plasma discharge
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2021 ◽  
Vol 12 (1) ◽  
pp. 58
Author(s):  
Mohammad Zeagham ◽  
Tariq Mohammad Jadoon ◽  
Mohammad Iqbal Qureshi ◽  
Basit Qureshi ◽  
Syed Sabir

Nanofluids are considered as the next generation of dielectric fluids due to their higher thermal conductivity and dielectric properties. In this investigation, locally produced ester oils, such as rice bran oil (RBO) and jatropha oil (JO), were compared with mineral oil (MO). Initially, hydrophilic SiO2 nano particles were used to prepare nanofluids using RBO and MO. However, results showed that with loading of nanoparticles (NPs) up to 0.075 g/L, the dielectric strength (DS) of MO based NFs increased but decreased drastically with further increase in loading as these suffered agglomeration and sedimentation in less than 72 h. To overcome this drawback, NPs were functionalized under plasma discharge. These efforts also did not yield many favorable results. Instead, hydrophobic fumed silica NPs grafted with hexamethyldi-siloxane (HMDS) were utilized for further study. Plasma treated NFs exhibited improved DS, as well as excellent dispersibility and stability.


Author(s):  
Emiliano Fable ◽  
Filip Janky ◽  
W Treutterer ◽  
Michael Englberger ◽  
Raphael Schramm ◽  
...  

Abstract A newly developed tool to simulate a tokamak full--discharge is presented. The tokamak "flight--simulator" Fenix couples the tokamak control system with a fast and reduced plasma model, yet realistic enough to take into account several of the plasma non--linearities. Distinguishing feature of this modeling tool is that it only requires the Pulse Schedule (PS) as input to the simulator. The output is a virtual realization of the full discharge, which time traces can then be used to judge if the PS satisfies control/physics goals or needs to be revised. This tool is thought for routine use in the control--room before each pulse is performed, but can also be used off--line to correct PS in advance, or to develop and validate reduced models, control schemes, and in general the simulation framework.


2021 ◽  
Vol 6 (1) ◽  
pp. 4
Author(s):  
Rudy Trejo-Tzab ◽  
Alejandro Avila-Ortega ◽  
Patricia Quintana-Owen ◽  
Ricardo Rangel ◽  
Mayra Angélica Álvarez-Lemus

In the present work, N-TiO2−x/Pt was synthesized using a homemade nitrogen plasma (AC) discharge system. The overall procedure use of low-power nitrogen plasma (100 watts) with 1 and 2 h of plasma discharge to successfully impregnate platinum nanoparticles on P25 titanium dioxide. The obtained samples were characterized using X-ray diffraction (XRD), UV–Vis diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), and high-resolution transmission electron microscopy (HRTEM). The results reveal the incorporation of metallic Pt up to 2.9% on the surface of TiO2 by increasing the duration of plasma discharge by up to two hours with a constant power of 100 watts. Likewise, the incorporation of nitrogen atoms into a lattice crystal was also favored, confirming a direct relationship between the amount of Pt and nitrogen atoms introduced in TiO2 as a function of the duration of plasma treatment. By characterizing nanoparticles loaded on a N-TiO2−x/Pt surface, we show that joined platinum nanoparticles have two different patterns, and the boundary between these two regions coalesces. The results demonstrate that the use of nitrogen plasma to impregnate platinum nanoparticles on the surface of TiO2 to obtain N-TiO2−x/Pt allows wide and relevant physics and chemistry applications.


2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Qun Ma ◽  
Ping Wang ◽  
Xiaomin Chen ◽  
Chunqing Zhang

Abstract Plasma electrolytic oxidation (PEO) ceramic coating modified by carbon nanotubes (CNTs) was prepared on Mg–Gd–Y alloy. The microstructure, hydrophobicity and corrosion resistance of the coating were investigated by SEM, contact angle meter and electrochemical test system. Carbon nanotubes (CNTs) are staggered in the ceramic coating and partially filled with plasma discharge micropores. To some extent, CNTs can promote the plasma discharge and improve the film formation rate. With the increase of the content of CNTs, the content of carbon nanotubes in the ceramic coating increases. CNTs can effectively improve the hydrophobicity of ceramic coating. With the increase of the content of CNTs, the corrosion potential E coor and polarization resistance R p increase, the corrosion current i coor decreases and the AC impedance |Z| increases, which leads to the decrease of corrosion rate.


2021 ◽  
pp. 107-110
Author(s):  
Z.O. Znak

The process of plasmochemical decomposition H2S in a rotating reactor is studied. The generation of ultrahigh-frequency radiation in pulsed mode was synchronized with the rotation of the rotor. The influence of the rotor speed on the formation of the region of existence of a plasma discharge in the reactor and separation of H2S de-composition products are established. The content of hydrogen and hydrogen sulfide in the gas phase was analyzed at different points of the reactor along its radius. The concentration of H2 and H2S was determined by chromatog-raphy.


2021 ◽  
pp. 1-9
Author(s):  
James Shaffer ◽  
Omid Askari ◽  
Saeid Zare

Abstract Previous methods of achieving ignition in the Plasma, Combustion and Fluid imaging (PCFi) Laboratory's Constant Volume Combustion Chamber (CVCC) utilizes either a standard or modified spark plug. The standard spark plug achieves a representation of side wall ignition (similar to a combustion engine) while modified spark plug has an extended electrode to allow for a center camber ignition used for laminar burning speed (LBS) measurements. The creation of the modified spark plug required welding a stainless-steel wire to the electrode of the plug. The creation of these electrodes is time consuming and requires a large quantity to effectively test a wide range of parameters such as gap size or electrode geometry. Two custom-design electrodes are presented in this paper which extend the experimental range of the PCFi's CVCC system. Electrode Design A, gives the ability to test thin wire electrode with adjustability of gap size and different diameters through use of a compression fitting. This electrode design (i.e., tip-to-tip) is utilized with a traditional style of automotive ignition system (i.e., capacitive discharge) to study ignition process (i.e., thermal plasma) and spherical flame propagation. Electrode Design B, adds the ability to change tip geometry (i.e., plate-to-plate, tip-to-plate, tip-to-sphere, plate-to-sphere, etc). In this paper the plate-to-plate configuration is demonstrated to study uniform low-temperature nanosecond plasma discharge. Both electrode designs reduce structural weakness by removing the welded joint and allow for linear gap size adjustment. The electrode utilizes high-temperature epoxy, ceramic and grafoil seals to make parameter adjustments easy and precise. The design was analyzed, prior to building and testing, based on the stress induced from the sealant, the total rated voltage, the rated temperature and the fracture stress of the ceramic material. The stress induced in the electrodes was analyzed with Finite Element Analysis (FEA) and the results were found to be within the limits of the material in terms of the compressive and fracture strengths. The maximum voltage was found to be around 30 kV. Design A is presented with 3 different electrode diameters of 1.3, 1 and 0.5 mm and Design B which utilizes a threaded connection for adjustable tip geometry. A sample of data, visual and electrical, is presented for the newly created electrode with a 0.5 mm diameter as well as combustion images for up to 10 atm of initial pressure for methane-air mixture. The new electrode design was able to survive several months of experimental use with few issues compared with the previous welded design.


AIP Advances ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 125221
Author(s):  
Liang Qiao ◽  
Xiaobing Zhang ◽  
Bing Yan ◽  
Zhen Han ◽  
Chao Yang ◽  
...  

Author(s):  
Walied A.A. Mohamed ◽  
Alaa Fahmy ◽  
Ahmed Helal ◽  
El-Sayed A.E. Ahmed ◽  
Badr A. El-Sayed ◽  
...  

2021 ◽  
Author(s):  
Igor Timofeev ◽  
Vladimir Annenkov ◽  
Evgeniia Volchok ◽  
Vladimir Glinskiy

Abstract The paper presents the results of numerical simulations of the collective relaxation of an electron beam in a magnetized plasma at the parameters typical to experiments on the ignition of a beam-plasma discharge in the Gas Dynamic Trap. The goal of these simulations is to confirm the ideas about the mechanism of the discharge development, which are used to interpret the results of recent laboratory experiments [Soldatkina et al 2021 {\it Nucl. Fusion}]. In particular, a characteristic feature of these experiments is the localization of the beam relaxation region in the vicinity of the entrance mirror. A strong mirror magnetic field compresses the beam so that its transverse size becomes less than the wavelength it excites. In addition, near the mirror, the electron cyclotron frequency is much higher than the plasma one, which can significantly affect the possibility of propagation of the most unstable waves outside the beam. Particle-in-cell simulations make it possible not only to find how efficiently intense plasma oscillations penetrate the rarefied periphery, but also to prove that the turbulent zone in a realistic nonuniform plasma has regions dominated by transverse electric fields. This creates the necessary conditions for efficient acceleration of the trapped particles to energies much higher than the initial beam energy.


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