Electron-Ion Collider (EIC) is a next generation particle accelerator to be built at Brookhaven National Laboratory, in partnership with Thomas Jefferson National Accelerator Facility. In Electron Storage Ring (ESR), 18 single-cell 591 MHz SRF cavities are required to compensate for energy loss from synchronic radiation. Effective damping of higher-order-modes (HOMs) is also critical to ensure...
In modern particle accelerators, multiple superconducting cavities are often driven simultaneously by one high-power klystron, thereby reducing the cost of the power supplies. The CEPC TDR specifies 96 cryomodules for 650 MHz 2-cell cavities, with each cryomodule originally housing two cavities. During the horizontal testing phase, however, we plan to simultaneously drive six superconducting...
In order to reduce the cost of superconducting cavities, we propose a new method of manufacturing cavities using 0.2 mm thick niobium foil tubes. We came up with the idea of applying a plastic processing technology called elctromagnetic forming (EMF). As a result of a feasibility study, we found that niobium is a difficult material to form by EMF, and experimental results showed that it was...
As for all superconducting radio-frequency (SRF) cavities preserving the performance during accelerator operation is even more essential for an SRF gun, because the accelerating field is typically very high and cannot be compensated by a neighboring cavity. One of the main limiting factors remains field emission, that is originating either from particulates or hydrocarbon contaminants on the...
The Linear IFMIF Prototype Accelerator (LIPAc) is a deuteron linear accelerator (linac) designed to validate the acceleration of a 125-mA beam up to 9 MeV in continuous wave (CW) operation, contributing to the realization of the IFMIF project. The 125-mA deuteron beam is initially accelerated to 5 MeV by a radio-frequency quadrupole (RFQ) and subsequently to 9 MeV by a superconducting...
During the present technical commissioning run of the ESS linac several measurements were taken to extract beam properties (e.g. phase and current) on the base of beam transient induced voltage and comparing with beam diagnostic based measurements.
High-intensity accelerators, particularly Accelerator-Driven Systems (ADS), require high availability and reliability for proper operation. For superconducting linear accelerators, the ability to continue operating even when one of the RF cavities fails is key to achieving the required availability, known as cavity compensation. Beam dynamics studies of the JAEA-ADS linear accelerator have...
Firmware for the Low-level Radiofrequency (LLRF) systems used in the Jefferson Lab C100 and C75 cryomodules was upgraded to allow for a variable duty factor pulsed mode operation with triggered waveforms available through EPICS. A new type of gaseous helium flow meter that has been under development for the past 2 years was also opportunistically installed in cryogenic return U-tubes of 14 of...
Coating Nb with thin superconducting layers (with or without insulating layers, i.e., SS or SIS) with longer penetration depth λ can enhance the accelerating gradient by maintaining the Meissner state above each layer’s superheating field Bsh, due to reduced surface screening currents and interfacial energy barriers. We review previously published studies using radioactive beam-based...
In the last years, low frequency gravitational waves (GWs) have been consistently measured by the LIGO-Virgo collaboration, but little to no attention has been paid to higher frequencies GWs in the range of 10 kHz to 100 MHz, at which confirmation for current theories or even new physics could be hidden. The MAGO 2.0 project aims at filling this gap in the parameters space using...
The Linear IFMIF Prototype Accelerator (LIPAc) is designed as a high-current deuteron linear accelerator (linac) capable of accelerating a 125-mA beam up to 9 MeV in continuous wave (CW) mode. The RFQ linac and subsequent beam transport lines equipped with several diagnostics successfully commissioned a 119-mA deuteron beam with an 8.75% duty cycle. The superconducting RF (SRF) linac is the...
The BESSY Variable pulse-length Storage Ring (VSR) Demo project aimed to provide short and long pulses simultaneously in the BESSY II storage Ring. To achieve this goal HZB has developed high current Continuous Wave (CW) Superconducting Radio Frequency (SRF) cavities operating at 1.5 GHz for 300 mA beams with large damping capabilities to cope with the HOM powers expected. This paper presents...
The design of the ten additional CEBAF Upgrade Cryomodules leads to significantly higher fault rates than the 40 original cryomodules, due to sensitivity to microphonics. Cartridges that compress pellets of boron nitride nanotubes (BNNT) are mounted in parallel to the SRF cavities of two refurbished Upgrade Cryomodules. Now substituted into CEBAF, these cryomodules exhibit significant...
Previous research has shown that Nb3Sn cavities with tin-rich grain boundaries tend to show significant Q-slope behavior, while cavities with grain boundaries of the “ideal” 25 %-tin composition have higher quality factors and reach higher quench fields. In this paper, we make the case that it is possible to improve the properties of Nb3Sn grain boundaries even further. We use...
The superconducting linac is proposed for effective acceleration of proton beam in a new project of China Institute of Atomic Energy. A 975MHz superconducting radio frequency cavity is designed to accelerate the H+ ion beam in the energy range from 500 MeV to 1000 MeV. This paper will present the design and simulation， including the multi-parameter electromagnetic design and optimization,...
The RF accelerating module is crucial for imparting kinetic energy to particle beams in accelerators. Superconducting RF (SRF) technology offers key advantages over conventional room-temperature RF systems, including lower operational costs, reduced beam loss, and higher accelerating power. The superconducting cavity, SRF's core component, requires ultra-low temperatures. While liquid helium...
This report presents the design of an MTCA.4-based low-level radio frequency (LLRF) tuning controller for the Shenzhen Superconducting Soft X-ray Free Electron Laser (S3FEL). A standard 1.3 GHz cryomodule at S3FEL comprises eight superconducting cavities, each requiring one slow tuner motor control, two fast piezoelectric actuator (PZT) controls, and an additional motor control for high-power...
A 5-year project called MEXT Advanced Accelerator element Technology Development began in FY2023 at KEK. The goal of this project is to manufacture one cryomodule (CM) that meets the requirements of International Linear Collider (ILC) and to test completed CM at cryogenic temperature. ILC model CM consists of nine cell superconducting cavities, magnetic shields, power couplers, tuners, cooling...
The QWR/HWR cavity cryomodules have been designed for High Intensity heavy-ion Accelerator Facility (HIAF) at the Institute of Modern Physics (IMP) of the Chinese Academy of Science (CAS). There are 17 cryomodules operating at 2 K&3130 Pa of HIAF linac, which consist of 6 QWR007 cryomodules and 11 HWR015 cryomodules, respectively. These cryomodules are being processed in the vendor currently....
Post-coating surface treatment is a crucial approach for eliminating surface flaws and enhancing the RF performance of Nb₃Sn. The bipolar pulsed electropolishing (BPEP) technique, originally developed for Nb, is adaptable to Nb₃Sn and offers precise, controllable surface removal at slow rates—an essential feature for this application. In BPEP, the net removal rate is proportional to the...
RF testing is a key element in the development of superconducting thin film coated cavities. Initially RF tests are performed for thin film coatings on planar copper disks, before moving to cavities. To further progress in understanding the thin film deposition process, a new RF cavity has been designed, optimized specifically for use in thin film testing. This cavity serves as an intermediary...
Nb₃Sn in the form of thin film on copper is one of the most promising routes in the field of superconducting radio-frequency accelerating cavities for future colliders. At INFN – Legnaro National Laboratories, thin films of Nb₃Sn have been successfully deposited on small copper samples via DC magnetron sputtering the process enabled the production of films with critical temperature > 17 K, at...
SPIRAL2 is a state-of-the-art superconducting linear accelerator for heavy ions, utilizing 26 bulk niobium cavities. The radiofrequency (RF) operation of the SPIRAL2 linac can be disrupted by anomalies that affect its reliability. This work leverages fast, multivariate time-series postmortem data from the Low-Level RF (LLRF) system, processed using a Field-Programmable Gate Array (FPGA), to...
Fermilab is one of the leaders in development of vapor diffused Nb3Sn films inside niobium cavities. This material has a higher critical temperature (Tc) than niobium, enabling cavity operation at 4.2 K. This higher operational temperature significantly reduces the infrastructure required for cooling compared to 2 K systems, making superconducting radio-frequency (SRF) technology more...
Electropolishing (EP) is used for the surface treatment of Nb cavities used in superconducting accelerators. The electrolyte for Nb material EP is a mixture of hydrofluoric acid and sulfuric acid, which makes EP work in Nb cavities very expensive. In this study, the development of a new EP method for Nb cavity using fluoride salts and organic solvents will be reported. The organic solvents...
Superconducting Radio Frequency (SRF) technology is a key component in many particle accelerators operating in a continuous wave, or high duty cycle, mode. The on-line performance of SRF cavities can be negatively impacted by the gradual reduction in the accelerating gradient that can be attained within a reasonable field emission level. Conventional cleaning procedures are both time- and...
A new surface treatment method is being developed, wet nitrogen doping, in which nitric acid is added during electro-polishing (EP). In the first trial on a FRIB beta = 0.53 half-wave resonator (HWR), a high quality factor (Q0 = 8E10) was observed at 2 K at low field (accelerating gradient ≤ 0.5 MV/m) without an anti-Q slope. It is known that the Q0 can be increased by shortening the mean...
The International Linear Collider (ILC) is a future linear collider using superconducting accelerating cavities. R&D for the radio frequency power distribution system, which will deliver the radio frequency power from the klystrons to the cavities, is ongoing. In scope of the ILC Technology Network (ITN) an ILC prototype CM featuring 8 cavities is developed and built at KEK. The cavities will...
HZDR has done pioneering work in the field of the superconducting photoelectron source (SRF gun). The development began more than 20 years ago with the first proof of concept experiment. This was the first time worldwide that electrons were generated from a normal-conducting semiconductor photocathode within a superconducting half-cell resonator [1]. Convinced by this success the work was...
As the application of superconducting cavities becomes increasingly widespread, the development of cost-effective coatings with enhanced performance has become a focal point for researchers. This study primarily focuses on depositing niobium-niobium-tin (Nb3Sn) multilayer thin films on the inner surface of a 6 GHz copper half-cell via the co-sputtering method. The emphasis is on preparing...
In the context of future accelerator studies, niobium coating of copper-based cavities plays a key role in achieving an optimal balance between radio-frequency performance and cost-effectiveness.
Recent advancements have focused on the development of bulk-machined elliptical cavities, featuring a seamless, weld-free equator. By optimizing the design of machining tools, the machining...
Field emission (FE) remains a significant hurdle for achieving optimal performance and reliability in superconducting radiofrequency (SRF) cavities used in accelerator cryomodules. A thorough understanding of the generation and propagation of FE-induced radiation is therefore essential to mitigate this problem. The absence of standardized measurement protocols further complicates the...
Particulate contamination in SRF cavities is known to trigger field emission, a phenomenon where electrons tunnel out from the surface of the cavities due to high electric fields. These rogue electrons limit the achievable accelerating gradient, affecting the final beam energy delivered by the accelerator. The TRIUMF e-Linac and ISAC-II heavy ion accelerators see a progressive onset of field...
The development of an easy and inexpensive Nb sheet preparation process, based on metallographic polishing has been presented earlier [1,2]. The aim is to remove the damage layer issued from the rolling process on the sheet in order to reduce the length of surface treatment on completed cavities. The process has been applied on a QPR sample and tested in RF, without any surface chemistry. Its...
In EIC Electron Storage Ring (ESR), 18 single-cell 591 MHz SRF cavities are required to compensate for up to 10 MW energy loss from synchronic radiation. There are two FPCs to deliver 800 kW RF power to each cavity. The FPC was design and under prototyping. This paper presents the FPC design and manufacture progress of FPC.
The SRF community has shown that high temperature annealing can improve the flux expulsion of niobium cavities during cooldown. The required temperature will vary between cavities and different batches of material, typically around 800 C and up to 1000 C. However, for niobium with a low residual resistance ratio (RRR), even 1000 C is not enough to improve its poor flux expulsion. The purpose...
At the Superconducting RIKEN Linear Accelerator (SRILAC), auxiliary control and monitoring tasks for the RF system, such as RF voltage and power readout, feeder control, and tuner adjustments, are managed using a Mitsubishi MELSEC iQ-R series programmable logic controller (PLC). This PLC is directly connected to the FPGA-based LLRF controller, forming an integrated system for low-level RF...
In order to reduce the cost of superconducting cavities, research has been actively conducted in recent years to realize inexpensive cavities by making the cavity body out of copper and coating the inside with niobium to induce superconductivity. The inner surface of the accelerating cavity must be smooth, and a seamless cavity is ideal as a base for the coating. We came up with the idea of...
A method to enhance ATLAS low-beta superconducting cavities has been developed at Argonne National Laboratory in collaboration with MSU/FRIB, Fermilab, IJCLab, JLab, and BNL. At the center of the accelerator, a cryostat containing seven 72 MHz QWR installed in 2014 has world-leading performance for ion linacs at v/c~0.1, though performance has been reduced by ~20 % over the past decade due to...
A dedicated series of tests on the superconducting Medium-Beta and High-Beta cavities has been proposed to determine various parameters critical for future LINAC and LLRF system operation. These studies include measurement of the cavity stiffness coefficient (expressed as the Lorentz Force Detuning factor), evaluation of piezo tuner range and polarity, investigation of piezo capacitance as a...
The LCLS-II-HE project has completed qualification testing of the 9-cell 1.3 GHz cavities and has completed construction and testing of 22 out of 24 new cryomodules. All but 9 cavities out of over 200 tested have met the qualification requirements in vertical test. The cryomodules have met specifications, exceeding the required accelerating voltage by an average of 25 MV per module. Here we...
Field emission (FE) is one of the main issues limiting the performance of superconducting cavities. Various studies have been conducted to mitigate FE using methods such as computer simulations, microscopic surface analysis, plasma processing, and X-ray or temperature mapping. Among these, X-ray and temperature mapping are the most direct methods for localizing FE emitters. However, due to...
A vibrating sample magnetometer (VSM) is being developed with the capability to measure field penetration on ellipsoidal superconducting samples intended for use in superconducting radio frequency cavities. The explicit goal of this machine is to perform field penetration measurements on atomic layer deposition (ALD) coated niobium ellipsoids (ie., thin film MgB2, Nb3Sn on Nb), as well as on...
As the demand for more efficient SRF technology continues to rise, so does the need to improve the performance of Nb3Sn, the most promising alternative to niobium. Leveraging recent breakthroughs in Nb3Sn research from Cornell University and Fermilab, namely the electrochemical synthesis-based growth of Nb3Sn and the centrifugal barrel polishing (CBP) technique to smoothen the final Nb3Sn...
A fundamental-mode power coupler (FPC) for the 591 MHz superconducting RF (SRF) cavities is currently being designed and prototyped for use in the Electron Storage Ring of the Electron-Ion Collider. Due to limitations in power source availability and in consideration of the FPC fabrication schedule, the initial high-power tests of the prototyped FPCs are planned to be conducted using a 704 MHz...
Nb3Sn has great potential to be the next generation superconducting material on the inside of Cu superconducting radiofrequency cavities (SRF) due to its relatively high critical temperature Tc ≈ 18 K compared to other low temperature superconductors e.g., Nb with Tc ≈ 9 K. For Axion detection, cavities might operate below 100 mK, and copper bodies are preferred. Here, we report methods to...
In this study, superconducting Nb3Sn films were synthesised on different substrate such as sapphire, diamond turned copper and polished Nb, by DC magnetron sputtering from a single stoichiometric alloy Nb3Sn target. The structural, morphological and superconducting properties of the films were investigated. The effect of different deposition and substrate was examined. The film properties are...
Thread-mounted cathode installation directly at the backwall of the gun cavity allows cavity cleaning following cathode installation and thus beneficial for RF performance of the injector. Recent vertical tests of the CW L-band SRF gun cavity with a copper cathode installed demonstrated world-record high axial electric fields (up to 50 MV/m). While beneficial for RF performance, photoemissive...
The 82 SRF cavities of the present 2 MW configuration of the ESS Linac have been operated up to their specification during the first technical commissioning run on the temporary beam dump. Operational experience and comparison of cavity performances between vertical tests at the project in kind members and those measured at the cryomodule test stands and in the tunnel is described.
Bogorad et al. proposed Superconducting Radio-Frequency (SRF) cavities with high quality factors as a platform for detecting axions, which are a dark matter candidate, as well as low-energy QED corrections that give rise to photon-photon scattering [1]. The idea is to use the cubic nonlinearity of axion-electrodynamics to detect the axion field by measuring photons at a signal frequency ω3 = 2...
Plasma Electrolytic Polishing (PEP) is under active development at INFN-LNL as a flexible, environmentally friendly alternative to conventional electropolishing (EP). Since 2019, our research has focused on optimizing PEP for a variety of accelerator-relevant materials and geometries, ranging from standard planar samples to complex components, including parts fabricated via Additive...
Plasma treatment has emerged as an effective method for mitigating field emission and recovering the performance of superconducting radiofrequency (SRF) cavities. A collaborative effort involving CEA, ESS, FNAL, and INFN is currently focused on applying this technique to low-beta elliptical cavities for both the ESS and PIP-II linacs. This paper reports on the ongoing work aimed at developing...
Point Contact Tunneling Spectroscopy (PCTS) is a powerful technique ideal for investigating the surface superconducting properties of materials. Since it utilizes the oxides present on the sample’s surface to probe the superconducting density of states, this tool is valuable for studying superconducting devices such as qubits and SRF cavities, where a native or engineered oxide layer is...
Here we investigate the magnetic phase behaviour of an impure superconductor, and predict the critical fields of the Meissner/vortex state in the presence of impurities. To do this, we derive the Gibbs free energy of an impure superconductor immersed in an external magnetic field. We then use this Gibbs free energy to derive modified Ginzberg-Landau equations, which if solved describe the...
A high beam brightness is an important requirement for an electron linear accelerator, with the electron source setting the lower limit for the achievable brightness. A superconducting radio-frequency photoelectron injector (SRF gun) ) stands out as an advanced electron source capable of delivering beams with superior properties compared to other continuous-wave injectors. Currently, SRF guns...
Researches on preparation of Nb3Sn superconducting cavities has been carried at Peking University. Nb3Sn films were prepared by tin vapor method with a high vacuum furnace. We proposed a coating scheme of 1.3 GHz single cell Nb3Sn cavity with three tin sources inside. Nb3Sn films with a tin content of more than 25 % were obtained. The vertical tests show the Q of the prepared Nb3Sn cavities...
Powerful Energy Recovery Linac for Experiments (PERLE) is a compact three-pass ERL project based on SRF technology, being as a new generation machine targeting the 5 MW beam power regime. PERLE will serve as a hub for the validation and exploration of a broad range of accelerator phenomena in an unexplored operational power regime serving for the development of ERL technology for future energy...
We present further progress on a theoretical model linking nanohydride formation to mid- and high-field Q-slope in SRF cavities. Using time-dependent Ginzburg-Landau theory, we calculate Q-vs-E curves for cavities with a range of hydride distributions corresponding to different global hydrogen concentrations and different distributions of hydride nucleation sites. We show that hydrides smaller...
The native oxides of niobium cause surface losses during cavity operation arising from two-level systems/defects (TLS). These losses dominate the quality factor at low accelerating gradients (Eacc < 0.1 MV/m). In particular, the amorphous Nb2O5 is identified as a prominent host for the TLS. Nb2O5 dissociates when the material is baked above 200 °C for several hours in vacuum (the so-called...
At KEK, an International Linear Collider prototype cryomodule containing eight TESLA-type cavities is currently under development and is scheduled for testing in 2028. To evaluate the performance of the low-level RF (LLRF) system, a Red Pitaya-based cavity simulator is being developed. The simulator will also be used at the STF VT stand to support the development of the digital LLRF system,...
Robotic R&D for SRF started from FY2022 at KEK. Some works related to auto-cleaning and assembly in clean room have been done in FY2023. In FY2024, a simulator ‘ROBOGUIDE’ was introduced, enabling precise orbit development and positioning, moreover, any 3D models developed by CAD became available on ROBOGUIDE. In FY2025, assembly between mock-up cavity and mock-up coupler will be demonstrated,...
Research of Nb3Sn superconducting radio-frequency (SRF) cavities was conducted at the Institute of High Energy Physics Chinese Academy of Sciences (IHEP), in order to improve the intrinsic quality factor (Q0) and accelerating gradient (Eacc). Various recipes of coating were attempted at SRF cavities and samples made of Nb, which resulted in different Sn content. It was found that the Sn...
We report on the easily accomplished, in situ measurement of individual SRF Cavity dissipation in CEBAF cryomodules at the Thomas Jefferson National Accelerator Facility (JLab). Calculated Q0s from the data allows assessing the health of cryomodules over time. A 2022 SBIR Grant from the Office of Nuclear Physics, DOE Office of Science, to Hyperboloid LLC enabled development. JLab provided the...
Nb3Sn thin film cavities are new generation of superconducting cavities, which have the potential to replace traditional pure niobium cavities owing to their superior theoretical radio frequency (RF) performance. Higher theoretical acceleration gradient and quality factor give Nb3Sn cavities more possibilities in the future. There have been relatively high success in producing such cavities by...
From the production and testing of Nb/Cu elliptical cavities by hydroforming, it was found that there is a problem of poor surface roughness due to the large plastic deformation of the copper substrate. To improve this problem, we are trying to apply Plasma Electrolytic Polishing (PEP), which has been developed by INFN-LNL. PEP has the features of extremely high polishing speed compared to...
Dark matter with masses much less than 1 eV/c² is treated as a classical field, commonly referred to as wavelike dark matter. Among the leading candidates is the axion, which may have a mass on the order of μeV and can be converted into ordinary microwave photons of minuscule amplitude under a strong magnetic field. Leading wavelike dark matter searches often employ SRF cavities as detectors...
A five-year project (MEXT advanced Accelerator element Technology Development (MEXT-ATD)) funded by the Ministry of Education, Culture, Sports, Science and Technology (MEXT) began at KEK in FY2023. The goal is to manufacture, construct and test a cryomodule (CM) that satisfies the ILC (International Linear Collider Project) specifications and conduct cooling tests. The MEXT-ATD program is...
Field emission is one of the main problems that is difficult to completely avoid in superconducting accelerator project construction, and it is usually considered to be caused by particles or foreign materials. Although careful assembly and cleaning can minimize or eliminate this issue, field emission may still occur to some extent. This report focuses on the field emission problem faced by...
We have Cavity Fabrication Facility (CFF) at KEK which is a dedicated facility to fabricate SRF cavities. CFF was constructed in the year 2011 and now it has two Electron-Beam Welding (EBW) machines, a press-forming machine, a lathe, a Chemical-Polishing room, and so on in clean rooms. We have been mainly focusing on the fabrication of 1.3-GHz Nb elliptical 9-cell cavities. Recently we...
All elliptical cryomodules are tested at the ESS Test Stand in Lund before their installation in the linac. In June 2024 21 of the 30 cryomodules have been tested, 8 more are being prepared for test. This contribution presents a review of the testing experience, success rate, non-conformities encountered, and their resolution.
Currently a prototype cryomodule for the International Linear Collider featuring eight 1.3 GHz TESLA-type superconducting radio frequency cavities is being designed and built at KEK. In this contribution we report on the status of the development and production of the cavity frequency tuner. The design of the tuner body was finalized and the procurement of the first four series units is...
The Helmholtz Linear Accelerator HELIAC is a superconducting (sc) continuous wave linear accelerator for heavy ions currently under development at GSI in Darmstadt. In order to fully test the new cryomodules a new area was set up. The construction started already in 2018 by clearing the necessary space for a radiation protection bunker near the existing pre-accelerator HLI at GSI. Because of a...
As a practical technique to mitigate field emission effect of superconducting cavities on-line, plasma processing has been developed for CSNS-II superconducting Linac. Experimental platform has been set up and experiments of plasma ignited in various cavities with different frequencies have been conducted. The details of the research will be presented in the paper.
A Ferro Electric Fast Reactive Tuner(FE-FRT) for UK-XFEL superconducting Tesla Cavities is under development, which is used to suppress the microphonics of the superconducting cavities, a fast dynamic detuning. The EF-FRT tuner doesn't have moving parts and so has an extremely fast tuning process to compensate the microphonics. The RF design of the FRT includes the optimization of the Figure...
The LCLS-II project has installed a new superconducting linac at SLAC National Accelerator Laboratory to enable free electron laser science at repetition rates up to 1 MHz. The installed 35 1.3 GHz cryomodules produce an electron beam with energy of up to 4 GeV. Commissioning of the superconducting linac began in mid-2022, leading to the achievement of first light in 2023 and subsequent user...
Superconducting radio frequency (SRF) cavities which are made from bulk niobium and operated at cryogenic temperatures around 2 K, are essential components in modern particle accelerators. Due to the sustainability issues related to niobium, which is considered a critical metal, and the huge power consumption of accelerator facilities, the community has discussed alternative...
