The study deals with amplification of a propagating slow wave interacting with an annular hollow electron beam in a helix slow wave structure (SWS). The role of thermal plasma density in a ratio of the axial pointing flux in the plasma region is also investigated. This ratio is small for lower plasma densities. The effects of the variations of the hollow electron beam velocity on the normalized growth rate and the poynting flux ratio at the hybrid mode frequency are presented. The maximum gain is obtained in the frequency of hybrid mode and the poynting flux ratio reaches its maximum value at the hybrid mode frequency. Also is analyzed the trend of changes for the normalized growth rate for a different beam velocities. The results show that for all beam velocities the maximum growth rate is for hybrid mode frequencies. The numerical method used in this paper is complex transcendental. Manuscript profile

Thermal plasma treatment is considered as a suitable alternative for the treatment of highly-hazardous wastes such as industrial, radioactive and medical waste. Therefore, a Plasma-Gasification-Melting (PGM) system for treatment of Chemical and Pharmaceutical Wastes (CPW) with a capacity of 1 ton/day is developed using a melting and gasification furnace equipped with two non-transferred thermal plasma torches. In this article, the whole method of chemical and pharmaceutical waste disposal is presented along with exhaust gas analysis, and slag and energy balance approach for improving the relevant technology process. It is successfully demonstrated that the thermal plasma process converts chemical and pharmaceutical wastes into harmless slag. Also, the associated emission level of air pollutants is shown to be very low. The synthetic gas produced can be used as a source of energy. (11.7 Nm3 / hr for CO and 16.4 Nm3 / hr for H2). The total power consumption of the system is 120 k W including 90 kW for thermal plasma torch and 30 kW for utilities with natural gas flow rate of 1.3 Nm3/hr. Manuscript profile

AbstractA linearized relativistic field theory of a plasma-loaded helix traveling-wave tube is presented for a configuration where a solid electron beam propagate through a sheath helix enclosed within a loss-free wall in which the gap between the helix and the outer wall is filled with a dielectric. Numerical study of the effect of plasma density on the phase velocity and growth rate has been done. Numerical results show that the plasma have different behaviors in different density limits. Manuscript profile

AbstractField theory is applied to analyze the behavior of the electromagnetic wave in the presence of a solid electron beam and magnetized plasma-loaded tape helix traveling-wave tube. The obtained dispersion relation implicitly includes azimuthal variations and all spatial harmonics of the tape helix. Results indicate that the frequency and the phase velocity of (Xbp − Xp) and (Obp − Xp) modes increase with cyclotron frequency and for (Obp − Op) and (Xbp − Op) modes decrease. In the strong magnetic field limit, the maximum growth rate and frequency of all modes are constant at different values of cyclotron frequency and beam energy. If the plasma density increases, the frequency and phase velocity of four modes will increase. The maximum growth rates of the four modes in the lower plasma density are equal and for higher values of plasma density the (Obp − Xp) mode has greatest value. The phase velocity and the frequency of (Xbp − Xp) with (Xbp − Op) modes and (Obp − Op) with (Obp − Xp) modes are coinciding with each other and for first case increase with beam density, but for latter decrease. The maximum growth rate of (Obp − Op) mode and the maximum frequency of (Xbp − Xp) mode have highest values as a function of the electron beam density. Manuscript profile

In the present paper, the micron-size silver and titanium powder with desired weight ratios is used to produce the silver-titanium nanocomposite using the self-developed thermal plasma equipment. The mixture is fed into the plasma torch flame by the powder feed system and argon carrier gas. After evaporation, the particles are cooled inside the cooling chamber and collected from the surface of the water-cooled double-walled chamber. The production of Titanium-Silver bimetallic nanoparticles is achieved in two ways: the cooling chamber is once filled with argon and once with atmospheric air. The nanoparticles are analyzed using scanning electron microscope (SEM), Energy Dispersive X-ray Spectroscopy (EDS), and X-ray Diffraction (XRD) methods to identify the nanoparticle size distribution, morphology and chemical composition properties. The morphology of the produced nanocomposites is spherical and their average size is 30 nm. The results indicate that the average size of nanoparticles produced in the presence of air is smaller than those in the presence of argon Manuscript profile

AbstractLinear theory of the two-stream free-electron laser consisting of a relativistic electron beam transported along the axis of thermal plasma-loaded helical wiggler is proposed and investigated. The dispersion relation is derived employing linear fluid theory. The characteristics of the dispersion relation are analyzed by numerical solutions. The results show in that in the special values of the plasma temperature the growth rate is considerably enhanced. It is also shown that the growth rate after critical plasma density gradually decreases. Moreover, in the presence of the two-electron beam the growth rate of electrostatic mode is two times greater than that for electromagnetic mode. Manuscript profile

AbstractA relativistic traveling wave tube with thermal plasma-filled corrugated waveguide is driven by a finite solid electron beam with the entire system immersed in a strong longitudinal magnetic field that magnetized plasma and electron beam. The dispersion relation for the relativistic traveling wave tube is obtained by linear fluid theory. The numerical results show that the growth rate decreases by increasing plasma temperature, waveguide radius, plasma density and electron beam energy. As show in this paper the effect of electron beam density and corrugation period is to increase growth rate. Manuscript profile

AbstractThe outbreak of the disease and infection in the hospital environment and medical equipment is one of the concerns of modern life. One of the effective ways for preventing and reducing the complications of infections is modification of the surface. Here, the handmade atmospheric plasma spray system is used for accumulating copper as an antibacterial agent on the 316L stainless steel substrate, which applies to hospital environment and medical equipment. As a durable coating with proper adhesion is needed on the substrate, the effect of stand-off distance (SOD) which is an important parameter of the spray on the microstructure, the hardness and adhesion of the copper coating on the 316L stainless steel were investigated. The structure and phase composition of copper depositions were investigated using scanning electron microscopy and X-ray diffraction. The adhesion and hardness of depositions are evidenced using the cross cut tester and Vickers hardness tester, respectively. The findings confirm that the voids in the coatings increase with increasing SOD, which leads to decreasing the hardness of coatings and also the adhesion strength between depositions and substrate. In addition, by increasing the SOD, the oxygen content and the size of grains in the lamellae (fine structure) of coatings also increase. Manuscript profile

Abstract A theory of relativistic traveling wave tube with magnetized thermal plasma-filled corrugated waveguide with annular electron beam is given. The dispersion relation is obtained by linear fluid theory. The characteristic of the dispersion relation is obtained by numerical solutions. The effect of plasma density, corrugated period, waveguide radius and plasma thermal effect on the dispersion relation and growth rate are analyzed. Some useful results are given. Manuscript profile

AbstractIn this paper, examples of all types of signal injection such as different signal , harmonic signal and multiple signal injections in a TWT including hollow electron beam near frequency 1800 MHz and within input powers lower than TWT saturation power has been analyzed using approximate analytical solution of S-MUSE model. Later, the results obtained from approximate analytical solution with large signal code LATTE, that is a Lagrangian model, have been tested and simulated so that the effect of input phase difference between drive and injected wave and the effect of input powers on the amplification value of drive and generated second-order harmonic waves were investigated. The phase difference between drive and harmonic waves is a key parameter in harmonic injection for increasing the output power of drive and second-order harmonic frequencies. Manuscript profile

In the present paper, a novel thermal plasma method is proposed to synthesize ZnO-Fe2O3 nanocomposite, with different percentages of iron, namely 3, 5, and 7%. This method is an efficient feasibility of the Zno-Fe2O3 nanocomposite synthesis. The nanocomposites are synthesized by homemade direct current (DC) plasma torch. They are analyzed by different methods. The bandgap is determined by diffuse reflectance spectroscopy (DRS). The photocatalytic performance of Zno-Fe2O3 is evaluated. The results show that the structure of nanoparticles is spherical, which is more favored in the industry. Also, the particle size distribution is uniform. The average size of nanoparticle crystals increases with increasing iron content. Despite the formation of nanocomposites, due to the lack of support for nanoparticles, the results of photodegradation are not satisfactory. Manuscript profile