Design Of Vacuum System Research Articles

Design and development of vacuum system for electron beam powder bed fusion process

A vacuum system is one of the crucial components of the Electron Beam-Powder Bed Fusion Process (EB-PBF). It ensures the generation of a high-intensity electron beam. This paper presents a vacuum system design for the EB-PBF process. The work chamber and EB gun chamber have been designed and verified using ANSYS workbench for stress, strain, and deformation limits and found satisfactory. The analytical calculations have been performed for all the pumps, considering the various gas loads during the process. After the design, the vacuum system has been fabricated and tested for its stability, ultimate vacuum, and leak rate. The helium leak test results show that all the joints have a leak rate better than 1 × 10−8 mbar l/s. Further, the analytical results of each pump have been compared with experimental results and found almost in line with the theoretical results. The results show that a pressure lower than 1 × 10−5 mbar and 5 × 10−6 mbar can be achieved in the work chamber and EB gun chamber in less than 23 min and 10 min respectively. The chamber was evacuated multiple times and found that the chamber could still hold pressure better than 1 × 10−2 mbar after 48 h.

Comparison of two vacuum system technologies for the synchrotron storage ring: case study of Iranian Light Source Facility

The current study compares two vacuum system designs for the Iranian Light Source Facility (ILSF) storage ring: conventional vacuum system design with stainless-steel vacuum chambers that are pumped by Non-Evaporable Getter (NEG) cartridges and ion pumps. In this design, all synchrotron radiation is absorbed by the local photon absorbers. In the second design, the water-cooled copper tubes that are coated with NEG materials are used as the vacuum chambers. This study will illustrate the advantages of using the NEG-coated vacuum chambers over the conventional design with the stainless-steel chambers. Since the two designs for ILSF are now completed, some of the details of this comparison might be interesting to other light sources, especially those that have plans to upgrade to a 4th generation.

Vacuum System of the LINAC-200 Accelerator

The LINAK-200 linear accelerator at the JINR Nuclear Power Plant is being built to provide electronic test beams with an energy of up to 200 MeV for research and development in the field of particle detectors, to study advanced methods for diagnosing electron beams and to work as an irradiation unit for applied research. Although the LINAK-200 uses MEA accelerator equipment (NIKHEF), the vacuum system has been significantly upgraded. This paper presents the design and condition of the new vacuum system.

Centralized design and production of the ultra-high vacuum and laser-stabilization systems for the AION ultra-cold strontium laboratories

This paper outlines the centralized design and production of the ultra-high-vacuum sidearm and laser-stabilization systems for the AION Ultra-Cold Strontium Laboratories. Commissioning data on the residual gas and steady-state pressures in the sidearm chambers, on magnetic field quality, on laser stabilization, and on the loading rate for the 3D magneto-optical trap are presented. Streamlining the design and production of the sidearm and laser stabilization systems enabled the AION Collaboration to build and equip in parallel five state-of-the-art Ultra-Cold Strontium Laboratories within 24 months by leveraging key expertise in the collaboration. This approach could serve as a model for the development and construction of other cold atom experiments, such as atomic clock experiments and neutral atom quantum computing systems, by establishing dedicated design and production units at national laboratories.

Residual gas noises in vacuum of optical interferometer for ground-based gravitational wave detection

Gravitational waves (GWs) are ripples in spacetime caused by most violent and energetic processes in the universe, such as the rapid motion of massive celestial bodies. The GWs carry energy when they propagate through the universe. The detection of GWs holds significance for advancing human understanding of the nature and driving scientific and technological progress. The continual upgrading and optimizing of GW detectors offer novel avenues for cosmic measurements. However, ground-based GW detectors based on a large interferometer necessitate addressing various noises which are harmful to the sensitivity of the GW detectors. Among these noises, the noise from residual gas in the light beam of the interferometer is a crucial factor to affect the sensitivity. Consequently, it is necessary to establish a vacuum system to shield the laser interferometer from the effects of gas flow. This paper focuses on China’s third-generation ground-based GWs detector, conducting theoretical analysis of the influence of residual gas noise on both a 20-meter arm-length prototype and a full-scale device with a 10-kilometer arm-length. In this paper, a theoretical model for the residual gas particles passing through the laser beam is established and the effect on the beam phase is analyzed. The theoretical simulations are performed to discover the relations between the residual gas noise and significant parameters such as gas pressure of the vacuum system, temperature, mass of residual gas particles, polarization rate of the residual gas, and the curvature radius of the test mass. The simulations indicate that when the residual gas pressure is below 2×10<sup>–6</sup> Pa, the GW detector can achieve the enough sensitivity, 10<sup>–24</sup> Hz<sup>–1/2</sup>, in a frequency range from 10 to 10<sup>3</sup> Hz. The findings of this research offer crucial theoretical insights for designing and constructing the vacuum systems in future third-generation GWs detector prototypes and full-scale devices.

Beamline and vacuum system design of HEBT for the A-FNS accelerator

The Advanced Fusion Neutron Source (A-FNS) project is progressing at the QST Rokkasho institute, Japan. The A-FNS will conduct fusion neutron irradiation tests of materials for a fusion demonstration reactor (DEMO reactor). For these tests a high intensity deuteron beam accelerator is used to produce a high neutron flux with the neutron energies around 14 MeV. The accelerator system accelerates a deuteron beam to a beam energy of 40 MeV, guides the beam towards a liquid lithium target and shapes the uniform beam at the Li target using a magnet system.Two of the main considerations for the A-FNS high energy beam transport (HEBT) design are protection of the Superconducting Radio-Frequency linear accelerator (SRF) and vacuum system design for the interface of the HEBT and the target system. For the A-FNS, back streaming of Li vapor from the windowless free surface of the Li target is a concern. In addition, widely different vacuum pressure must be maintained between the accelerator system and the target system. This paper shows the detailed design of the A-FNS HEBT section regarding these considerations.

Design of vacuum system for NCST spherical tokamak

The NanChang Spherical Tokamak (NCST) is a new compact tokamak with an aspect ratio of R/a = 1.67. The vacuum system is one of the most important sub-systems of the tokamak device and has been designed especially for the NCST device. It consists of three main parts: a pumping system, a gas puffing system, and a wall conditioning system. The pumping system includes two turbo-molecular pumps, a cryopump, and two rotary pumps. The gas puffing system consists of a gas supply, transfer lines, a gas reservoir, pressure gauges, and piezoelectric valves. The wall conditioning system includes baking and glow discharge cleaning functions. The vacuum system and related experimental results are described in detail in this paper. The test results indicate that the NCST vacuum system is reliable. Inside the vessel, the ultimate pressure reached 4.2 × 10−6 Pa after 307 h of pumping. The upgraded gas puffing system can accurately control the gas entering the vacuum vessel. The wall conditioning systems, such as those for baking and glow discharge cleaning, also play a very important role in plasma operation. The plasma discharge results show that the basic function of the vacuum system meets the essential requirements of the present experiments on the NCST tokamak.

Design and experimental validation of differential pumped vacuum system for HINEG windowless gas target

High Intensity Neutron Generator (HINEG) is a facility aiming for neutronics design validation, materials and components irradiation test, nuclear waste transmutation and nuclear technology applications, etc. A high-pressure windowless gas target system is adopted for HINEG to achieve a higher neutron yield. Therefore, a three-stage differential vacuum system has been developed to couple the pressure transition of 6 orders of magnitude to the 300 kV/50 mA high-intensity beam transport in a series of large-diameter pipes. A suitable pumping system has been developed to increases the target pressure which is used to generate D-T neutron yield of 2.1 × 1013 n/s. A windowless pressure transition from high gas pressure (1 × 103 Pa) in the gas target chamber to high vacuum (3 × 10−3 Pa) in the accelerator is reached. In this paper, a new differential pumped vacuum system is designed for HIENG. Innovatively, the newly designed differential vacuum system can not only meet the transport requirements of the high-current low-energy deuteron beam, but also couple the pressure transition of 6 orders of magnitude, which can solve the contradiction of the large-diameter pipe required for high-intensity beam transport and the small diameter pipe needed for the high-pressure difference.The experimental validation and design optimization of differential pumped vacuum system is introduced. The experiment results indicate the validity of the theoretical calculation. Compared to molecular pumps, roots pumps might be more suitable for windowless differential vacuum system coupled to large-diameter apertures and pipes. The design could be used for reference in other windowless gas target systems coupled to accelerator with high-current low-energy ion beam.

The FCC-ee vacuum system, from conceptual to prototyping

The FCC-ee is a very challenging accelerator project from the point of view of vacuum. Apart from the sheer size of the machine, a twin-ring of 100 km circumference, the vacuum system design must be capable of dealing with the low-energy 45.6 GeV, high-current version of the machine (the Z-pole) as well as the higher energy, lower current versions. The main difficulty is related to the very much different synchrotron radiation (SR) spectra of the Z-pole vs the other energies, in particular the ttbar at 182.5 GeV. The critical energy of the SR spectrum of the Z-pole is 19.5 keV, while the ttbar exceeds 1.2 MeV. It is particularly challenging in terms of shielding the beryllium chamber in the detectors, for the Machine Detector Interface (MDI) area. We discuss the evolution of the vacuum system design for the arc sections, and some new ideas on NEG-coating, SR absorbers, and pumping system, with the aim to build prototypes soon, in the framework of the FCC Innovation Study program. The design of the vacuum hardware depends on the choices made for the magnets, and the required shielding from high-energy radiation generated by the circulating beam interacting with the residual gas and the interaction of the intense SR fans with the photon. There is also an important collaboration with the engineering integration of the vacuum system in the tunnel, particularly considering the full-energy booster injector, which is not detailed here. We also briefly describe the raytracing montecarlo modelling efforts carried out in the MDI area, and its pumping configuration.

Design and test of vacuum system for 40 T hybrid magnet superconducting outsert of China

The vacuum system for 40 T hybrid magnet superconducting outsert in the Chinese High Magnetic Field Laboratory has been successfully designed, fabricated, installed, and tested. The vacuum system has achieved stable operation after several rounds of optimization. The influence of the pressure and strong magnetic field on the long-term stable operation of the 40T hybrid superconducting outsert was investigated. In the process of structural verification of the vacuum system, the stress distribution of the vacuum system under the influence of assembly, cooling, and quench is analyzed, and the correctness of the analysis results is verified by the theoretical calculation results of circumferential stress. On this basis, the membrane stress, bending stress, and secondary stress were calculated, and the safety of a large vacuum chamber is evaluated by using ASME international vacuum standard code. According to the outgassing test data of the multilayer insulation under real working conditions, the pumping calculation formula was fitted for outgassing rate estimation. The results show that the vacuum system was pumped down from the atmospheric pressure to 5.0 × 10−3 Pa in approximately 72 h and that it worked stably for a fairly long time, affected little by the strong background magnetic field.

Progress of engineering design of CFETR vacuum systems

Vacuum systems for the China Fusion Engineering Test Reactor (CFETR), including pumping system, fueling system, wall conditioning, as well as their control systems, are required to achieve high vacuum, effective plasma fueling, and good wall condition for steady-state plasma operation and to facilitate remote flexible control with high reliability to ensure safe operation. In the last few years, based on the requirements of vacuum systems and subsystems of CFETR, their features and challenges have been analysed, basic parameters have been defined, and preliminary designs have been developed. Herein, nine cryopumps with pumping speed of 68 m³/s for D2 in a molecular flow regime are proposed for use in a torus vacuum chamber to achieve vacuum pressure <1.0 × 10−5 Pa before plasma operation. The throughput of the torus pumping system is designed to be >290 Pa•m³•s−1 to meet the requirement of steady-state operation of CFETR discharge. Pellet injectors and the gas injection system for seeding the fuel and impurity gas and wall conditionings, including baking, GDC, and ICRF-DC, for removal of hydrogen isotopes/impurities of the torus vacuum are also designed. Moreover, integrated design of vacuum systems and space layout of all subsystems are also investigated.

Effect of the film thickness on pumping properties of Ti–Zr–V coating

Non-evaporable getter (NEG) coating is widely used for vacuum system of charged particle accelerators. The RF surface resistance of NEG coating is increasing with its thickness. Therefore, knowing how NEG coating properties depend on its thickness is essential for vacuum system design of accelerators. This paper describes the results of studying the pumping properties of Ti–Zr–V NEG films deposited from an alloy target for thicknesses in the range between 0.1 and 1μm. Good pumping properties for H2 and CO have been demonstrated after activation to 140 °C. It has been demonstrated that initial CO sticking probability does not depend on thickness, however, initial H2 sticking probability and CO sorption capacity are almost proportional to NEG thickness. The NEG coating degradation with a number of activations has been observed, the thinner NEG film the stronger the degradation.

Gravitational-wave physics with Cosmic Explorer: Limits to low-frequency sensitivity

Cosmic Explorer (CE) is a next-generation ground-based gravitational-wave observatory concept, envisioned to begin operation in the 2030s, and expected to be capable of observing binary neutron star and black hole mergers back to the time of the first stars. Cosmic Explorer's sensitive band will extend below 10 Hz, where the design is predominantly limited by geophysical, thermal, and quantum noises. In this work, thermal, seismic, gravity-gradient, quantum, residual gas, scattered-light, and servo-control noises are analyzed in order to motivate facility and vacuum system design requirements, potential test mass suspensions, Newtonian noise reduction strategies, improved inertial sensors, and cryogenic control requirements. Our analysis shows that with improved technologies, Cosmic Explorer can deliver a strain sensitivity better than $10^{-23}/\mathrm{Hz}^{1/2}$ down to 5 Hz. Our work refines and extends previous analysis of the Cosmic Explorer concept and outlines the key research areas needed to make this observatory a reality.

Building a Differential Electrochemical Mass Spectrometry (DEMS): A Powerful Toll for Investigation of (photo)Electrochemical Processes

The development of electrochemical devices more efficient for energy conversion and storage are a challenge for modern society. Among this class of devices, fuel cells, batteries, and photovoltaic cells stand out. Despite their importance and practicality, the electrochemical processes that take place in these devices are not always easily understood. In addition, the detection and identification of the products and intermediaries, as well as the reaction paths usually are extremely complex, due to the different species produced and also several reaction steps that take place simultaneously in this type of system. In this context, analytical techniques have been combined to electrochemistry systems to investigate the electrochemical processes in real-time. FTIR (infrared spectroscopy with Fourier transform), MS (mass spectrometry) are some of examples that coupled techniques. Therefore, these setups provide great opportunities for the electrochemistry field, which also includes catalysts design improvement and reaction investigations under different experimental conditions.1-3 The electrochemical mass spectrometry (EMS) technique has stood out as an important tool for the identification and analyses of qualitatively/quantitatively gaseous, volatile intermediates, and products generated during electrochemical reactions. The interface between the mass spectrometer’s high-vacuum system and the electrochemical cell’s room pressure was composed of a hydrophobic porous membrane connected to the inlet system. The ionic current intensity associated with the products was monitored and correlated to the faradaic current3. In 1984 Wolter and Heitbaum4 refined the Electrochemical Mass Spectroscopy technique, employing a new vacuum system design consisting of two pumping stages, giving high sensitivity to the technique and allowing the on-line detection of gaseous with response-time ≤ 0.5 s, four times faster than the first setup developed. The Wolter and Heitbaum’s method was called Differential Electrochemical Mass Spectroscopy (DEMS). Here, differential pumping is related to a two-stage pressure reduction, where the gas flow is initially expanded to a low vacuum and later to a high vacuum, where the mass spectrometer is located4. This work presents the instrumental design used to construct a DEMS to investigate and elucidate (photo)electrochemical reactions. The DEMS design selected was composed of a two-stage differentially pumped vacuum system (Figure 1(I)). The instrument is composed of three main sections: electrochemical cell; hydrophobic microporous membrane, and mass spectrometer, including the vacuum system (turbomolecular and pre-vacuum pumps). The electrochemical cell used, was employed initially by Baltruschat5, this cell use a modified Polytetrafluoroethylene (PTFE) porous membrane interface as the working electrode, which is prepared by metal sputtering onto a microporous membrane.An example of the relation between cyclic voltammogram (CV) and mass-spectrum cyclic voltammograms (MSCV) using the DEMS constructed in this work is shown in Fig. 1((II)a-b), respectively (CVs only in H2SO4 is presented as an insert in Fig. 1(a)). The working electrode was sputtered of platinum (50 nm thickness) onto the PTFE microporous membrane interface. The counter electrode was a platinum mesh with a high surface area, the reference electrode was a reversible hydrogen electrode (RHE). The electrochemical cell was directly attached to the pre-vacuum chamber of the mass spectrometer High purity N2 was used to de-aerate the solution.The cyclic voltammograms were recorded at a sweep rate of 10 mV s-1. While the faradaic current and the ion mass current for the generated product, CO2 (m/z = 44 (CO2 +), were monitored at the same time. Fig. 1(c-e) shows the faradaic (d) and ionic currents (e) profiles vs. time obtained for 6 CVs, the potential is also presented. As can be observed, the faradaic current has an excellent correlation with the ionic current, conducting to a great synchronization between the voltammetric scans and the ionic signal profile. Besides, the results show a significant deactivation of the electrocatalyst, which is followed by the ionic signal (m/z = 44). As reported in the literature6, the formic acid electrooxidation produces a poison intermediate, which is formed from the dissociative adsorption of formic acid on the electrode surface, this poison specie was posteriorly identified as CO. Therefore, the DEMS technique can provide important information to determine the reaction mechanisms. Bashyam, R.; Zelenay, P., Nature 2006, 443 (7107), 63-66. Bruckenstein, S.; Gadde, R. R., Journal of the American Chemical Society 1971, 93 (3), 793-794. Chen, A.; Lipkowski, J., The Journal of Physical Chemistry B 1999, 103 (4), 682-691. Wolter, O.; Heitbaum, J., 1984, 88 (1), 2-6. Baltruschat, H., Journal of the American Society for Mass Spectrometry 2004, 15 (12), 1693-1706. Herrero, E.; et al.., Journal of Electroanalytical Chemistry 1993, 350 (1), 73-88. Figure 1

Development of a combined XRF/XPS surface-analysis system for the surface-layer quantification of 28Si spheres

&lt;p class="Abstract"&gt;To achieve a new kilogram definition using the X-ray crystal density method, the Center for Measurement Standards, Industrial Technology Research Institute in Taiwan has established the combined XRF (X-ray fluorescence)/XPS (X-ray photoelectron spectroscopy) surface analysis system for the quantitative surface-layer analysis of Si spheres. The surface layer of a Si sphere is composed primarily of an oxide layer, carbonaceous contamination and physisorbed/chemisorbed water. This newly combined instrument has been implemented to measure the XRF for the direct determination of the mass deposition of oxygen (ng/cm&lt;sup&gt;2&lt;/sup&gt;) with a calibrated silicon drift detector and the XPS for the ratio between the elements (O, Si, C) and composition identification. These two complementary methods of X-ray metrology allow an accurate determination of the surface-layer mass of the Si sphere. In this paper, the construction of a combined XRF/XPS surface-analysis system is reported, including the surface characterisation method, the assembly of parts of the load-lock chamber and ultra-high-vacuum analysis chamber, the vacuum-system design, hardware integration and the intended research on surface-layer measurement. It is anticipated that the measured surface-layer mass will be combined with the core mass of the Si sphere.&lt;/p&gt;

Development of an ultra-high vacuum system for a cold atom physics rack in space

We present the design and testing of the ultra-high vacuum (UHV) system, which is a key apparatus for the Cold Atom Physics Rack (CAPR) operated on the Chinese Space Station that allows study of ultracold atoms in microgravity. The simulation of the gas flow and experimental tests show that our UHV has a pressure of 3.4×10−9Pa in the science chamber, two orders of magnitude lower than that of the 2D magneto-optical trap (2D-MOT) chamber. Moreover, we demonstrate that the system can not only self-sustain an equilibrium pressure for more than 1 month without power but also restore the desired pressure in the interaction zone. The loss dynamics of the trapped atoms are also measured to assess the performance of the UHV system.

Design, simulation and implementation of an efficient vacuum system and gas load calculations for a 6 MeV industrial LINAC

The design of vacuum system for a 6 MeV, commercial LINAC is presented. Unlike many commercial LINACs, the LINAC being developed has demountable electron gun, RF-waveguide and X-ray target assemblies. This design scheme is more efficient and economical. The LINAC has a total internal volume of 1.9 land surface area of ~3.2 × 103cm2, and is operated at Ultra High Vacuum. An iterative Simulation-Experimental approach is adopted to freeze a viable vacuum system for the LINAC. The vacuum simulations are performed in MOLFLOW+2.7.7, and the results are benchmarked experimentally. Due to compact geometry of the LINAC, reduced pumping speeds are experienced. The system was implemented using two 550 l/s commercially available turbo molecular pumps backed by rotary pumps, consuming ~2.4 kW. Particle dynamics simulations were performed using PARMELA 3. These simulations quantified the beam loss in the LINAC and predicted the sites of beam impingement. The system was experimentally verified for establishment of base pressure, activation of dispenser cathode, electron gun conditioning and the full power operation of LINAC at repetition rate of 50–110 Hz. Through all these regimes the vacuum system performed within permissible limits. The gas loads induced in the system were also evaluated using steady state and transient analysis. The pumping speed is optimized, and it is shown that base pressure of 1 × 10−9mbarcan be achieved at reduced pumping speed of ~100 l/s at the pumping ports. This reduced pumping speed also performed well for routine LINAC operation. Therefore, using benchmarked simulated results, an optimized and commercially economical vacuum system is proposed with reduced pumping speed of ~100 l/s consuming 6 times reduced power (0.4 kW) and ~40% reduced cost.

Vacuum system design, construction, and operation for the Cornell High Energy Synchrotron Source upgrade

During the summer and fall 2018, the Cornell High Energy Synchrotron Source (CHESS), underwent an upgrade that recast the facility as primarily a low emittance X-ray source. The upgrade replaced one sixth of the Cornell Electron Storage Ring (CESR) with six double-bend achromats, featuring four novel CHESS Compact Undulator (CCU) insertion devices, and switched CESR to single particle beam operation. At the time of this writing, the upgraded storage ring has achieved the CHESS-U design goal of operating with 200 mA of positron current at 6.0 GeV beam energy. Seven out of eleven CHESS-U beamlines are currently in X-ray user operation. The construction and the commissioning of the new section of the CESR accelerator required novel solutions to design, fabrication, and vacuum system operations. Significant design considerations and efforts were made to minimize X-ray ‘dark-time’, returning to operation less than 1 year. This paper describes the important milestones of the process, the solutions implemented, and the present status of CHESS-U.

Reflectivity and photoelectron yield from copper in accelerators

For the design of high-performance particle accelerators and vacuum systems for high-energy colliders, the choice of materials and of their surface treatment is an essential prerequisite. Physical and optical properties of such materials and their coatings are input parameters for programs to simulate their performance and to validate machine design. Materials behavior after exposure to synchrotron radiation (SR), produced by the circulating particles, need to be studied because of its detrimental consequences, such as photo induced desorption, heat load, vacuum and beam induced instabilities. Reflectivity, its angular distribution and photo yield, i.e., the number of photoelectrons produced per incident photon, are essential ingredients to simulation codes. Such parameters must be studied not only on materials as they are in accelerators, but also in conditions as close as possible to the operative ones. In this work, we present results of such an experimental campaign, carried out at the Optics Beamline of BESSY-II. This experimental setup, designed to investigate quasiperfect x-ray-optical elements by ``at-wavelength'' metrology (from 35 eV to 1850 eV), is also an ideal tool to perform reflectivity and photo yield studies of vacuum chamber materials. As will be discussed, different roughness and various nano-, micro- or macro- modifications of a Cu-surface significantly influence the parameters under study. Energy- and angle-integrated values for the total reflectivity and photo yield are derived. Such integrated values are representative for material behavior under ``white-light'' irradiation for the various accelerators discussed here.

Vacuum system design for the storage ring of Iranian Light Source Facility

The current study describes the vacuum system of ILSF storage ring. The design uses the stainless steel vacuum chambers with a continuing keyhole profile all around the storage ring. The NEG cartridge and Ion pumps which are installed in the antechamber will pump all the vacuum sectors. Using Monte-Carlo simulation proved that the machine could reach an average pressure of 1 nTorr after the commissioning phase, which could guarantee a vacuum life time of about 13 h. The general layout of the vacuum system and the construction steps for the vacuum chambers will also be elaborated on. Several discrete photon absorbers which are designed in three types will absorb all the synchrotron radiations. For the heat load study, a simulation with Synrad is performed to calculate the power distribution on the absorber surfaces. Then the result is used to calculate the stress and strain on the absorbers by Finite Element Analysis (FEA).