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.

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.

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.

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.

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.

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.

The Hefei Advanced Light Facility (HALF) is the fourth-generation synchrotron radiation light source based on Diffraction-limited Storage Ring (DLSR) with low beam emittance, high brightness and coherent photon flux. According to the physical design requirements of the HALF, the vacuum chamber structural materials should have low outgassing rate, good electrical and thermal conductivity, high strength, and non-magnetic. CuZr and CuCrZr were selected as structural materials for the HALF storage ring vacuum chamber structural materials, taking into account material properties and manufacturing process. In this paper, thermal outgassing performance of CuZr and CuCrZr alloy pipes under temperature rise was investigated for the design and calculation of HALF vacuum systems.

The design study of a distributed pumping system using NEG (Non-Evaporable Getter) strips for the slender beam pipes of the Hefei Advanced Light Facility (HALF) is presented. To achieve a high pumping speed and pumping capacity in a limited pumping space, a NEG strip with distributed pumping capacity was considered. A prototype of HALF vacuum chamber, which can be inserted into NEG strip and matched with magnet system, is designed. The activation temperature of NEG strip and the ultimate vacuum after activation are tested, and the results are in good agreement with those obtained from the simulation.

The Iranian Light Source Facility (ILSF) is a 3 GeV synchrotron light source designed to serve as a cutting-edge tool for scientific research, providing high-brightness X-rays for a wide range of applications. In the booster ring, particles are accelerated to a final energy of 3 GeV and then stored in a storage ring with a maximum beam current of 400 mA. The RF cavity is a fundamental component of synchrotron light sources, playing a critical role in ensuring optimal machine performance. Optimizing the operational characteristics of the RF cavity significantly enhances the quality of the emitted radiation. The conceptual design of the RF cavity system of storage ring for ILSF to meet these requirements consisting of three 100 MHz main cavities plus two 300 MHz for bunch lengthening. A Monte Carlo simulation was conducted using Molflow and Synrad to calculate the pressure profile along the RF cavity straight of the ILSF. The results indicate that three diode ion pumps, each with a pumping speed of 300 l/s for 100 MHz, and two diode ion pumps, each with a pumping speed of 75 l/s for 300 MHz, will be necessary to achieve the desired pressure in the ultra-high vacuum regime.

The Iranian Light Source Facility (ILSF) Booster, which is currently in the design phase, has a circumference of 504 meters and accelerates electron bunches from 150 MeV to 3 GeV. The RF cavity section of the Booster is a key area, where maintaining ultra-high vacuum (UHV) conditions is essential to ensure stable beam acceleration and minimize beam-gas interactions. This work presents the integrated layout of the vacuum system for the RF cavity section of the Iranian Light Source Facility Booster. The conceptual design of the RF cavity section for the ILSF Booster, developed to meet these requirements, consists of three 100 MHz main cavities. The pressure profile has been calculated using Monte Carlo simulations, and the results fall within the accepted operational limits of the machine. These results suggest that three diode ion pumps, each with a pumping speed of 300 l/s, will be required to attain the desired pressure in the ultra-high vacuum regime.

The demand for cost- and time-effective and customizable components for High Vacuum (HV) and Ultra-High Vacuum (UHV) has prompted exploration into the application of 3D-printing technology. This study investigates the viability of utilizing 3D-printed plastics in UHV by evaluating their outgassing. An extensive evaluation of 3D-printing materials was carried out, highlighting the best polymer candidates using two of the most common 3D-printing techniques, Fused Deposition Modelling and Stereolithography. Further investigations were conducted to assess the performance of select 3D-printed plastics under UHV, focusing on their low outgassing and resistance to baking temperatures. Furthermore, residual gas analysis was used to evaluate the materials compatibility with NEG coating and possible presence of other contaminants. The findings suggest that certain 3D-printed plastics exhibit promising characteristics for use in HV and UHV, with notable examples including cyclic olefin copolymer and PEEK along with Rigid 10K and Tullomer™. A comparison between machined and 3D-printed parts showed that challenges such as porosity and surface roughness are not to be a cause of great concern.

The Korea-4GSR is a fourth-generation synchrotron radiation accelerator with an energy of 4 GeV, a beam current of 400 mA, and a circumference of 800 m. To satisfy the performance requirements of the storage ring, the gap between the electromagnets and the vacuum chamber is designed to be extremely narrow, from 1.5 mm to 2 mmA portion of the synchrotron radiation generated in the storage ring is delivered to the beamlines, with most absorbed within the storage ring using various types of photon absorbers installed throughout the system, while some photons are directly absorbed by the vacuum chamber. To prevent interference caused by thermal deformation of the vacuum chamber during this process, stress, deformation, and temperature distributions due to synchrotron radiation were analyzed using Ansys. This study proposes optimization strategies to ensure the mechanical stability of the vacuum chamber under synchrotron radiation exposure.

The Korea-4GSR storage ring vacuum chamber is composed of materials such as aluminum and stainless steel. Among these, the aluminum extruded chamber for Pill getter insertion undergoes in-situ bake-out and getter activation in the storage ring tunnel at a temperature of 180°C for over 24 hours. The gap between the electromagnet and the vacuum chamber is as narrow as 1–2 mm, which could lead to physical interference between the magnet and the chamber due to thermal expansion caused by the bake-out process. Therefore, the displacement of the aluminum vacuum chamber due to temperature increase has been calculated and measured based on the position and type of supports. This presentation aims to discuss the optimization of the bellows and support designs for the aluminum vacuum chamber.

The feasibility of incorporating ozonized water into the ultra-high vacuum (UHV) chemical cleaning process for aluminum vacuum chambers was investigated. The experiments were conducted using custom-designed wet bench equipment under various temperature and time conditions. Auger analysis was used to evaluate the removal of organic contaminants, and TEM analysis measured changes in oxide layer thickness. Subsequently, similar experiments were conducted on a prototype 4GSR vacuum chamber, and vacuum quality was assessed through outgassing rate measurements and RGA analysis. Based on these results, we quantitatively and qualitatively determined the optimal reaction time, temperature, and process sequence for ozonized water treatment in UHV chemical cleaning. This method is expected to more effectively remove initial chemical impurities and physical contaminants from the surface or interior of aluminum materials under specific conditions. Consequently, it may help reduce photon-stimulated desorption rates, contributing to a shorter conditioning time in the 4GSR project and ultimately enabling the achievement of higher vacuum levels.

The pumping speed of pill-type getter pumps for low-temperature activation, fabricated under different sintering conditions, were measured at various temperatures. To reduce uncertainty, the pumping speed measurements were performed on more than 70 getter pumps. This measurement method has limitations: it measures the pumping speed only on one side of the getter and may overestimate the speed due to the influence of getter powder. Therefore, the pumping speed of a single pill-type getter pump was measured and compared in accordance with ASTM F798-97.

The Hefei Advanced Light Facility (HALF) is positioned as an internationally advanced fourth-generation synchrotron radiation light source in the low-energy range, based on a diffraction-limited storage ring. The stainless steel vacuum chamber is a key component of HALF, with 316LN stainless steel chosen as the primary material. Its mechanical strength, corrosion resistance, low outgassing rate, and excellent process adaptability make it the ideal material for HALF. The vacuum chamber operates in an environment subject to vibrations and radiation, necessitating high welding process requirements to prevent weld cracks and leaks. The vacuum leak rate is controlled within 2×10-11mbar.l/s. The vacuum chamber is designed to withstand baking temperatures above 250°C. After machining, the magnetic permeability of the chamber is kept at 𝜇≤1.01.For certain stainless steel vacuum chambers, the inner surface of the beam channel is coated with oxygen-free copper (TU0). This reduces the outgassing rate from the inner wall, lowers the photon-stimulated desorption coefficient, and ensures a uniform and low vacuum pressure distribution.

Non-evaporable getter (NEG) films are ideal for maintaining ultra-high vacuum (UHV) conditions in particle accelerators, owing to their uniform pumping speeds and negligible outgassing characteristics. However, the requirement for thermal activation limits the applicability of NEG films. Prolonged exposure to atmospheric conditions and repeated activation cycles lead to a gradual increase in their activation temperature. This poses significant challenges for accelerator maintenance. The Pd/Ti composite film, created by depositing a palladium (Pd) layer onto a titanium (Ti) film, enhances oxidation resistance and reduces activation temperatures. In this study, a double-layer Pd/Ti film was deposited onto oxygen-free copper (OFC) samples, and a specialized device for measuring its pumping speed was designed and constructed. Additionally, the microstructures, cross-sectional elemental distributions, surface elemental compositions, and pumping properties of the films were tested and analyzed.

The premise of the stable operation of charged particles in the accelerator storage ring is a stable and clean vacuum environment, and the level reached by the vacuum system is directly related to beam intensity, beam quality and beam lifetime. Therefore, the design of vacuum system is an indispensable part of accelerator engineering. HALF is a fourth generation advanced synchrotron radiation light source in low energy region. The beam emittance in the storage ring reaches the diffraction limit. At present, the circumference of the storage ring as the main body of HALF is 480m and is set to 20 cycles. According to the characteristics of the fourth generation light source storage ring, such as small vacuum chamber space, large calorific value, small flow conductivity of the storage ring and limited effective pumping speed of the vacuum pump, the alloy copper with high strength, good thermal conductivity and non-magnetic should be selected as the main material of the ring vacuum chamber. At the same time, the exhaust of intermittent sputtering ion pump can not meet the requirement of vacuum, so the inner surface of copper vacuum chamber of storage ring must be coated with NEG film.

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.

To coat the inner surface of antechamber type vacuum chamber for Hefei Advanced Light Facility (HALF) with nonevaporable getter material (NEG), a dedicated magnetron sputtering setup has been prepared at National Synchrotron Radiation Laboratory (NSRL). The magnetron sputtering device and the coating method are introduced in this paper. The properties of the films were tested. This coating method has been proved to be feasible and ensures the stability of the discharge and the reliability of the NEG film quality, which satisfy the stringent engineering requirements of HALF. This study may also offer a reference for similar vacuum chamber coating applications.

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.

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.

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.

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.

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.

The Booster Ring (BRing), which requires an average vacuum to be better than the 10-10Pa，is the key part of the High Intensity Heavy Ion Accelerator Facility. The total length of BRing is 569.0985 meters, the characteristics of long circumference, large cross-section and a large amount of gas load, pose great challenges for on-site installation and achieving the vacuum index. Therefore, optimization has been carried out from several aspects. Firstly, in order to reduce eddy current, 0.3mm thick low permeability stainless steel is required. Different from the commonly used ceramic vacuum chamber or 0.3mm thin-walled chamber with ribs, the structure of placing high-strength, low gas load inner lining skeleton at intervals inside the 0.3mm thin-walled chamber is proposed for the first time. Using 3D printing technology to process the inner lining skeleton and coating it with getter film to reduce the pressure gradient. Secondly, the kicker chambers are equipped with ferrite, which brings high gas load. So a process for reducing the outgassing rate of ferrite has been explored, which can make the outgassing rate of ferrite ≤ 1.125×10-9Pa.L.S-1.cm-2. After testing, the vacuum of the kicker chamber is better than 7×10-10Pa. Thirdly, the pressure distribution of BRing was calculated by Molflow software, and the pumping scheme has been optimized. The BRing vacuum system has been installed, and the entire ring has undergone on-site baking, with an average vacuum better than 7×10-10Pa.

A large scientific facility, High Intensity heavy-ion Accelerator Facility (HIAF), was being built to study basic and interdisciplinary sciences. The Booster ring (BRing), as the core device of the HIAF, has a magnetic rigidity of up to 34 Tm，and the field ramping rate of the pulsed dipole magnet is up to 12 T/s. To reduce the eddy current effect and beam loss caused by the rapid ramping of the magnetic field. A 0.3 mm stainless steel thin-walled titanium alloy lined arc vacuum chamber was proposed, in which titanium alloy liners are sequentially arranged inside to improve mechanical properties. The arc vacuum chamber with a cross-section of 230 mm x 97 mm and a length of 3.4 m，to reduce the pressure gradient inside the thin-walled arc vacuum chamber，Ti-Zr-V thin films were deposited on the titanium alloy liner and 0.3 mm stainless steel thin wall, respectively, by magnetron sputtering coating technology. After activation of Ti-Zr-V thin films，the ultimate pressure can be as low as 5.0E-10 Pa, and the pressure at the middle of the thin-walled arc vacuum chamber could decreased from 1.5E-9 Pa to 6.6E-10 Pa. Furthermore, 0.3mm thin-walled titanium alloy lined arc vacuum chamber and Ti-Zr-V thin films have been successfully applied to HIAF-BRing.

HIAF-BRing, the booster synchronous ring of the High Intensity Heavy-Ion Accelerator Facility, is rapid cycling synchrotron. It requires a vacuum pressure of 5 ×10 -10Pa and a vacuum pipeline that generates small eddy currents under high-frequency magnetic fields of 12 T/s. A new type of vacuum chamber has been successfully developed to reduce effectively the eddy current effect. It also significantly reduces the gap of the dipoles and quadrupoles, compared to the thin-walled stainless steel vacuum chamber with reinforced ribs. The chamber consists of stainless steel pipe with a thickness of 0.3mm and ceramic lining rings. Ceramic rings are gradually and intermittently arranged along the pipeline as a support frame for metal thin-walled chamber. High strength ceramics and stainless steel of the chamber can be baked safely at 300 ℃. Through experimental testing, vacuum pressure of the chamber reaches 4.2 × 10-10pa. The ceramic rings are Au-coated to effectively reduce the beam impedance and the desorption rate of ceramic materials.