Vacuum Technology Research Articles

Field instrumentation and evaluation of ground treatment by combined air-booster and straight-line vacuum preloading without sand

Ground treatment via the vacuum preloading technique has been extensively used in coastal belts worldwide in the field of civil engineering. However, due to the poor effect of traditional ground treatment, a new technology of combined air-booster and straight-line vacuum preloading without sand was proposed. Field tests were conducted in this study to illustrate the treatment effect. Based on the monitoring data of field tests, this paper carefully studied the pore water pressure, and an empirical formula for predicting the average consolidation degree and settlement was provided. In addition, both the soil sensitivity and the undrained shear strength before and after vacuum preloading treatment were discussed. Finally, to illustrate the phenomenon in which the combined air-booster and straight-line vacuum preloading without sand technique can decrease the pore water pressure or accelerate the soil consolidation, a two-dimensional elastoplastic model was established, and the validity of the model was verified.

Production, Measurement and Applications of Vacuum Systems

The most common type of vacuum pumps and measuring gauges based on available literature are studied with emphasis on how new research and development will enable the new generation of vacuum technology specially in designing, its operational procedure and applications. The technologies were developed to meet the operational goal which include vacuum chamber structures, compatible materials, specialized vacuum pump and gauges. There are many areas where different vacuum condition is required for conducting experiments therefore modeling of pumping system is on demand. The basic understanding of how and when the particular pumping and measurement system can be applied most effectively and economically is essential. The poor choice of pumping and measurement system will interfere the scientific objectives and may leads to substantial maintenance demands and an unpleasant working environment. The development and fundamental investigation of innovative vacuum techniques for creation and measurement of vacuum used for various applications necessary for the research work to be done in future are presented.

Conceptual design of a PAV-based tritium extractor for the WCLL breeding blanket of the EU DEMO: Effects of surface-limited vs. diffusion-limited modeling

In order to close the fuel cycle, the EU DEMO will be equipped with a breeding blanket (BB) for the on-site tritium production. In the water cooled lithium lead (WCLL) BB concept, the tritium will be generated in the liquid PbLi from which it must then be extracted.The conceptual design of the tritium extraction and removal system for this BB concept is addressed here. It relies on the permeator against vacuum (PAV) technology, where the tritium dissolved in the PbLi is forced to cross a metal (Nb) membrane by pumping the vacuum on the secondary side. The proposed PAV geometrical configuration is based on the shell-and-tube concept, where the walls of the pipes in which the PbLi flows are the permeator membrane. The dimensioning of one permeator vessel for one of the PbLi loops is carried out here, adopting two different models for the tritium permeation: diffusion-limited (for the case of a non-contaminated membrane) and surface-limited (suitable for a contaminated Nb surface).The results show that in the case of a non-contaminated membrane it is possible to reach the target tritium extraction efficiency also at the PbLi nominal operating temperature, while in the case of a contaminated membrane the PbLi should be heated to enhance the permeation.

Main Results of the 27th International Conference on Vacuum Technique and Technology (VTT2020)

In this preface the main results of the 27th International Conference on Vacuum Technique and Technology (VTT2020) that was held on 27–29 October 2020 in Saint Petersburg, Russia are discussed.From 27 to 29 October 2020, the 27th International Conference on Vacuum Technique and Technology was held in the virtual form at the Saint Petersburg Electrotechnical University “LETI”. The Conference was organized by the Ministry of Science and Higher Education of the Russian Federation, Saint Petersburg Electrotechnical University “LETI” named after V I Ulyanov (Lenin), All-Russian Research Institute of Metrology named after D I Mendeleev, Institute of Problems of Mechanical Engineering of the Russian Academy of Sciences, Russian Scientific and Technical Vacuum Society named after Academician S A Vekshinskiy, Peter the Great Saint Petersburg Polytechnic University, Euro-Asian Cooperation of National Metrology Institutes (COOMET), National Metrology Institute (TUBITAK UME, Turkey).List of Images, Organizing Committee, Program Committee, Members, are available in this pdf.

Vacuum technology in the extraction of cannabinoids

Vacuum technology in the extraction of cannabinoids

Standard absolute pressure transducers MIDA-SA-15-S for vacuum equipment

High-precision digital (RS485 / Modbus) absolute pressure transducer based on “silicon on sapphire” structures for vacuum technology is presented.

Atomic-molecular and acoustoelectronic processes in a rarefied gas medium

The features of the interaction of surface acoustic waves with a rarefied gas medium are considered. The relationship between acoustoelectronic and atomic-molecular phenomena accompany the processes of adsorption and desorption of atoms and molecules on the surface of a solid is analyzed. Two types of sorption processes are discussed: adsorption and desorption of gas on a solid surface; adsorption and vapour desorption. In the first process, the temperature of the adsorbent is higher than the boiling point of the corresponding liquid. In the second, the adsorbent temperature corresponds to the area of coexistence vapour and liquid. In each case, the use of vacuum technology in the processes under investigation is noted.

FT-ICR mass spectrometry: Superconducting magnet, external ion source, ion-molecule reactions, and ion-ion traps.

The world of Fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometry has witnessed, especially in the last 30 years significant advances in many fields of science, such as electronics, magnets, new ICR cell designs, developed ICR event sequences, modern external ionization sources, and linear ion beam guides, as well as modern vacuum technology. In this review, a brief account is given focusing especially on the studies performed in Wanczek's group and ICR research laboratory at the University of Bremen. An FT-ICR mass spectrometer has been developed with a high magnetic field superconducting magnet, operating at 4.7 T. At this magnetic field, a trapping time of 13.5 h was obtained with 30% efficiency. For the tetrachloromethane molecular ion, m/z 166, a mass-resolving power m/Δm = 1.5 × 106 was measured at a pressure of 2 × 10-8 Torr. The transition from magnet sweep to frequency sweep and the application of Fourier-transform has greatly enhanced the ICR technology. External ion sources were invented and differential pumping schemes were developed for enabling ultrahigh vacuum condition for ICR detection, while guiding ions at relatively higher pressures, during their flight to the ICR cell. With the external ion source, a time-of-flight ICR tandem instrument is built. A method to measure the ion flight time and to trap the ions in the ICR cell is described. Many ICR cell characteristics such as z-axis ion ejection and coupling of radial and axial ion motions in a superposed homogeneous magnetic and inhomogeneous trapping electric field were extensively studied. Gas-phase ion-molecule reactions of several reactive inorganic compounds with a focus on phosphorous and sulfur as well as silicon chemistry were also studied in great detail. The gas-phase ion chemistry of several trifluoromethyl-reagents such as trifluoromethyltrimethylsilane and tris(trifluoromethyl)phosphine were also investigated in ICR. Dual polarities multisegmented ICR cells were invented and deeply characterized. Sophisticated ICR pulse event programs were developed to enable long-range ion-ion interactions between simultaneously trapped positive and negative ions.

Reactive Alloys of IIA Metals: Gas Sorption and Corrosion as One Process

The present work summarizes the results of previously known, as well as the latest sorption measurements, which were carried out on IIA metal alloys in the form of films, powders and macrobodies with a monolithic structure. Analysis of these data made it possible to construct an empirical sorption model, according to which the corrosive decomposition of reactive alloys is one of the driving forces of the sorption process. This model provides a qualitative description of the sorption behavior of these alloys in a gas environment and can be useful in solving practical problems in the field of vacuum and gas technologies.

Applications of Vacuum Measurement Technology in China’s Space Programs

The significance of vacuum measurement technology is increasingly prominent in China’s thriving space industry. Lanzhou Institute of Physics (LIP) has been dedicated to the development of payloads and space-related vacuum technology for decades, and widely participated in China’s space programs. In this paper, we present several payloads carried on satellites, spaceships, and space stations; the methodologies of which covered the fields of total and partial pressure measurement, vacuum and pressure leak detection, and standard gas inlet technology. Then, we introduce the corresponding calibration standards developed in LIP, which guaranteed the detection precision of these payloads. This review also provides some suggestions and expectations for the future development and application of vacuum measurement technology in space exploration.

Manufacturing features, structure, and properties of high-purity Mo-Re thin sheets

Manufacturing features, structure and properties of low-alloyed molybdenum sheets 0.5 mm thick made from the experimental Mo-3 wt.% Re single crystal are described and discussed in the present work. The developed technological scheme includes warm rolling of the initial ingot at a temperature of 1150 °C, with heating in the argon protective atmosphere, subsequent annealing at 850 °C for 2/3 h in a vacuum, no less than 1 ·103 mmHg, cold rolling at a temperature of 400 °C, and post-deformation annealing at 800 C for 1/2 h. The results of micro structure analysis, physical and mechanical studies show that thin sheets are characterized by simultaneously high strength and plasticity, as well as the required temperature coefficient of linear expansion (TCLE), necessary for bonding with a glass by a thermo-compression welding. Obtained results reveal perspectives for the development of the application of thin Mo-3 wt.% Re sheets in vacuum engineering for the vacuum-tight metal-glass parts.

다공성 알루미늄 소재를 적용한 진공 박막성형 금형개발

In an injection-molding operation that applies vacuum technology, the thin-film sheet product must be molded to a uniform thickness. However, the dike part of the indoor panel of a refrigerator undergoes large variations in its thickness and a high defect rate. Therefore, porous aluminum was used so that a uniform distribution of vacuum pressure can be applied to the entire acrylonitrile butadiene styrene resin in the indoor panel. The pore density of porous aluminum was determined using finite-element analysis, and the products from the developed mold were inspected for corner thickness, cotton flannel marks, and air-hole marks. The defect rate was significantly reduced, and the appearance quality of the product was improved. The improved thin-film-forming technology is expected to greatly contribute to the development of the mold industry.

Universal gripper for fabrics – design, validation and integration

PurposeThe paper aims to present the design, validation and integration of a universal fabric gripper. Flexible material handling is one of the most challenging problems occurring in the field of manipulator robots. Because textile products shape and properties can widely vary, each textile and each technological operation should have its own specialized gripper. The objective of the work described here is therefore to design a universal gripper able to grip and transfer every kind of textile.Design/methodology/approachThe design objectives are the ability to handle panels of varying shapes and sizes without material deformation and/or folding, and the easy integration with commercially available manipulator robots. To answer initial requirements and increase the textile gripping reliability, we opted to combine three different gripping technologies: vacuum, intrusion and pinch.FindingsEach system was first validated independently through static tests. The vacuum technology offers a high reliability to handle impermeable materials. The intrusion technology is reliable for the manipulation of high porosity materials, while the pinch technology shows good results for all soft fabrics when combined with the vacuum technology. Then, the limits of the new gripper in terms of gripping capacity, compressed air consumption and characteristics and limitations of the flexible material handled were put in evidence using a robot arm. An automated selection program of the gripper based on the material characteristics has also been developed and implemented.Originality/valueThis paper fulfills an identified need to design a universal gripper able to grip and transfer every different kind of cut textile.

Novel Non-Evaporable Getter Materials and Their Possible Use in Fusion Application for Tritium Recovery.

Non-evaporable getters (NEGs) are metallic compounds of the IV group, particularly titanium and/or zirconium-based alloys and are usually used as pumps in vacuum technologies since they are able to sorb, by chemical reactions, most of the active gas molecules, with particular efficacy towards hydrogen isotopes. This work suggests an alternative application of these materials to fusion nuclear reactors, where there is the need to recover small amount of tritium from the large helium flow rate composing the primary coolant loop. Starting from the tritium mass balance inside the primary coolant loop, the amount of coolant to be routed inside the coolant purification system (CPS) is identified. Then a feasibility study, based on the bulk getter theory, is presented by considering three different commercial alloys, named ST707, ST101 and ZAO. The results provide the mass, the area and the regeneration parameters of the three different alloys necessary to fulfill the requirements of the CPS unit. By comparing the features of the three alloys, the ZAO material appears the most promising for the proposed application because it requires the lower amount of material and a lower number of regeneration cycles.

3C-SiC growth by sublimation in vacuum technology optimization

Results of an epitaxial growth of 3C-SiC epilayers on hexagonal 6H-SiC, 4H-SiC substrates are described. The study of the obtained epitaxial layers grown on 6H substrates was made by photoluminescence and optical microscopy. Also, an image analysis of the interface of 3C-SiC epitaxial layers with 6H, 4H, and 15R substrates obtained by Transmission Electron Microscopy (TEM) are presented. Difference between the layers on the Si and C faces are discussed.

A flange-type standard leak element and its vacuum applications

A previous article [C.K. Chan et al., Vacuum 180, 109650 (2020)] described a gasket-type standard leak element (SLE) that could be employed to solve the problem of serious outgassing and the constraint of a low baking temperature (<120 °C) caused by the use of an epoxy resin sealant (Torr Seal®) on a sealing interface. Here, we propose a leak element of a new type using femtosecond laser micromachining to drill a microscale channel on a double-sided ConFlat (CF) flange. Not only is the flange-type SLE reusable but also its performance is as effective as that of a gasket-type SLE. This useful device can be widely applied to many vacuum technologies and applications, which are also described in this paper.

Preparation of large area graphene on SiC(0 0 0 −1) by moderate vacuum technology

Owing to its compatibility with existing Si technology, epitaxial graphene on SiC is expected to replace III-V materials in future. This paper proposes an available approach to overcome the low quality and the high cost properties of traditional epitaxial growth access. The epitaxial graphene grows in low vacuum environment, using Ar as the filling gas. The epitaxial graphene was investigated with optical microscope, atomic force microscopy and Raman spectroscopy. It is found that large area graphene cover on SiC C-face conformally. The Raman results show that the materials obtained in lower vacuum environment are ordered and put free standing monolayer graphene.

The Thermodynamic Model for Vacuum Technology

The paper is focused on developing a mathematical model capable to describe thermodynamic processes connected with the vacuum technique. The model is based on the laws of energy and mass conservation, the air state behavior, and the principles of airflow, including the critical flow. The problem has been solved numerically by MATLAB. The results of the solution include the pressure evolution for a given pumping speed and the volume to be evacuated. Solutions are obtained for cases of airflow to the vacuum chamber through an inlet opening for three various diameters. The solutions are validated by comparing with experimental data. The presented model agrees with the experiment quite well. One very useful application is the determination of the relation between the diameter of the inlet opening and the pumping speed of the vacuum pump at the pressure steady state condition. This is an important knowledge for a simple and reliable quantitative pressure control in vacuum systems.

Synthesis and Characterization of Ordered Cobalt Phosphide Nanowire Arrays As a Potential Catalyst for HER/Oer Reactions.

Nowadays, increased interest in the field of nano-scale materials is observed [1]. Knowledge about the physicochemical properties of nano-objects is desirable since they exhibit completely different properties than their macroscopic counterparts. The greatest advantage of nanomaterials is their developed specific surface area. This feature is useful in many fields of science, e.g., catalysis, that uses a large number of active centers (resulting from the developed surface), as well as modifications of the electronic structure of nanoparticles that change their redox properties.For many years, an effective evolution of hydrogen, which is recognized as a zero-emission fuel, has been a problem. The gaseous hydrogen can be obtained via a very important reaction of water decomposition. In this field, developing a catalyst that enables low-cost, efficient, and fast water lysis is the main challenge. One of the potential catalysts for an electrochemical water decomposition is the cobalt phosphide [2], which can be obtained via the phosphorization of cobalt. Undoubtedly, the application of the cobalt phosphide nanowire arrays electrode will be beneficial due to the large surface area.In this study, an attempt to the electrodeposition of cobalt nanowires using two types of baths (i.e., aqueous and non-aqueous), via constant current and constant potential modes at different temperature ranges was made. Thus, the influence of these factors on the surface morphology of the obtained nanowires as well as their growth rate was investigated. The cobalt phosphide nanowires were obtained via annealing of the Co nanowires inside the AAO (anodic aluminum oxide) membranes, with red phosphorus in an inert atmosphere at 500 ºC for 2 h. The morphology and chemical composition of cobalt and cobalt phosphide nanowires were examined using scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). Electrochemical tests were carried out in a three-electrode cell using 0.5 M H2SO4 as an electrolyte. For all experiments, except XRD, the AAO templates were removed in 1 M NaOH.[1] Baer, D. R., Engelhard, M. H., Johnson, G. E., Laskin, J., Lai, J., Mueller, K., Moon, D. Surface characterization of nanomaterials and nanoparticles: Important needs and challenging opportunities, Journal of vacuum science & technology, 2013, 31(5), 50820[2] Pan, Y.& Lin, Y. & Chen, Y. & Liu, Y. & Liu, C., Cobalt phosphide-based electrocatalysts: Synthesis and phase catalytic activity comparison for hydrogen evolution, Journal of Materials Chemistry A., 2016, 4(13), 4745-4754This work was supported by the National Science Centre Poland (Grant No. 2017/26/M/ST5/00715). The participation in this conference was made possible by financial support from the Polish Ministry of Science and Higher Education within a conceptual non-competitive project entitled "Best of the best! 4.0." (Measure 3.3). The project is co-financed from the European Social Fund under the Operational Programme Knowledge, Education, Development 2014-2020 (POWR.03.03.00-00-P019/18).

Деконтаминация ртутьсодержащих отходов с использованием озона

Technologies and equipment for the disposal of mercury containing lamps related to class 1 waste sold in industry are considered (vacuum distillation of waste with cryogenic condensation of mercury vapor, thermal vacuum technology most suitable for “clean” waste, reagent demercurization. Their advantages and disadvantages are analyzed. A cold technology is proposed for decontamination of mercury-containing materials - treatment of the battle of fluorescent lamps using ozone. Recommended equipment for the implementation of this technology. Cold technology using ozone will allow for the management of mercury-containing wastes in accordance with the Minamata Convention on Mercury.