A comparative study of different injection configurations in the wakefield generated by a chirped... more A comparative study of different injection configurations in the wakefield generated by a chirped laser pulse is done. The preferable electron injection region is considered for different injection schemes. For injection in the chirped laser pulse region, the energy spread has approximately the same final value independently of its injection position while energy spread changes strongly for injection in the wakefield region. It is demonstrated that an externally injected electron bunch with an initial energy of 100 MeV can achieve an energy gain of 8 GeV by using periodical chirped laser pulses. In particular, strong bunch decoherence is observed for off-axis injection in a plasma-channelguided-laser wakefield. This strong bunch decoherence leads to a considerable increase in the bunch emittance growth. The emittance growth in off-axis injection is at least ten orders of magnitude higher than in on-axis injection.
Iranian Journal of Pharmaceutical Research : IJPR, 2020
Retinoblastoma (RB) is a common malignancy in childhood, with an incidence of 1 per 20,000 live b... more Retinoblastoma (RB) is a common malignancy in childhood, with an incidence of 1 per 20,000 live births. Several approaches such as chemotherapy, laser, and radiotherapy have been used for the treatment of RB. However, the effectiveness of these methods is not sufficient and the mechanisms involved in the pathogenesis of the disease are not well understood. The disruption of the apoptotic process is considered as one of the mechanisms involved in the pathogenesis of RB. This study was designed to examine the in-vitro selective toxicity of cold atmospheric plasma (CAP) on RB cells’ mitochondria and lysosomes. The results showed that CAP decreased cell viability and GSH content and also increased caspase-3 activity and lipid peroxidation (LPO) in cancerous ocular cells isolated from the rat model of RB compared to the normal rat ocular cells. Furthermore, results demonstrated that CAP significantly increased ROS generation, mitochondrial membrane potential (MMP) collapse, mitochondrial...
In this review, we present a comprehensive survey of techniques used to fabricate superhydrophobi... more In this review, we present a comprehensive survey of techniques used to fabricate superhydrophobic—extreme nonwetting—textiles by plasma systems. First, we provide a brief introduction to superhydrophobic surfaces, plasma sources, and plasma surface processing. We then assess the plasma-based techniques capable of producing the required rough surface micronanotextures of superhydrophobic surfaces. The implications of tailoring the specific surface chemistry and texture will be discussed, and finally, we summarize future challenges and issues to be addressed for ensuring a better understanding and use of superhydrophobic fabrics.
In this paper, the optimal design of a grid-connected the hybrid energy system for a sample area ... more In this paper, the optimal design of a grid-connected the hybrid energy system for a sample area in the north Iran is studied. A new innovative cost-based objective function is proposed which is combination of life cycle cost and reliability cost. Also, loss of power supply probability (LPSP) criteria, is considered as constraint for ensuring at the same time certain level of system reliability. Designing process is implemented in such a way that the total cost of the system reaches its minimum. For this purpose, a modified version of Bee algorithm has been proposed to achieve this goal. In order to carry out studies, the actual sample system, whose data has been available, has been studied. The results indicate the good performance of proposed hybrid system to reduce system cost.
Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards, 2019
Hydraulic power can lead to the erosion of rock and cause dams to be at risk of failure. Methods ... more Hydraulic power can lead to the erosion of rock and cause dams to be at risk of failure. Methods exist to predict the degree of erosion for rock masses in spillways; however, these deterministic approaches are unable to consider the uncertainties of rock mass parameters. We develop a methodology that determines the vulnerability of a rock mass to hydrological erosion, and this approach takes into consideration the uncertainties related to the parameters of the rock mass at the study site. Monte Carlo simulation is used to create a dataset for each class of rock for then developing fragility and vulnerability curves. The effects of each geomechanical parameter on erosion level can be determined by applying this methodology to individual spillway sites. As a result, sensitivity analysis shows that the discontinuity orientation factor is a critical parameter for explaining the erosion of a rock mass; increasing this parameter decreases the vulnerability of the rock mass to erosion. Our approach has an advantage over deterministic methods as the uncertainties of rock mass parameters have been considered. The error associated with the predicted erosion level via our probability-based approach is significantly less than the error obtained via deterministic methods.
Surface characterization of an organosilane-grafted moisture-crosslinked polyethylene compound tr... more Surface characterization of an organosilane-grafted moisture-crosslinked polyethylene compound treated by air atmospheric pressure non-equilibrium gliding arc plasma, Applied Surface Science,
Atmospheric plasma treatment followed by a plasma polymerisation coating produced an aluminium su... more Atmospheric plasma treatment followed by a plasma polymerisation coating produced an aluminium surface having high water repellency and icephobicity. We varied the plasma parameters and the amount of hexamethyldisiloxane precursor to optimise surface hydrophobicity. The static contact and sliding angles of the surface reached 163°and <1°, respectively. Furthermore, the prepared surfaces remained superhydrophobic after seven days of immersion in acid-base media as well as after five icing/de-icing cycles.
In this paper, we present a paraxial description of relativistic self-focusing of a Gaussian lase... more In this paper, we present a paraxial description of relativistic self-focusing of a Gaussian laser beam in a plasma channel with the density distribution as a function of radial and axial variations. We have derived the nonlinear dielectric permittivity of plasma due to ponderomotive force and relativistic effects. The effect of different conditions of the inhomogeneous plasma and the laser pulse on self-focusing and defocusing of Gaussian laser beam propagation in the plasma is studied. We find that with an increase in the value of intensity of the beam, self-focusing enhances and shifts toward lower values of normalized propagation distance. The self-focusing length also increases with an increase in channel width. When the density rapidly increases along the propagation distance, the nonlinearity increases and gives self-focusing at shorter values of z.
ABSTRACT An interferometer-based technique has been used to determine the change in the refractiv... more ABSTRACT An interferometer-based technique has been used to determine the change in the refractive index induced by a Q-switched Nd–YAG laser (λ = 532 nm and pulse duration 6 ns) on an aluminum target under atmo-spheric air pressure. The average density changes in front of the target irradiated by two laser pulse energy were observed for different focusing conditions. An Abel inversion technique is also presented for calculating three-dimensional density distributions in cylindrical coordinates.
This study is devoted to tracing and identifying the elements available in bone sample using Lase... more This study is devoted to tracing and identifying the elements available in bone sample using Laser-Induced Breakdown Spectroscopy (LIBS). The bone samples were prepared from the thigh of laboratory rats, which consumed 325.29 g/mol lead acetate having 4 mM concentration in specified time duration. About 76 atomic lines have been analyzed and we found that the dominant elements are Ca I, Ca II, Mg I, Mg II, Fe I, and Fe II. Temperature curve and bar graph were drawn to compare bone elements of group B which consumed lead with normal group, group A, in the same laboratory conditions. Plasma parameters including plasma temperature and electron density were determined by considering Local Thermodynamic Equilibrium (LTE) condition in the plasma. An inverse relationship has been detected between lead absorption and elements like Calcium and Magnesium absorption comparing elemental values for both the groups.
International Journal of the Physical Sciences, 2012
The paper presents a numerical study of the periodic self focusing behavior of a laser pulse prop... more The paper presents a numerical study of the periodic self focusing behavior of a laser pulse propagation in a gas filled capillary plasma with a parabolic electron density profile. An implicit and inherently stable Crank-Nicholson method was used to demonstrate the periodic laser beam waist behavior inside the tube discharge. The dependence of the tube radius and beam waist on maximum intensity delivered to the waveguide and its influence on the modulated Rayleigh length was discussed.
The influence of adding chlorine on the characteristics of a dielectric barrier discharge in Argo... more The influence of adding chlorine on the characteristics of a dielectric barrier discharge in Argon is investigated on the basis of a one-dimensional fluid model. The spatio-temporal characteristics of the discharge are obtained by applying a sinusoidal voltage with a frequency and amplitude of 7 kHz and 350 V, respectively. The study shows that the discharge has a homogeneous feature across the electrodes and has only one current pulse per half cycle of the applied voltage. The calculated electric field and electric potential as well as species number densities indicated that the discharge is in glow mode, and adding chlorine as electronegative gas up to 50% does not change its mode. It is observed that the most abundant negative species are Cl À ions even in low additive chlorine. As a result, the maximum of plasma electronegativity takes place at 30% amounts of chlorine additive. The study of plasma radiations on the discharge gap shows that the main spontaneous emissions are observed at the wavelengths of 128.5 nm and 258 nm due to de-excitation of ArCl à and Cl à 2 molecules, respectively. Between different Ar/Cl 2 mixtures, 0:99Ar À 0:01Cl 2 has the nearly uniform radiation in the positive column region. V
An ultrashort laser pulse propagating in plasma can excite a nonlinear plasma wakefield which can... more An ultrashort laser pulse propagating in plasma can excite a nonlinear plasma wakefield which can trap and accelerate charged particles up to GeV. One-dimensional analysis of electron injection, trapping, and acceleration by different chirped pulses propagating in plasma is investigated numerically. In this paper, we inject electron bunches in front of the chirped pulses. It is indicated that periodical chirped laser pulse can trap electrons earlier than other pulses. It is shown that periodical chirped laser pulses lead to decrease the minimum momentum necessary to trap the electrons. This is due to the fact that periodical chirped laser pulses are globally much efficient than nonchirped pulses in the wakefield generation. It is found that chirped laser pulses could lead to much larger electron energy than that of nonchirped pulses. Relative energy spread has a lower value in the case of periodical chirped laser pulses.
In present paper, the chirp effect of an electromagnetic pulse via an analytical model of wakefie... more In present paper, the chirp effect of an electromagnetic pulse via an analytical model of wakefield generation is studied. Different types of chirps are employed in this study. Our results show that by the use of nonlinear chirped pulse the longitudinal wakefield and focusing force is stronger than that of linear chirped pulse. It is indicated that quadratic nonlinear chirped pulses are globally much efficient than periodic nonlinear chirped pulses. Our calculations also predict that in nonlinear chirped pulse case, the overlap of focusing and accelerating regions is broader than that achieved in linear chirped pulse.
Theoretical analysis of stimulated Brillouin scattering (SBS) in high power ytterbium-doped doubl... more Theoretical analysis of stimulated Brillouin scattering (SBS) in high power ytterbium-doped double-clad (YDDC) fiber lasers is presented by solving the steady-state rate equations with regard to SBS at different pumping configurations. Distribution of pump, signal and Stokes waves powers in forward, backward and bi-directional pumping configurations through the fiber are investigated. Also, distribution of population inversion through the fiber is shown. Studies shows that amount of backward Brillouin Stokes power in forward pumping configuration is higher than other configurations.
A comparative study of different injection configurations in the wakefield generated by a chirped... more A comparative study of different injection configurations in the wakefield generated by a chirped laser pulse is done. The preferable electron injection region is considered for different injection schemes. For injection in the chirped laser pulse region, the energy spread has approximately the same final value independently of its injection position while energy spread changes strongly for injection in the wakefield region. It is demonstrated that an externally injected electron bunch with an initial energy of 100 MeV can achieve an energy gain of 8 GeV by using periodical chirped laser pulses. In particular, strong bunch decoherence is observed for off-axis injection in a plasma-channelguided-laser wakefield. This strong bunch decoherence leads to a considerable increase in the bunch emittance growth. The emittance growth in off-axis injection is at least ten orders of magnitude higher than in on-axis injection.
Iranian Journal of Pharmaceutical Research : IJPR, 2020
Retinoblastoma (RB) is a common malignancy in childhood, with an incidence of 1 per 20,000 live b... more Retinoblastoma (RB) is a common malignancy in childhood, with an incidence of 1 per 20,000 live births. Several approaches such as chemotherapy, laser, and radiotherapy have been used for the treatment of RB. However, the effectiveness of these methods is not sufficient and the mechanisms involved in the pathogenesis of the disease are not well understood. The disruption of the apoptotic process is considered as one of the mechanisms involved in the pathogenesis of RB. This study was designed to examine the in-vitro selective toxicity of cold atmospheric plasma (CAP) on RB cells’ mitochondria and lysosomes. The results showed that CAP decreased cell viability and GSH content and also increased caspase-3 activity and lipid peroxidation (LPO) in cancerous ocular cells isolated from the rat model of RB compared to the normal rat ocular cells. Furthermore, results demonstrated that CAP significantly increased ROS generation, mitochondrial membrane potential (MMP) collapse, mitochondrial...
In this review, we present a comprehensive survey of techniques used to fabricate superhydrophobi... more In this review, we present a comprehensive survey of techniques used to fabricate superhydrophobic—extreme nonwetting—textiles by plasma systems. First, we provide a brief introduction to superhydrophobic surfaces, plasma sources, and plasma surface processing. We then assess the plasma-based techniques capable of producing the required rough surface micronanotextures of superhydrophobic surfaces. The implications of tailoring the specific surface chemistry and texture will be discussed, and finally, we summarize future challenges and issues to be addressed for ensuring a better understanding and use of superhydrophobic fabrics.
In this paper, the optimal design of a grid-connected the hybrid energy system for a sample area ... more In this paper, the optimal design of a grid-connected the hybrid energy system for a sample area in the north Iran is studied. A new innovative cost-based objective function is proposed which is combination of life cycle cost and reliability cost. Also, loss of power supply probability (LPSP) criteria, is considered as constraint for ensuring at the same time certain level of system reliability. Designing process is implemented in such a way that the total cost of the system reaches its minimum. For this purpose, a modified version of Bee algorithm has been proposed to achieve this goal. In order to carry out studies, the actual sample system, whose data has been available, has been studied. The results indicate the good performance of proposed hybrid system to reduce system cost.
Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards, 2019
Hydraulic power can lead to the erosion of rock and cause dams to be at risk of failure. Methods ... more Hydraulic power can lead to the erosion of rock and cause dams to be at risk of failure. Methods exist to predict the degree of erosion for rock masses in spillways; however, these deterministic approaches are unable to consider the uncertainties of rock mass parameters. We develop a methodology that determines the vulnerability of a rock mass to hydrological erosion, and this approach takes into consideration the uncertainties related to the parameters of the rock mass at the study site. Monte Carlo simulation is used to create a dataset for each class of rock for then developing fragility and vulnerability curves. The effects of each geomechanical parameter on erosion level can be determined by applying this methodology to individual spillway sites. As a result, sensitivity analysis shows that the discontinuity orientation factor is a critical parameter for explaining the erosion of a rock mass; increasing this parameter decreases the vulnerability of the rock mass to erosion. Our approach has an advantage over deterministic methods as the uncertainties of rock mass parameters have been considered. The error associated with the predicted erosion level via our probability-based approach is significantly less than the error obtained via deterministic methods.
Surface characterization of an organosilane-grafted moisture-crosslinked polyethylene compound tr... more Surface characterization of an organosilane-grafted moisture-crosslinked polyethylene compound treated by air atmospheric pressure non-equilibrium gliding arc plasma, Applied Surface Science,
Atmospheric plasma treatment followed by a plasma polymerisation coating produced an aluminium su... more Atmospheric plasma treatment followed by a plasma polymerisation coating produced an aluminium surface having high water repellency and icephobicity. We varied the plasma parameters and the amount of hexamethyldisiloxane precursor to optimise surface hydrophobicity. The static contact and sliding angles of the surface reached 163°and <1°, respectively. Furthermore, the prepared surfaces remained superhydrophobic after seven days of immersion in acid-base media as well as after five icing/de-icing cycles.
In this paper, we present a paraxial description of relativistic self-focusing of a Gaussian lase... more In this paper, we present a paraxial description of relativistic self-focusing of a Gaussian laser beam in a plasma channel with the density distribution as a function of radial and axial variations. We have derived the nonlinear dielectric permittivity of plasma due to ponderomotive force and relativistic effects. The effect of different conditions of the inhomogeneous plasma and the laser pulse on self-focusing and defocusing of Gaussian laser beam propagation in the plasma is studied. We find that with an increase in the value of intensity of the beam, self-focusing enhances and shifts toward lower values of normalized propagation distance. The self-focusing length also increases with an increase in channel width. When the density rapidly increases along the propagation distance, the nonlinearity increases and gives self-focusing at shorter values of z.
ABSTRACT An interferometer-based technique has been used to determine the change in the refractiv... more ABSTRACT An interferometer-based technique has been used to determine the change in the refractive index induced by a Q-switched Nd–YAG laser (λ = 532 nm and pulse duration 6 ns) on an aluminum target under atmo-spheric air pressure. The average density changes in front of the target irradiated by two laser pulse energy were observed for different focusing conditions. An Abel inversion technique is also presented for calculating three-dimensional density distributions in cylindrical coordinates.
This study is devoted to tracing and identifying the elements available in bone sample using Lase... more This study is devoted to tracing and identifying the elements available in bone sample using Laser-Induced Breakdown Spectroscopy (LIBS). The bone samples were prepared from the thigh of laboratory rats, which consumed 325.29 g/mol lead acetate having 4 mM concentration in specified time duration. About 76 atomic lines have been analyzed and we found that the dominant elements are Ca I, Ca II, Mg I, Mg II, Fe I, and Fe II. Temperature curve and bar graph were drawn to compare bone elements of group B which consumed lead with normal group, group A, in the same laboratory conditions. Plasma parameters including plasma temperature and electron density were determined by considering Local Thermodynamic Equilibrium (LTE) condition in the plasma. An inverse relationship has been detected between lead absorption and elements like Calcium and Magnesium absorption comparing elemental values for both the groups.
International Journal of the Physical Sciences, 2012
The paper presents a numerical study of the periodic self focusing behavior of a laser pulse prop... more The paper presents a numerical study of the periodic self focusing behavior of a laser pulse propagation in a gas filled capillary plasma with a parabolic electron density profile. An implicit and inherently stable Crank-Nicholson method was used to demonstrate the periodic laser beam waist behavior inside the tube discharge. The dependence of the tube radius and beam waist on maximum intensity delivered to the waveguide and its influence on the modulated Rayleigh length was discussed.
The influence of adding chlorine on the characteristics of a dielectric barrier discharge in Argo... more The influence of adding chlorine on the characteristics of a dielectric barrier discharge in Argon is investigated on the basis of a one-dimensional fluid model. The spatio-temporal characteristics of the discharge are obtained by applying a sinusoidal voltage with a frequency and amplitude of 7 kHz and 350 V, respectively. The study shows that the discharge has a homogeneous feature across the electrodes and has only one current pulse per half cycle of the applied voltage. The calculated electric field and electric potential as well as species number densities indicated that the discharge is in glow mode, and adding chlorine as electronegative gas up to 50% does not change its mode. It is observed that the most abundant negative species are Cl À ions even in low additive chlorine. As a result, the maximum of plasma electronegativity takes place at 30% amounts of chlorine additive. The study of plasma radiations on the discharge gap shows that the main spontaneous emissions are observed at the wavelengths of 128.5 nm and 258 nm due to de-excitation of ArCl à and Cl à 2 molecules, respectively. Between different Ar/Cl 2 mixtures, 0:99Ar À 0:01Cl 2 has the nearly uniform radiation in the positive column region. V
An ultrashort laser pulse propagating in plasma can excite a nonlinear plasma wakefield which can... more An ultrashort laser pulse propagating in plasma can excite a nonlinear plasma wakefield which can trap and accelerate charged particles up to GeV. One-dimensional analysis of electron injection, trapping, and acceleration by different chirped pulses propagating in plasma is investigated numerically. In this paper, we inject electron bunches in front of the chirped pulses. It is indicated that periodical chirped laser pulse can trap electrons earlier than other pulses. It is shown that periodical chirped laser pulses lead to decrease the minimum momentum necessary to trap the electrons. This is due to the fact that periodical chirped laser pulses are globally much efficient than nonchirped pulses in the wakefield generation. It is found that chirped laser pulses could lead to much larger electron energy than that of nonchirped pulses. Relative energy spread has a lower value in the case of periodical chirped laser pulses.
In present paper, the chirp effect of an electromagnetic pulse via an analytical model of wakefie... more In present paper, the chirp effect of an electromagnetic pulse via an analytical model of wakefield generation is studied. Different types of chirps are employed in this study. Our results show that by the use of nonlinear chirped pulse the longitudinal wakefield and focusing force is stronger than that of linear chirped pulse. It is indicated that quadratic nonlinear chirped pulses are globally much efficient than periodic nonlinear chirped pulses. Our calculations also predict that in nonlinear chirped pulse case, the overlap of focusing and accelerating regions is broader than that achieved in linear chirped pulse.
Theoretical analysis of stimulated Brillouin scattering (SBS) in high power ytterbium-doped doubl... more Theoretical analysis of stimulated Brillouin scattering (SBS) in high power ytterbium-doped double-clad (YDDC) fiber lasers is presented by solving the steady-state rate equations with regard to SBS at different pumping configurations. Distribution of pump, signal and Stokes waves powers in forward, backward and bi-directional pumping configurations through the fiber are investigated. Also, distribution of population inversion through the fiber is shown. Studies shows that amount of backward Brillouin Stokes power in forward pumping configuration is higher than other configurations.
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Papers by Esmaeil Eslami