vacuum
MOCD3
Observations and efforts to reduce sudden beam loss at SuperKEKB
57
The SuperKEKB accelerator recorded a peak luminosity more than twice that of the KEKB accelerator, but there are various challenges in updating the luminosity beyond that. One of the challenges is to eliminate sudden beam loss (SBL), in which a significant part of the circulating beam is lost in a few short turns. SBLs of the positron ring were investigated and found that the SBLs are characterized by vacuum pressure bursts at specific locations in the ring and an increase in beam size. From these measurements, it can be inferred that some phenomenon occurred at the location where the pressure burst was occurring, causing the beam size to increase and the beam to be lost in the narrow aperture of the ring. We performed knocker tests to artificially cause SBL and looked for possible sources of SBL. Based on several assumptions, we performed several works, including swapping the chamber up and down, cleaning the inside of the chamber, and knocking the chamber before operation. Of these works, the cleaning inside the chamber was found to be likely to be effective. This paper summarizes the measurement of SBL when it occurred and the countermeasures that contributed to its reduction.
Paper: MOCD3
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOCD3
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 08 Sep 2025
MOPB005
SLS 2.0 storage ring upgrade overview
79
The Swiss Light Source, SLS, storage ring has been rebuilt as SLS2.0, to improve the radiation brightness by about two orders of magnitude. All components of the storage ring lattice and its supporting infrastructure are newly constructed and were installed during a 15-month shutdown that began in October 2023. The linac and booster synchrotron received only small modifications with the exception of a new power supply for the main magnet circuit with its 3 Hz current ramp. The new 7 bend achromat arcs had to fit the existing tunnel footprint and the location of the beamline exit ports resulting in tiny distances between magnets. In addition, all bends (and reverse bends) are based on permanent magnets necessitating thorough cross-talk studies due to larger stray magnetic field. The high density of magnets prevented the installation of vacuum bellows required for in-situ bake-out, so the twelve vacuum arc strings, of 18 m in length each, were installed in the ring after activation and pumping to a pressure around 1.e-11 mbar. Four HOM damped RF cavities at 500 MHz are installed in a row and supplied by four solid-state amplifiers of 150kW each. Two beamlines are dedicated to beam diagnostics and newly developed BPM and feedback systems monitor and stabilize the beam. This paper describes the main challenges faced during the SLS storage ring upgrade and gives an overview of the presently achieved performance. Beam commissioning details are described in a companion paper.
Paper: MOPB005
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPB005
About: Received: 23 May 2025 — Revised: 04 Jun 2025 — Accepted: 06 Jun 2025 — Issue date: 08 Sep 2025
MOPB074
SOLEIL II project: entrance in the construction phase
212
SOLEIL II is the French upgrade project to build the science of tomorrow with synchrotron light radiation. Providing the highest brilliance in its class while maintaining the radiation range from IR to hard X-rays, the project is an ambitious triple upgrade of the SOLEIL facility: accelerators (new booster and storage ring), 29 beamlines and 3 laboratories, and an information technology transformation plan. High Order Achromat based on multi-bend achromat lattices will be used to replace both the storage (SR) and booster rings of the Synchrotron SOLEIL. The achieved equilibrium emittance of the SR (below 100 pm.rad, 354 m, 2.75 GeV) is about 50 times smaller than that of the existing Storage Ring (4000 pm.rad). To ensure the technical feasibility, an intensive R&D phase based on extensive numerical simulations, prototyping and measurements has been carried out. This paper presents the latest status of the project, the updated timeline, and describes the main results obtained so far in terms of performance and the prototypes launched in many technical domains (lattice, magnets, insertion device, vacuum, alignment…).
Paper: MOPB074
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPB074
About: Received: 03 Jun 2025 — Revised: 03 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 08 Sep 2025
MOPM036
Beam losses due to beam-residual gas interactions in the FCC-ee
390
The Future Circular electron-positron Collider, FCC-ee, is a design study for a luminosity-frontier and highest-energy e+e- collider with a 91 km circumference. In a circular machine, the interactions between the beam particles and the residual gas in the vacuum chamber may degrade the beam quality, potentially affecting the beam lifetime and the collider luminosity, and cause local beam losses. In addition, experimental backgrounds may be increased. Ideally, the vacuum system must be able to keep vacuum conditions sufficiently good so that beam-residual gas interaction effects are tolerable for collider operation. This paper presents a study of the beam loss distribution arising from beam-residual gas interactions in the FCC-ee, together with beam-gas lifetime estimates.
Paper: MOPM036
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM036
About: Received: 28 May 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 08 Sep 2025
MOPM064
Operational experience and design improvement studies of the LHC MKI cool
466
In view of the unprecedented beam intensities expected in the High-Luminosity era of the Large Hadron Collider (HL-LHC), an upgrade of the LHC injection kickers (MKIs) is currently underway. This upgrade aims to mitigate excessive beam-induced heating of the MKIs and to limit resulting vacuum activity. The first MKI Cool was installed in the LHC during the Year End Technical Stop (YETS) in 2022-2023, and the upgrade of the entire system of 8 injection kickers is expected to be completed during Long Shutdown 3 (LS3). This paper discusses the operational performance of the new MKI Cool magnets and compares it to the magnets of the post-LS1 design. Additionally, it focuses on investigations aimed at understanding the observed results, with the goal of further enhancing the performance of the MKI Cool design.
Paper: MOPM064
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM064
About: Received: 28 May 2025 — Revised: 01 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 08 Sep 2025
MOPM066
Performance improvement studies for the CERN SPS MKDH system
474
The CERN-SPS beam dump system (SBDS) is equipped with a dilution kicker system, the so-called MKDH. During the 2022 and 2023 beam commissioning, the vacuum rise in the MKDH became a concern for reaching the anticipated higher beam intensities. Dedicated conditioning of the SPS kickers enabled successful attainment of High-Luminosity (HL) beam intensities during 2024 operation. However, the conditioning time required after replacing an MKDH magnet remains a significant concern, leading to a study aimed at optimizing its high intensity performance. This paper presents a feasibility assessment, a detailed characterization of the operational kickers and the spare units, and proposed modifications designed to optimize the MKDH kicker magnet performance. The modifications focus on minimizing interactions and coupling between the kicker and the beam, with the ultimate goal of improving the operational efficiency with high intensity beams.
Paper: MOPM066
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM066
About: Received: 28 May 2025 — Revised: 01 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 08 Sep 2025
MOPM107
Status of construction of the new heavy ion synchrotron SIS100 at FAIR
567
The construction of the new FAIR heavy ion accelerator facility at GSI is progressing well. With the start of installation of SIS100 an important new milestone in project execusion has been reached. SIS100 is the first superconducting, fast ramped synchrotron with special design features dedicated to the acceleration of high intensity, low charge state heavy ions. The full performance of the specific functional systems, stabilizing the dynamic vacuum at operation with high Uranium intensities in combination with high repetition rates, was recently demonstrated at the SIS100 string test. Even under the influence of eddy current heating of the chamber walls at high ramp rates, its separatly cooled cryogenic vacuum system assures a stabilization of the residual gas pressure at extremely low values. The first straight sectors and arc modules have been installed heading towards a first hardware commissioning in 2026.
Paper: MOPM107
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPM107
About: Received: 01 Jun 2025 — Revised: 03 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 08 Sep 2025
MOPS043
ALBA II accelerator upgrade project status
706
ALBA is working on the upgrade project that shall transform the actual storage ring, in operation since 2012, into a 4th generation light source, in which the soft X-rays part of the spectrum shall be diffraction limited. The project was launched in 2021 with an R&D budget to build prototypes of the more critical components. The storage ring upgrade is based on a MBA lattice which has to comply with several constraints imposed by the decision of maintaining the same circumference (269m), the same number of cells (16), the same beam energy (3GeV), and as many of the source points as possible unperturbed. At present, the lattice optimization, iterating with the technical constraints of space and performance, is ongoing. This paper presents the situation of the project, with the present proposed lattice and equipment design; the status of the prototyping of magnets, pulsed elements. vacuum chambers, buttons BPMs, and girders; the proposed RF system with fundamental and harmonics cavities; and the general context of the upgrade.
Paper: MOPS043
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPS043
About: Received: 26 May 2025 — Revised: 03 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 08 Sep 2025
MOPS055
Magnet assembly of IVUE32 in-vacuum-APPLE II at BESSY II
741
At HZB / BESSY II the first in-vacuum APPLE II undu-lator is under construction. The design includes three magnet arrays for each of the four magnet rows for an efficient force compensation. The support and drive sys-tem has been delivered. Currently the magnets for the 10-period prototype are fabricated by Vacuumschmelze. Within the project IVUE32 a new soldering technique based on reactive foils has been developed in collabora-tion with Vacuumschmelze. The magnet structure of the IVUE32 undulator will employ the soldering technique aiming for enhanced assembly simplicity. Two new ex-perimental setups for the characterization of soldered subassemblies have been built for obtaining stress-strain curves and for lifetime (fatigue) tests. These instruments will be presented and measurements will be discussed.
Paper: MOPS055
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPS055
About: Received: 19 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 08 Sep 2025
MOPS060
Undulators for BESSY III
748
Helmholtz Zentrum Berlin is engaged in the conceptual design of the BESSY III facility. The BESSY III storage ring will be a fourth generation synchrotron light source with an emittance of about 100 pm rad and an energy of 2.5 GeV. It will be equipped with advanced undulators to provide users with tailor-made light. So far cryogenic permanent magnet undulators, hybrid planar undulators and a variety of APPLE II undulators - conventional (in-air) and in-vacuum are planned to meet user requirements in terms of spectral range, flux and polarisation. In this paper we give an overview of the planned undulators, discuss some of the design aspects and present their expected performance.
Paper: MOPS060
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPS060
About: Received: 25 May 2025 — Revised: 01 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 08 Sep 2025
MOPS061
MAX 4U: an upgrade of the MAX IV 3 GeV ring
752
The MAX IV 3 GeV storage ring in Lund, Sweden, was the first implementation of a multibend achromat (MBA) lattice fourth-generation light source. Since it started delivery of light in 2016, three succeeding MBA-based rings and variants have come on-line: ESRF-EBS, Sirius and APS-U. Several others are being planned, designed, built or commissioned. All of these capitalize on the MBA concept and expand it to push the brightness and coherence performance even further. In order to continue to offer the Swedish and international scientific communities competitive tools beyond the end of this decade, MAX IV Laboratory launched in 2024 the conceptual design of MAX 4U , an upgrade of its 3 GeV storage ring aiming at an emittance below 100 pmrad. This performance boost is to be achieved through a minimum-interference upgrade in which localized interventions in selected subsystems and components are carefully chosen to provide the maximum performance increase with minimum cost and, equally important, minimum dark time for the MAX IV user community. This contribution describes the accelerator physics and engineering aspects of the MAX 4U conceptual design and presents the latest developments.
Paper: MOPS061
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPS061
About: Received: 21 May 2025 — Revised: 03 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 08 Sep 2025
MOPS065
Physics-driven specifications for the EIC ESR magnet power supply ripple
760
To avoid unacceptable proton emittance growth via beam-beam interaction, the EIC electron storage ring (ESR) requires very stringent tolerances for beam position and size stability at the interaction point. These tolerances imply tight specifications for several accelerator systems, including magnet power supplies (PS). While the magnetic field ripple requirements are most stringent at the betatron frequency and harmonics, the main PS challenges occur below ~1 kHz, where the ripple attenuation due to the vacuum chamber is insufficient. In the original ESR dipole powering scheme with ~20 families, the dipole PS current ripple specifications were found to be near or beyond the state-of-the-art. A recently adopted scheme with a single ESR main dipole PS relaxes these requirements to ~10 parts per million (ppm) rms, which is achievable. Additionally, the vacuum chambers of non-standard cross-sections required at some dipoles must be modified to match the field penetration time constant to that of the standard vacuum chamber. The paper presents the physics reasoning and simulations behind the latest PS ripple specifications, ranging from 5 to 100 ppm rms, depending on the magnet type.
Paper: MOPS065
DOI: reference for this paper: 10.18429/JACoW-IPAC25-MOPS065
About: Received: 28 May 2025 — Revised: 01 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 08 Sep 2025
TUZD2
SPS-II project: Status update
903
Siam Photon Source II (SPS-II) is a 4th-generation synchrotron light source set to be constructed in Thailand, aimed at becoming a major synchrotron facility for Southeast Asia. It is designed with a 3 GeV low-emittance electron storage ring, featuring a DTBA lattice and a circumference of 327.6 meters. Recently, the design and machine parameters have been carefully revised, with a particular focus on optimizing vacuum performance and the main RF frequency to ensure beam stability and reliable operation. In parallel with the design phase, significant progress has been made in developing key prototypes, including magnets, vacuum chambers, and girders, through collaboration with local Thai companies.
Paper: TUZD2
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUZD2
About: Received: 28 May 2025 — Revised: 30 May 2025 — Accepted: 31 May 2025 — Issue date: 08 Sep 2025
TUPB017
First results of the new eddy current septum for the CERN PS fast extraction
983
CERN has developed a new fast pulsed septum magnet to replace the aging PS proton extraction septum. The aim is to increase the refurbishment intervals of the magnet and to phase out the old power converter, while allowing energy savings during operation. The new system includes a novel under vacuum eddy current septum magnet, a new third-harmonic fast pulse generator and dedicated control system with post pulse fault analysis for achieving the required flat top precision. This paper will briefly describe the system development and focus on the lessons learned from its construction and report the results of the testing phase.
Paper: TUPB017
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPB017
About: Received: 27 May 2025 — Revised: 31 May 2025 — Accepted: 31 May 2025 — Issue date: 08 Sep 2025
TUPB034
Status of the pulsed hydrogen gas stripper project at GSI
1044
The operation of the specifically upgraded pulsed gas stripper development setup for the user beamtime lasted until July 2024. It was very successful in terms of both providing stripped ions and gaining valuable experience in the long-term operation of the pulsed stripper. The long periods of high duty nitrogen operation revealed a severe service life issue of the fast injection valves, which was already anticipated in the risk assessment for the hydrogen operation. This emphasizes the need for the safety measures incorporated in the design of the pulsed stripper facility. During the user beamtime, several measurement campaigns were conducted. Extensive data on the stripping efficiencies for 12 projectile-target combinations could be obtained. In this contribution the obtained results and lessons learned are presentet as well as the necessary next steps to finaly bring the hydrogen stripping to routine operation.
Paper: TUPB034
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPB034
About: Received: 27 May 2025 — Revised: 30 May 2025 — Accepted: 04 Jun 2025 — Issue date: 08 Sep 2025
TUPM020
An upgraded multiprobe surface analysis tool for photocathode research and development
1205
STFC Daresbury laboratory has developed a suite of analysis equipment for characterisation of photocathode materials. This includes the TESS spectrometer for measuring the mean transverse energy* and a multiprobe surface analysis system for measuring the chemical and physical properties of samples**. Recently, the multiprobe system has been upgraded to include a monochromated X-ray source which in conjunction with the high-resolution analyser should produce improved ability to resolve the chemical state of surface constituent atomic species. This could be particularly useful in the analysis of telluride and antimonide cathodes where incomplete reaction of the constituent species could significantly influence performance. The atomic force microscope has also been recommissioned giving access to surface topological information in the same vacuum environment. Finally, a new sample deposition chamber has been added which will allow additional deposition sources to be attached thus broadening the range of photocathode research that can be carried out.
Paper: TUPM020
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPM020
About: Received: 23 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 08 Sep 2025
TUPM043
Surface cleaning and chemical process analysis of high quantum efficiency magnesium photocathode
1249
Magnesium (Mg) has been demonstrated to be a safe, stable, and reliable photocathode for both normal-conducting and superconducting RF guns. Pure magnesium, with its low work function of 3.6 eV, exhibits significant quantum efficiency (QE) improvement — by up to two orders of magnitude — following appropriate surface cleaning procedures. This study investigates the chemical processes occurring on the material's surface in its as-received state and after thermal and plasma cleaning. These findings provide critical insights into the mechanisms underlying QE enhancement on this metallic photocathode.
Paper: TUPM043
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPM043
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 08 Sep 2025
TUPM046
Study on deposition method for improving quantum efficiency and lifetime of NEA-GaAs photocathode using cesium, antimony and oxygen
1256
Negative Electron Affinity (NEA) activated GaAs photocathodes are the only one capable of generating spin-polarized electron beam larger than 90%. However, the NEA layer currently made from mainstream cesium (Cs) and oxygen (O) is chemically unstable, the NEA-GaAs photocathode has a rapid quantum efficiency degradation over time or electron beam. As a result, it requires an operating vacuum pressure of below 10-9 Pa and has a short lifetime. Recently, a new NEA layer using heterojunctions with semiconductor thin films of alkali metals and antimony (Sb) or tellurium has been proposed. Recent works have shown that the deposition of the NEA layer was realized using cesium, antimony and oxygen. In this work, we attempted to introduce Sb at two different timing. One is introduction from the beginning, and the other one is introduction after Cs and oxygen deposition. We systematically investigate the deposition temperature and antimony thickness to find the optimal conditions for improving quantum efficiency and lifetime. We will report the latest results.
Paper: TUPM046
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPM046
About: Received: 20 May 2025 — Revised: 03 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 08 Sep 2025
TUPM064
Cryogenic APPLE undulator development at Helmholtz-Zentrum Berlin
1300
In order to achieve polarization control at tender photon energies at a medium energy light source, a cryogenic in-vacuum APPLE device is being developed at Helmholtz Zentrum Berlin. The project builds on the innovative design of the in-vacuum APPLE II IVUE32 also in development at HZB. The state of the magnet and mechanical design is presented, in addition to the expected spectral performance of the device upon installation in the BESSY II storage ring.
Paper: TUPM064
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPM064
About: Received: 28 May 2025 — Revised: 02 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 08 Sep 2025
TUPM066
Universal mode of operation of the APPLE II undulators at the MAX IV 1.5 GeV ring
1307
At the MAX IV 1.5 GeV ring, two APPLE II undulators with period lengths of 84 mm (Bloch) and 95.2 mm (FinEstBeams) cover minimum photon energies of 7 eV and 4 eV, respectively. Operating below 80 eV, the polarization state is distorted significantly by the beamlines' optical elements. A combination of helical and linear inclined modes during undulator operation - the so-called universal mode - can compensate for the distortions. In this paper, we describe how we compensate for the effect of the undulators on the beam orbits and ring optics when operating in universal mode. Additionally, some of the achieved commissioning results at both beamlines will be shown.
Paper: TUPM066
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPM066
About: Received: 13 May 2025 — Revised: 31 May 2025 — Accepted: 03 Jun 2025 — Issue date: 08 Sep 2025
TUPM068
First magnetic experience with APPLE X knot undulators for SLS 2.0
1315
The next generation of synchrotrons will have undulators with shorter periods, stronger magnetic fields, and thus higher radiation power. Consequently, concepts for reducing on-axis heat load will become more relevant. One possible idea is to introduce so-called APPLE “knot” undulators that shift the main energy peak off-axis. Thanks to almost on-axis injection, APPLE X undulators with a round vacuum chamber can be used for the upgraded SLS 2.0 at the Paul Scherrer Institute (PSI). This contribution presents an adaptation of the APPLE “knot” concept tailored to the needs of SLS 2.0 in the form of two-meter-long APPLE X undulators with a 36 mm period length and a gap of 11.5 mm. Our design faces the challenge of dealing with up to 16 different magnetization angles introduced by combining and merging NdFeB magnets into four arrays with peak fields around 1 T. Consequently, the magnetic design and the first measurement results are discussed with an outlook on magnet optimization.
Paper: TUPM068
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPM068
About: Received: 27 May 2025 — Revised: 30 May 2025 — Accepted: 30 May 2025 — Issue date: 08 Sep 2025
TUPM070
Progress of SUNDAE2 magnetic measurement setup for superconducting undulators at European XFEL
1319
At European XFEL up to six superconducting undulators with 18 mm period and 1.83 T magnetic field are planned to enlarge the hard X-ray photon range above 30 keV. Currently, S-PRESSO, a prototype with 2x 2m long undulator sections plus phase shifter in a 5m long cryostat is being produced. The SUNDAE2 (Superconducting UNDulAtor Experiment 2) magnetic field test facility aims to perform in-vacuum magnetic field measurements of superconducting undulators (SCUs). This work provides an update on the progress of SUNDAE2, which employs Hall probe, moving wire, and pulsed wire techniques for precise magnetic field characterization to meet the specifications for the FEL operation.
Paper: TUPM070
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPM070
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 08 Sep 2025
TUPM071
Finalizing the multiphysics design of a high heat-load superconducting undulator
1322
RadiaBeam is developing and manufacturing a 15mm period, high temperature superconductor undulator using Magnesium Diboride (MgB2) wire at 10K-15K temperature range. This temperature range can be achieved by cryocooler, a simpler and less expensive cryogenic solution compared to a liquid helium approach. After optimizing the thermal-mechanical design, the operating temperature is finalized at 7K. We examine the current density, critical field, tensile stress, tensile strain, and temperature of MgB2 wire in multiphysics approach and determine the operating field to be 1.13T with safety margin. A quench-protected power system is developed for training the SCU to the operating point in controlled ramp rate. The SCU will be characterized by in-vacuum pulse wire measurement system.
Paper: TUPM071
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPM071
About: Received: 28 May 2025 — Revised: 31 May 2025 — Accepted: 31 May 2025 — Issue date: 08 Sep 2025
TUPM072
Two in-vacuum undulators developed for the Sirius
1326
The Shanghai Synchrotron Radiation Facility (SSRF) project team developed two in-vacuum undulators (IVUs) with a period length of 18.5 mm and a gap of 4 mm for the SIRIUS. This paper introduces the design and magnetic field measurements. The results indicate that with a gap range of 4-20 mm, the phase error is less than 3°, the quadrupole field is less than 37 Gs, the sextupole field is less than 83 Gs/cm, and the octupole field is less than 84 Gs/cm².
Paper: TUPM072
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPM072
About: Received: 27 May 2025 — Revised: 31 May 2025 — Accepted: 14 Jun 2025 — Issue date: 08 Sep 2025
TUPS041
PEEK-Polymer as a vacuum-window in high power rf-couplers
1521
PEEK is an advanced polymer known for its exceptional mechanical strength, thermal stability, and radiation resistance, making it a promising candidate for applications in extreme environments. This study explores the viability of PEEK as a vacuum window material in high-power radio frequency (RF) couplers. Traditionally, materials such as ceramics are employed for this purpose; however, they are costly to manufacture and impose limitations during the design process. PEEK offers additional advantages, including the possibility of additive manufacturing, which enables the integration of cooling channels for efficient thermal management. The research evaluates PEEK's electrical, thermal, and mechanical properties under conditions typical of high-power RF couplers, such as vacuum stability, RF-induced heating, and electromagnetic transparency. At the Institute for Applied Physics (IAP), PEEK is tested as a vacuum window material in high-power experiments up to 35 kW. Following these tests, the material is analyzed to assess its performance and suitability for RF applications.
Paper: TUPS041
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPS041
About: Received: 28 May 2025 — Revised: 02 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 08 Sep 2025
TUPS047
Assembly and testing of a QWR for the new ISIS MEBT
1530
The quarter wave resonator (QWR, a.k.a. λ/4 resonator) for the new ISIS MEBT is a bunching cavity that longitudinally compresses the H- beam into smaller bunches. It has two gaps with a distance of βλ/2 between mid-gaps, and works in π mode at the resonant frequency of 202.5 MHz, with a phase angle of -90 degrees, and a maximum voltage per gap (E0L) of 55 kV. The detailed RF and thermal design was developed, followed by the manufacturing of a prototype, all being presented elsewhere. Several mechanical issues were noticed with the RF finger strips and tuners during the assembly of the prototype cavity. The manual tuner (to account for the manufacturing tolerances and the vacuum load) was machined to the final dimension to achieve the desired resonant frequency, according to the Vector Network Analyser (VNA) measurements. The measured quality factor was found to be much lower than expected, which required a redesign of some of the RF seals. The cavity was powered and conditioned in a relatively short time up to a nominal power, but severe multipacting was observed, initially only at low power, but later also at medium power levels, which required a creative approach to be fixed without a major cavity redesign.
Paper: TUPS047
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPS047
About: Received: 03 Apr 2025 — Revised: 02 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 08 Sep 2025
TUPS050
Mechanical design of a spin rotator for the ISIS Super MuSR beamline
1542
The Super MuSR spin rotators (SR) are electromagnetic devices with a horizontal dipolar magnetic field to rotate the muon spin by 34o and a perpendicular electric field that operates at +/-192 kV. The electromagnetic design was already presented elsewhere. The mechanical design is now complete, and the manufacturing of components has started, both of which are discussed here. The stainless steel vessel is 598 mm in diameter, 1.8 m long and has several ports along it. Most notably the large feedthrough port with a 15 mm inner radius to reduce the electrical fields. Mirror polished electrodes are mounted on ceramic insulators, optimised to shield the triple points from the high electric fields. The insulator mechanical design, manufacture & testing will also be discussed here. A high voltage test rig has been developed in parallel to test critical aspects such as the high voltage feedthrough, insulator design, vessel manufacture and surface finish requirements, before testing and assembling the main vessel. The magnet yoke is H-shaped with traditional racetrack coils. It was designed to be assembled around the around the vacuum vessel with kinematic feet for adjustment and alignment.
Paper: TUPS050
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPS050
About: Received: 06 May 2025 — Revised: 01 Jun 2025 — Accepted: 02 Jun 2025 — Issue date: 08 Sep 2025
TUPS062
Assembly of the IFMIF SRF Linac cryomodule
1570
Complementing its contributions to the JT-60SA and ITER fusion reactors, Fusion for Energy contributes to the R&D for material characterization facilities. Under the Broader Approach agreement, Europe and Japan are developing the Linear IFMIF Prototype Accelerator (LIPAc) in Japan, a deuteron accelerator demonstrator producing neutrons by nuclear stripping reactions on a liquid lithium target, part of the International Fusion Materials Irradiation Facility (IFMIF) project. In 2024, LIPAC prepared for the installation of the SRF cryomodule, concluding its construction. As first prototype, the cryomodule assembly faced challenges at various stages. Started in March 2019, the assembly was paused during its cleanroom phase due to quality issues with the superconducting solenoids, resuming in Aug. 2022. Further issues delayed the completion of the cleanroom activities until Sept. 2024. In 2024, the cryomodule assembly progressed at a good rate. The clean room worked concluded in Sept. and by late 2024 the cold mass was ready for insertion into the vacuum vessel, with transfer to the vault planned for early 2025. In this paper, we will outline the critical steps of this assembly process.
Paper: TUPS062
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPS062
About: Received: 29 May 2025 — Revised: 02 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 08 Sep 2025
TUPS074
Packaged photocathodes for X-ray free electron lasers
1586
Alkali photocathodes are vital for generating high-performance electron beams in accelerator technologies, but their production remains challenging. Current in-house fabrication methods are complex, costly, and unreliable, limiting the potential of these materials for bright electron sources. Our innovative approach seeks to commodify photocathodes, offering a ready-to-use product for accelerator facilities and scientific institutions. We use a proprietary sputtering process with in-house-manufactured bulk targets, ensuring consistent quality and streamlined production. Unlike traditional vacuum suitcases, which are heavy and require active power, our photocathodes are stored in portable, palm-sized vacuum canisters that maintain vacuum without power. This design preserves their integrity during transport and handling, addressing their extreme sensitivity to air and moisture, which demands ultra-high vacuum protection. By delivering pre-fabricated, protected photocathodes, we eliminate the need for facilities to invest in specialized equipment, enabling broader adoption and reducing downtime. Our work paves the way for accessible, affordable, and readily available photocathodes.
Paper: TUPS074
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPS074
About: Received: 31 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 08 Sep 2025
TUPS092
Wakefield studies of the taper section of the elliptical in-vacuum undulator - IVUE32
1591
The elliptical in-vacuum undulator (IVU) IVUE32 is being developed at Helmholtz-Zentrum Berlin (HZB). The APPLE-II design allows for not only gap changes but also longitudinal shift movements, putting additional design challenges on the tapers at the entrance and exit of the undulator. The chosen design philosophy separates the gap and shift movement compensation into two assemblies respectively. This approach allows for a solid foil taper as gap movement compensation, which is proven in previously commissioned planar IVUs e.g. CPMU17 at HZB. The shift movement compensation, which requires a slit foil, can be kept parallel. The proximity of this complex structure to the electron beam makes the device susceptible to wakefield effects which can influence beam stability. Investigating and understanding these effects is vital for accelerator operation. The taper design will be presented alongside wakefield simulations and model measurements.
Paper: TUPS092
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPS092
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 08 Sep 2025
TUPS094
Diagnosing an In-Vacuum Undulator in the ALS storage ring
1598
The Advanced Light Source (ALS) has an in-vacuum undulator named “LEDA”. It was installed in 2019 and provides high-brightness, high-energy photons for the ALS macromolecular crystallography beamline, Gemini. The undulator is a hybrid design with a minimum gap of 4.3 mm, a magnetic period of 15 mm, and a photon energy range of 5–19 keV. When the device was commissioned in the ALS storage ring, it had a negligible impact on ring operations. Recently, there has been a measured degradation in storage ring performance correlated with the Leda gap. Prior to conducting an invasive magnetic measurement, we performed a suite of beam-based measurements to characterize Leda. Herein, we detail these measurements and share them with the accelerator community, who may find them useful when encountering similar challenges.
Paper: TUPS094
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPS094
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 08 Sep 2025
TUPS140
Design of Pelletron accelerator using novel accelerating tube without gap insulators
1637
A novel modular electrostatic accelerating tube*, free from gap insulators, is designed that addresses the limitations of traditional metal-insulator bonded accelerating tubes**, which are costly and prone to damage from high-voltage discharges and beam impacts. This design uses ultra-high vacuum (UHV) as the insulator, with electrodes placed in series under vacuum. High voltage is coupled longitudinally to the first cylindrical electrode via a ceramic-bonded stainless steel flange, with homogeneous electric field flatness of 0.001. Electrostatic analysis using COMSOL Multiphysics and TRAVEL code confirms the field homogeneity and smooth beam acceleration, respectively. Designed for 75 kV operation, extendable to q×100keV energy gains, it leverages vacuum-compatible resistors for inter-electrode HV coupling. Field flatness is extendable to few meters of length and thus enabling megavolts. Beam optics and electrical specifications for Pelletron accelerators using these tubes supports practical feasibility. The grounded cylindrical structure ensures safety and offers an economical, scalable design for small low-energy implanters, Pelletron accelerators, and mass spectrometers.
Paper: TUPS140
DOI: reference for this paper: 10.18429/JACoW-IPAC25-TUPS140
About: Received: 29 May 2025 — Revised: 01 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 08 Sep 2025
WEAD1
20 years of CESR-B cavity operation at the CLS
1656
The Canadian Light Source (CLS), a 3<sup>rd</sup> generation synchrotron light source, has operated the CESR-B type superconducting radio frequency cavity since 2005. We report on 20 years of operating experience of the facility with this type of accelerating cavity.
Paper: WEAD1
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEAD1
About: Received: 28 May 2025 — Revised: 02 Jun 2025 — Accepted: 02 Jun 2025 — Issue date: 08 Sep 2025
WEAD3
Further high power tests of the additive manufacturing IH-type cavity
1666
Additive manufacturing (AM) has become a powerful tool for rapid prototyping and manufacturing of complex geometries. A 433 MHz IH-DTL cavity has been constructed as a proof of concept for direct additive manufacturing of linac components. In this design, the internal drift tube structure has been produced from pure copper using AM. We present the most recent results from high-power tests with the AM IH-type structure, including additional tests with improved surfaces to reduce field emission during operation.
Paper: WEAD3
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEAD3
About: Received: 26 May 2025 — Revised: 03 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 08 Sep 2025
WEPB048
Magnetic measurement of a decommissioned insertion device at the Canadian Light Source
1843
The Canadian Light Source has decommissioned three insertion devices in recent years, replacing each with upgraded devices. The decommissioned devices are planar undulators that have seen approximately 15 years of operation in a 2.9 GeV storage ring, two being out-of-vacuum devices with 45 mm and 185 mm periods and one being an in-vacuum 20 mm device. In this paper we present magnetic measurements of the decommissioned 185 mm device (U185) with comparisons against the original measurements from before it was put into service.
Paper: WEPB048
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPB048
About: Received: 24 May 2025 — Revised: 30 May 2025 — Accepted: 31 May 2025 — Issue date: 08 Sep 2025
WEPB055
Design and development a measurement system for magnetic tuning of undulator magnets
1861
The permanent-magnet in-vacuum undulator technique is critical for the Taiwan Photon Source(TPS) at the National Synchrotron Radiation Research Center(NSRRC). Before installing the magnet arrays in the vacuum chamber, the phase error of the undulator is optimized by adjusting the magnetic field. Optimizing phase errors is a complex and time-consuming task. The conventional measurement method involves using Hall probes to measure the magnetic field and a stretched-wire(SW) to measure the integral field of the undulator. In this work, we propose a method for tune the local magnetic field by utilizing the correlation between the gap and the magnetic field. We have demonstrated that using gap sensors allows us to more effectively determine whether to tune the magnetic field of the upper or lower magnet array. Additionally, we have demonstrated for the first time the use of the pulsed wire measurement (PWM) method for magnetic sorting.
Paper: WEPB055
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPB055
About: Received: 14 May 2025 — Revised: 01 Jun 2025 — Accepted: 02 Jun 2025 — Issue date: 08 Sep 2025
WEPB059
Testing and characterization of surface treatment techniques for enhancing the HV performance of kickers
1872
Accelerator kicker magnets, which commonly use ferrite and other insulating materials, can encounter High Voltage (HV) performance limitations due to interactions with the particle beam. These interactions, can lead to electron cloud buildup and charging phenomena on exposed surfaces, negatively impacting kicker performance, particularly at high beam intensities. To mitigate these effects, surface treatment techniques are investigated to improve the HV kicker performance under such conditions. A dedicated set-up is under development to perform HV testing of treated surfaces in both ambient and in vacuum conditions, closely simulating operational conditions. This paper presents insights into the effects of these surface treatments on material properties, supporting strategies to enhance HV kicker reliability at higher beam intensities.
Paper: WEPB059
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPB059
About: Received: 28 May 2025 — Revised: 02 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 08 Sep 2025
WEPB064
Development of a 13 kV SiC-MOSFET-based pulsed power supply for evaluating metallic materials under high electric fields
1890
To perform high electric field experiments for evaluating the vacuum breakdown characteristics of accelerator materials, we have developed a high-voltage pulsed power supply capable of providing a 10 kV peak voltage, 1 µs pulse width, and 1 kHz repetition rate. This system is designed to reliably apply intense fields to metallic electrodes with load capacitances up to 650 pF. To ensure operational reliability and prevent potential equipment damage, it incorporates an interlock system that halts operation when load short-circuits or external interlock signals are detected. By employing a 13 kV SiC-MOSFET developed under the Tsukuba Power Electronics Constellation (TPEC), we reduced the number of components and improved overall reliability. This report presents the technical features and performance of the power supply, demonstrating that it meets the operational specifications necessary for evaluating candidate materials under high electric field conditions.
Paper: WEPB064
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPB064
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 08 Sep 2025
WEPB077
Performance on high-power test bench of RF couplers for the LIPAc’s RFQ
1907
The Linear IFMIF Prototype Accelerator (LIPAc) in Rokkasho, Japan, designed to accelerate p+ to 4.5 MeV and D+ to 9 MeV at 62.5 mA and 125 mA in Continuous Wave (CW) mode, respectively, is under commissioning and about to enter into its final stages. A high-power test bench was developed for the testing and conditioning of the Radio-Frequency (RF) couplers of the RF Quadrupole (RFQ) cavity. The processing, requiring thermomechanical validation up to 200 kW and CW, is currently ongoing. Several tests were done, during which multipacting and thermal outgassing was observed in numerous power bands, particularly at 70 - 90 kW for the couplers, which is crucial for RFQ conditioning at nominal voltage. Subsequent tests showed that the cavity and couplers performed as expected at forward power levels close to beam operation (~ 160 kW).
Paper: WEPB077
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPB077
About: Received: 27 May 2025 — Revised: 02 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 08 Sep 2025
WEPB107
A technique to improve the energy leakage of TM020-mode cavity for Super Tau Charm Facility
1937
TM020-mode cavity with a higher quality factor and a lower R/Q as compared to TM010 cavity is an attractive candidate for RF system of Super Tau-Charm Facility. However, the symmetrical electromagnetic field distribution at radial nodes is diluted by the introduction of a high-power input port and cavity frequency tuners. This results in the leakage of the accelerating mode and a weak damping of harmful modes. In order to address these issues, this paper proposes elliptic coaxial slots and tuning bumps on the inner wall to optimize the performance of the accelerating mode and harmful modes. Simulation results demonstrate that the energy leakage of the accelerating mode can be reduced below 1% during operation and all of harmful modes can be strongly damped.
Paper: WEPB107
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPB107
About: Received: 27 May 2025 — Revised: 31 May 2025 — Accepted: 03 Jun 2025 — Issue date: 08 Sep 2025
WEPM073
Electromagnetic modeling of cryogenic vacuum chambers using a hybrid neural network-boundary integral equation approach
2133
Recently, artificial intelligence and machine learning are actively discussed in the particle accelerator community. The physics-informed neural network (PINN) method, which is a powerful approach for solving differential equations with deep neural networks (DNN), has been successfully applied to the calculation of electromagnetic fields and beam coupling impedances in particle accelerators. In this work, a hybrid PINN method combined with the boundary integral equation (BIE) method is developed to calculate the fields and impedances in accelerator vacuum chambers at cryogenic temperature. The surface impedance boundary condition for the anomalous skin effect is included to model the electromagnetic characteristics of chamber wall surfaces. Transfer learning can accelerate training processes for DNN parameters in a wide frequency band. The hybrid PINN-BIE approach is verified through applications to various chamber cross sections.
Paper: WEPM073
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM073
About: Received: 26 May 2025 — Revised: 30 May 2025 — Accepted: 02 Jun 2025 — Issue date: 08 Sep 2025
WEPM075
Beam impedance investigation of the elliptical interconnecting vacuum modules of the LHC and prospect for HL-LHC
2141
In view of ensuring the successful completion of the third operational run of the Large Hadron Collider (LHC) and preparing for the High-Luminosity LHC era, a systematic assessment of the risk of failure of all the vacuum interconnection modules installed in the accelerator is being carried out. This was prompted by a significant pressure rise in 2023, localized near an interconnection module (212 mm inner diameter) caused by a localized impedance-induced heating on the tension spring. This led to degradation and loss of electrical contact of the Radiofrequency (RF) sliding fingers. The studies include the evaluation of the various modules currently present in the LHC, alongside the description of a mitigation strategy. In this paper, we focus on the study of elliptical vacuum modules both from the point of view of electromagnetic simulations and of experimental validation. We report also on the general strategy where the most critical vacuum modules with sliding contact RF fingers, featuring tension springs, will be replaced with upgraded designs to avoid issues and therefore ensure improved reliability under future operational conditions with higher bunch intensities.
Paper: WEPM075
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM075
About: Received: 27 May 2025 — Revised: 02 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 08 Sep 2025
WEPM076
Beam coupling impedance wireless measurements and application to HL-LHC accelerator components
2145
A novel wireless method for beam coupling impedance measurements is currently under development, with preliminary measurements on beam pipes serving as proof of concept for its validity. This innovative approach overcomes the limitations of existing methods by not only evaluating impedance with high accuracy but also enabling the characterization of an unknown Device Under Test (DUT) as it will be installed in the accelerator. This capability is crucial for constructing accurate impedance models of accelerators and may help resolve or reduce discrepancies between modelled and measured impedance contributions. While analytical computations or simulations can provide accurate predictions of the beam coupling impedance for simple beam pipes with well-defined material properties, they often fail to account for real-world imperfections, such as surface roughness. Potential applications of this method are the characterization of High-Luminosity LHC collimators and other beam vacuum components planned for future installation. By providing detailed insights into their impedance contribution, this method could play a pivotal role in achieving a highly accurate HL-LHC impedance model.
Paper: WEPM076
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM076
About: Received: 27 May 2025 — Revised: 01 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 08 Sep 2025
WEPM077
Resistive wall impedance calculations and effects of NEG coated insertion device vacuum pipes for the PF-HLS ring
2149
I show analytical expressions of the longitudinal and transverse impedances of a two-layered circular pipe and their practical expressions at high frequencies derived by using asymptotic expansions of the Bessel functions. These expressions are applied to resistive-wall impedance calculations of NEG-coated insertion-device(ID) pipes for the PF-HLS ring*, which is proposed as a 2.5/5.0 GeV energy switchable ring and can simultaneously provide synchrotron light pulses emitted by electron bunches stored in the ring and by extremely short electron bunches (50 fs in length) injected from the superconducting linac. Both real and imaginary parts of the impedances rise up in high frequency regions depending on the NEG coating thickness. The heating powers of the ID pipes are calculated from the real parts of the longitudinal impedances for the stored electron beam and for the short electron bunches injected from the superconducting linac. The kick factors and the coherent betatron tune shifts due to the ID pipes are calculated from the imaginary parts of the transverse impedances for the stored electron beam. These dependences on the NEG-coating thickness are shown in this presentation.
Paper: WEPM077
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM077
About: Received: 27 May 2025 — Revised: 30 May 2025 — Accepted: 30 May 2025 — Issue date: 08 Sep 2025
WEPM078
Impedance benchmarking of resistive wall and tapered transitions for the PF-HLS
2153
The PF Hybrid Light Source (PF-HLS) has been proposed in the High Energy Accelerator Research Organization (KEK), capable of utilizing both high-quality beams from a superconducting linac and beams from a low-emittance storage ring. The coupling impedance will cause beam instability, which must be carefully handled. It is essential to benchmark impedance models using analytical methods and different simulation codes. This paper focuses on the impedance benchmarking of resistive wall and tapered transitions in PF-HLS. The regular round chamber (radius of 12 mm), insertion device (ID) chamber (half-height of 4 mm), and the corresponding tapered transitions are studied. Simulation codes, including ImpedanceWake2D (IW2D), CST, and Azimuthal Beam Cavity Interaction (ABCI), are used. For resistive wall calculations, some analytical formulae describing the round chamber impedance and the Yokoya form factors of the ID chamber are applied. For tapered transitions, some formulae calculating the impedance at low-frequency regions (inductive regime) are chosen to compare with results from CST. In high-frequency regions, the impedance result comparison between CST and ABCI is carried out.
Paper: WEPM078
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM078
About: Received: 21 May 2025 — Revised: 29 May 2025 — Accepted: 02 Jun 2025 — Issue date: 08 Sep 2025
WEPM091
Estimation of the microwave instability at ALBA
2183
In a collaborative work between ALBA and KEK the computation of the microwave instability threshold of the current ALBA ring was initiated. This analysis involves solving the dispersion relation equation* and conducting simulations using a Vlasov-Fokker-Planck (VFP) solver**. The longitudinal wake fields of geometric origin of all vacuum elements were computed with GdfidL*** using a bunch whose length is at least 5x smaller than the bunch length given by usual 3MV RF-voltage applied at ALBA. The resistive wall contribution was computed at first as longitudinal impedance by IW2D**** to be converted in a second step into wake fields via Fourier transform. The CSR contribution will also be considered. The impact of the 3 types of wakes on the microwave instability will be studied. The microwave instability single bunch threshold will be computed combining the 3 contributions. This work also serves as a preparation of the future evaluation of the microwave instability of the ALBA upgrade, which is expected for 2030.
Paper: WEPM091
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPM091
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 08 Sep 2025
WEPS135
RF window ghost mode analysis
2447
The RF window acts as a barrier between the vacuum and air, gas, or water while allowing RF power to pass through with minimal loss. Resonant modes (called "ghost modes") can occur within the ceramic disk of a window. The frequencies of these modes depend on the material and size of the ceramic. Ceramic disk dimensions must be carefully optimized to minimize reflections and avoid ghost mode resonances within the operating bandwidth. In this paper we present the design of an input window used in an X-band klystron. The dimensions of the window and ceramic disk are optimized to minimize insertion and reflection losses while preventing ghost mode resonances in the operating bandwidth. In addition to this, we ensure that the maximum electric field at the window surface is kept low to reduce the probability of RF breakdowns. Analytical analysis, numerical simulations and experimental measurements of the ghost modes of ceramic disks were carried out. The measured ghost mode frequency was used to evaluate the ceramic dielectric constant. In this article we present simulated and measured results.
Paper: WEPS135
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPS135
About: Received: 29 May 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 08 Sep 2025
WEPS148
INFN LASA in-kind contribution to PIP-II
2466
This paper reports the status and recent progress of INFN LASA’s in-kind contribution to the PIP-II project at Fermilab, with updates on key activities and major procurements. Production efforts for the 38 INFN LASA-designed, 5-cell cavities (β=0.61) for the LB650 section of the linac are underway and two pre-series prototypes are being realized as a first step to validate the manufacturing and treatment sequence. Concurrently, preliminary testing on existing prototypes is progressing to gain a deeper understanding of the surface preparation and qualification procedures, including cross-validation at different infrastructures. Series LB650 cavities will be industrially produced and surface-treated to achieve the stringent performance targets, qualified via vertical cold tests at DESY AMTF, and delivered installation-ready for string assembly.
Paper: WEPS148
DOI: reference for this paper: 10.18429/JACoW-IPAC25-WEPS148
About: Received: 28 May 2025 — Revised: 02 Jun 2025 — Accepted: 02 Jun 2025 — Issue date: 08 Sep 2025
THPB001
Conceptual design of the vacuum system of cSTART
2499
The Karlsruhe Institute of Technology (KIT) operates research accelerator facilities for the development of new technologies for future compact light sources at the Institute for Beam Physics and Technology (IPBT). Within the cSTART project (**c**ompact **ST**orage ring for **A**ccelerator **R**esearch and **T**echnology), a Very Large Acceptance compact Storage Ring will be realized to combine a compact storage ring and a laser-plasma accelerator. The new design, based on 45° bending magnets, is suitable to store a wide momentum spread beam. Good vacuum conditions are essential for the successful operation of such an accelerator system. In our case, a final pressure of <1E-8 mbar is required. For cSTART, special care was taken to find a compact (43 m circumference), space- and cost-saving, yet efficient vacuum system design that fulfils this requirement. This article presents the vacuum concept that will be used at cSTART. This includes the selection of vacuum components, the design of the vacuum chamber and vacuum simulations.
Paper: THPB001
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPB001
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 08 Sep 2025
THPB002
Vacuum system of MAX4U – an upgrade of MAX IV 3 GeV storage ring
2503
MAX 4U is an upgrade project of the MAX IV 3 GeV storage ring, to be realized by the early 2030’s in Lund, Sweden. The goal of the upgrade is to reduce the horizontal electron beam emittance to below 100 pm.rad. A new magnet lattice will be used, thus the vacuum system will have to be adapted to follow the new beam orbit of MAX 4U. Several lattices imposing the most severe changes to the beam orbit were studied. One proposal for the MAX 4U vacuum system is to re-use and adapt under vacuum the shape of the MAX IV 3 GeV ring vacuum chambers (coated with non-evaporable getter (NEG) thin film) by bending-to fit to the new magnet lattice. In such scenario, the vacuum system will not be vented, thus the NEG coating will not have to be re-activated. Such approach is very cost-effective and reduces the installation and commissioning time to the minimum. This scenario is presented here, together with the performed simulations, validation studies and tests.
Paper: THPB002
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPB002
About: Received: 16 May 2025 — Revised: 02 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 08 Sep 2025
THPB004
Development of residual gas analyzer measurement system capable of operating in the 10 Torr vacuum range
2507
Residual Gas Analyzers (RGA) are widely used to mon-itor gas composition in vacuum systems. However, they are typically limited to high-vacuum environments and cannot be used directly in processes that operate at higher pressures. To solve this problem, we developed a modular and easy-to-build differential pumping system that allows an RGA to monitor vacuum environments up to 10 Torr. In this study, we present the design of this system. Thanks to its modular design, the system can be easily extended to operate at higher working pressures by adding more modules.
Paper: THPB004
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPB004
About: Received: 26 May 2025 — Revised: 02 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 08 Sep 2025
THPB005
Surface characterization of vacuum chambers with synchrotron radiation exposure at a beamline
2510
Exposure of synchrotron radiation on the vacuum chambers induces high yield of photoelectrons and the consequent increase of pressure from stimulated gas desorption. Characterization of the surface quality of vacuum chambers, either after chemical cleaning or with thin film coating, by synchrotron radiation exposure at a beamline is powerful and sensitive. In this study, analysis of photo-desorption and photoelectron yield for various vacuum chambers, metallic tubes with or without NEG-coatings, at the BL19B-beamline of Taiwan Light Source (TLS) with critical photon energy of 2.14 keV will be described and compared.
Paper: THPB005
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPB005
About: Received: 28 May 2025 — Revised: 31 May 2025 — Accepted: 31 May 2025 — Issue date: 08 Sep 2025
THPB006
Improvement of PLS-II Photon Absorbers
2513
In synchrotron accelerators, managing the intense photon flux generated by bending magnets is very important for maintaining the accelerator's performance. The emitted synchrotron radiation, characterized by its high intensity and broad spectrum, imposes significant thermal and structural demands on accelerator components. Photon absorbers are essential to effectively block excess photons, ensuring stable operation and extending the lifespan of the vacuum components. In this poster, I would like to introduce the new shape and analysis results to improve the performance of the vertical-type photon absorbers operating in PLS-II.
Paper: THPB006
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPB006
About: Received: 28 May 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 08 Sep 2025
THPB008
Sputtering characteristics of a compact NEG-coating device and performance evaluation of the TiZrV thin films
2517
Non-evaporable Getter (NEG) coating is a breakthrough technology wherein the inner walls of a vacuum chamber are coated with a material that functions as a vacuum pump. This technology is expected to gain widespread adoption across various fields in the future. However, the current coating method, originally developed for long beam ducts, is not adaptable to a wide range of vacuum chamber designs. Therefore, we have developed a compact NEG coating device that can be adapted to chambers of various geometries. The primary advantage of this device is its ability to coat complex-shaped chambers, which was difficult with conventional methods. Additionally, by reducing the uncoated surfaces as much as possible, it significantly improves pumping performance in terms of pumping speed and reducing Photon Stimulated Desorption (PSD) yields. We explore the optimal sputtering conditions for depositing high-performance NEG thin films with the device, and have performance evaluations of the NEG films, with observing the morphologies, measuring the pumping speed and PSD yields.
Paper: THPB008
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPB008
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 08 Sep 2025
THPB013
The wire alignment method in a magnetic field measurement system
2526
In the magnetic field measurement system, a single-core CuZr wire is used in both the stretched-wire (SW) and pulsed wire measurement (PWM) systems. Before measuring the magnetic field of the undulators, the CuZr wire must be aligned with the center of the undulator mechanism. The SW system is then employed to locate the magnetic field center of the undulator. The traditional method involves using a theodolite and level to align the CuZr wire with the center of the undulator mechanism. However, for cryogenic permanent magnet undulators (CPMUs), superconducting magnets, or any magnets installed in a vacuum chamber, aligning the CuZr wire with the center of the mechanism using traditional methods presents challenges. In this paper, we propose a method that utilizes the wire's contact with the magnet to observe changes in resistance for positioning purposes, thereby overcoming the limitations of center alignment in chamber-surrounded undulator mechanisms.
Paper: THPB013
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPB013
About: Received: 22 May 2025 — Revised: 02 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 08 Sep 2025
THPB031
Experimental studies of thermal contact conductance between copper, stainless steel and aluminum samples using a setup developed at ALBA Synchrotron Light Source
2580
Accurate knowledge of the Thermal Contact Conductance (TCC) between surfaces is of great importance for the design of components in particle accelerators, such as mirrors, monochromators, filters, detectors, among others. The TCC depends on many variables such as surface finish, type of material, pressure between samples, temperature and interface materials. The TCC can be found in specialized literature, but it is not always possible to find this information for all applications. This forces the design engineer to assume conservative or optimistic values that can result in over or under sized designs. In this context, an experimental setup has been developed in the Engineering Division of ALBA to evaluate thermal contacts under ambient and cryogenics conditions, in vacuum and for different pressure ranges between samples. This work presents the latest experimental results obtained for sample combinations of Copper, Stainless Steel and Aluminium materials.
Paper: THPB031
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPB031
About: Received: 23 May 2025 — Revised: 01 Jun 2025 — Accepted: 01 Jun 2025 — Issue date: 08 Sep 2025
THPB045
Permanent magnet-based dipole-quadrupole magnet for SPring-8-II
2602
In recent years, permanent magnet (PM) based multi-pole magnets have become an increasing concern as a replacement for conventional electro-magnets for light sources. The PMs are possible to save both energy and costs for operating and construction the facilities due to the absence of a power supply and cooling system. They have other advantages such as less space without magnetic coils and fewer failures than the conventional electro-magnets. PMs have specific issues, such as the adjustability of the magnetic field, demagnetization, and temperature dependence. Solutions to these issues were already confirmed with dipole structures for SPring-8-II, a major upgrade project of SPring-8 to the fourth generation. We have extended the knowledge and schemes to a dipole-quadrupole combined-function magnet (DQM) that comes in a quadrupole structure. The DQM is readily splittable into an upper and lower half for installation of a vacuum chamber. The reproducibility of the field gradient with half-splitting was less than 0.1%, which is within the required value. We report on the design and trial-manufacture of the PM based DQM.
Paper: THPB045
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPB045
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 08 Sep 2025
THPB050
Development of robust beam window by additive manufacturing
2609
Construction of the COMET experimental facility is underway to explore the muon-electron conversion process at the J-PARC Hadron facility. An 8 GeV proton beam supplied from the main ring irradiates a target in a superconducting capture solenoid magnet, and the produced pions and muons are transported to the experimental area. In the beam line, the muon transport solenoids are composed of superconducting magnets cooled by liquid Helium (LHe). The beam windows should be robust enough to withstand against rapid and high pressure increase in emergency of LHe quenching until rupture disks break. Simultaneously, the density of the beam window material must be low, and the thickness must be as thin as possible, while minimizing the beam energy loss for high transmission efficiency. Therefore, we have been developing a beam window built by additive manufacturing. We have successfully developed a beam window made of Ti-6Al-4V with a diameter of 269 mm, a thickness of 0.5 mm, and a proof pressure of 30 atm, and have now started development of a beam window made of AlSi10Mg. In this presentation, we will report on the development status of the beam window by additive manufacturing.
Paper: THPB050
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPB050
About: Received: 28 May 2025 — Revised: 02 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 08 Sep 2025
THPB058
Status of the low-Z SPS slow extraction electrostatic septum development
2630
The impact of high-flux protons on beam loss during slow extraction from the SPS to the North Area has been discussed, and improvements have been proposed focusing on reducing activation, lifetime reduction, and anode body distortion. The conducted studies shall demonstrate the feasibility of replacing the stainless-steel tank, flanges, and anode body with low-Z materials. A reduced-length prototype was fabricated to demonstrate mechanical, electrical, and vacuum performance. The paper presents the vacuum vessel development from the reduced-length prototype to the full-length setup, including numerical analysis. Prototype qualification tests, including vacuum performance, leak-tightness, high-voltage feedthrough performance, and deformation during evacuation, will be discussed to confirm that the tank remains within predicted non-linear buckling limits.
Paper: THPB058
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPB058
About: Received: 28 May 2025 — Revised: 30 May 2025 — Accepted: 31 May 2025 — Issue date: 08 Sep 2025
THPB079
Investigation of properties of CuZr alloy for vacuum chamber structural materials
2644
CuZr alloy is considered for the structural material of the vacuum chamber of the Hefei Advanced Light Facility (HALF) storage ring. We tested the outgassing rate of CuZr material. The outgassing rate of CuZr alloy can reach 4.93×10^-11 Pa·L/s·cm² after baking at 180°C for 48h, which is more than one order of magnitude lower than that of SS. These results indicate that CuZr alloy is easier to degas by baking at lower temperatures and is a material with very low outgassing rates. At the same time, it is a highly competitive structural material for future accelerator vacuum chamber based on its good electrical conductivity, high strength and hardness.
Paper: THPB079
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPB079
About: Received: 17 May 2025 — Revised: 30 May 2025 — Accepted: 30 May 2025 — Issue date: 08 Sep 2025
THPB085
Design and structural analysis of a bending chamber for EPU applications in the SPS-II storage ring
2647
Designing a vacuum chamber for the Elliptically Polarized Undulator (EPU) in the SPS-II storage ring presents challenges due to a constrained bore aperture, minimal clearance between magnet poles, and requirements for synchrotron radiation delivery. This study focuses on a vacuum chamber design that accommodates the large opening angle necessary for EPU operation. A complex transition cross-section was developed to achieve the required beam aperture while maintaining compatibility with the magnet structure. The limited clearance of 0.5 mm between the chamber and magnets necessitates precision machining and fabrication. Structural reinforcements were added to the thin sections of the chamber to ensure mechanical stability, and a specialized welding approach was implemented to minimize deformation. The chamber is fixed to supports designed to control thermal deformation during operation. Finite element analysis (FEA) evaluates the chamber’s structural performance, including stress, safety factors, and deformation, confirming the design meets the operational requirements for EPU applications in the SPS-II storage ring.
Paper: THPB085
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPB085
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 08 Sep 2025
THPB094
Large-area atomic layer deposition of titanium nitride for RF windows
2668
High-power particle accelerators, like the Spallation Neutron Source, require reliable radio-frequency waveguide windows to transmit power while maintaining a vacuum. These windows face performance challenges due to multipacting, an electron cascade disrupting vacuum integrity. Thin TiN coatings can suppress this by reducing secondary electron emission, but traditional methods struggle to uniformly coat complex ceramic surfaces. We developed an atomic layer deposition (ALD) process to create conformal TiN films (<10 nm) at low temperatures (130°C), achieving smooth, conductive coatings with a secondary electron yield below 2.0. Collaborating with Microwave Techniques LLC and Oak Ridge National Laboratory, we designed RF windows with replaceable TiN-coated ceramic disks to improve performance and reduce downtime. In our next phase, we will scale up manufacturing and develop a modular ALD tool for in-situ coating of waveguide and SRF cavity metallic surfaces, crucial for next-generation accelerators operating at higher power. These innovations enhance efficiency, reliability, and design flexibility, advancing accelerator technology and fostering high-tech sector growth.
Paper: THPB094
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPB094
About: Received: 30 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 08 Sep 2025
THPB099
Design overview of the medium energy beam transport line for the ANTHEM project
2680
The ANTHEM (Advanced Technologies for Human-centered Medicine) research project will establish a Research and Clinical Center in Caserta, Italy, for the study and application of Boron Neutron Capture Therapy (BNCT). The Radio-Frequency Quadrupole (RFQ), designed by INFN, produces proton beam of 30 mA at 5 MeV, impinging on a beryllium target. A 12 m long Medium Energy Beam Transport (MEBT) line, located after the RFQ, is responsible for transporting the beam to the target for optimal neutron production. This paper gives an overview of the design of MEBT line and details its main characteristics about beam dynamics, vacuum system and its mechanical layout.
Paper: THPB099
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPB099
About: Received: 25 May 2025 — Revised: 30 May 2025 — Accepted: 30 May 2025 — Issue date: 08 Sep 2025
THPB101
Study of a girder system for the Korea-4th Generation Synchrotron Radiation (4GSR) accelerator
2683
The Korea 4th-Generation Synchrotron Radiation (4GSR) accelerator requires exceptionally high mechanical stability to ensure reliable beam operation with an extremely small beam size. To achieve this, a robust grid-er system is essential for supporting accelerator components such as magnets, vacuum chambers, and beam position monitors (BPMs). The girder system must suppress vibrations originating from the ground to prevent disturbances in the electron beam trajectory, while also maintaining sufficient mechanical rigidity to support heavy components like electromagnets. In the Korea 4GSR project, the girder system is required to maintain a misalignment tolerance within ±100 μm and limit vibration amplitudes to less than 10% of the beam size to ensure beam stability. However, with a storage ring circumference of approximately 800 meters, meeting these specifications poses significant challenges. This study presents the development of a girder system using finite element analysis (FEA) methods to achieve both mechanical stiffness and adjustability, thereby ensuring the required beam stability.
Paper: THPB101
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPB101
About: Received: 23 May 2025 — Revised: 02 Jun 2025 — Accepted: 06 Jun 2025 — Issue date: 08 Sep 2025
THPM085
Design and development of a beam scraper system for Siam Photon Source II
2856
This paper presents the development of a beam scraper system for the 3 GeV storage ring of Siam Photon Source II (SPS-II). Beam scrapers are essential for removing halo particles, protecting accelerator components, and managing aperture limitations. The scraper blade material is carefully chosen for its superior thermal conductivity and mechanical strength. The design prioritizes considering wakefield impedance to minimize beam disturbances, incorporates detailed thermal simulations to ensure operational stability, and optimizes the mechanical structure for easy installation and long-term durability. This design approach significantly enhances the performance and reliability of the SPS-II beam scraper system.
Paper: THPM085
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM085
About: Received: 28 May 2025 — Revised: 30 May 2025 — Accepted: 04 Jun 2025 — Issue date: 08 Sep 2025
THPM096
Top-up safety simulations for Elettra 2.0
2886
A comprehensive program of tracking studies has been carried out to ensure that no train of injected electron bunches can traverse an open beamline during top-up operations at Elettra 2.0. The analysis explored various error scenarios, considering realistic magnetic field variations, trajectory shifts, aperture constraints, and energy deviations. This paper presents the tracking techniques employed, the scenarios investigated, and the proposed interlock systems designed to ensure safety during top-up operations.
Paper: THPM096
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM096
About: Received: 28 May 2025 — Revised: 02 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 08 Sep 2025
THPS035
Detector protection system used in the Taiwan Photon Source 13A experimental station
3043
At the Taiwan Photon Source 13A experimental station, the detector is prone to noise interference in a vacuum environment ranging from 750 torr to 7 mtorr, which can lead to malfunctions. Therefore, a rapid automatic power-off system has been designed to immediately shut down the detector's power when it is in an abnormal vacuum range, reducing the impact of noise on the detector and thereby extending its lifetime.
Paper: THPS035
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPS035
About: Received: 27 May 2025 — Revised: 31 May 2025 — Accepted: 03 Jun 2025 — Issue date: 08 Sep 2025
THPS058
Cryogenic inserts in the room temperature synchrotron SIS18 at GSI
3094
The existing room temperature heavy ion synchrotron SIS18 at GSI will be used as booster for the future SIS100 at FAIR. One of its features the the generation of high intensity heavy ion beams. In order to create such beams, medium charge states are used, which have a lower space charge limit and can be created with less stripping losses. Unfortunately, such heavy ions have very high ionization cross sections in collisions with residual gas particles, yielding in beam loss and subsequent pressure rises via ion impact stimulated gas desorption. Although an extensive upgrade plan, including NEG-coated magnet chambers and an ion-catcher system, has been realized, the required intesity goals will not yet be reached. Simulations including cryogenic surfaces around the ion catchers show, that their high sticking probability prevents from pressure built-ups during operation. A prototype ion catcher, including such cryogenic surfaces cooled by a commercial cold-head has been developed, built, and tested. It has recently been installed in SIS18 and will undergo further tests, including measurements with heavy ion beams. Findings for the operation and further cryogenic inserts are presented.
Paper: THPS058
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPS058
About: Received: 20 May 2025 — Revised: 30 May 2025 — Accepted: 31 May 2025 — Issue date: 08 Sep 2025
THPS059
Comparison of various outgassing rate measurements for UHV systems
3098
Outgassing rate is one of the most important criteria for vacuum acceptance of various components used in ultra-high vacuum (UHV) systems. There are numerous methods to measure the outgassing rate of UHV components. One of the most common techniques is the so called ‘pressure-rise’ method. In this method the component under test is enclosed in a system and disconnected from the pump. The outgassing rate is calculated from the pressure rise that occurs due to the outgassing of the component. Comparing this with other techniques, the pressure-rise method is more straightforward and allows easier analysis of the data. Nevertheless, the outgassing rate obtained from the pressure-rise method tends to be much lower than the actual outgassing rate. This paper presents an investigation of another approach to analysing the data obtained from the pressure-rise method. The objective of this approach is to provide a greater accuracy in the outgassing rate measurement, as well as to understand the reason behind the large error obtained using the pressure-rise method. The new approach of calculating the outgassing rate from the ‘pressure-rise’ method is then compared to other methods.
Paper: THPS059
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPS059
About: Received: 19 May 2025 — Revised: 30 May 2025 — Accepted: 30 May 2025 — Issue date: 08 Sep 2025
THPS060
Photon stimulated desorption from cryogenic surfaces of high temperature superconductor and amorphous carbon thin films
3101
High Temperature Superconductor (HTS) and amorphous Carbon (a-C) thin films, and their combination, are being considered as possible surface coatings for the FCC-hh beam screen (BS) with the aims of reduction of the resistive wall impedance and mitigation of the electron cloud. Along with these required properties, i.e., the high electron conductivity and low secondary electron yield, the Photon Stimulated Desorption (PSD) yield is one of the most essential characteristics in the design and operation of the FCC-hh vacuum systems. For this purpose, a series of the PSD measurements is currently conducted at a dedicated beamline in the KEK Photon Factory, where similar conditions to FCC-hh in terms of the Synchrotron Radiation energies and power density are available. In order to realize a similar cryogenic condition of the BS (40-60 K), the sample container is equipped with a LN2 jacket (77 K) and installed in an insulation vacuum chamber. The conditioning behaviors of the PSD yields as a function of the photon dose are being obtained for uncoated copper and HTS, and a-C coated copper and HTS, and each sample is examined at cryogenic and room temperatures for comparative analysis.
Paper: THPS060
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPS060
About: Received: 31 May 2025 — Revised: 02 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 08 Sep 2025
THPS061
Surface resistance measurement of Pd coating films using cavity resonator method
3105
Recently, it was found that Pd coating films exhibited ultra-low photon-stimulated desorption and low resistivity values. These advantages suggest that Pd coatings could be applied to small aperture tubes, including undulator vacuum tubes, which have a significant effect on resistive wall impedance. In previous studies, the DC electrical resistivity of Pd films was measured using the four-probe technique. The surface resistance under high-frequency conditions relevant to accelerators remained insufficiently explored. This study aims to address this gap by employing the “cavity resonator method” to measure the surface resistance of this film under high-frequency electromagnetic fields. By depositing Pd films onto the inner surface of a copper alloy resonator, the quality factor (Q-factor) was measured and compared to that of the uncoated copper alloy, allowing for the calculation of the practical surface resistance. These results could provide a basis for evaluating the heat generation and cooling requirements of this film in accelerator applications.
Paper: THPS061
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPS061
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 08 Sep 2025