB396

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paper received ※ 18 May 2021 paper accepted ※ 31 August 2021 issue date ※ 20 August 2021

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TUPAB398

Vacuum Issues with Argon Gas in the LANSCE Accelerator

neutron, linac, 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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TUPAB400

Manufacturing of Ceramic Vacuum Chambers for Sirius On-Axis Kicker

kicker, HOM, niobium, target

2457

R. Defavari, O.R. Bagnato, M.W.A. Feitosa, F.R. Francisco, D.Y. Kakizaki, R.L. Parise, R.D. Ribeiro
LNLS, Campinas, Brazil

Ceramic vacuum chambers were produced by LNLS for the Sirius kickers. Alumina tubes with an elliptical inner shape of 9.5 mm (V) x 29 mm (H) and 500 mm long were successfully manufactured by a Brazilian company. Metallic F136 titanium flanges were brazed to Nb inserts using Ag-58.5Cu-31.5Pd wt% alloy, these inserts were brazed to the ceramic using Ag-26.7Cu-4.5Ti wt% active filler metal. A titanium film was coated inside the chamber using argon plasma by RF Magnetron Sputtering technique. Samples have been investigated by Scanning Electron Microscopy (SEM) to measure film thickness along the inner section of the tube, coating morphology, chemical composition and homogeneity. The total electrical resistance of the tube was also monitored during the sputtering process to achieve the desired value (0.2 ohms/square). In this contribution, we present the results of an On-Axis kicker manufacturing process developed by LNLS.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB400

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paper received ※ 18 May 2021 paper accepted ※ 31 May 2021 issue date ※ 29 August 2021

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TUPAB401

Mechanical Design, Fabrication and Characterization of Electron Beam Position Monitors for Sirius

pick-up, operation, impedance, storage-ring

2461

R. Defavari, O.R. Bagnato, M.W.A. Feitosa, F.R. Francisco, G.R. Gomes, D.Y. Kakizaki, R.L. Parise, R.D. Ribeiro
LNLS, Campinas, Brazil

Beam Position Monitors were designed and manufactured to meet Sirius operation requirements. Final dimensional accuracy and stability of the BPM were achieved by careful specification of its components’ manufacturing tolerances and materials. AISI-305 Stainless Steel was used for the BPM support fabrication due to magnetic and thermal expansion constraints. High purity molybdenum for the electrode pin and Ti6Al4V F136 G23 alloy for housing was used to manufacture the sensor components for their thermal characteristics. The electrical insulator was made of high alumina. The materials were joined by an active metal brazing process using 0,01mm accurate fixtures. The brazed sensors were subjected to dimensional, mechanical, and metallurgical testing, as well as leak detection and optical microscopy inspection at each stage. The sensors were joined in Ti6Al4V F136 BPM bodies using TIG welding. Dimensional sorting was used to choose groups of sensors-to-body, and body-to-support pairs during the final assembly. 160 BPMs are currently in operation on Sirius storage ring. In this contribution, we present the results of BPM manufacturing and testing processes developed for Sirius.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB401

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paper received ※ 18 May 2021 paper accepted ※ 31 May 2021 issue date ※ 29 August 2021

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WEXB01

The ESS Elliptical Cavity Cryomodules Production at CEA

cryomodule, cavity, status, site

2536

C. Madec
CEA, Gif-sur-Yvette, France
C. Arcambal, S. Berry, A. Bouygues, G. Devanz, C. Mayri, P. Sahuquet, T. Trublet
CEA-DRF-IRFU, France
P. Bosland, E. Cenni, C. Cloué, T. Hamelin, O. Piquet
CEA-IRFU, Gif-sur-Yvette, France
P. Pierini
ESS, Lund, Sweden

CEA in Kind contribution to the ESS superconducting LINAC includes 30 elliptical medium and high-beta cryomodules. CEA is in charge of the production of all the components (except the cavities delivered by LASA and STFC) as well as the assembly of the cryomodules and a few cryogenic and RF tests. The power couplers operating at a maximum power of 1.1MW on a 3.6ms pulse at 14Hz are conditioned at high RF power on a dedicated stand. The assembly of the cryomodules is performed at CEA by a private Company under the supervision of CEA. This paper presents the status of the cryomodules production and the infrastructure dedicated to this project at CEA Saclay.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEXB01

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paper received ※ 18 May 2021 paper accepted ※ 19 July 2021 issue date ※ 30 August 2021

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WEPAB032

Studies of the Short-Range Wakefields for the Electron Storage Ring in the Electron Ion Collider

simulation, electron, wakefield, dipole

2675

G. Wang, M. Blaskiewicz, A. Blednykh, M.P. Sangroula
BNL, Upton, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
During the estimates of impedance budget for the Electron Storage Ring (ESR) of Electron-Ion Collider (EIC), various codes, including GdfidL, CST and ECHO3D, have been used to calculate the short-range wake-fields due to the vacuum components. The ECHO 3D code demonstrates more reliable results for the tapered type of structures rather than the GdfidL code, where the stepsize needs to be dramatically decreased to achieve a high-performance calculation. Impedance of the following components are discussed and compared in details: Interaction Region (IR) chamber, bellows, and synchrotron radiation mask (flange absorber).

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB032

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

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WEPAB041

Testing of the Milliampere Booster Prototype Cavity

cavity, linac, 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]

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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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WEPAB081

The Broad-Band Impedance Budget in the Storage Ring of the ALS-U Project

impedance, cavity, wakefield, storage-ring

2779

D. Wang, K.L.F. Bane, R. Bereguer, T. Cui, S. De Santis, P. Gach, D. Li, T.H. Luo, T. Miller, T. Oliver, O. Omolayo, C. Steier, T.L. Swain, M. Venturini, G. Wang
LBNL, Berkeley, California, USA

Design work is underway for the upgrade of the Advanced Light Source (ALS-U) to a diffraction-limited soft x-rays radiation source. Like other 4th-generation light source machines, the ALS-U multiple-bend achromat storage-ring (SR) is potentially sensitive to beam-coupling impedance effects. This paper presents the SR broad-band impedance budget in both the longitudinal and transverse planes. In our modeling we follow the commonly accepted approach of separating the resistive-wall and the geometric parts of the impedance, the former being described by analytical formulas and the latter obtained by numerical electromagnetic codes (primarily CST Studio software) assuming perfectly conducting materials. We discuss the main sources of impedance. Results of our analysis are the basis for the single bunch instability study and would feedback on the design of critical vacuum components.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB081

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

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WEPAB131

Magnetic Tuning and Installation Modifications of U48 Undulator for the Delhi Light Source (DLS)

undulator, electron, controls, focusing

2918

M. Tischer, P. Neumann, A. Schöps, P. Vagin, T. Vielitz, T. Wohlenberg
DESY, Hamburg, Germany
M. Aggarwal, R.N. Dutt, S. Ghosh, J. Karmakar, S. Sahu
IUAC, New Delhi, India
J. Bahrdt, E.C.M. Rial
HZB, Berlin, Germany

A compact THz radiation facility based on the principle of a pre-bunched Free Electron Laser, called Delhi Light Source (DLS) is at the final stage of commissioning at IUAC, New Delhi, India. For generation of THz radiation in DLS, an undulator with period length of 48 mm (U48), built by HZB and refurbished at DESY will be used. The magnetic tuning and the field measurements have been done on the U48 along with the design and installation of correction coils at the entrance/exit of the U48. In addition, horizontal and vertical ambient field correction coils were integrated into the magnet girders. A quadrupole correction coil along the vacuum chamber in order to mitigate the defocusing effect of the U48 on the electron beam has been designed. The current through all coils has been adjusted as a function of the gap by the new control system designed for the U48. In addition, an extruded aluminium vacuum chamber was designed and fabricated and will be aligned with the the undulator soon.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB131

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paper received ※ 19 May 2021 paper accepted ※ 05 July 2021 issue date ※ 11 August 2021

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WEPAB132

Towards a Superconducting Undulator Afterburner for the European XFEL

FEL, photon, undulator, electron

2921

S. Casalbuoni, J.E. Baader, G. Geloni, V. Grattoni, D. La Civita, C. Lechner, B. Marchetti, S. Serkez, H. Sinn
EuXFEL, Schenefeld, Germany
W. Decking, L. Lilje, S. Liu, T. Wohlenberg, I. Zagorodnov
DESY, Hamburg, Germany

We propose to develop, characterize and operate a superconducting undulator (SCU) afterburner consisting of 5 undulator modules (1 module = 2 times SCU coil of 2 m length and 1 phase shifter) at the SASE2 hard X-ray beamline of European XFEL. This afterburner has the potential to produce an output of more than 10¹⁰ ph/pulse at photon energies above 30 keV. The project is divided into the production of a pre-series prototype module and a small-series production of 5 modules. Central goals of this R&D activity are: the demonstration of the functionality of SCUs at an X-ray FEL, the set up of the needed infrastructure to characterize and operate SCUs, the industrialization of such undulators, and the reduction of the price per module. In this contribution, the main parameters and specifications of the pre-series prototype module (S-PRESSO) are described.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB132

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paper received ※ 15 May 2021 paper accepted ※ 05 July 2021 issue date ※ 14 August 2021

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WEPAB133

First Numerical Wakefield Studies of New In-Vacuum Cryogenic and APPLE II Undulators for BESSY II

impedance, simulation, undulator, factory

2925

M. Huck, J. Bahrdt, A. Meseck
HZB, Berlin, Germany
A. Meseck
KPH, Mainz, Germany

While the new in-vacuum cryogenic undulator is in its last commissioning stages, a worldwide new in-vacuum APPLE II undulator is being designed and constructed for BESSY II storage ring. Besides the challenging mechanical design of these small-gap and short-period undulators, challenges arise due to interaction with the electron beam. Therefore, detailed studies of this interaction is required to minimize the adverse effects on beam dynamics and the device itself. For this purpose, the wakefield effects have been computed numerically for critical parts of these devices i.e. the RF-shields, flexible tapers and taper sections. A brief overview of simulation results and discussions are presented in this paper.

Poster WEPAB133 [0.795 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB133

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

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WEPAB134

Experimental Studies of the In-Vacuum-Cryogenic Undulator Effect on Beam Instabilities at BESSY II

undulator, feedback, damping, impedance

2929

M. Huck, J. Bahrdt, A. Meseck, G. Rehm, M. Ries, A. Schälicke
HZB, Berlin, Germany

A new in-vacuum cryogenic permanent magnet undulator (CPMU17) has been installed in summer 2018 in the BESSY II storage ring at HZB. Such a small gap in-vacuum undulator device increases the impedance of the storage ring and can contribute to the instabilities that adversely affect the beam quality and the device itself. To identify and explore the effects of CPMU17 on the instabilities at BESSY II, grow-damp and drive-damp experiments have been conducted using the installed bunch-by-bunch feedback system. In this paper, the first results of the mode and gap analysis of these studies with a brief overview of other impedance studies will be presented.

Poster WEPAB134 [1.079 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB134

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paper received ※ 17 May 2021 paper accepted ※ 02 July 2021 issue date ※ 23 August 2021

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WEPAB144

A New Flux Concentrator Made of Cu Alloy for the SuperKEKB Positron Source

positron, operation, target, GUI

2954

Y. Enomoto, K. Abe, N. Okada, T. Takatomi
KEK, Ibaraki, Japan

Flux concentrator (FC) is one of important device for positron source which translates position and momentum spread of the particles adiabatically to match them to the acceptance of the following section. To realize higher positron yield, higher magnetic field is desired. However, higher field by higher current generate stronger force on the coil. Since the gap between each turn of the coil is as narrow as 0.2 mm and the voltage across them is about as high as 1 kV at the design current, slight deformation of the coil cause discharge between the gap. To avoid such problem, a new FC made of Cu alloy which has 40 times higher yield strength than that of pure Cu was designed and tested. Finally, during summer shutdown in 2020, the old FC made of pure Cu was replaced by the new one made of Cu alloy in the KEK electron positron injector linac. The new one has been working stably at the design current, 12 kA, since Oct. 2020, and positron yield of 0.5 was realized. There were no discharge and other trouble till now.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB144

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paper received ※ 08 May 2021 paper accepted ※ 01 July 2021 issue date ※ 26 August 2021

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WEPAB152

Carbon Nanotubes as Cold Electron Field Emitters for Electron Cooling in the CERN Extra Low Energy Antiproton (ELENA) Ring

electron, proton, experiment, antiproton

2975

B. Galante, G. Tranquille
CERN, Meyrin, Switzerland
O. Apsimon, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
J. Resta-López
IFIC, Valencia, Spain

In ELENA electron cooling reduces the emittance of the antiproton beam allowing to deliver a high-quality beam to the experiments at the unprecedented low energy of 100 keV. To cool the antiproton beam at this low energy, the electron gun must emit electrons with as monoenergetic a distribution as possible. The currently used thermionic gun limits the cooling performance due to the relatively high transverse energy spread of the emitted electrons. Optimization is therefore being studied, aiming at developing a cold-cathode electron gun. This has led to the investigation of carbon nanotubes (CNTs) as cold electron field emitters. CNTs are considered the most promising field emitter material due to their high aspect ratio, chemical stability, and capability to deliver high current densities. To assess the feasibility of using such material operationally a full characterization is required, focussing on key parameters such as emitted current, emission stability, and lifetime. This contribution will present the status of ongoing experiments reporting on the conditioning process necessary to reach good stability over time and the emitting performance of different CNT arrays.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB152

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paper received ※ 18 May 2021 paper accepted ※ 25 June 2021 issue date ※ 16 August 2021

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WEPAB164

Electrodeless Diamond Beam Halo Monitor

electron, experiment, coupling, radiation

2990

S.V. Kuzikov, S.P. Antipov, P.V. Avrakhov, E. Dosov, E.W. Knight, Y. Zhao
Euclid TechLabs, Solon, Ohio, USA
J.G. Power, J. Shao
ANL, Lemont, Illinois, USA

Funding: This work was supported by DoE SBIR grant # DE-SC0019642.
Beam halo measurement is important for novel x-ray free-electron lasers which have remarkably high repetition rate and average power. We propose diamond as a radiation hard material that can be used to measure the flux of passing particles based on a particle-induced conductivity effect. Our diamond electrodeless monitor is based on a microwave measurement of the change in the resonator coupling and eigenfrequency. For measurements, we put a sensitive diamond sample in a resonator that intercepts the halo. By measuring the change in RF properties of the resonator, one can infer the beam halo parameters scanning across the beam to map its transverse distribution. In recent experiments we used a Vertical Beam Test Stand (VBS), delivered DC electron beam of the 20-200 keV energy with the current up to 50 µA, to characterize several diamond samples. We have designed and fabricated a scanning diamond monitor, based on an X-band resonator, which was tested at Argonne Wakefield Accelerator (AWA) with a multi-MeV electron beam.

Poster WEPAB164 [5.138 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB164

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paper received ※ 14 May 2021 paper accepted ※ 07 June 2021 issue date ※ 31 August 2021

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WEPAB165

Metamaterial Waveguide HOM Loads for SRF Accelerating Cavities

HOM, GUI, cavity, SRF

2994

S.V. Kuzikov
Euclid TechLabs, Solon, Ohio, USA

Suppression of beam induced HOMs is necessary for most SRF accelerating cavities driven with high currents. One of the problems in design of a HOM load is that vacuum compatible materials with high enough imaginary part of the dielectric permittivity, which provides absorption, have also a high real part of the permittivity. This does not allow absorbing RF radiation at short distance and in broad frequency band. We propose considering artificial metamaterials where besides lossy dielectric pieces, an absorber with high magnetic permeability is included. In our proposal, we suggest composing a waveguide HOM load of a metamaterial consisted of well-known ceramic and ferrite plates placed periodically in a stack. Such a design provides low return losses, compactness and broad frequency range of the operation.

Poster WEPAB165 [1.844 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB165

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paper received ※ 19 May 2021 paper accepted ※ 02 June 2021 issue date ※ 24 August 2021

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WEPAB172

Recent Developments of the IDEAS-Halo Detector

experiment, detector, electron, FEL

3005

A. Liu, J.R. Callahan, B.T. Freemire
Euclid TechLabs, Solon, Ohio, USA
J.F. Power, J.H. Shao
ANL, Lemont, Illinois, USA

Funding: This work was performed at Euclid and Argonne National Laboratory, and was supported by the US DOE Office of Science under contract number DE-SC0019538.
Euclid Techlabs has been designing and testing a cost-effective iris diaphragm beam halo/profile detector, which can be easily configured to work with various primary beam energies and sites. Besides working as a measurement device, it can also work as a controllable beam scraper/collimator. This novel iris diaphragm detector utilizes the current signal produced by the beam charge deposition on the moveable conductive iris blades, to accurately measure the beam distribution from the outlier to the beam core. In this paper, we discuss the recent developments of our iris diaphragm e-beam apparatus series (IDEAS)-halo detector, including its geometry upgrades and newest beam experiments done at the AWA cathode testbed (ACT) of Argonne National Laboratory.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB172

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paper received ※ 03 June 2021 paper accepted ※ 22 July 2021 issue date ※ 27 August 2021

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WEPAB189

EIC Hadron Beamline Vacuum Studies

hadron, electron, emittance, cryogenics

3060

D. Weiss, M. Mapes, J.E. Tuozzolo, S. Verdú-Andrés
BNL, Upton, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Ninety percent of the EIC hadron ring beamline is cold-bore comprising strings of interconnected 4.55 K RHIC superconducting (SC) magnets. The EIC operating specification requires shorter bunches and 3x higher intensity beams which are not appropriate for the present RHIC stainless steel cold-bore beam tube. The intensity and emittance of the hadron beams will degrade due to interactions with residual gas or vacuum instabilities arising from the expected resistive-wall (RW) heating, electron clouds, and beam-induced desorption mechanisms. Without strategies to limit RW heating, major cryogenic system modifications are needed to prevent SC magnet quenches. The SC magnet cold-bore beam tubes will be equipped with a high RRR copper clad stainless steel sleeve to significantly reduce RW heating and so the effect on the SC magnet cryogenic heat load and temperature. A thin amorphous carbon film applied to the beam facing copper surface will suppress electron cloud formation. This paper discusses the vacuum requirements imposed by the EIC hadron beams and the plans to achieve the necessary vacuum and thermal stability that ensure acceptable beam quality and lifetime.

Poster WEPAB189 [3.321 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB189

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paper received ※ 17 May 2021 paper accepted ※ 25 August 2021 issue date ※ 26 August 2021

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WEPAB199

Study on the Important Technologies of 300MeV Upgrade for the CSNS Injection System

injection, electron, power-supply, neutron

3089

M.Y. Huang, C.D. Deng, L. Kang, L. Liu, Y. Liu, X. Qi, S. Wang, Q.B. Wu, Y.W. Wu, S.Y. Xu, W.Q. Zhang, Y.L. Zhang
IHEP, Beijing, People’s Republic of China
J.X. Chen, T. Huang, H.C. Liu
IHEP CSNS, Guangdong Province, People’s Republic of China

Funding: This work was supported by National Natural Science Foundation of China (Project Nos. U1832210 and 12075134).
The China Spallation Neutron Source (CSNS-I) have achieved the design goal of 100kW beam power on the target in Feb., 2020. As the second phase of the CSNS, CSNS-II will achieve a beam power on the target of 500 kW. The injection energy of CSNS-II will be increased from 80 MeV to 300 MeV and the average beam current of the Linac will increase 5 times. Therefore, the injection system will require a complete upgrade. In this paper, the design scheme of the injection system for CSNS-II will be introduced. The key technologies of the upgrade injection system will be carefully analyzed and pre-developed, such as the pulse power supplies and their magnets, the special-shaped ceramic vacuum chambers, the main stripping foil, the stripped electron collection, and so on.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB199

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paper received ※ 17 May 2021 paper accepted ※ 09 June 2021 issue date ※ 21 August 2021

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WEPAB224

Update of the Transverse Proton Synchrotron Impedance Model

impedance, factory, injection, space-charge

3149

S. Joly, N. Mounet, B. Salvant
CERN, Geneva, Switzerland
S. Joly
La Sapienza University of Rome, Rome, Italy
M. Migliorati
INFN-Roma1, Rome, Italy
M. Migliorati
Sapienza University of Rome, Rome, Italy

The CERN Proton Synchrotron (PS) was recently upgraded to allow reaching the ambitious performance goal of the High-Luminosity LHC Project. This upgrade is part of the LHC Injectors Upgrade project. The final part of the upgrade was performed during Long Shutdown 2 (LS2) to allow injection at higher energy from the PS Booster and a twofold increase in beam intensity and brightness. These changes must be considered in the PS impedance model. The effect on the impedance of the removal of obsolete injection equipment, changes of several accelerator components and new injection energy will be reviewed, as well as the wall impedance of the elliptic beam pipe, thanks to a newly developed code that allows taking into account both the ellipticity and the non-ultra-relativistic nature of the beam.

Poster WEPAB224 [0.654 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB224

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

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WEPAB235

TMCI Theory of Flat Chambers Revisited

impedance, coupling, storage-ring, simulation

3181

T.F. Günzel
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain

By accounting for the transverse impedance’ quadrupolar component according to the work of R.Lindberg *, no TMCI-instability can be observed in case of a pure horizontal resistive wall impedance of flat vacuum chambers. In order to study this effect more closely, TMCI-theory is reviewed and Lindberg’s work is further developed by including the resonator model as impedance type. The theory is applied to the ALBA-impedance model for the calculation of horizontal TMCI-detuning and threshold. Moreover, a couple of example cases are presented including vertical TMCI-detuning and threshold. Results on both planes are compared to simpler descriptions which account for the quadrupolar impedance effect only by tune shift.
* Ryan Lindberg, Fokker-Planck analysis of transverse collective instabilities in electron storage rings, Phy. Rev. Acc. Beams 19, 124402 (2016)

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB235

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

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WEPAB249

Model of Curvature Effects Associated with Space Charge for Long Beams in Dipoles

space-charge, dipole, emittance, shielding

3217

C.E. Mitchell, K. Hwang, R.D. Ryne
LBNL, Berkeley, California, USA

Funding: This work was supported by the Director, Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
For modeling the dynamics within a dipole of a bunch whose length is much larger than the vacuum pipe radius, it is typical to use a 2D (or 2.5D) Poisson solver, with arc length taken as the independent variable. However, sampled at a fixed time, the beam is curved, space charge is not truly 2D, and the usual cancellation between E and B contributions to the Lorentz force need not exactly hold. The size of these effects is estimated using an idealized model of a uniform torus of charge rotating inside a toroidal conducting pipe. Simple expressions are provided for the correction of the electric and magnetic fields to first order in the reciprocal of the curvature radius.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB249

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

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WEPAB329

LCLS-II Average Current Monitor

cavity, coupling, simulation, network

3443

P. Borchard, J.S. Hoh
Dymenso LLC, San Francisco, USA

The LCLS-II project at SLAC is a high power upgrade to the existing free-electron laser facility. The LCLS-II Accelerator System will include a new 4 GeV continuous-wave superconducting linear accelerator in the first kilometer of the SLAC linear accelerator tunnel and supplements the existing low power pulsed linac. Average Current Monitors (ACMs) are needed to protect against excessive beam power which might otherwise cause damage to the beam dumps. The ACM cavities are pillbox-shaped stainless steel RF cavity with two radial probe ports with couplers, one radial test port with a coupler, and a mechanism for mechanically fine-tuning the cavity resonant frequency. The ACM RF cavities will be located at points of known or constrained beam energy and will monitor the beam current, a safety system will trip off the beam if the beam power exceeds the allowed value.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB329

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paper received ※ 19 May 2021 paper accepted ※ 16 June 2021 issue date ※ 22 August 2021

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WEPAB333

Installation and Commissioning of the Sirius Vacuum System

booster, storage-ring, MMI, target

3455

R.M. Seraphim, R.O. Ferraz, H.G. Filho, G.R. Gomes, P.H. Lima, R.F. Oliveira, B.M. Ramos, T.M. Rocha, D.R. Silva, M.B. Silva
LNLS, Campinas, Brazil

The installation of the Sirius accelerators was completed in 2019. The vacuum installation of the booster took place in October 2018. The booster vacuum chambers were baked-out ex-situ and the vacuum pumps, gauges and valves were assembled prior to the installation in the tunnel. The vacuum installation of the storage ring took place from May to August 2019. The vacuum system of the storage ring is based on fully NEG-coated chambers and each sector was baked-out in-situ for NEG activation. The average static pressure in the booster is in the range of low 10^-9 mbar. In the storage ring, 95% of the pressures are in 10-11 mbar range and 5% are in 10-10 mbar range. The first beam was stored in the storage ring in December 2019. The vacuum system has been performing well, and an effective beam cleaning effect has been observed for the NEG-coated chambers. At a beam dose of 70 A-h, the storage ring already achieved the design normalized average dynamic pressure of 3x10 12 mbar/mA. A summary of the installation and the commissioning status of the vacuum system will be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB333

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paper received ※ 20 May 2021 paper accepted ※ 14 June 2021 issue date ※ 22 August 2021

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WEPAB334

Development of Diffusion Bonded Joints of AA6061 Aluminum Alloy to AISI 316LN Stainless Steel for Sirius Planar Undulators

undulator, interface, MMI, operation

3459

R.L. Parise, O.R. Bagnato, R. Defavari, M.W.A. Feitosa, F.R. Francisco, D.Y. Kakizaki, R.D. Ribeiro
LNLS, Campinas, Brazil

LNLS has been commissioning Sirius, a 4th-generation synchrotron light source. The commissioning of the beamlines has been mainly done by using planar undulator, which uses in-house built aluminum vacuum chambers with ultra-high vacuum tight bimetallic flanges. In order to manufacture these flanges, diffusion bonded joints of AA6061 aluminum alloy to AISI 316LN stainless steel were developed. Diffusion bonding was carried out at 400-500°C for 45-60 min, applying a load of 9.8MPa in a vacuum furnace. Also, the surface preparation for Al and SS was investigated. SEM observation revealed that an 1-3 µm reaction layer was formed at the AA6061/Ni-plated interface. The intermetallic compound Al3Ni was identified in the reaction layer. The obtained Al/SS joints showed mean ultimate strength of 84 MPa, with the fracture occurring in the Al/reaction layer interface. Bake-out cycles followed by leak tests were carried out to validate the process and approve their use on the planar undulator vacuum chambers. Two undulators with Al/SS flanges have been installed and are under operation in the storage ring.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB334

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

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WEPAB335

Aluminum Vacuum Chamber for the Sirius DELTA 52 Undulator

undulator, storage-ring, synchrotron, emittance

3463

T.M. Rocha, O.R. Bagnato, R.O. Ferraz, H.G. Filho, P.P.S. Freitas, G.R. Gomes, P.H. Lima, R.F. Oliveira, B.M. Ramos, F. Rodrigues, R.M. Seraphim, D.R. Silva, M.B. Silva
LNLS, Campinas, Brazil

Sirius is a 3 GeV fourth generation synchrotron light source under commissioning by the Brazilian Synchrotron Light Laboratory (LNLS). Delta Undulators with magnet vertical aperture of 13.6 mm, and period of 52.5 mm will be used for the generation of soft X rays to photoemission spectroscopy and X ray absorption experiments. Extruded aluminum vacuum chambers having small vertical aperture of 7.6 mm and horizontal aperture of 13 mm is proposed. This paper details the design and manufacturing processes of a complete chamber. Challenges regarding the TIG welding for aluminum and NEG coating for small aperture chambers will also be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB335

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paper received ※ 18 May 2021 paper accepted ※ 19 July 2021 issue date ※ 20 August 2021

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WEPAB336

Aluminum Vacuum Chamber for the Sirius Commissioning Undulators

undulator, cathode, MMI, storage-ring

3467

B.M. Ramos, O.R. Bagnato, R.O. Ferraz, H.G. Filho, P.P.S. Freitas, G.R. Gomes, P.H. Lima, R.F. Oliveira, T.M. Rocha, F. Rodrigues, R.M. Seraphim, D.R. Silva, M.B. Silva
LNLS, Campinas, Brazil

Sirius is a 3 GeV fourth generation light source under commissioning by the Brazilian Synchrotron Light Laboratory (LNLS). Compact Linear Polarizing Undulators with magnet vertical aperture of 8 mm have been used for the commissioning of some beam lines. Extruded aluminum vacuum chambers having small vertical aperture of 6 mm and horizontal aperture of 40 mm, were built. This paper details the design and manufacturing processes of a complete chamber and its installation procedure at the storage ring. Challenges regarding the precision machining of the 0.5 mm wall thickness, TIG welding for aluminum, NEG coating for small apertures will also be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB336

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paper received ※ 18 May 2021 paper accepted ※ 25 August 2021 issue date ※ 20 August 2021

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WEPAB337

Some Methods of Making Titanium Vacuum Chamber Act as Getter Pump for UHV/XHV

ECR, electron, experiment, hadron

3471

J. Kamiya, T. Takano, H. Yuza
JAEA/J-PARC, Tokai-mura, Japan
K. Wada
Tokyo Electronics Co. Ltd., Kokubunji, Tokyo, Japan

Funding: JSPS KAKENHI Grant Number JP18K11925
The non-evaporable getter (NEG) coating has been developed in CERN to make a beam pipe act as a distributed vacuum pump by coating the getter materials with the ability to adsorb/absorb gas molecules on the beam pipe surface. The NEG coating materials used in the LHC are alloys of titanium, zirconium, and vanadium. In high-power beam accelerators, titanium has been used as the beam pipe chamber material due to its low radio activation characteristics. The ordinal titanium surface has no getter function because it is covered with a titanium oxide film. The new technique, which removes the titanium-oxide surface by some methods, such as baking or sputtering, has been investigated. The dependence of the surface oxide film and the getter characteristics on the baking temperature have been measured. Also, by sputtering the inner surface of the titanium chamber, clear evidence that shows the chamber acts as a vacuum pump has been obtained. Furthermore, the NEG coating on the pure titanium surface can suppress the rapid decrease of the sticking probability by the repeated air purge and reactivation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB337

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paper received ※ 14 May 2021 paper accepted ※ 25 June 2021 issue date ※ 19 August 2021

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WEPAB338

Amorphous Carbon Coating in SPS

electron, target, operation, multipactoring

3475

W. Vollenberg, P. Chiggiato, P. Costa Pinto, P. Cruikshank, H. Moreno, C. Pasquino, J. Perez Espinos, M. Taborelli
CERN, Meyrin, Switzerland

Within the LHC Injector Upgrade (LIU) project, the Super Proton Synchrotron (SPS) needs to be upgraded to inject into the LHC higher intensity and brighter 25-ns bunch spaced beams. To mitigate the Electron Multipacting (E.M.) phenomenon, a well-known limiting factor for high-intensity positively charged beams, CERN developed carbon coatings with a low Secondary Electron Yield (SEY). During the 2016 & 2017 year-end technical stops, such coatings were deposited on the inner wall of the vacuum chambers of some SPS quadrupole and dipole magnets by a dedicated in-situ setup. A much larger scale deployment was implemented during the Long Shutdown 2 (2019-2020) to coat all beam pipes of focussing quadrupoles (QF) and their adjacent short straight sections. In this contribution, we remind the motivation of the project, and present the results and the quality control of the carbon coating campaign during the latter phase of implementation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB338

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paper received ※ 19 May 2021 paper accepted ※ 16 June 2021 issue date ※ 13 August 2021

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WEPAB340

Pressure Simulations for the EIC Interaction Region

photon, electron, detector, simulation

3483

M.L. Stutzman
JLab, Newport News, Virginia, USA

Background detector rates in the Electron Ion Collider depend in part on the pressure in the interaction region. Materials choice, synchrotron radiation induced desorption, conditioning time and pumping configuration all affect the pressure in the system. Simulations of the region using Synrad and Molflow+ coupled simulation codes will be presented for various configruations and conditioning times.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB340

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paper received ※ 18 May 2021 paper accepted ※ 20 July 2021 issue date ※ 11 August 2021

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WEPAB344

Studies for Mitigating Flashover of CERN-LHC Dilution Kicker Magnets

electron, kicker, simulation, high-voltage

3498

A.M. Loebner, M.J. Barnes, W. Bartmann, C. Bracco, L. Ducimetière, V. Namora, V. Senaj
CERN, Geneva 23, Switzerland

The LHC beam dump system is used for extracting beam from the LHC and, as such, is a safety critical system whose proper functionality must be assured. Dilution kicker magnets (MKBs) sweep the extracted beam over the cross-sectional area of a dump block as the energy density would otherwise be too high and damage the block. In 2018, a high voltage flashover occurred in a vertical MKB (MKBV) vacuum tank, during a beam dump, which resulted in non-ideal sweep of the beam over the block. The location of the flashover could not be identified during a subsequent inspection of the magnet. Hence, electrical field simulations have been carried out to identify potentially critical regions, to determine the most probable region of the flashover. One potentially critical region is a rectangular beam pipe (RBP) between the end of the tank and the MKBV magnet, whose purpose is to reduce plasma propagation to the adjacent tank in the event of a flashover. Mitigating measures were studied and are reported in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB344

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paper received ※ 16 May 2021 paper accepted ※ 06 July 2021 issue date ※ 22 August 2021

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WEPAB347

Design, Construction and Testing of a Magnetic Probe for Fast Kicker Magnets

impedance, kicker, injection, operation

3510

N. Ayala, A. Ferrero Colomo, T. Kramer
CERN, Geneva, Switzerland

The CERN PS injection kicker has been modified in the framework of the LHC Injector Upgrade (LIU) project to allow injecting proton beams with an energy of 2 GeV. One of the most important items of the system parameter validation is the measurement and analysis of the magnetic field in the magnet aperture. To meet the required measurement precision without compromising the magnet vacuum performance, a dedicated magnetic probe has been designed, constructed and tested. The results are presented in this paper highlighting the mitigations of electrical, mechanical and vacuum complications. The paper concludes with an analysis of the probe performance during the first magnetic field measurements in the laboratory.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB347

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

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WEPAB348

Injection and Extraction Systems of the SIS100 Heavy Ion Synchrotron at FAIR

kicker, extraction, injection, septum

3514

I.J. Petzenhauser, U. Blell, S. Heberer
GSI, Darmstadt, Germany

The "Facility for Antiproton and Ion Research" (FAIR) is a new international accelerator complex, which is currently built in Darmstadt, Germany. Part of this complex is the SIS100 heavy ion synchrotron with a circumference of ~1086 m. To inject ions into the SIS100, an injection kicker system will we required. For fast extraction of the particle beam from the SIS100, an extraction kicker is used. This extraction kicker will be a bipolar system, this way it works as an emergency kicker at the same time. The fast kicker systems have to produce a current pulse >6 kA. To achieve this, energy storages are charged up to voltages >70 kV and are quickly discharged. The pulse durations vary from 0.5 us to 7 us, depending on the kicker type and the operation mode. Slow extraction of the ion beam will include an electrostatic septum, operating with voltages up to 160 kV. The requirements of these injection/extraction devices will be described in detail and the status of the projects will be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB348

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paper received ※ 17 May 2021 paper accepted ※ 11 June 2021 issue date ※ 20 August 2021

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WEPAB355

Series Production of the SIS100 Cryocatchers

quadrupole, site, cryogenics, heavy-ion

3529

L.H.J. Bozyk, S. Ahmed, P.J. Spiller
GSI, Darmstadt, Germany

The superconducting heavy ion synchrotron SIS100, which is the main accelerator of the FAIR-facility will be equipped with cryocatcher to suppress dynamic vacuum effects and to assure a reliable operation of high intensity heavy-ion beams. Subsequent to the successful validation of the prototype in 2011 as well as a First-of-Series cryocatcher, the series production of 60 cryocatcher modules meanwhile has been completed. It was released in 2018 after further design optimizations. Key findings from the series production and acceptance tests are presented as well. The First-of-Series cryocatcher has been integrated into the First-of-Series quadrupole module and has undergone several tests. These results are also illustrated in this report.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB355

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paper received ※ 19 May 2021 paper accepted ※ 06 July 2021 issue date ※ 16 August 2021

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WEPAB361

New Generation CERN LHC Injection Dump - Assembly and Installation (TDIS)

injection, alignment, radiation, operation

3548

D. Carbajo Perez, E. Berthomé, C. Bertone, N. Biancacci, C. Bracco, G. Bregliozzi, B. Bulat, C. Cadiou, M. Calviani, G. Cattenoz, A. Cherif, P. Costa Pinto, A. Dallocchio, M. Di Castro, P. Fessia, M.I. Frankl, R. Franqueira Ximenes, J.-F. Fuchs, H. Garcia Gavela, J.-M. Geisser, L. Gentini, S.S. Gilardoni, M.A. Gonzalez De La Aleja Cabana, J.L. Grenard, J.M. Heredia, S. Joly, A. Lechner, J. Lendaro, J. Maestre, E. Page, M. Perez Ornedo, A. Perillo-Marcone, D. Pugnat, E. Rigutto, B. Salvant, A. Sapountzis, K. Scibor, R. Seidenbinder, J. Sola Merino, M. Taborelli, E. Urrutia, A. Vieille, C. Vollinger, C. Yin Vallgren
CERN, Meyrin, Switzerland

Funding: Work supported by the Hilumi Project
During CERN’s LS2, several upgrades were performed to beam intercepting devices in the framework of the HL-LHC Project. Upgraded equipment includes two internal beam dumps (TDIS) intended for machine protection located at the injection points from the SPS to the LHC. These two devices have been assembled, tested, and installed around LHC Point 2 and Point 8 and are currently ready to get commissioned with the beam. They are 5.8m-long, three-module-segmented vacuum chambers, with large aperture to accommodate the injected and circulating beam and equipped with absorbing materials, These comprise graphite and higher Z alloys that are embedded on sub-assemblies reinforced with back-stiffeners made of TZM. The current contribution covers three main matters. First, it details the TDIS design and its key technical features. The second topic discussed is the outcome of an experiment where a prototype module was tested under high-energy beam impacts at CERN’s HiRadMat facility. To conclude it is presented the return of experience from the pre-series construction, validation and installation in the LHC tunnel.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB361

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paper received ※ 18 May 2021 paper accepted ※ 11 June 2021 issue date ※ 17 August 2021

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WEPAB376

The Inner Triplet String Facility for HL-LHC: Design and Planning

cryogenics, quadrupole, operation, MMI

3592

M.B. Bajko, S. Bertolasi, C. Bertone, S. Blanchard, D. Bozzini, O.S. Brüning, P. Cruikshank, D. De Luca, N. Dos Santos, F. Dragoni, N. Heredia Garcia, A. Herty, A. Kosmicki, S. Le Naour, W. Maan, A. Martínez Sellés, P. Martinez Urios, P. Orlandi, A. Perin, M. Pojer, F. Rodriguez-Mateos, G. Rolando, L. Rossi, H. Thiesen, E. Todesco, E. Vergara Fernandez, D. Wollmann, S. Yammine, J.J. Zawilinski, M. Zerlauth
CERN, Geneva, Switzerland

In the framework of the HL-LHC project, full-scale integration and operational tests of the superconducting magnet chain, from the inner triplet quadrupoles up to the first separation/recombination dipole, are planned in conditions as similar as possible to the final set-up in the LHC tunnel. The IT String includes all of the required systems for operation at nominal conditions, such as vacuum, cryogenics, warm and cold powering equipment, and protection systems. The IT String is intended to be both an assembly, and an integration test stand, and a full rehearsal of the systems working in unison. It will, closely reproducing the mechanical, electrical, and thermo-hydraulic interfaces of the final installation, as well as allowing a full rehearsal of the systems working in unison. This paper describes the conceptual design, the test stand’s reference configuration, and the main goals. It also summarizes the status of the main activities, including the detailed design of the test infrastructure, procurement of main equipment, the baseline installation schedule, and major milestones. The first version of the experimental program and the associated planning are also presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB376

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paper received ※ 19 May 2021 paper accepted ※ 22 July 2021 issue date ※ 22 August 2021

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WEPAB387

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

linac, gun, electron, operation

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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WEPAB390

High-Quality, Conformal Bellows Coatings Using Ultra-Fast HiPIMS with Precision Ion Energy Control

plasma, target, operation, experiment

3626

T.J. Houlahan, I. Haehnlein, W.M. Huber, B.E. Jurczyk, I.A. Shchelkanov, R.A. Stubbers
Starfire Industries LLC, Champaign, USA

Funding: This material is based upon work supported by the U.S. Department of Energy under Award Number DE-SC0020481.
In this paper we demonstrate a replacement for traditional ’wet’ chemical deposition processes using a vacuum, ionized physical vapor deposition (iPVD) process that results in a conformal metal film, capable of coating complex, convoluted parts that are common in modern particle accelerators (e.g., bellows, RF cavities). Results are presented for a process utilizing the combined deposition and etching that are achieved using ultra-fast high-power impulse magnetron sputtering (HiPIMS) coupled with precision control of the ion energy using a positive voltage reversal. This process results in a conformal film and has been used to coat both test coupons and full bellows assemblies. The resulting Cu films, which are 5-10 µm in thickness, exhibit excellent adhesion. Further, they have been shown to tolerate temperature extremes ranging from 77 K to a 400 C vacuum bakeout as well as extreme plastic deformation of the substrate without any buckling, cracking, or delamination.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB390

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paper received ※ 19 May 2021 paper accepted ※ 02 July 2021 issue date ※ 31 August 2021

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WEPAB396

First Measurements on Multipactor Study

multipactoring, electron, simulation, ECR

3633

Y. Gómez Martínez, J. Angot, M.A. Baylac, T. Cabanel, P.-O. Dumont, N. Emeriaud, O. Zimmermann
LPSC, Grenoble Cedex, France
D. Longuevergne
FLUO, Orsay, France
G. Sattonnay
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France

Multipactor (MP) is an undesired phenomenon of resonant electron build up encountered on particle accelerators. It can induce anomalous thermal losses, higher than the Joule losses, inducing a decrease of the superconducting cavities quality factor, it can even lead to a cavity quench. On couplers, it can produce irreversible damages or generate a breakdown of their vacuum window. Multipactor may lead to Electron Cloud build up as well. The accelerator group at LPSC has developed a test bench dedicated to the multipactor studies. This paper presents the experimental set-up and its first measurements.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB396

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paper received ※ 18 May 2021 paper accepted ※ 14 July 2021 issue date ※ 17 August 2021

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THPAB049

Modeling the Magnetic Field of the LCLS-I Undulator for THz@PITZ

undulator, FEL, simulation, experiment

3855

M. Krasilnikov, X. Li, A. Lueangaramwong, F. Mueller, F. Stephan
DESY Zeuthen, Zeuthen, Germany
A. Brachmann, H.-D. Nuhn
SLAC, Menlo Park, California, USA
M. Tischer, P. Vagin
DESY, Hamburg, Germany

Funding: This work was supported by the European XFEL research and development program
An accelerator-based THz source for pump-probe experiments at the European XFEL is under development at the Photo Injector Test Facility at DESY in Zeuthen (PITZ). For the proof-of-principle experiments an LCLS-I undulator is planned to be installed downstream of the PITZ accelerator. The fields of the undulator module 26 have been re-measured at DESY in Hamburg and the results are consistent with earlier SLAC measurements. A model for 3D field reconstruction based on the undulator magnetic measurements has been developed. It includes also a horizontal gradient of the vertical field. Tracking of the 17 MeV/c beam has revealed that the transverse gradient will lead to a significant off-axis trajectory in the horizontal plane. This offset has to be corrected with a steering coil, the design of which is also presented. The performance of the THz generation with the correction coil is discussed as well.

Poster THPAB049 [1.409 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB049

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paper received ※ 12 May 2021 paper accepted ※ 12 July 2021 issue date ※ 02 September 2021

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THPAB052

Insertion Devices at the MAX IV 3 GeV Ring

wiggler, photon, undulator, MMI

3865

H. Tarawneh, M. Ebbeni, M. Gehlot, M. Holz
MAX IV Laboratory, Lund University, Lund, Sweden

Currently, there are 8 Insertion Devices (ID) installed and in operation and 2 new ones to be installed end of 2021 at the MAX IV 3 GeV storage ring. In this paper, the first commissioning results of the three newly installed IDs in 2020 will be described. The new IDs are one APPLE II for SoftiMAX beamline and two In-vacuum Undulators (IVU) for the DanMAX and CoSAXS beamlines. The mitigation scheme adopted to reduce undulator-like radiation from BALDER in-vacuum wiggler will be discussed. Two new IVUs with a period length of 17 mm and 18 mm for the ForMAX and MicroMAX beamlines will be installed during the winter shutdown of 2021-2022. Both IDs have 3 m lengths and a minimum gap of 4 mm. In this paper, the magnetic measurement results will be presented in terms of the achieved field quality and phase error.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB052

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paper received ※ 11 May 2021 paper accepted ※ 02 July 2021 issue date ※ 02 September 2021

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THPAB057

Goubau-Line Set Up for Bench Testing Impedance of In-Vacuum Undulator Components

impedance, undulator, wakefield, radiation

3883

P.I. Volz, S. Grimmer, M. Huck, A. Meseck
HZB, Berlin, Germany
A. Meseck
KPH, Mainz, Germany

The worldwide first in-vacuum elliptical undulator, IVUE32, is being developed at Helmholtz Zentrum Berlin. The 2.5 m long device with a period length of 3.2 cm and a minimum gap of about 7 mm is to be installed in the BESSY II storage ring. It will deliver soft X-radiation to several beamlines. The proximity of the undulator structure to the electron beam makes the device susceptible to wakefield effects which can influence beam stability. A complete understanding of its impedance characteristics is required prior to installation and operation, as unforeseen heating of components could have catastrophic consequences. Since its complex structure makes numerical calculations, such as CST simulations, at high frequency very resource intensive, bench testing the device may proof invaluable. A Goubau-line is a single wire transmission line for high frequency surface waves with a transverse electric field resembling that of a charged particle beam out to a certain radial distance. This can be used to measure the impedance of vacuum chamber components. A concept optimized for bench testing IVUE32-components will be discussed and progress towards the test bench set up will be shown.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB057

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

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THPAB065

Experimental Verification of the Source of Excessive Helical SCU Heat Load at APS

radiation, photon, synchrotron-radiation, synchrotron

3904

V. Sajaev, J.C. Dooling, K.C. Harkay
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.
Immediately after the installation of the Helical superconducting undulator (HSCU) in the APS storage ring, higher than expected heating was observed in the cryogenic cooling system. Steering the electron beam orbit in the upstream dipole reduced the amount of synchrotron radiation reaching into the HSCU and allowed the device to properly cool and operate. The simplest explanation of the excessive heat load was higher than expected heat transfer from the vacuum chamber to the magnet coils. However, modeling of the synchrotron radiation interaction with the HSCU vacuum chamber showed that Compton scattering could also result in synchrotron radiation penetrating the vacuum chamber and depositing energy directly into the HSCU coils**. In this paper, we present experimental evidence that the excessive heat load of the HSCU coils is not caused by the heat transfer from the vacuum chamber but resulted from the synchrotron radiation penetrating the vacuum chamber.
* M. Kasa et. al., Phys. Rev. AB, v. 23 050701 (2020)
** J. Dooling et. al., IPAC 2019 Proc., THPTS093 (2019)

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB065

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paper received ※ 12 May 2021 paper accepted ※ 02 September 2021 issue date ※ 16 August 2021

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THPAB078

SOLEIL Update Status

controls, photon, injection, synchrotron

3945

L.S. Nadolski, G. Abeillé, Y.-M. Abiven, F. Bouvet, P. Brunelle, A. Buteau, N. Béchu, I. Chado, M.-E. Couprie, X. Delétoille, A. Gamelin, C. Herbeaux, N. Hubert, J.-F. Lamarre, V. Leroux, A. Lestrade, A. Loulergue, P. Marchand, O. Marcouillé, A. Nadji, R. Nagaoka, S. Pierre-Joseph Zéphir, F. Ribeiro, G. Schagene, K. Tavakoli, M.-A. Tordeux
SOLEIL, Gif-sur-Yvette, France

SOLEIL is both a synchrotron light source and a research laboratory at the cutting edge of experimental techniques dedicated to matter analysis down to the atomic scale, as well as a service platform open to all scientific and industrial communities. This French 2.75 GeV third generation synchrotron light source provides today extremely stable photon beams to 29 beamlines (BLs) complementary to ESRF. We report facility performance, ongoing projects and recent major achievements. Major R&D areas will also be discussed, and progress towards a lattice baseline for making SOLEIL a diffraction limited storage ring.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB078

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paper received ※ 22 May 2021 paper accepted ※ 12 July 2021 issue date ※ 22 August 2021

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THPAB142

Optical and Surface Characterization of Alkali-Antimonide Photocathodes

cathode, electron, photon, emittance

4037

P. Saha, O. Chubenko, G.S. Gevorkyan, A.H. Kachwala, S.S. Karkare, C.J. Knill
Arizona State University, Tempe, USA
E.J. Montgomery, S. Poddar
Euclid Beamlabs, Bolingbrook, USA
H.A. Padmore
LBNL, Berkeley, California, USA

Alkali-antimonides, characterized by high quantum efficiency and low mean transverse energy in visible light, are excellent electron sources to drive x-ray free electron lasers, electron cooling and ultrafast electron diffraction applications etc. Existing studies of alkali-antimonides have focused on quantum efficiency and emittance, but information is lacking on the fundamental aspects of the electronic structure, such as the energy gap of the semiconductor and the density of defects as well as the overall nano-structure of the materials. We are, therefore, conducting photoconductivity measurements to measure fundamental semiconductor properties as well as using atomic force microscope (AFM) and kelvin probe force microscope (KPFM) to measure the nanostructure variations in structure and surface potential.

Poster THPAB142 [1.211 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB142

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paper received ※ 16 May 2021 paper accepted ※ 14 July 2021 issue date ※ 13 August 2021

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THPAB153

Design, Construction and Tests of the Cooling System with a Cryocooler for Cavity Testing

cavity, cryogenics, SRF, simulation

4056

P. Pizzol, J.W. Lewellen, E.R. Olivas, E.I. Simakov, T. Tajima
LANL, Los Alamos, New Mexico, USA

Cryogenically cooled normal-conducting cavities have shown higher gradients than those operated at room temperature. We are constructing a compact cooling system with a cryocooler to test C-band normal-conducting cavities and 1.3 GHz superconducting cavities. This paper describes the design, construction, and cooling test results as well as some low-power cavity Q measurement results.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB153

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paper received ※ 17 May 2021 paper accepted ※ 21 June 2021 issue date ※ 12 August 2021

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THPAB178

The SIS100 Extraction and Emergency Kicker Magnet System

kicker, extraction, high-voltage, HOM

4115

J.H. Hottenbacher, K. Dunkel, M. Eisengruber, M. Osemann, A. Padvi, C. Piel
RI Research Instruments GmbH, Bergisch Gladbach, Germany
S. Heberer, I.J. Petzenhauser
GSI, Darmstadt, Germany

The extraction and emergency kicker system for SIS100 is a bipolar kicker system that allows for an in-situ choice between two directions: extraction to the experiments or to the beam dump. For that, both magnet ends are connected to a PFN each which are being charged simultaneously up to 80kV continuously. Due to the static HV operation, different to usually in other pulsed kicker systems, not only displacement current is flowing in the ferrite material. After less than 1s, the ferrite material is nearly field-free and the E-field is concentrated in the surrounding ceramic magnet clamp mechanism. As the field is further concentrated in gaps between ceramic and metallic parts, the HV layout of the magnet is a critical design task. As a magnetic field homogeneity of ±1% is required, special shaping of the coil is required as found during iterative 3D field simulations. The kicker chamber is designed to operate at a pressure level of 3·10^-11 mBar. As one 3 meter-chamber contains 3.5 m² ferrite surface, careful vacuum heat treatment of the ferrite is required to reach this pressure level. The paper will describe design principles for HV and UHV and effects found by 3D modeling.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB178

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paper received ※ 18 May 2021 paper accepted ※ 28 July 2021 issue date ※ 26 August 2021

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THPAB233

Could "Flakes" of Neutral Paramagnetic or Dipolar Molecules Explain Beam Losses in the LHC?

solenoid, dipole, electron, electromagnetic-fields

4254

G. Franchetti
GSI, Darmstadt, Germany
F. Zimmermann
CERN, Meyrin, Switzerland

"Flakes" of neutral water or oxygen molecules carrying an electric or magnetic dipole moment can be attracted and trapped by the electromagnetic field of the circulating LHC proton beam. The possible presence of such flakes in the vacuum system could explain beam losses and beam instabilities encountered during the 2017 and 2018 LHC runs, and the observed effect of an external magnetic field.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB233

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paper received ※ 09 May 2021 paper accepted ※ 12 July 2021 issue date ※ 02 September 2021

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THPAB238

An Overview of the Collective Effects and Impedance Calculation for the EIC

electron, simulation, wakefield, dipole

4266

A. Blednykh, D.M. Gassner, B. Podobedov, S. Verdú-Andrés
Brookhaven National Laboratory (BNL), Electron-Ion Collider, Upton, New York, USA
M. Blaskiewicz, C. Hetzel, B. Lepore, V.H. Ranjbar, M.P. Sangroula, P. Thieberger, G. Wang, Q. Wu
BNL, Upton, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
A new high-luminosity Electron-Ion Collider (EIC) is being designed at Brookhaven National Laboratory (BNL). Stable operation of the electron beam at an average current of 2.5A within 1100 bunches with a 7mm bunch length is one of the challenging tasks in achieving an electron-proton luminosity of 1033-1034 cm^-2 ses⁻¹ range. Beam induced heating, short-range and long-range wakefield analysis is discussed for some of the vacuum components of the electron storage ring (ESR), the hadron storage ring (HSR), and the rapid cycling synchrotron (RCS) and as well as the impact of the collective effects on the beam stability.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB238

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paper received ※ 15 May 2021 paper accepted ※ 24 June 2021 issue date ※ 29 August 2021

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THPAB239

Impedance Optimization of the EIC Interaction Region Vacuum Chamber

electron, impedance, detector, wakefield

4270

A. Blednykh
Brookhaven National Laboratory (BNL), Electron-Ion Collider, Upton, New York, USA
E.C. Aschenauer, M. Blaskiewicz, C. Hetzel, M.P. Sangroula, G. Wang, H. Witte
BNL, Upton, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
The interaction region chamber has a complex geometry at the crossing location of electron and proton beam pipes. In the direction of the electron beam, the pipe is designed in a way to avoid joints with cavity characteristics. The horizontal slot on the upstream side and the tapered transition on the downstream side are applied to minimize the IR chamber contribution to the total impedance of the electron ring and to avoid generating Higher Order Modes and heating-related issues. The synchrotron radiation mask is included to protect the IR chamber from synchrotron radiation without significant aperture reduction. In the direction of the proton beam, the main area for optimization is the transition area right after the detector.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB239

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

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THPAB245

A Simulation Study of Beam Pipe Eddy Current Effects on Beam Optics

quadrupole, simulation, operation, power-supply

4288

T. Asami, T. Koseki
The University of Tokyo, Graduate School of Science, Tokyo, Japan
S. Igarashi, T. Koseki, Y. Kurimoto, Y. Sato
KEK, Ibaraki, Japan

In synchrotrons, fast changes of magnetic field induce eddy currents at the wall of beam pipes. The eddy currents cause a phase delay between excitation currents of the magnets and the magnetic field. The undesired magnetic field affected by eddy currents might be a serious obstacle in controlling beam optics precisely. In fact, in the operation of a high-intensity proton synchrotron J-PARC MR, the largest beam loss is observed at the beginning of acceleration when the magnetic field starts to vary in time. Therefore, it is important to estimate and understand the effects of eddy currents on beam optics. In this study, we have calculated the effect of eddy currents on magnetic field for some magnets in J-PARC MR, using electromagnetic simulation software. In this paper, we would like to report the details and results of the simulation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB245

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

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THPAB251

Efficient Terahertz Generation by Tilted-Pulse-Front Pumping in Lithium Niobate for the Split-Ring Resonator Experiment at FLUTE

electron, laser, experiment, diagnostics

4299

M. Nabinger, E. Bründermann, S. Funkner, B. Härer, A.-S. Müller, M.J. Nasse, G. Niehues, R. Ruprecht, J. Schäfer, T. Schmelzer, N.J. Smale
KIT, Karlsruhe, Germany
M.M. Dehler, R. Ischebeck, M. Moser, V. Schlott
PSI, Villigen PSI, Switzerland
T. Feurer, M. Hayati, Z. Ollmann
Universität Bern, Institute of Applied Physics, Bern, Switzerland

Funding: This work is co-funded via the European Union’s H₂020 research and innovation program, GA No 730871, ARIES.
A compact, longitudinal diagnostics for fs-scale electron bunches using a THz electric-field transient in a split-ring resonator (SRR) for streaking will be tested at the Ferninfrarot Linac- Und Test- Experiment (FLUTE). For this new streaking technique, intensive THz pulses are required, which will be generated by laser-based optical rectification. We present a setup for generating THz pulses using tilted-pulse-front pumping in lithium niobate at room temperature. Excited by an 800 nm Ti:Sa pump laser with 35 fs bandwidth-limited pulse length, conversion efficiencies up to 0.027% were achieved. Furthermore, the status of the SRR experiment is shown.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB251

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

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THPAB258

Status of Time-Domain Simulation for the Fast Orbit Feedback System at the HEPS

simulation, feedback, power-supply, emittance

4311

Y. Wei, Z. Duan, X.Y. Huang, Y. Jiao
IHEP, Beijing, People’s Republic of China

High Energy Photon Source (HEPS) is a complex designed at ultra-low emittance. A fast orbit feedback system is proposed to meet the requirement of beam orbit stability at the sub-micron level. In this paper, we present our work on setting up an orbit feedback process combined with noise model, system modeling, and particle tracking in the time domain. RF phase parameter is adjusted together with fast correctors to mitigate the orbit fluctuation due to energy vibration. The preliminary results are shown here. By the following optimization, we hope to provide an effective tool to specify and configure the FOFB system with the simulation.

Poster THPAB258 [1.334 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB258

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paper received ※ 19 May 2021 paper accepted ※ 27 July 2021 issue date ※ 31 August 2021

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THPAB290

Evolution of the LHC Beam Screen Surface Conditioning Upon Electron Irradiation

electron, radiation, ECR, gun

4370

S. Bilgen, S. Della-Negra, D. Jacquet, B. Mercier, I. Ribaud, G. Sattonnay
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
V. Baglin
CERN, Meyrin, Switzerland

For the vacuum scientists and the accelerator community, finding solutions to mitigate pressure rises induced by electron, photon, and ion desorption, and also beam instabilities induced by ion and electron clouds is a major issue. Moreover, it is worth noting that the OFE copper beam screen of the LHC is initially cleaned with standard industrial processes, leading to residual chemical contamination. Along the time, changes in the surface chemistry of vacuum chambers are observed during beam operations, leading to modifications of outgassing rates, stimulated desorption processes, and secondary emission yields (SEY). The impact of ions on molecule desorption and electron production was investigated to identify their influence on the global pressure rises and to quantify the ion conditioning effect on copper surfaces: (i) SEY evolution was measured to understand the changes of surface conditioning upon particle irradiation; (ii) surface chemistry evolution after electron irradiation was investigated by both XPS and TOF-SIMS analyses using the ANDROMEDE facility at IJCLab. Finally, the relationship between surface chemistry and the conditioning phenomenon will be discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB290

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paper received ※ 19 May 2021 paper accepted ※ 14 July 2021 issue date ※ 10 August 2021

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THPAB291

DYVACS (DYnamic VACuum Simulation) Code: Gas Density Profiles in Presence of Electron Cloud in the LHC

electron, proton, injection, photon

4373

S. Bilgen, B. Mercier, G. Sattonnay
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
V. Baglin
CERN, Meyrin, Switzerland

The computation of residual gas density profiles in particle accelerators is an essential task to optimize beam pipes and vacuum system design. In a hadron collider such as the LHC, the beam induces dynamic effects due to ion, electron, and photon-stimulated gas desorption. The well-known VASCO* code developed at CERN in 2004 is already used to estimate vacuum stability and density profiles in steady-state conditions. Nevertheless, some phenomena are not taken into account such as the ionization of residual gas by the electron clouds and the evolution of the electronic density related to the electron cloud build-up. Therefore, we propose an upgrade of this code by introducing electron cloud maps** to estimate the electron density and the ionization of gas by electrons leading to an increase of induced desorption. The pressure evolution computed with DYVACS reproduces with good accuracy the experimental pressure recorded in the VPS beam pipes sector*** of the LHC from the proton beam injection to the stable beam period. Additionally, DYVACS can also be used as a predictive tool to compute the pressure evolution in the beam pipes for Future Circular Colliders (FCC-hh or -ee).
* A. Rossi, Tech. Report, LHC Project Note 341
** T. Demma et al Phys. Rev. Acceler. and Beams 10, 114401 (2007)
*** B. Henrist et al, Proc. IPAC2014, Dresden

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB291

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paper received ※ 19 May 2021 paper accepted ※ 02 August 2021 issue date ※ 31 August 2021

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THPAB292

Dynamic Pressure in the LHC: Detection of Ions Induced by Ionization of Residual Gas by the Proton Beam and by the Electron-Cloud

electron, proton, experiment, ECR

4377

S. Bilgen, B. Mercier, G. Sattonnay
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
V. Baglin
CERN, Meyrin, Switzerland

Ultra-High Vacuum is an essential requirement to achieve design performances and high luminosities in high-energy particle colliders. Consequently, the understanding of the dynamic pressure evolution during accelerator operation is fundamental to provide solutions to mitigate pressure rises induced by multiple effects leading to beam instabilities. For the LHC, the appearance of instabilities may be due to the succession of several phenomena: (i) the induced desorption of gases adsorbed on the surfaces leading to pressure rises; (ii) the creation of secondary particles (ions, electrons); (iii) the production of the so-called Electron Cloud build-up by multipacting effect. This work aims to investigate some fundamental phenomena which drive the dynamic pressure in the LHC, namely the effects induced by electrons and ions interacting with the copper surface of the beam screens. Electron and ion currents, as well as pressure, were recorded in situ in the Vacuum Pilot Sector (VPS*) located on the LHC ring during the RUN II. By analyzing the results, more ions than expected were detected and the interplay between electrons, ions, and pressure changes was investigated.
* The LHC Vacuum Pilot-Sector Project, B. Henrist, V. Baglin, G. Bregliozzi, and P. Chiggiato, CERN, Geneva, Switzerland, Proceedings of IPAC2014, Dresden, Germany

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB292

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paper received ※ 19 May 2021 paper accepted ※ 01 July 2021 issue date ※ 27 August 2021

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THPAB341

TiN Metalizing and Coating for Multi-Megawatt RF Vacuum Windows

Windows, electron, multipactoring, high-voltage

4457

M.L. Neubauer, A. Dudas, R.P. Johnson
Muons, Inc, Illinois, USA

Coatings on microwave windows and high-voltage ceramics are required to eliminate secondary electron emission (SEE), which initiates multipactoring discharge causing local heating and ceramic failures due to cracking and loss of vacuum. The region surrounding the triple junction (ceramic+metal+vacuum) is the primary source of free electrons and in microwave windows and high-voltage ceramics. This region is located at the metalizing and braze joint of the ceramic support structure making the vacuum seal. On very large microwave windows typically at low frequencies, this critical region is difficult to coat by the traditional techniques of sputter coating anti-multipactoring titanium nitride or other materials. The novel processes proposed here include a means for applying and controlling the thickness of titanium nitride both in the metallizing (controlling the source) and on the surface of the window, eliminating SEE and the multipactoring discharge.

Poster THPAB341 [0.845 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB341

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paper received ※ 23 May 2021 paper accepted ※ 21 July 2021 issue date ※ 01 September 2021

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THPAB343

Test Results of the Prototype SSR1 Cryomodule for PIP-II at Fermilab

cavity, cryomodule, SRF, focusing

4461

D. Passarelli, J. Bernardini, C. Boffo, B.M. Hanna, S. Kazakov, T.N. Khabiboulline, A. Lunin, J.P. Ozelis, M. Parise, Y.M. Pischalnikov, V. Roger, B. Squires, A.I. Sukhanov, G. Wu, V.P. Yakovlev, S. Zorzetti
Fermilab, Batavia, Illinois, USA
C. Contreras-Martinez
FRIB, East Lansing, Michigan, USA

Funding: Work supported by Fermi Research Alliance, LLC under Contract No. DEAC02- 07CH11359 with the United States Department of Energy
A prototype cryomodule containing eight Single Spoke Resonators type-1 (SSR1) operating at 325 MHz and four superconducting focusing lenses has been successfully assembled and cold tested in the framework of PIP-II project at Fermilab. The performance of cavities and focusing lenses along with test results of other cryomodule’s key parameters are presented in this contribution.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB343

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paper received ※ 20 May 2021 paper accepted ※ 08 August 2021 issue date ※ 28 August 2021

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FRXB04

Newly Development of Ceramics Chamber with Integrated Pulsed Magnet for Super-Narrow Bore in KEK-PF

injection, kicker, multipole, dipole

4524

C. Mitsuda, K. Harada, Y. Kobayashi, S. Nagahashi, T. Nogami, T. Obina, R. Takai, H. Takaki, T. Uchiyama, A. Ueda
KEK, Ibaraki, Japan
K. Hamaji, K. Iwamoto, A. Sasagawa, A. Yokoyama
KYOCERA Corporation, Higashiomi-city, Shiga, Japan
Y. Lu
Sokendai, Ibaraki, Japan

Ceramics chamber with integrated pulsed magnet (CCiPM) is a new air-core type magnet that has a plan to be used as a multipole injection magnet, a dipole injection kicker, and a fast correction kicker in the next-generation light source. The magnet coils are implanted completely into the thickness of cylindrical ceramic and integrated with ceramic structurally. The first CCiPM was developed for an internal diameter of 60 mm as a magnet bore to establish the basic production techniques. The technique has been enhanced to realize narrower bore over 3 years, and finally, the achieved internal diameters were 40 and 30 mm in newly developed CCiPM. These super small bores have an expectation to conform to the size of the vacuum beam duct in the ring of a future light source. New CCiPMs are under the off-line test to confirm the vacuum durability, electrical characteristics, and magnetic performance, and the beam test for the CCiPM with 30 mm diameter has also proceeded in parallel. The points of production technique and the recent results of the off-line test will be presented in this conference.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-FRXB04

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

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