Investigation of Ultradispersed Powders FexOy Obtained in the Electric Discharge Plasma

2015 ◽  
Vol 756 ◽  
pp. 325-328 ◽  
Author(s):  
Alexander A. Sivkov ◽  
Aleksander S. Ivashutenko ◽  
A.A. Lomakina ◽  
I.I. Shanenkov
Keyword(s):  
Magnetic Nanoparticle ◽  
Discharge Plasma ◽  
Plasma Discharge ◽  
Atmospheric Conditions ◽  
Specific Saturation Magnetization ◽  
Ultradispersed Powders ◽  
Hypersonic Jet ◽  
Magnetite Phase ◽  
Nanoparticle Sizes ◽  
Coaxial Magnetoplasma Accelerator

The paper shows the iron oxide powder production in the hypersonic jet of electro discharge plasma generated by a coaxial magnetoplasma accelerator with steel electrodes. The influence of gaseous atmosphere parameters has been investigated by carrying out experiments in normal atmospheric conditions and with the introduction of additional oxidant into the plasma discharge. Studies of the structure of synthesized powders and their magnetic properties have been carried out. It has been found that by introducing of additional oxidant it is possible to regulate the phase composition in the direction of increasing the yield of magnetite phase. Specific saturation magnetization decreases with decreasing of the magnetic nanoparticle sizes.

Flame Stability in Inverse Coaxial Injector Using Repetitive Nanosecond Pulsed Plasma

2019 ◽  
Author(s):  
Saeid Zare ◽  
Hao Wei Lo ◽  
Shrabanti Roy ◽  
Omid Askari
Keyword(s):  
High Speed ◽  
Research Work ◽  
Plasma Discharge ◽  
Critical Conditions ◽  
Single Element ◽  
Flame Stability ◽  
Rocket Engines ◽  
Pulsed Plasma ◽  
Atmospheric Conditions ◽  
Temperature Plasma

Abstract There has been recently a growing interest in the use of methane as a strong candidate for both interplanetary and descent/ascent propulsion solutions. The higher boiling point and higher density of methane compared with hydrogen, makes its storage tank lighter, cheaper and smaller to launch. Methane is abundant in the outer solar system and can be harvested on Mars, Titan, Jupiter, and many other planets and therefore, it can be used in reusable rocket engines. However, there are still some technological challenges in methane engines development path. Among those challenges, ignition reliability and flame stability are of great importance. These challenges can be addressed by integrating low-temperature plasma (LTP) through repetitive nanosecond pulsed (RNP) discharge to the injector design. This research work focuses on Air/CH4 jet flames in a single-element coaxial shear injector coupled with RNP plasma discharge to study the influence of LTP on ignition characteristics and flame stability using advanced diagnostic techniques. The experiments have been performed for different fuel composition, jet velocities, discharge voltages and frequencies at atmospheric conditions. The transient flame behavior including flame oscillation is studied using direct photography by CMOS high-speed camera. The effect of plasma discharge location on flame stability is also investigated. To demonstrate the effectiveness of RNP discharge on liftoff and blowout/blowoff velocities, the jet velocity at the critical conditions is measured in terms of discharge frequencies and the enhancement of flame stability is then evaluated. The collected experimental data have shown that the RNP discharge can significantly extend the flame stability by reducing the liftoff height and increasing the velocity at which blowout/blowoff occurs.

scholarly journals Synthesis of aluminum oxide nanoparticles in overstressed nanosecond discharge plasma with the ectonic sputtering mechanism of aluminum electrodes

2020 ◽  
Author(s):  
Alexander Shuaibov ◽  
Alexander Minya ◽  
Antonina Malinina ◽  
Alexander Malinin ◽  
Zoltan Gomoki
Keyword(s):  
Aluminum Oxide ◽  
Discharge Plasma ◽  
Oxide Nanoparticles ◽  
Nanosecond Discharge ◽  
Atmospheric Conditions ◽  
Large Area ◽  
Aluminum Oxide Nanoparticles ◽  
Alumina Films ◽  
Vacuum Technology ◽  
Aluminum Electrodes

The results of studying the conditions of synthesis and luminescence of aluminum oxide nanoparticles in a plasma of an overstressed nanosecond discharge ignited between aluminum electrodes at an interelectrode distance of 2 mm and air pressure in the range of 50-202 kPa are presented. It was shown that the plasma of the investigated discharge is characterized by a wide luminescence band in the spectral range of 300–430 nm, which is associated with the formation of F and F + centers. The research results can be used in micro-nanotechnology, biomedical engineering to obtain nanostructured alumina substrates, on which other nanodevices and films from biomaterials can be placed. The aim of the work was to establish the possibility of detecting small nanoparticles - aluminum oxide nuclei by emission spectroscopy methods and the synthesis of nanostructured alumina films under atmospheric conditions (without the use of vacuum technology) over a large area.

Effect of Energy on Plasmodynamic Synthesis Product in the Carbon-Nitrogen System

2014 ◽  
Vol 880 ◽  
pp. 36-41 ◽  
Author(s):  
Alexander Sivkov ◽  
Alexander Y. Pak ◽  
Ivan Shanenkov ◽  
Yuliya Shanenkova ◽  
Igor P. Prosvirin
Keyword(s):  
Energy Storage ◽  
High Speed ◽  
Carbon Nitride ◽  
Discharge Plasma ◽  
Nitrogen Atmosphere ◽  
Synthesis Product ◽  
Capacitive Energy Storage ◽  
Energy Value ◽  
Good Accordance ◽  
Coaxial Magnetoplasma Accelerator

Carbon nitride (CNx) powders were synthesized in the high-speed carbon electric discharge plasma jet flowing into the chamber filled with the nitrogen atmosphere at normal conditions. A coaxial magnetoplasma accelerator (CMPA) was used to generate the plasma flow. The CMPA was supplied from the pulse capacitive energy storage. Effect of input to the CMPA energy value on powders was studied by using several analytical methods (XRD, TEM, XPS). According to XRD with the increasing of input energy value the content of CNx in the product increased about 1.5 times. Its in a good accordance with the XPS data according to which the presence of nitrogen increased from 0.5 to 1.4 mass percent. Furthermore, the particles morphology was noticeable changed with the energy increasing. The obtained results revealed that by changing the energy parameters of the capacity energy storage its possible to influence on the product synthesized in the carbon-nitrogen system.

scholarly journals Improving water absorption time and the natural silk strength (Bombyx Mori) using atmospheric dielectric barrier discharge plasma

2021 ◽  
Vol 3 (2) ◽  
pp. 165-169
Author(s):  
Zaenul Muhlisin ◽  
Muhammad Adrian Lathif ◽  
Fajar Arianto ◽  
Pandji Triadyaksa
Keyword(s):  
Water Absorption ◽  
Discharge Plasma ◽  
Barrier Discharge ◽  
Plasma Discharge ◽  
Dielectric Barrier Discharge Plasma ◽  
Dielectric Barrier ◽  
Absorption Time ◽  
Natural Silk ◽  
Plane Electrode ◽  
Barrier Discharge Plasma

This researchaimed to obtain Dielectric Barrier Discharge plasma discharge characteristics with and without the placement of natural silkBombyx Mori on one of the electrodes. Furthermore, the strength and the water absorption time of the irradiated silk samples will be analyzed.  Plasma discharge is generated by connecting electrodes of point-to-plane configuration with a sheet of glass inserted on the plane electrode at atmospheric conditions. The characterization of plasma discharge, either with or without the natural silk samples' placement on the plane electrode, was performed by increasing A.C.'s high voltage power source to reach arch discharge. Theelectrode spacing varied from 0.7 cm to 2.5 cm with a 0.3 cm increment. Sample irradiation was performed using cold plasma for 5, 15, and 30 minutes respectively. Placing or not placing the natural silk samples on the plane electrode will increase the plasma's discharge current and increase the high voltage. Moreover, increasing the distance between the electrodes and placing the sample on the plane electrode decreases the discharge current. Using Scanning Electron Microscopy, it was found that increasing plasma irradiation time on samples decreases the silk thread'sdiameterand shortening its water absorption time. The strength of irradiated fabric was reduceduntil 15 minutes of irradiation. However, at 30 minutes of irradiation, there was an increase in sample thickness compared to control samples.

scholarly journals Thermal Fluctuation Characteristics around a Nanosecond Pulsed Dielectric Barrier Discharge Plasma Actuator using a Frequency Analysis based on Schlieren Images

Energies ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 628 ◽  
Author(s):  
Takahiro Ukai ◽  
Konstantinos Kontis
Keyword(s):  
Frequency Analysis ◽  
Discharge Plasma ◽  
Thermal Fluctuation ◽  
Plasma Discharge ◽  
Pulse Frequency ◽  
Dielectric Barrier Discharge Plasma ◽  
Burst Event ◽  
Maximum Fluctuation ◽  
Barrier Discharge Plasma ◽  
Schlieren Images

A thermal fluctuation driven by a burst plasma discharge is experimentally investigated using a frequency analysis based on the Schlieren images. The burst plasma discharge is controlled by an interval frequency fint = 200 Hz and a pulse frequency fB = 3.6 kHz as well as the duration time of the burst event: Ton. A burst feature is defined as a burst ratio BR = Ton/(1/fint). The burst plasma discharge generates a burst-induced hot plume growing above a ground electrode. In a high burst ratio, which is BR = 0.45 and 0.57, the burst-induced hot plume is formed as a wave thermal pattern that is mainly fluctuated at the interval frequency of 200 Hz. Additionally, a maximum fluctuation spot of 200 Hz appears near the edge of an exposed electrode in a low burst ratio, whereas it moves towards the ground electrode in the high burst ratio. The possible scenario is that a relatively strong ionic wind and/or an induced jet generated in the high burst ratio might cause the movement of the maximum fluctuation spot.

Fabrication of Nanoparticles by Electric Discharge Plasma in Liquid

2013 ◽  
Vol 58 (2) ◽  
pp. 425-429 ◽  
Author(s):  
S. Yatsu ◽  
H. Takahashi ◽  
H. Sasaki ◽  
N. Sakaguchi ◽  
K. Ohkubo ◽  
...  
Keyword(s):  
Discharge Plasma ◽  
High Resolution Electron Microscopy ◽  
Plasma Discharge ◽  
Nanoscale Particles ◽  
Resolution Electron ◽  
Si Nanoparticles ◽  
Oxidation Layers ◽  
Discharge Method ◽  
Microstructural Surface

The electric plasma discharge method involves the application of a voltage between a cathode and anode in a conductive electrolytic solution to create a discharge plasma at the cathode. When certain material is used as the cathode, small droplets are emitted with the plasma discharge, and the melted droplets are rapidly cooled in the solution to form nanoscale particles of the material. In this work, nanoparticles of Al, Au, Si, and various alloys of between 100 nm and less than 10 nm in size were produced and characterized. Characterization of Si nanoparticles is especially important because their use in lithium batteries greatly influences battery performance. It was found by high resolution electron microscopy and microstructural surface analysis that oxidation layers of a few nm in thickness were formed on the surface of the Si nanoparticles.

Streamer Corona Plasma Assisted Nonpremixed Flame Holding of a Propane Jet

2013 ◽  
Vol 631-632 ◽  
pp. 988-991
Author(s):  
Li Wei Duan ◽  
Yan Ji Hong ◽  
Di Ma ◽  
Yin Jun Yang
Keyword(s):  
Discharge Plasma ◽  
Nonequilibrium Plasma ◽  
Plasma Discharge ◽  
Power Source ◽  
Flame Stability ◽  
Jet Flame ◽  
Corona Plasma ◽  
Nonpremixed Flame ◽  
Streamer Corona ◽  
Corona Discharge Plasma

A streamer corona discharge plasma was used to assist a propane-jet flame. The nonequilibrium plasma was produced by a 10k Hz sinusoidal power source. The experimental results shows that a streamer corona was generated between the flame edge and the nozzle, and the use of the streamer corona plasma discharge resulted in significant increase in flame stability.

scholarly journals Flame Stability in Inverse Coaxial Injector Using Repetitive Nanosecond Pulsed Plasma

2020 ◽  
Vol 142 (8) ◽  
Author(s):  
Saeid Zare ◽  
Hao Wei Lo ◽  
Omid Askari
Keyword(s):  
High Speed ◽  
Plasma Discharge ◽  
Diagnostic Techniques ◽  
Critical Conditions ◽  
Single Element ◽  
Flame Stability ◽  
Rocket Engines ◽  
Pulsed Plasma ◽  
Atmospheric Conditions ◽  
Temperature Plasma

Abstract Recently, methane has been investigated as a feasible fuel for propulsion systems. The higher boiling point and higher density of methane, compared with hydrogen, makes its storage tank lighter, cheaper, and smaller to launch. Methane is abundant in the outer solar system and can be harvested on Mars, Titan, Jupiter, and many other planets and therefore, it can be used in reusable rocket engines. However, there are still some technological challenges in the methane engines development path. For example, ignition reliability and flame stability are of great importance. These challenges can be addressed by integrating low-temperature plasma (LTP) through repetitive nanosecond pulsed (RNP) discharge to the injector design. This research focuses on air/CH4 jet flames in a single-element coaxial shear injector coupled with RNP plasma discharge to study the influence of LTP on ignition characteristics and flame stability using advanced diagnostic techniques. The experiments have been performed for different fuel composition, jet velocities, discharge voltages, and frequencies at atmospheric conditions. The transient flame behavior including flame oscillation is studied using direct photography by CMOS high-speed camera. The effect of plasma discharge location on flame stability is also investigated. To demonstrate the effectiveness of RNP discharge on liftoff and blowout/blowoff velocities, the jet velocity at the critical conditions is measured and the enhancements of flame stability are then evaluated. The collected experimental data have shown that the RNP discharge can significantly extend the stability by reducing the liftoff height and increasing the velocity of blowout/blowoff phenomena.

Selective Corrosion of brazed joint between BNi-2 filler metal and stainless steel 316

1996 ◽  
Vol 54 ◽  
pp. 218-219
Author(s):  
H. S. Kim ◽  
R. U. Lee
Keyword(s):  
Stainless Steel ◽  
Filler Metal ◽  
Surface Preparation ◽  
Optical Microscope ◽  
Heating Element ◽  
Incomplete Fusion ◽  
Atmospheric Conditions ◽  
Leak Test ◽  
High Temperature Side ◽  
Inconel 600

A heating element/electrical conduit assembly used in the Orbiter Maneuvering System failed a leak test during a routine refurbishment inspection. The conduit, approximately 100 mm in length and 12 mm in diameter, was fabricated from two tubes and braze-joined with a sleeve. The tube on the high temperature side (heating element side) and the sleeve were made of Inconel 600 and the other tube was stainless steel (SS) 316. For the filler metal, a Ni-Cr-B brazing alloy per AWS BNi-2, was used. A Helium leak test spotted the leak located at the joint between the sleeve and SS 316 tubing. This joint was dissected, mounted in a plastic mold, polished, and examined with an optical microscope. Debonding of the brazed surfaces was noticed, more pronounced toward the sleeve end which was exposed to uncontrolled atmospheric conditions intermittently. Initially, lack of wetting was suspected, presumably caused by inadequate surface preparation or incomplete fusion of the filler metal. However, this postulation was later discarded based upon the following observations: (1) The angle of wetting between the fillet and tube was small, an indication of adequate wetting, (2) the fillet did not exhibit a globular microstructure which would be an indication of insufficient melting of the filler metal, and (3) debonding was intermittent toward the midsection of the sleeve.

Recent Progress In High-Resolution Shadowing For Biological Transmission Electron Microscopy

1990 ◽  
Vol 48 (1) ◽  
pp. 510-511 ◽  
Author(s):  
Heinz Gross ◽  
Katarina Krusche ◽  
Peter Tittmann
Keyword(s):  
Heavy Metal ◽  
High Resolution ◽  
Freeze Drying ◽  
Atmospheric Conditions ◽  
Vacuum Equipment ◽  
Transmission Electron ◽  
Gas Atmosphere ◽  
Gas Molecules ◽  
Residual Gas ◽  
Backing Layer

Freeze-drying followed by heavy metal shadowing is a long established and straight forward approach to routinely study the structure of dehydrated macromolecules. Very thin specimens such as isolated membranes or single macromolecules are directly adsorbed on C-coated grids. After rapid freezing the grids are transferred into a suitable vacuum equipment for freeze-drying and heavy metal shadowing.To improve the resolution power of shadowing films we introduced shadowing at very low specimen temperature (−250°C). To routinely do that without the danger of contamination we developed in collaboration with Balzers an UHV (p≤10-9 mbar) machine (BAF500K, Fig.2). It should be mentioned here that at −250°C the specimen surface acts as effective cryopump for practically all impinging residual gas molecules from the residual gas atmosphere.Common high resolution shadowing films (Pt/C, Ta/W) have to be protected from alterations due to air contact by a relatively thick C-backing layer, when transferred via atmospheric conditions into the TEM. Such an additional C-coat contributes disturbingly to the contrast at high resolution.

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