Vacuum Technology Research Articles

A gigawatt-level metamaterial-based relativistic transit-time oscillator with coaxial energy extraction

This manuscript presents a 2 + 2 metamaterial (MTM) transit-time oscillator (TTO) employing coaxial extraction, engineered to leverage the advantages of MTM and TTO. Cold cavity testing was conducted to examine the electromagnetic properties of the MTM resonator, revealing that at least 1/3 of the radial size can be reduced compared to traditional designs. Comparison of various energy extraction techniques has also been conducted, highlighting the effectiveness of coaxial method over other axial schemes. Computational simulations with electron beams, conducted under parameters of 650 kV, 5.36 kA, and 1.2 T magnetic field, yields a 1 GW microwave output at 1.54 GHz, exhibiting a stable, single mode without competition. This MTM integration significantly reduces the diode impedance in high-power microwave devices, resulting in a shorter axial length and achieving GW-level power output. This design suggests a potential step forward for MTM-based high-power microwave sources, offering the possibility of greater power density and compactness, and may contribute to the advancement of MTM applications in electron vacuum technology.

COMBINED SOLAR-ELECTRIC HEAT SUPPLY SYSTEMS

The article examines combined solar-electric heating systems that integrate renewable and traditional energy sources to provide heating and hot water. An alternative to existing light-absorbing coatings in solar collectors based on low-vacuum aluminum condensates is proposed. Coatings manufactured using vacuum technologies are recommended, when a combined cluster and molecular flow of matter is deposited on the substrate due to a forced increase in pressure. Choosing aluminum as a material for low-vacuum coating adds advantages to this technology, because aluminum has a fairly low melting point, and the controlled formation of oxide phases on the surface of the deposited film significantly increases the corrosion resistance of the coating. The designs of solar collectors, their principle of operation and the advantages of using selective light-absorbing coatings, which can increase the efficiency of collectors by 18–22 %. An innovative infrared heating system is proposed, which ensures increased heat transfer efficiency, reduced energy consumption, and stable operation even at a low level of insolation. the task of the proposed installation is to use energy carriers more efficiently.This becomes possible due to a more rational combination of traditional energy (supply from the network) and the use of secondary energy resources; active turbulation of the heat carrier mass supplied by the circulation pump into the internal volume of the annular chamber; regulation of the heating temperature; equalization of temperature field gradients in the inner volume of the ring chamber; possibilities of regulating the productivity of the heating installation, increasing technological reliability; unification of heating elements and modes; the possibility of power supply from the network and non-traditional sources. The use of heat accumulators and multilayer systems, which allow to increase the duration of hot water selection, have been analyzed. The possibilities of combined schemes with additional energy sources, such as electric boilers or biofuel boilers, which reduce dependence on fossil energy resources, are considered. These solutions contribute to increasing energy efficiency and sustainable development of the energy industry. The conclusions emphasize the potential of integrating such systems into modern energy networks, ensuring environmental friendliness, energy independence and reducing operating costs.

Notched Gate and Graded Gate Oxide Processing for Reduced Capacitance Application in RF MOSFETs

As the demands of RF applications are rising, optimization of internal MOSFETs capacitances is a key issue to improve the cut-off frequency. In this abstract we report the development of a novel N-MOS architecture processed on 8-inch SOI wafers. This architecture has a gate oxide with variable thickness along the channel and a reduced bottom gate length aiming at minimizing Gate to Drain/Source capacitance (1) (2). This improvement on Gate to Drain/Source capacitance mainly comes from a decrease in overlap capacitances as described in (3).The new process flow is composed as usual until Poly-Si gate etching. By controlling the species flow and process time during plasma etching steps, over etch at the bottom of the gate is performed (fig.1(a,b)). Poly-Si gate notching engineering is possible due to reduction of the passivation layer thickness at the bottom of the gate during plasma etch. As described in (4) the gate is first etched using a HBr/CL2/O2 chemistry until reaching close to the bottom of the gate, allowing the formation of a passivation layer made of SiOxCly and the anisotropy of the etch. To etch the remaining thickness HBr flow is augmented while CL2 and O2 flow are reduced, preventing formation of passivation layer. This leads to isotropic etch of the bottom gate and reduction of the gate length as regard to the top Poly-Si dimension. This over-etch reduces the physical gate length without changing the effective and the on-mask gate lengths, leading to overlap capacitance reduction.To produce gate oxide with variable thickness under gate sidewalls a two-steps process is performed. First, full plate oxide is grown before poly-Si deposition to act as middle gate thickness. Then undercut is performed, consisting of lateral etching of the gate oxide under gate sidewall after gate etch (fig.2.a). To achieve this undercut, hydrofluoric acid (HF) wet etch has been chosen. First trials with very low HF concentration become quickly saturated leading to small lengths under gate sidewalls (fig.2.b). Then more acidic solutions were used allowing satisfying undercut lengths (fig.2.c).Finally rapid thermal oxidation (RTO) is performed to obtain an oxide bird beak at both gate side as both Poly-Si gate and Si from the active region react with ambient O2 in the chamber. This leads to a gate oxide with variable thickness along the channel (fig.3(a.b)) which has both effects: to get smoother poly-Si foot and a down step in the active between channel and Source/Drain regions. During this process step, a built-in spacer on the gate sides for LDD implantation is formed. RTO process step has grown a thicker oxide over Source/Drain areas which has to be reduced to allow an accurate LDD implantation, this is done by anisotropic etching. After these new steps, the process goes back to a standard N-MOS process flow.Some early versions of the notched gate have been investigated (5), and these experiments and details on processing recipe seem promising for electrical results. As poly-Si foot has been smoothed and graded gate oxide (GGO) on top of overlaps region is formed. It would allow a reduction in parasitic capacitances improving cut-off frequency of RF applications.References RF LDMOSFET with Graded Gate Structure. Xu Shuming, Foo Pan Dow. Toronto : s.n., 2001. 1th International Symposium on Power Semiconductor Devices and ICs. ISPSD'99 Proceedings. pp. 221-224. DOI:10.1109. Notched-Gate pMOSFET with ALD TiN/High-κ Gate Stack Formed by Selective Wet Etching. Zhang, D. Wu and J. Lu and P.-E. Hellström and M. Östling and S.-L. s.l. : The Electrochemical Society, Inc., 2004, Electrochemical and Solid-State Letters, Vol. 7, p. 228. 10.1149/1.1795612. A simple efficient model of parasitic capacitances of deep-submicron LDD MOSFETs. Fabien Pregaldiny, Christophe Lallement,Daniel Mathiot. s.l. : Solid State Electronics, 2002, Vol. 46, pp. 2191–2198. https://doi.org/10.1016/S0038-1101(02)00248-4. Design of notched gate processes in high density plasmas. J. Foucher, G. Cunge, L. Vallier, and O. Joubert. s.l. : AVS: Science & Technology of Materials, Interfaces, and Processing, 2002, Vols. Journal of Vacuum Science & Technology B 20,. http://dx.doi.org/10.1116/1.1505959. Notched gate MOSFET for capacitance reduction in RF SOI technology. al, L. Antunes et. s.l. : 2023 IEEE International Conference on Design, Test and Technology of Integrated Systems (DTTIS), 2023. doi: 10.1109/DTTIS59576.2023.10348288. Figure 1

Manufacturing of high strength bimetallic section steel with hot-rolling process

This study aimed to develop a 316L/35# stainless steel–bimetallic section steel to satisfy plasticity and strength standards. The stainless steel bimetallic section was made of 316L stainless steel, whereas the base metal was made of 35# carbon steel, rolled using 13 rolling mills at 1150 ​°C by applying interface vacuum technology. Moreover, the mechanical properties and microstructure of the composite interface of hot-rolled stainless steel–bimetallic section steel were analyzed at multiple scales. The finished, rolled-section steel was selected as the research object. Various experiments were conducted from multiple scales: transmission electron microscopy (TEM), electron probe micro-analyses (EPMA), and scanning electron microscopy (SEM) were utilized, among other techniques for testing the mechanical properties. The results revealed that distinct carburized and decarburized zones were formed on both sides of the composite interface due to the diffusion of elements. The width of the carburized zone was 30–50 ​μm, and the hardness was 184.3HV, whereas the width of the decarburized zone was 80–100 ​μm, and the hardness was 146.4HV. In the carburized zone, short, rod-like martensite, second-phase precipitates, and chromium carbide and oxides were observed. The shear strength of the stainless clad section steel was 384.62 ​MPa and the ultimate strength was 599.76 ​MPa, far exceeding the 210 ​MPa required in the standard, which revealed that the bimetal achieved good metallurgical bonding. This study serves as an important theoretical basis for conducting structural integrity evaluations of bimetallic materials.

Leybold presents innovative vacuum portfolio at ANUGA FoodTec

At the leading trade fair Anuga FoodTec in Cologne, Leybold presents its vacuum technologies for the food processing and packaging industry from. The efficient solutions of the vacuum supplier are used worldwide. In a wide variety of applications, the pumps, systems and measuring devices of this long-established company make a significant contribution to sustainable and competitive products and processes in the food and beverage industry.

Preliminary Removal of Mercury from Depleted Coal Sorbents by Thermal Vacuum Method with Associated Extraction of Precious Metal Composite

This paper presents the results of laboratory studies for the distillation of mercury from depleted coal sorbents produced in gold recovery factories using CIP technology. The mercury content in these materials is more than 1%. The developed technology was tested in a large-scale laboratory on a pilot vacuum sublimation electric furnace with the rheological movement of dispersed material. The use of this equipment makes it possible to demercurize various materials with fairly high moisture (up to 20%). It eliminates the use of an additional technological operation—drying the material in a vacuum drying oven. It has been shown that a high degree of mercury distillation is achieved (more than 99.8%) at 350–400 °C in the reaction space and residual pressure in the system of less than 1.33 kPa, with residual mercury content in the material of less than 0.001% (10 mg/kg), which complies with the European environmental standards. Mercury-free coal sorbents are sent for combustion for the additional extraction of precious metal composites. The proposed vacuum technology is characterized by its environmental safety because the process is performed in sealed equipment, eliminating toxic emissions of mercury vapor into the atmosphere. The proposed vacuum technology equipment is characterized by reliability and ease of use.

Effect of vacuum combined with ultrasound on color protection of pomegranate juice

AbstractPomegranate juice is prone to color fission during processing and storage due to the instability of anthocyanins, resulting in significant economic losses. This study aims to inhibit the browning of pomegranate juice during processing using the combined technology of vacuum and ultrasound for maintaining its color as much as possible. Pomegranate juice was treated with vacuum (0.5 MPa) and ultrasound (300, 600, 900, 1200, and 1500 W; 15, 20, 25, 30, and 35 min), respectively, to investigate the effects on the color, antioxidant capacity, anthocyanin/polyphenol content, and polyphenol oxidase activity of pomegranate juice. The results showed that the combined treatment of vacuum and ultrasound had a better effect on improving the total anthocyanin content of pomegranate juice than vacuum or ultrasound treatment alone. Vacuum combined with ultrasound can reduce the browning during pomegranate juice processing, increasing browning inhibition rates by 46.01% and 46.19%; reduce the activity of PPO enzyme and increase the inhibition rate of PPO enzyme activity by 35.58%; maintain a high total phenolic content, increasing the total phenolic content of pomegranate juice by 29.27% and 33.79%, respectively; and improve the ABTS scavenging rates by 2.89% and 1.92%, and increase DPPH scavenging rates by 1.35% and 3.01%. Moreover, vacuum ultrasound treatment had no significant effect on the odor of pomegranate juice. Vacuum combined with ultrasonic treatment is beneficial for protecting the color of pomegranate juice and improving its antioxidant performance during the processing. Therefore, combined technology of vacuum and ultrasound would be a promising method for future food processing.Practical applicationsThis study provides a simple and novel method for protecting the color of pomegranate juice during processing. The combination of vacuum and ultrasound has a certain protective effect on the color of pomegranate juice during processing, and also provides new ideas for color protection research.

Standardization of Graphical Symbols for Vacuum Technology

Standardization of Graphical Symbols for Vacuum Technology

Feasibility analysis of the veil convection business using value engineering for cost efficiency

The veil business is a business that operates in the veil manufacturing industry. The products produced vary according to consumer demand and the stock produced. This headscarf product has spread to several areas of Aceh, such as Banda Aceh, Lhokseumawe, and Langsa, especially the Bireuen City area, and has collaborated with several Islamic boarding schools. The headcarf models released by this company greatly influence consumer demand. The better the material, model, and quality, the more consumer demand for convection will increase. This research aims to analyze the feasibility of developing a veil convection business using a value engineering method and financial feasibility. The research results were obtained using the analytical hierarchy process method and vacuum engineering. The chosen alternative is model 1, with a weight of 0.53, a square hijab type, standard material, soft colors, and zipper accessories according to consumer demand. And the results of the financial aspect calculations show that the Ita Hijab convection business has a positive NPV of IDR 29,373,042, with a BEP of 480 units. The payback period for investment capital is 5 months. If you look at the payback period calculation with a BCR value > 1, then the veil convection business is said to be worthy of investment

Developing Effective Radio Frequency Vacuum Drying Processes for Moutan Cortex: Effect on Moisture Migration, Drying Kinetics, Physicochemical Quality, and Microstructure.

This study aims to maximize the post-harvest quality of Moutan Cortex and reduce energy consumption. Radio frequency vacuum (RFV) technology was used to dehydrate Moutan Cortex in this study to investigate the effects of different drying temperatures, plate spacing, and vacuum degree on the drying kinetics, physicochemical quality, and microstructure of Moutan Cortex. The results showed that RFV drying shortened the dehydration time of the Moutan Cortex by 10.71-28.57% and increased the drying rate by 15.79-54.39% compared to hot-air drying. The best color (∆E = 6.08 ± 0.28, BI = 26.97 ± 0.98) and relatively high retention of polysaccharides, total phenolics, total flavonoids, antioxidant properties, paeonol, gallic acid, paeoniflorin, and benzoylpaeoniflorin contents were observed in the dried products of Moutan Cortex at a drying temperature of 50 °C, spacing of 90 mm, and vacuum of 0.025 MPa. Analyzing the microstructure, it was found that RFV drying could effectively inhibit the shrinkage and collapse of the cellular structure, and a regular and loose honeycomb pore structure appeared inside the samples, which contributed to the rapid migration of the internal moisture. This study can provide a theoretical reference basis for the selection and application of industrialized processing methods of high-quality Moutan Cortex.

Vacuum technology and new Helium leak detector "Phoenix 4"

The use of vacuum in analytical technology and research and development is an essential factor that enables modern applications, for example in the field of measuring instruments. The selection of suitable equipment and the associated vacuum components is therefore crucial for success in laboratories. Since 1850, Leybold has been a partner of customers who have dedicated themselves to research. With innovative products such as the new ECODRY plus dry compressing vacuum pump, this company tradition is continuing into the future, and Leybold has received an award recognizing this. Leybold is launching the PHOENIX 4, a new family of helium leak detectors to meet the increasing quality requirements. This innovative product is equally suited to the demands of research and development as for those of industrial applications – from securing the ultra-high vacuum demands in CERN’s particle accelerator, to industrial applications such as leak detection in the Hyperloop vacuum transport system or for semiconductor production.

Numerical Study of Rarefied Gas Flow in Diverging Channels of Finite Length at Various Pressure Ratios

In the present work, the gas flows through diverging channels driven by small, moderate, and large pressure drops are studied, considering a wide range of the gas rarefaction from free molecular limit through transition flow regime up to early slip regime. The analysis is performed using the Shakhov kinetic model, and applying the deterministic DVM method. The complete 4D flow problem is considered by including the upstream and downstream reservoirs. A strong effect of the channel geometry on the flow pattern is shown, with the distributions of the macroscopic quantities differing qualitatively and quantitatively from the straight channel flows. The mass flow rate data set from the complete solution is compared with the corresponding set obtained from the approximate kinetic methodology, which is based on the fully developed mass flow rate data available in the literature. In addition, the use of the end-effect approach significantly improves the applicability range of the approximate kinetic methodology. The influence of the wall temperature on the flow characteristics is also studied and is found to be strong in less-rarefied cases, with the mass flow rate in these cases being a decreasing function of the temperature wall. Overall, the present analysis is expected to be useful in the development and optimization of technological devices in vacuum and aerospace technologies.

In-plane oxygen diffusion measurements in polymer films using time-resolved imaging of programmable luminescent tags

Oxygen diffusion properties in thin polymer films are key parameters in industrial applications from food packaging, over medical encapsulation to organic semiconductor devices and have been continuously investigated in recent decades. The established methods have in common that they require complex pressure-sensitive setups or vacuum technology and usually do not come without surface effects. In contrast, this work provides a low-cost, precise and reliable method to determine the oxygen diffusion coefficient D in bulk polymer films based on tracking the phosphorescent pattern of a programmable luminescent tag over time. Our method exploits two-dimensional image analysis of oxygen-quenched organic room-temperature phosphors in a host polymer with high spatial accuracy. It avoids interface effects and accounts for the photoconsumption of oxygen. As a role model, the diffusion coefficients of polystyrene glasses with molecular weights between 13k and 350k g/mol are determined to be in the range of (0.8–1.5) × 10–7 cm2/s, which is in good agreement with previously reported values. We finally demonstrate the reduction of the oxygen diffusion coefficient in polystyrene by one quarter upon annealing above its glass transition temperature.

Preface

The International Summer School on Vacuum, Electron and Ion Technologies (VEIT) has been organized biennially since 1978, when the series of VEIT Schools was launched by the Institute of Electronics, Bulgarian Academy of Sciences, with the aim to act as a forum for exchange and dissemination of knowledge and ideas on the latest developments in electron-, ion-, and plasma-assisted technologies. The organizers of the 2023 edition of the event were the Institute of Electronics, Bulgarian Academy of Sciences, Sofia, Bulgaria and the Dutch Institute for Fundamental Energy Research, Eindhoven, The Netherlands. The School is a major scientific event and a meeting place for young scientists involved in research and development associated with high-tech industries. Many former School participants went on to become successful scientists in their field of research in leading institutions and companies all over the world. The School Proceedings have been published in special issues of the international journals Vacuum, Plasma Processes and Polymers, Journal of Physics: Conference Series.The twenty-third edition of VEIT was held in the Black Sea resort Sozopol, Bulgaria, from 18 to 22 September 2023. It was attended by 108 participants (33 students and young researchers) from 16 countries on two continents: Belgium, Bulgaria, Czech Republic, Estonia, France, Germany, Japan, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, The Netherlands, Ukraine, UK.The School Program covered a large spectrum of fundamental problems of the nanotechnologies, the interaction of charged particles with solid surfaces, the deposition and characterization of thin films, which were balanced out by reports on a wide range of significant high-technology applications – from equipment for deposition of hard coatings or thin optical/protective films to nanostructures prepared via evaporation, sputtering or irradiation. By their subjects, the lectures and reports were grouped for presentation and discussion in three sessions, each of them including oral presentations at plenary sessions and posters.List of Chairs of the School, International Advisory Committee, Local Organizing Committee, Invited Speakers, Participants are available in the pdf.

Integration of Renewable Energy Sources in Industrial Parks: Medicool European Demonstration Project

The present paper is focused on describing a demonstrative project, financially supported by the European Union, aiming of providing a real example of sustainable solution for space cooling in large storages and industrial applications. The proposed solution has been implemented in the pharmaceutical distribution sector, presenting strict and rigid European and national regulations regarding storage temperature conditions. The developed installation involves one of the largest systems ever built in Europe based on solar cooling/heating technologies. Collectors based on Ultra High Vacuum (UHV) technology have been selected, with a global collecting surface of 22,500 m2. These collectors also reduce significantly both convection and conduction heat losses. The proposed system involves two absorption chillers of 675 and 855 kW each one. An additional control system is included to fit the capacity of cold production according to the real necessities of the refrigerated system. This system is expected to provide an annual energy savings estimated in around 795 MWh only for the cooling system, accounting over 70% of the global energy currently needed for conditioning the global installations.

Analysis of Thermodynamic Events Taking Place during Vacuum Drying of Corn

Agricultural materials (LF products) can be considered biologically living organisms due to their structure and the composition of colloidal capillary-porous substances in them. They contain a large number of microscopic pores, microcapillaries and macrocapillaries, in which water is able to pass from the inner parts to the surface of the grain, and vice versa. Thus, it can be concluded that drying is an important and demanding aspect of agricultural production. To determine the optimal drying process for agricultural cereals from a nutritional, energy, economic and environmental point of view, it is necessary to address in detail the application of the technology of vacuum drying from a thermodynamic point of view. An analysis of the research results shows that drying temperature, harvest date and corn variety can significantly affect the properties of the main components of corn grain. This study investigates the individual technological parameters of the vacuum drying process for corn, such as the pressure used in the drying chamber, the grain drying temperature and the heating time, in order to achieve a maximum reduction in water content. The aim of the investigation is to determine the optimal parameters for the design of a functional prototype of a vacuum dryer. For this purpose, laboratory and semi-operational experiments using different types of organic materials are necessary. The structural design of the individual elements of the vacuum dryer is based on an analysis of laboratory and experimental tests, whose results are presented in this article.

Creating the Future of Food with Vacuum Technology

Creating the Future of Food with Vacuum Technology

Application of Vacuum Technology in the Food Industry

Application of Vacuum Technology in the Food Industry

A high-performance TiO2 protective layer derived from non-high vacuum technology for a Si-based photocathode to enhance photoelectrochemical water splitting

A non-high vacuum technique was used to fabricate a TiO2 protective layer of a Si-based photocathode, in which MOF derivatives enhance carrier transfer efficiency. The photocathode has high onset potential, high photocurrent and long-term stability.

Design and thermal test of high-vacuum insulator for heat delivery pipes

Thermal piping insulation of implants is crucial for heat delivery, production, collection, or storage at high temperature values. It is currently obtained by enveloping low thermal conductivity materials such as rockwool, fiberglass, polyurethane, polystyrene, and aerogel. However, better performances can be reached by adopting vacuum technology. In this case, conductive losses are annihilated, and the radiative heat transfer mechanism represents the only loss mechanism. Here, we compare a high vacuum-based novel solution and the traditional insulation for heat delivery applications. We propose a high vacuum- based solution consisting of an evacuated gap that surrounds the hot pipe coated by a thin aluminium foil. Experimental results using this novel solution show a fivefold reduction of the thermal radiation losses compared to the traditional solutions when in the temperature range between 100 °C and 250 °C.