Thickness Of Plasma Layer Research Articles

Suspension model for blood flow through a catheterized arterial stenosis with peripheral layer of plasma free from cells

The present article describes the blood flow in a catheterized artery with radially symmetric and axially asymmetric stenosis. To understand the effects of red cell concentration, plasma layer thickness and catheter size simultaneously, blood is considered by a two-layered model comprising a core region of suspension of all the erythrocytes (particles) supposed to be a particle-fluid mixture and a peripheral zone of cell-free plasma. The analytical expressions for flow features, such as fluid phase and particle phase velocities, flow rate, wall shear stress and resistive force are obtained. It is witnessed that the presence of the catheter causes a substantial increase in the frictional forces on the walls of arterial stenosis and catheter, shear stress and flow resistance, in addition to that, have occurred due to the presence of red cells concentration (volume fraction density of the particles) and the absence of peripheral plasma layer near the wall of the stenosed artery. The introduction of an axially asymmetric nature of stenosis and plasma layer thickness causes significant reduction in flow resistance. One can notice that the two-phase fluid (suspension model) is more profound to the thickness of peripheral plasma layer and catheter than the single-phase fluid.

Radially polarized terahertz radiation in laser-induced linear plasma wake

The radially polarized terahertz radiation from laser-induced oscillating current is investigated by employing a two-dimensions plasma wakefield analytical model. It is shown that in linear plasma wake the currents have a periodical change along laser axis, and the current directions in potential well and potential barrier are opposite. The radial currents vanish at laser axis, which is different from longitudinal current, thus leading to a angle deviation of peak radiated power of radially polarized THz wave from laser axis. The deviation is more significant in thick plasma layer. The dependance of peak radiated power and total power of THz emission on thickness of plasma layer and laser intensity is discussed.

Fields in the focal region of an elliptical reflector coated with an unmagnetized plasma layer

Theoretical formulation of the electromagnetic field distribution in the focal region of an elliptical reflector that has its surface coated with an unmagnetized collisional plasma is derived in this paper. The incident wave is considered to be with a general oblique incidence. Expressions for the electromagnetic field intensity along the focal region have been obtained accurately using Maslov’s method. Maslov’s method is systematic procedure, which combines the simplicity of ray optics and the generality of transform methods. The derived analytical field expressions in the focal region have been solved numerically. The effects of the plasma layer thickness on the reflected and transmitted field intensity distributions were inspected. Other physical parameters such as the plasma electron density, the angle of incidence and the effective collisional frequency have been observed to have an evident influence on the levels of the transmitted field intensities along the focal region. The problem discussed in this paper has been, also, solved using Kirchhoff’s approximation and the results of the two methods are in a good agreement.

Optical Properties of Plasma Photonic Crystals

In the present communication, the optical properties of a one-dimensional plasma photonic crystal (PPC) containing alternate dielectric and plasma layers has been studied. The photonic band structure, reflection spectra and group velocity of such photonic crystals have been presented. It is found that the photonic bandgap can be increased with the thickness of plasma layers and group velocity reaches negative values at a certain frequency.

Exactly solvable model of resonance tunneling of an electromagnetic wave in plasma containing short-scale inhomogeneities

Different variants of resonance tunneling of a transverse electromagnetic wave through a plasma layer containing short-scale (subwavelength) inhomogeneities, including evanescence regions to which approximate methods are inapplicable, are analyzed in the framework of an exactly solvable one-dimensional model. Complex plasma density profiles described by a number of free parameters determining the permittivity modulation depth, the characteristic scale lengths of plasma structures, their number, and the thickness of the inhomogeneous plasma layer are considered. It is demonstrated that reflection-free propagation of the wave incident on the layer from vacuum (the effect of wave-barrier transillumination) can be achieved for various sets of such structures, including plasma density profiles containing a stochastic component. Taking into account cubic nonlinearity, it is also possible to obtain an exact solution to the one-dimensional problem on the nonlinear transillumination of nonuniform plasma. In this case, the thicknesses of the evanescence regions decrease appreciably. The problem of resonance tunneling of electromagnetic waves through such barriers is of interest for a number of practical applications.

Electromagnetic field intensity distribution along focal region of a metallic circular reflector covered with a plasma layer

Theoretical analyses has been carried out to study the deviation of the electromagnetic field intensity distribution in the focal region of a long metallic circular reflector that contains a uniform cold collisional plasma layer on its surface. The electromagnetic field intensity expressions along the focal region have been obtained using Maslov’s method. Maslov’s method is systematic procedure, which combines the simplicity of ray optics and the generality of transform methods. The derived analytical field expressions in the focal region have been solved numerically. The reflected and transmitted field intensity distributions from the plasma layer along the focal point were examined. The effects of some physical parameters such as the plasma frequency, the thickness of plasma layer and the effective collision frequency on the transmitted field intensity distribution along the focal region are studied. The results are found to be in a good agreement with results obtained using Kirchhoff’s approximation.

Caustic region fields of an elliptical reflector covered by an anisotropic magnetized plasma layer

Theoretical formulations of the electromagnetic (EM) field distribution in the focal or caustic region of an elliptical reflector with its curved surface coated by collisional magnetized anisotropic plasma have been derived. Both parallel and perpendicular polarizations of the normal incident wave are considered. Expressions for the EM field intensity along the focal region have been obtained accurately using Maslov’s method. The effect of the plasma-layer thickness on the reflected and transmitted field intensity distributions was investigated. Other physical parameters such as the plasma electron density, the cyclotron frequencies, and the collisional frequency have been noticed to have an evident influence on the levels of the transmitted field-intensities along the focal region. The problem discussed in this paper has, also, been solved using Kirchhoff’s approximation and the results of the two methods are found to be in a good agreement.

Influence of magnetic field and heat transfer on two-phase fluid model for oscillatory blood flow in an arterial stenosis

The unsteady two-fluid blood flow model in an artery with mild stenosis is considered by taking into account of effects of both heat transfer and magnetic field. Such a combination has not been reported in the literature of blood flow. The effects of plasma layer thickness, magnetic field, radiation parameter, thermal conductivity and viscosity ratio on flow variables are discussed and depicted graphically. The phase lag between pressure gradient and flow variables has been predicted and the effects of magnetic and radiation parameters, thermal conductivity, plasma layer thickness and Grashof number on the phase lag are brought out which form new information that are, for the first time, added to the literature. It has been pointed out here that the temperature and shear stress (or wall shear stress) decrease with increasing of plasma layer thickness. The flow resistance decreases with the increase in Grashof number and plasma layer thickness. Hence, the existence of the peripheral plasma layer and the pivotal role of Grashof number could be useful for the functions of the diseased arterial system and hence it is concluded that the present study is believed to yield some good improvement over two-fluid models discussed in the literature.

Electromagnetic modeling of the energy distribution of a metallic cylindrical parabolic reflector covered with a magnetized plasma layer

The energy distribution along the focal axis of a long metallic cylindrical parabolic reflector with a plasma layer on its surface in the presence of an external magnetic field is investigated. The effects of some physical parameters, such as the plasma frequency, the wave frequency and the thickness of plasma layer on the energy distribution and the reflected and transmitted electromagnetic fields, are simulated. These investigations for both S- and P-polarizations have been done separately. It is found that the maximum value of the reflected intensity increases by increasing the incident wave frequency and by decreasing the plasma layer thickness and the plasma frequency for both polarizations. Furthermore, the results show that the increase of the magnetic field strength can cause an increase in the reflected intensity for S-polarization and a slight decrease for P-polarization.

Energy Distribution Along the Focal Axis of a Metallic Cylindrical Parabolic Reflector Covered With a Plasma Layer

The deviation of the energy distribution along the focal axis of a long metallic cylindrical parabolic reflector, which on its surface contains a uniform cold collisionless plasma, is investigated. In addition, the effects of some physical parameters such as the plasma and wave frequencies and the thickness of plasma layer on this energy distribution and the reflected and the transmitted electromagnetic fields are studied. It is shown that the maximum value of the reflected intensity increases by increasing the incident wave frequency and by decreasing the plasma layer thickness and the plasma frequency.

Enlargement of the omnidirectional photonic band gap by one-dimensional plasma-dielectric photonic crystals with fractal structure

In this paper, an omnidirectional photonic band gap (OBG) which originates from Bragg gap compared to \(\text{ zero- }\overline{n}\) gap or single negative (negative permittivity or negative permeability) gap, realized by one-dimensional plasma-dielectric photonic crystals with fractal structure (Thue–Mores aperiodic structure), which is composed of plasma and one kind of homogeneous, isotropic dielectric is theoretically studied by the transfer matrix method in detail. Such OBG is insensitive to the incident angle and the polarization of electromagnetic wave. From the numerical results, the bandwidth and central frequency of OBG can be notably enlarged by tuning the thickness of plasma and dielectric layers but cease to change with increasing the Thue–Mores order. The OBG also can be manipulated by the plasma density. Moreover, the plasma collision frequency has no effect on the bandwidth of OBG.

Blood flow in stenosed arteries with radially variable viscosity, peripheral plasma layer thickness and magnetic field

A novel approach of combined mathematical and computational models has been developed to investigate the oscillatory two-layered flow of blood through arterial stenosis in the presence of a transverse uniform magnetic field applied. Blood in the core region and plasma fluid in the peripheral layer region are assumed to obey the law of Newtonian fluid. An analytical solution is obtained for velocity profile and volumetric flow rate in the peripheral plasma region and also wall shear stress. Finite difference method is employed to solve the momentum equation for the core region. The numerical solutions for velocity, flow rate and flow resistance are computed. The effects of various parameters associated with the present flow problem such as radially variable viscosity, hematocrit, plasma layer thickness, magnetic field and pulsatile Reynolds number on the physiologically important flow characteristics namely velocity distribution, flow rate, wall shear stress and resistance to flow have been investigated. It is observed that the velocity increases with the increase of plasma layer thickness. An increase or a decrease in the velocity and wall shear stress against the increase in the value of magnetic parameter (Hartmann number) and hematocrit is dependent on the value of t. An increase in magnetic field leads to an increase in the flow resistance and it decreases with the increase in the plasma layer thickness and pulsatile Reynolds number. The information concerning the phase lag between the flow characteristics and how it is affected by the hematocrit, plasma layer thickness and Hartmann number has, for the first time, been added to the literature.

Measurements and kinetic modeling of energy coupling in volume and surface nanosecond pulse discharges

Nanosecond pulse discharge plasma imaging, coupled pulse energy measurements, and kinetic modeling are used to analyze the mechanism of energy coupling in high repetition rate, spatially uniform, nanosecond pulse discharges in air in plane-to-plane geometry. Under these conditions, coupled pulse energy scales nearly linearly with pressure (number density), with energy coupled per molecule being nearly constant, in good agreement with the kinetic model predictions. In spite of high-peak reduced electric field reached before breakdown, E/N ∼ 500–700 Td, the reduced electric field in the plasma after breakdown is much lower, E/N ∼ 50–100 Td, predicting that a significant fraction of energy coupled to the air plasma, up to 30–40%, is loaded into nitrogen vibrational mode.A self-similar, local ionization kinetic model predicting energy coupling to the plasma in a surface ionization wave discharge produced by a nanosecond voltage pulse has been developed. The model predicts key discharge parameters such as ionization wave speed and propagation distance, electric field, electron density, plasma layer thickness, and pulse energy coupled to the plasma, demonstrating good qualitative agreement with experimental data and two-dimensional kinetic modeling calculations. The model allows an analytic solution and lends itself to incorporation into existing compressible flow codes, at very little computational cost, for in-depth analysis of the nanosecond discharge plasma flow control mechanism. The use of the model would place the main emphasis on coupling of localized thermal perturbations produced by the discharge with the flow via compression waves and would provide quantitative insight into the flow control mechanism on a long time scale.

Enlarged omnidirectional band gap in one-dimensional plasma photonic crystals with ternary Thue–Morse aperiodic structure

In this paper, an omnidirectional photonic band gap (OBG) which originates from Bragg gap compared to zero-n˜ gap or single negative (negative permittivity or negative permeability) gap, realized by one-dimensional (1D) plasma photonic crystals (PPCs) with ternary Thue–Morse aperiodic structure, which is composed of plasma and two kinds of homogeneous, isotropic dielectric is theoretically studied by the transfer matrix method (TMM) in detail. Such OBG is insensitive to the incident angle and the polarization of electromagnetic wave (EM wave). From the numerical results, the bandwidth and central frequency of OBG can be notably broadened by changing the thickness of plasma and dielectric layers but cease to change with increasing Thue–Morse order. The OBG also can be manipulated by plasma density. However, the plasma collision frequency has no effect on the bandwidth of OBG. These results may provide theoretical instructions to design the future optoelectronic devices based on plasma photonic crystals.

Optimization of THz semi-insulating surface plasmon waveguide structures of GaSb/AlSb quantum cascade lasers

We designed and analyzed the semi-insulating surface plasmon waveguide structures of GaSbbased quantum cascade lasers (QCLs) operating in the terahertz (THz) region of 2.6–6.5 THz using the finite element method. For improving the guiding property of THz QCL waveguide structures, a low threshold gain (gth) and a high optical confinement (Γ) could be achieved by optimizing the doping concentration and the thickness of plasma layer, the waveguide width, the substrate thickness, and the number of stages in active core region at various operating frequencies (2.6–6.5 THz). The effect of different substrates on the gth and Γ of THz QCL waveguide structures was also investigated.

Properties of omnidirectional photonic band gap in one-dimensional staggered plasma photonic crystals

In this paper, the properties of the omnidirectional photonic band gap (OBG) realized by one-dimensional (1D) photonic crystals (PCs) with a staggered structure which is composed of plasma and isotropic dielectric layer have been theoretically studied by the transfer matrix method (TMM). From the numerical results, it has been shown that such OBG is insensitive to the incident angle and the polarization of electromagnetic wave (EM wave), and the frequency range and central frequency of OBG can be effectively controlled by adjusting the plasma frequency, the average thickness of plasma layer, the average thickness of dielectric layer and staggered parameters, respectively. The frequency range of OBG can be notably enlarged with increasing the plasma frequency, average thickness of plasma layer, respectively. Moreover, the bandwidth of OBG can be narrowed with increasing the average thickness of dielectric layer. Changing staggered parameters of dielectric and plasma layer means that the OBG can be tuned. It is shown that 1D plasma dielectric photonic crystals (PPCs) with such staggered structure have a superior feature in the enhancement of frequency range of OBG compared with the conventional 1D binary PPCs. This kind of OBG has potential applications in filters, microcavities, and fibers, etc.

Enlarged omnidirectional photonic band gap in heterostructure of plasma and dielectric photonic crystals

In this paper, we have shown theoretically that total omnidirectional photonic band gap (OBG) is enlarged considerably by using one-dimensional photonic crystal heterostructure composed of dielectric–dielectric and dielectric-plasma periodic structures. The OBG originates from a Bragg gap. The reflectance of considered structures are calculated by transfer matrix method (TMM). From the analysis it is found that the heterostructure of dielectric photonic crystals (DPCs) and plasma photonic crystals (PPCs) has very wide range of total OBG for both polarizations in comparison to the DPCs or PPCs, and the OBG can be notably enlarged by increasing the thickness and density of plasma layer.

Enhancement of omnidirectional photonic band gaps in one-dimensional dielectric plasma photonic crystals with a matching layer

In this paper, we demonstrate by theoretical analysis a novel way to enhance the omnidirectional photonic band gap (OBG) in a type of photonic structure made of dielectric and plasma one-dimensional (1D) photonic crystals (1D PCs) by introducing a matching layer. Simulations by the transfer matrix method (TMM) show that such an OBG is insensitive to the incident angle and the polarization of electromagnetic (EM) wave; the frequency range and central frequency of OBG are significantly enlarged by introducing a matching layer in the heterostructure compared to 1D conventional binary dielectric photonic crystals (DPCs). The photonic band gap (PBG) of both polarizations also can be obviously enlarged as the incident angle is relatively small. The OBG originates from a Bragg gap in contrast to zero-ñ gap or single negative (negative permittivity or negative permeability) gap. From the numerical results, it has been shown that introducing a matching layer in such a heterostructure has a superior feature in the enhancement relative bandwidth of OBG compared with the conventional ternary plasma photonic crystals (PPCs); the frequency range of OBG can be notably enlarged by increasing the thickness and density of plasma layer.

A Novel Comb-Like Plasma Photonic Crystal Filter in the Presence of Evanescent Wave

The transmission properties of one-dimensional photonic crystals (PCs) consisting of plasma and lossless dielectric have been systematically studied through the transfer matrix method. In this structure, plasma is used as a kind of single-negative (permittivity-negative) material. Because of the coupling between evanescent waves in plasma layers and propagation waves in dielectric layers, comb-like resonant peaks in transmission band are formed without adding any defect layer in plasma PCs. The numbers and positions of peaks can be modulated by the number of the periods, the plasma frequency, the thickness of plasma layers, plasma collision frequency, and the incident angle.

Application of the Predictive and Inferential Control to Pulp Washing Process

In pulp washing process, as the series characteristic of Dilution Factor (DF), plasma layer thickness and washing water flow, a new predictive inference control algorithm is applied to pulp washing process. Simulation in pulp washing process shows that the algorithm not only improved the response speed of unpredictable variable but also can be an monitored value for the production process.