Search for: plasma
Total 391 records
Composite patterns formed by paraxial vortex-beams propagation in one-dimensional multilayer plasma photonic crystals, Article European Physical Journal D ; Vol. 68, issue. 2 , 2014 ; ISSN: 14346060 ; Bahrampour, A. R ; Sharif University of Technology
Optical properties of twisted electromagnetic beam propagating in one-dimensional binary dielectric-plasma photonic crystal are investigated. Reflection and transmission spectra by using nonlinear Transfer Matrix Method of Degenerate Four-Wave Mixing are calculated. These characteristics are studied in low intensity, high temperature range of plasma, large Rayleigh range and neglecting the pumps depletion. In our calculation, the standard slowly varying field approximation is employed. The results show that the composite vortex patterns in the left of photonic crystal structure is dependent on the beam vortex charge number, the incident beam frequency and plasma temperature. Also, it is...
Article European Physical Journal D ; Volume 70, Issue 8 , 2016 ; 14346060 (ISSN) ; Vaziri (Khamedi), M ; Rooholamininejad, H ; Bahrampour, A ; Sharif University of Technology
Springer New York LLC
The resonant vortex terahertz beam generation by the cross-focusing of two twistedcoaxial laser beams is investigated. For the resonant excitation of terahertz radiation,the rippled density in plasma and the ripple wave number is suitably chosen to satisfy thephase matching condition. The nonlinear current density at terahertz frequency arises dueto the spatial variation of two Laguerre-Gaussian coupled field. The terahertz intensityscales as the ponderomotive force of laser beams which imparts an oscillatory velocity tothe electrons and, in fact, input Laguerre-Gaussian laser beams properties such as vortexcharge number and beam waist. Various laser and plasma parameters are employed to...
Differential evolution algorithm for performance optimization of the micro plasma actuator as a microelectromechanical system, Article Scientific Reports ; Volume 10, Issue 1 , 2020 ; Mazaheri, K ; Sharif University of Technology
Nature Research 2020
Dielectric Discharge Barrier (DBD) plasma actuators are considered as one of the best active electro-hydrodynamic control devices, and are considered by many contemporary researchers. Here a simple electrostatic model, which is improved by authors, and uses the Maxwell’s and the Navier–Stokes equations, is proposed for massive optimization computations. This model is used to find the optimum solution for application of a dielectric discharge barrier on a curved surface of a DU25 wind turbine blade airfoil, in a range of 5–18 kV applied voltages, and 0.5 to 13 kHz frequency range. Design variables are selected as the dielectric thickness and material, and thickness and length of the...
A rapid and sensitive HPLC-fluorescence method for determination of mirtazapine and its two major metabolites in human plasma, Article Iranian Journal of Pharmaceutical Research ; Volume 13, Issue 3 , Summer 2014 , Pages 853-862 ; Giorgi, M ; Sheikholeslami, B ; Hedayati, M ; Rouini, M. R ; Sharif University of Technology
A rapid and sensitive HPLC method has been developed for the quantification of mirtazapine (MRZ), a noradrenergic and specific serotonergic inhibitor antidepressant (NaSSA) and its two major metabolites N-desmethyl mirtazapine (NDM) and 8-hydroxymirtazapine (8-OHM) in human plasma. The separation was achieved using Chromolith C18 column and a mobile phase of acetonitrile: phosphate buffer (pH = 3, 20:80, v/v) in isocratic mode at a flow rate of 2 mL/min. A fluorescence detector was set at 290 and 350 nm for excitation and emission, respectively. Zolpidem was used as the internal standard. Liquid-liquid extraction was applied for sample clean up. All analytes were eluted in less than 5...
Article Journal of Statistical Physics ; Volume 143, Issue 1 , 2011 , Pages 148-167 ; 00224715 (ISSN) ; Movahed, M. S ; Khorram, S ; Rahimi Tabar, M. R ; Sharif University of Technology
Using the Markovian method, we study the stochastic nature of electrical discharge current fluctuations in the Helium plasma. Sinusoidal trends are extracted from the data set by the Fourier-Detrended Fluctuation analysis and consequently cleaned data is retrieved. We determine the Markov time scale of the detrended data set by using likelihood analysis. We also estimate the Kramers-Moyal's coefficients of the discharge current fluctuations and derive the corresponding Fokker-Planck equation. In addition, the obtained Langevin equation enables us to reconstruct discharge time series with similar statistical properties compared with the observed in the experiment. We also provide an exact...
Simulation of body force field effects on airfoil separation control and optimization of plasma actuator, Article Journal of Physics D: Applied Physics ; Volume 41, Issue 17 , 2008 ; 00223727 (ISSN) ; Mirzaee, I ; Anvari, A ; Purmahmod, N ; Sharif University of Technology
Among all active flow control methods, EHD, MHD and EMHD are the only methods which operate on the basis of body force induction on flow field. The EHD plasma actuator is the proper method which has been used in various flow control applications recently. In this paper, the effects of different body force fields on different domains have been studied for separation control on NACA 0021 and the results have been discussed. The airflow velocity has been assumed to be 35 m s-1 at a post-stall angle of attack of 23°. Three different domains have been used around the airfoil to investigate body forces with different strengths and directions and those which give the best result in separation...
An analytical model of plasma cavity for producing of quasi-monoenergetic electron in intense laser-plasma interaction, Article 34th European Physical Society Conference on Plasma Physics 2007, EPS 2007, Warsaw, 2 July 2007 through 6 July 2007 ; Volume 31, Issue 3 , 2007 , Pages 1773-1776 ; 9781622763344 (ISBN) ; Sadighi Bonabi, R ; Afarideh, H ; Sharif University of Technology
During the recent experiments and PIC simulations, quasi-monoenergetic for electron is observed [1, 2]. Forming the free of cold plasma electrons cavity behind the laser pulse is possible instead of periodic plasma wave and plasma channel guided method . In this bubble cavity a dense bunch of relativistic electrons with a monoenergetic spectrum is self-generated .The profiles  and PIC simulation  show the ellipsoid shape cavity behind the laser pulse. In this work we present an analytical ellipsoid model and discuss how quasi-monoenergetic electron is produced in the bubble field
Dielectric magnifying of plasma blocks by nonlinear force acceleration with delayed electron heating, Article Physics of Plasmas ; Volume 17, Issue 11 , 2010 ; 1070664X (ISSN) ; Yazdani, E ; Cang, Y ; Hora, H ; Sharif University of Technology
Specific studies were performed in order to increase the thickness of laser generated directed space charge quasineutral plasma blocks with anomalously high ion current densities above 1011 A/ cm2. This may lead to an alternative scheme of laser driven fusion with the irradiation of petawatt-picosecond laser pulses. Initial electron densities were used with Rayleigh profiles, because these are unique for inhomogeneous plasmas for undistorted acceleration at very low reflectivity until thermal absorption processes disturb these ideal conditions. Numerical hydrodynamic results based on a genuine two-fluid code are presented to optimize the block generation for possible fast ignition and...
Article Saint Petersburg 2012 - Geosciences: Making the Most of the Earth's Resources, 2 April 2012 through 5 April 2012 ; April , 2012 ; Amani, S ; Sharif University of Technology
European Association of Geoscientists and Engineers, EAGE 2012
Plasma impulse technology (PIT) is one of the most innovative methods among the oil recovery enhancement (EOR) jobs. Although the low cost and persistent effects of this method has attracted researchers attentions to its self, the governing mechanisms of reservoir remediation in this method are still shrouded in mystery. This study presents a brief discussion on probable thermal mechanisms which govern the interaction between reservoir formation and plasma impulse jet. Minerals dissociation, opening the fused pathway and organic deposits melting seem to be of the most important thermal effects
Article Journal of High Energy Physics ; Volume 2012, Issue 6 , 2012 ; 11266708 (ISSN) ; Davody, A ; Sharif University of Technology
To study the rate of energy and momentum loss of a heavy quark in QGP, specifically in the hydrodynamic regime, we use fluid/gravity duality and construct a perturbative procedure to find the string solution in gravity side. We show that by this construction, the position of the world-sheet horizon and thereby the drag force exerted on the quark can be computed perturbatively, order by order in a boundary derivative expansion, for a wide range of quark velocities. At ideal order, our result is just the localized expression of the drag force exerted on a moving quark in thermal plasma, while for a quark whose velocity does not belong to the mentioned range, we predict a nonlocal drag force....
Article Journal of Applied Physics ; Volume 117, Issue 14 , April , 2015 ; 00218979 (ISSN) ; Yazdani, E ; Sadighi Bonabi, R ; Anvari, A ; Hora, H ; Sharif University of Technology
American Institute of Physics Inc 2015
The interaction of the sub-picosecond UV laser in sub-relativistic intensities with deuterium is investigated. At high plasma temperatures, based on the quantum correction in the collision frequency, the electron heating and the ion block generation in plasma are studied. It is found that due to the quantum correction, the electron heating increases considerably and the electron temperature uniformly reaches up to the maximum value of 4.91-×-107-K. Considering the quantum correction, the electron temperature at the laser initial coupling stage is improved more than 66.55% of the amount achieved in the classical model. As a consequence, by the modified collision frequency, the ion block is...
Article Journal of High Energy Physics ; Volume 2018, Issue 3 , 2018 ; 11266708 (ISSN) ; Taghinavaz, F ; Naderi, K ; Sharif University of Technology
Springer Verlag 2018
In the framework of chiral kinetic theory (CKT), we consider a system of right-and left-handed Weyl fermions out of thermal equilibrium in a homogeneous weak magnetic field. We show that the Lorentz invariance implies a modification in the definition of the momentum current in the phase space, compared to the case in which the system is in global equilibrium. Using this modified momentum current, we derive the linearized conservation equations from the kinetic equation up to second order in the derivative expansion. It turns out that the eigenmodes of these equations, namely the hydrodynamic modes, differ from those obtained from the hydrodynamic in the Landau-Lifshitz (LL) frame at the same...
Article Journal of High Energy Physics ; Volume 2019, Issue 5 , 2019 ; 11266708 (ISSN) ; Ghazi, A ; Taghinavaz, F ; Tavakol, O ; Sharif University of Technology
Springer Verlag 2019
We consider a fluid with weakly broken time and translation symmetries. We assume the fluid also possesses a U(1) symmetry which is not only weakly broken, but is anomalous. We use the second order chiral quasi-hydrodynamics to compute the magneto conductivities of this fluid in the presence of a weak magnetic field. Analogous to the electrical and thermoelectric conductivities, it turns out that the thermal conductivity depends on the coefficient of mixed gauge-gravitational anomaly. Our results can be applied to the hydrodynamic regime of every arbitrary system, once the thermodynamics of that system is known. By applying them to a free system of Weyl fermions at low temperature limit T ≪...
Efficient methane conversion to hydrogen and hydrocarbons by combination of corona and glow discharge, Article Czechoslovak Journal of Physics ; Volume 54, Issue SUPPL. 3 , 2004 , Pages C990-C994 ; 00114626 (ISSN) ; Matin, N. S ; Sharif University of Technology
Kluwer Academic Publishers 2004
In this study we offer a new type of plasma which consists of double, corona and glow, discharge to convert natural gas, the main part of which is methane. The most important future of this type of plasma is the steady increase of overall chemical energy efficiency by enhancement of repetition rate. At repetition rate of R = 80 Hz, the energy efficiency of 5.5% was increased to 10% at R = 330 Hz and more improvement was yet expected at higher repetition rates. Easy control of selectivity of products that were hydrogen, acetylene, ethylene, ethane and hydrocarbons with up to 5 carbons, was also possible by repetition rate
Article Fiber and Integrated Optics ; Volume 21, Issue 3 , 2002 , Pages 173-191 ; 01468030 (ISSN) ; Nojeh, A ; Rashidian, B ; Sharif University of Technology
Feasibility of a new integrated amplitude modulator/switch operating up to the visible spectrum, based on the absorption of light due to the linear interaction of the incident laser and a two-dimensional plasma layer is demonstrated. Plasma layers are generated via the Muller effect at the waveguide's interfaces. A plasma wave is excited in the two-dimensional gas when it is illuminated by electromagnetic radiation. Thus, due to the energy transfer from the electromagnetic wave to the plasma wave, the output light intensity can be controlled. The device is capable of amplitude modulation of guided beams in dielectric waveguides. Analysis based on both full-classical and semiclassical...
Article Surface and Coatings Technology ; Volume 201, Issue 9-11 SPEC. ISS , 2007 , Pages 4926-4930 ; 02578972 (ISSN) ; Shahidi, S ; Moazzenchi, B ; Anvari, A ; Rashidi, A ; Hosseini, H ; Sharif University of Technology
In this study, we have used a low temperature plasma, produced by a DC magnetron sputtering device, for decolorizing of denim fabrics, and the effect of using different gases such as Argon and Oxygen as the discharge medium have been investigated. The results obtained under equal periods of time have been compared and the effect of washing on the treated denims has been reported. © 2006 Elsevier B.V. All rights reserved
Article Laser and Particle Beams ; Volume 29, Issue 4 , 2011 , Pages 453-458 ; 02630346 (ISSN) ; Moshkelgosha, M ; Sharif University of Technology
This work is devoted to improving relativistic self-focusing of intense laser beam in underdense unmagnetized plasma. New density profiles are introduced to achieve beam width parameter up to the wavelength of the propagating laser. By investigating variations of the beam width parameter in presence of different density profiles it is found that the beam width parameter is considerably decreased for the introduced density ramp comparing with uniform density and earlier introduced density ramp profiles. By using this new density profile high intensity laser pulses are guided over several Rayleigh lengths with extremely small beam width parameter
Design and fabrication of a movable langmuir probe for plasma edge parameters measurement in the IR-T1 tokamak, Article Journal of Fusion Energy ; Volume 28, Issue 3 , 2009 , Pages 296-299 ; 01640313 (ISSN) ; Ghoranneviss, M ; Emami, M ; Anvari, A ; Van Oost, G ; Sharif University of Technology
For the edge plasma parameters measurement, a movable Langmuir probe is fabricated and installed on the IR-T1 tokamak. The set-up consists of two sets of single Langmuir probes with tungsten tip movable in the radial direction. Edge plasma parameters including electron temperature, Ion density, floating potential and the corresponding radial changes are measured. Using two-point correlation technique clearly reveal that in the SOL region the poloidal propagation of floating potential fluctuation is in the direction of ion diamagnetic drift and in the edge it propagates in the electron diamagnetic drift direction. © 2009 Springer Science+Business Media, LLC
Article Chinese Physics B ; Volume 19, Issue 6 , 2010 ; 16741056 (ISSN) ; Sadighi Bonabi, R ; Afarideh, H ; Sharif University of Technology
Using the ellipsoidal cavity model, the quasi-monoenergetic electron output beam in laser-plasma interaction is described. By the cavity regime the quality of electron beam is improved in comparison with those generated from other methods such as periodic plasma wave field, spheroidal cavity regime and plasma channel guided acceleration. Trajectory of electron motion is described as hyperbolic, parabolic or elliptic paths. We find that the self-generated electron bunch has a smaller energy width and more effective gain in energy spectrum. Initial condition for the ellipsoidal cavity is determined by laser-plasma parameters. The electron trajectory is influenced by its position, energy and...
M.Sc. Thesis Sharif University of Technology ; Rashidian, Bijan ; Faez, Rahim
Cold plasma has many applications in micro electronics industry. In this study, several examples of widely used plasmas systems have been investigated. First, the theory and physics of each type of plasma has been studied. Then the applications of each type have been discussed. Finally, the accuracy of the statements has been investigated using COMSOL multi physics software. In 1&2 D simulations the effects of all macroscopic parameters on plasma properties and its behavior have been investigated. In the design of plasma excitation source, plasma impedance is a very important parameter for maximum power transfer. Plasma impedance has been calculated with COMSOL software. Different modes of...