Papers by Keyword: Plasma

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Authors: Ching Shang Cheng, Xiao Yong Lin, Chun Hong Liou, Guang Xin Xing, Wai Pin Fu
Abstract: In our study, we tried to extend the preservative time of vegetables, and fruits to use the ethylene absorbent method, and the plasma reaction method to decrease the ethylene content of the conditions of the storage tank. In experimentation, we discovered that banana will release ethylene, and banana will be accelerated the ripening, when the ethylene was present. The ripening rate was equal to the ethylene production rate, that was a first order functional relationship of the ethylene concentration, γe=0.21C. The ethylene absorbent in the two experimental groups had removed indeed the ethylene, and had an effecting to keep fresh of the banana. In our plasma experimentation, we found that logarithmic value of the ethylene concentration(C) was direct proportion to the reaction time, and the ethylene reaction rate rp = -22.6C. In our study, the banana weight of each run of our experiment was 420 gram, and our plasma reactor can handle 45 kilogram banana because the │rp│is nearly 107 times of │re│.
Authors: Chien Jang Wu, Ya Ju Lee, Tzu Chyang King, Wen Kai Kuo
Abstract: A design of multichannel transmission filter at microwave is proposed. It is based on the use of the finite plasma photonic crystal operating at frequency below the plasma frequency. We consider a design structures of (AB)qA, where A is the dielectric material, B is the plasma layer, and q is the number of periods. It is found that the number of channels is equal to q-1. We show that the locations such multiple channels are in the pass band of the infinite plasma-dielectric photonic crystal. The idea of such design is thus to engineer the photonic pass band, which is fundamentally different from the usual design by engineering the photonic stop band like the multilayer Fabry-Perot transmission filter. The physical mechanism of multiple channels is also discussed.
Authors: Hajar Ja’afar, M.T. Ali, A.N. Dagang, H.M. Zali, N.A. Halili
Abstract: This research aimed at investigating the performance of plasma windowing concept in terms of radiation pattern, gain and return loss. The antenna structure consists of 12 tubes of commercial fluorescent lamps that containing the mixture of mercury vapour and argon gas which upon electrification, forms plasma. After get sufficient voltage the gas inside the fluorescent tube will ionize to plasma and formed plasma column. When all of the tubes surrounding the antenna are electrified, the radiation is trapped inside. By leaving one or more of the tubes in a non-electrified state, apertures are formed in the plasma shield which allows radiation to escape. The plasma frequency in this experiment is equal to 5.634e11 Hz. This antenna design at 4.9 GHz. The advantages from this research, the design and construction of plasma antenna with fluorescent tubes can be beneficial in term of advancement in antennas technology especially in reconfigurable antenna.
Authors: Xing Quan Wang, Qi Zhang, Feng Peng Wang, Wei Chen, Jun Huang, Xiu Rong Zhu, Xiang Hua Zeng, Si Ze Yang
Abstract: The conventional study of NOx removal is mainly concentrated on the various chemical reactions, but takes no account of the important effect of temperature increase caused by the discharge. In this paper, we present a method whereby the reactive temperature in reaction region can be easily measured without affecting the discharge. By measuring the reactive temperature, it is revealed that the temperature in reaction region is closely related and linearly enhanced with the discharge power, and that the catalysis is not the main reason for the reactive temperature increase. By the investigation on the temperatures effect on the NOx removal, it is found that the NOx removal rate increases with the rise of temperature in reaction region. Therefore, the NOx removal is tightly related with the temperature in reaction region that can be controlled by the discharge intensity under the various ambient temperatures.
Authors: Bai Lin Zha, Ding Yuan Huang, Su Lei Qiao, De Wen Wang, Wei He, Zhi Hong Zha, Bin Xiang Li
Abstract: C/C composite material is widely used as the insulation material since its advantage is obvious compared with other materials. It is necessary to evaluate its ablation, especially when it used in the warhead. An ablation/erosion test system based on plasma is researched. All the parameters related to the plasma can be monitored by it to calculate the enthalpy. Two ablation tests of the C/C composite material are carried by this system. The ablation of the carbon fiber and the erosion of the particle are mainly analyzed by the measure of the ablation rate and the SEM photos.
Authors: Hai Hong Huang, Ye Wang, Hai Xin Wang
Abstract: EAST (Experimental Advanced Superconducting Tokamak), a National Mage-project of Science Research of China, is a very important fusion experiment facility. The ability of magnetic confinement to plasma can be improved by elongating plasma cross-section to form divertor configuration in EAST. But elongated plasma has vertical displacement instability, without control, plasma will dash against wall of vacuum vessel and disrupt, that will cause failure of plasma discharge. So feedback control system is needed to restrain plasma vertical displacement. Fast control power supply excites active feedback coils, which produces magnetic field to control plasmas displacement. The validity of proposed scheme was confirmed by experiments, the active feedback system can reach design demand.
Authors: Ivan Venegoni, Matteo Consonni, Irene Bianchi, Enrica Ravizza, Salvatore Grasso, Simona Spadoni, Mario Pistoni, Paolo Colpani
Authors: Marcio W.D. Mendes, António Carlos P. Santos, Francisca de Fatima P. Medeiros, Clodomiro Alves Jr., A.G.P. Silva, Uilame Umbelino Gomes
Abstract: The aluminothermic reduction is a highly exothermal reaction between a metal oxide and aluminium. Conventionally this reaction is ignited by an electric resistance and the reaction products after cooling are in the form of a rigid block of mixed metal and aluminium oxide. In this work a new process of aluminothermic reduction is presented, in which the reaction is ignited by a hydrogen plasma. The niobium oxide and aluminium powders are high energy milled for six hours to form particles constituted of oxide and aluminum. Stoichiometric, substoichiometric and superstoichiometric mixtures were prepared. The mixture was placed in a stainless steel tube (the hollow cathode) inside the reactor chamber. The chamber was firstly evacuated. Then hydrogen at low pressure was introduced. In the following an electric discharge between the cathode and the anode localized just above the cathode ignites the plasma. The plasma heats the particles on the surface of the powder layer and starts the reaction that proceeds in each particle since the reactants are intimately mixed. The heat generated by the reaction propagates deeper in the layer until the whole mixture reacts. Substoichiometric mixtures can be used because hydrogen takes part of the reduction. The Nb2O5 – Al starting powder mixture and the products of the reaction are characterized by laser grain size measurement and X-Ray diffraction (XRD). The products are in form of powder or agglomerates of particles. Phases of reaction products was determined by XRD analysis and the particle size trough SEM.
Authors: G.R. Heath, P. Heimgartner, G. Irons, Robert D. Miller, Stefan Gustafsson
Authors: Jong Bong Kim, Myoung Soo Shin
Abstract: DBD (Dielectric Barrier Discharges) plasma is often used to clean the surface of semiconductors. The cleaning performance is affected by many process parameters such as electric voltage, the gas composition, gas speed, thickness of the dielectric wall, gap distance, and plasma duration time. In this study, the plasma density is predicted by a coupled simulation of gas flow, chemistry mixing and reaction, plasma generation, and electric field. A 13.56 MHz RF source is used to generate plasma. The effect of the dielectric thickness, the gap distance, the gas flow velocity, and electric voltage on the plasma density is investigated. It is shown that the plasma density increases as the dielectric thickness decreases, the gap distance increases, the gas velocity increases, and electric voltage increases, respectively. Finally, experiments are carried out to verify the analysis results.
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