AbstractTo study the combustion process of fuel in the microwave plasma torch, we designed a butane microwave plasma device exploiting a tungsten rod as an electrode. Through analysis of the image record by high-speed camera, we found that the discharge of butane microwave plasma torch is a cyclic process at atmospheric pressure at a frequency of around 100 Hz. During the discharge, the active particles continuously diffuse from the electrode to the outside like the bloom of the flower. Then, the variation of plasma torch of jet height and temperature with microwave power is obtained. In addition, we studied the effects of different butane flow rates on the plasma torch. The results illustrate that excessive butane will lead to carbon deposition on the electrode. All in all, this work provides a new understanding of the combustion of the microwave plasma torch, which is conducive to the further development of microwave plasma in the fields of waste gas treatment, fuel combustion, and plasma engine.
The principal objective of this work is to report on the power coupled to a tungsten target in the Proto-MPEX device during oblique injection of a microwave beam (< 70 kW at 28 GHz) into a high-power (~100 kW at 13.56 MHz) over-dense (n_e>1×10^19 m^(-3)) deuterium helicon plasma column. The experimental setup, electron heating system, electron heating scheme, and IR thermographic diagnostic for quantifying the power transport is described in detail. It is demonstrated that the power transported to the target can be effectively controlled by adjusting the magnetic field profile. Using this method, heat fluxes up to 22 MWm-2 and power transport efficiencies in the range of 17-20% have been achieved using 70 kW of microwave power. It is observed that most of the heat flux is confined to narrow region at the plasma periphery. Ray-tracing calculations are presented which indicate that power is coupled to the plasma electrons via an O-X-B mode conversion process. Calculations indicate that the microwave power is absorbed in a single pass at the plasma periphery via collisions and in the over-dense region via 2nd harmonic cyclotron resonance of the electron Bernstein wave. The impact of these results is discussed in the context of MPEX.
The role of hot electrons in the charging of dust grains is investigated in a two-temperature hydrogen plasma. A variety of dust particles are introduced into the system and secondary electron emission (SEE) from each of the dust grains has been reported. A cylindrical Langmuir probe is used for determining the plasma parameters and a Faraday cup is connected to an electrometer in order to measure the dust current. The electrometer readings confirm the electron emission from the dust and SEE is observed from the tungsten dust in a low-pressure experimental plasma device for the first time.
Objective: To familiarize the general scientific community with the latest electrotechnical innovative developments for the transport industry, carried out by the scientists of the Emperor Alexander I Petersburg State Transport University in the period from 2000 to 2021. Methods: We used the methods of calculation of electromagnetic fields and circuits, mathematical analysis, mathematical physics and numerical methods in the development of the described devices and systems. Results: 101 We developed a pipeline high-speed magnetolevitation transport system with vehicle movement in a rarefied atmosphere, a series of pantograph pantographs for heavy-loaded and high-speed trains using solid lubricants and a contactless method of transmitting electrical energy, a plasma device for fine cleaning of circuit boards for microcircuits, a device for creating a comfortable climate in office premises, electrohydroimpulse installations designed for loosening frozen coal in gondola cars in winter, shock tests of wagons, escalators and travalators using linear electric motors, high-speed electric switches-breakers, heat generators based on an electromechanical converter with the functions of a heater and pump, a wagon generator with a forced excitation system, a pulse voltage generator, allowing to measure the pulse resistance of the grounding conductors of the contact network supports, a complex of installations for various purposes using ozone technologies, a system for laser monitoring of the integrity of tanks, a device for diagnosing the degree of corrosion of the fittings of contact supports, an electrohydroimpulse installation for impact welding, treatment plants, technology for recycling car tires, security systems of the main trackbed. Practical importance: The use of the described developments will increase energy efficiency, energy saving and safety of production processes in transport
Among the applied challenges associated with the use of electric-arc plasma, the most urgent is the erosion of electrodes in plasmatrons, which determine the continuous operation of an electric-plasma device. Investigation results on the thermal state of hot cathodes and their erosion are presented depending on the main defining parameters, namely geometrical dimensions of electrodes, Joule heating, current of the arc discharge, and the gas medium. The conditions for the minimum specific erosion and long service life of tungsten thermionic cathodes are established experimentally.
The surface energy of the printing material can be increased to desired levels with different chemicals or methods. However, the important thing is that the surface properties of printing material are not affected negatively. In this way the aim of this paper provide that the surface properties of matte and glossy coated paper is improved by the argon containing atmospheric pressure plasma device because the plasma treatment method does not occur surface damaging on the papers.
In experimental studies, test samples cut from 160 mm × 30 mm in size from 115 g/m2 gloss- and matt-coated papers were used. The plasma treatments of paper samples were carried out with an argon containing atmospheric pressure plasma device of laboratory scale that produces plasma of the corona discharge type at radio frequency. The optimized plasma parameters were at a frequency of 20 kHz and plasma power 200 W. A copper electrode of length 12 cm and diameter 2.5 mm was placed in the centre of the nozzle.
Research findings showed that the surface energies of the papers increased with the increase in plasma application time. While the contact angle of the untreated glossy paper is 82.2, 8 second plasma applied G3 sample showed 54 contact angle value. Similarly, the contact angle of the base paper of matt coated is 91.1, while M3 is reduced to 60.4 contact angles by the increasing plasma time.
Plasma treatment has shown that no chemical coating is needed to increase the wettability of the paper surface by reducing the contact angle between the paper and the water droplet. In addition, the surface energies of all papers treated by argon gas containing atmospheric pressure plasma, increased. Plasma treatment provides to improve both the wettability of the paper and the adhesion property required for the ink, with an environmentally friendly approach.
Modern tokamaks have achieved significant fusion production, but further progress towards steady-state operation has been stymied by a host of kinetic and MHD instabilities. Control and identification of these instabilities is often complicated, warranting the application of data-driven methods to complement and improve physical understanding. In particular, Alfvén eigenmodes are a class of ubiquitous mixed kinetic and MHD instabilities that are important to identify and control because they can lead to loss of confinement and potential damage to the walls of a plasma device. In the present work, we use reservoir computing networks (RCNs) to classify Alfvén eigenmodes in a large, expert-identified database of DIII-D discharges, covering a broad range of operational parameter space. Despite the large parameter space, we show excellent classification and prediction performance, with an average hit rate of 91% and false alarm ratio of 7%, indicating promise for future implementation with additional diagnostic data and consolidation into a real-time control strategy.
A numerical simulation of a pulsed floating electrode dielectric barrier discharge (FE-DBD) at atmospheric pressure, used for melanoma cancer cell therapy, is performed using a plasma model in COMSOL Multiphysics software. Distributions of electron density, space charge, and electric field are presented at different instants of the pulsed argon discharge. Significant results related to the characteristics of the plasma device used, the inter-electrodes distance, and the power supply are obtained to improve the efficiency of FE-DBD apparatus for melanoma cancer cell treatment. The FE-DBD presents a higher sensitivity to short pulse durations, related to the accumulated charge over the dielectric barrier around the powered electrode. At higher applied voltage, more energy is injected into the discharge channel and an increase in electron density and electric consumed power is noted. Anticancer activity provided by the FE-DBD plasma is improved using a small interelectrode distance with a high electron emission coefficient and a high dielectric constant with a small dielectric thickness, allowing higher electron density, generating reactive species responsible for the apoptosis of tumor cells.