Effect Of Ponderomotive Force Research Articles

Observation of Alfvén Wave Reflection in the Solar Chromosphere: Ponderomotive Force and First Ionization Potential Effect

Observation of Alfvén Wave Reflection in the Solar Chromosphere: Ponderomotive Force and First Ionization Potential Effect

FEATURES OF THE FILM FLOW OF A LIQUID OVER A VERTICAL SURFACE IN A TRANSVERSE MAGNETIC FIELD

One of the actual problems of magnetohydrodynamics is the problem of the flow of electrically conductive liquids in thin liquid layers in the presence of a transverse magnetic field. Unfortunately, studies of these problems have not been sufficient so far. The influence of a transverse magnetic field can affect a number of factors: the change in the viscosity of the flow due to the magnetic field on the physico-chemical characteristics of the medium; manifestation of the effect of flow deceleration, which can have a significant effect on the hydrodynamic characteristics of the film flow in the processes of heat and mass transfer. In this regard, in this work was made an attempt to consider the influence of a constant magnetic field on the formation of a thin liquid layer on a vertical surface under the action of ponderomotive forces. As known, ponderomotive forces in the case under consideration can lead to a number of effects associated with a change in viscosity and flow deceleration. To a greater extent, this can manifest itself in thin liquid layers, depending on the ratio of gravitational forces, inertia forces and forces of a magnetic nature. An analysis of the influence of this phenomenon in the considered case of thin liquid layers, as shown in the work, significantly affects the length of the hydrodynamic initial section, the thickness of the liquid layer, and the damping of wave motion in the zone of stabilized flow. Recommendations for calculating these characteristics are presented in this article, in which much attention is paid to the definition of the liquid layer, depending on the ratio between the forces of inertia and the forces of a magnetic nature. An expression was also obtained for determining the distribution of velocities in the zone of a stabilized film flow in a transverse magnetic field. Thus, by comparing the expression for determining the distribution of velocities in a film without the influence of a magnetic field with the expression in the presence of a magnetic field, one can estimate the effect of ponderomotive forces on the flow of a liquid film.

Influence of plasma inhomogeneity and ohmic heating on the nonlinear absorption of intense laser pulse in collisional magnetized plasma

AbstractThe nonlinear absorption in the interaction of an intense laser pulse with a collisional magnetized plasma is studied by considering the effects of plasma inhomogeneity, ohmic heating, and ponderomotive force. For this purpose, we obtain the plasma electron density, the effective dielectric permittivity, and the wave equation using the Maxwell and hydrodynamic equations and solve this equation by the Runge–Kutta numerical method. The results are shown that by increasing the plasma inhomogeneity, the inverse bremsstrahlung absorption coefficient is increased, and also the density ramp parameter and its sign can affect more the absorption coefficient than the temperature ramp parameter . However, when the initial electron density and temperature increase, the laser field amplitude and the absorption coefficient are increased and the spatial damping rate of the laser pulse becomes highly peaked inside the plasma. It is shown by increasing laser pulse energy, the nonlinear bremsstrahlung absorption coefficient is decreased significantly. The results also indicate that by increasing the external magnetic field, the dielectric permittivity is decreased while the laser energy spatial damping, and the absorption coefficient are increased. Moreover, it is found that by considering the ohmic heating effect, the electrons absorb further energy from the fields and consequently the nonlinear absorption is increased.

Effect of relativistic ponderomotive force on shock waves in a relativistic degenerate plasma

Abstract We investigate the effect of relativistic ponderomotive force on the propagation of shock waves in relativistic degenerate plasma, which is relevant to high-intensity laser-plasma experiments aimed at replicating extreme conditions on white dwarfs. We derive the KdV-Burger’s equation by incorporating the density modification induced by the ponderomotive force and hence demonstrate that this equation is a suitable model for shock waves affected by ponderomotive force. Unlike previous studies that use ponderomotive force as a source of nonlinearity to derive the nonlinear Schrödinger equation for envelope solitons, our study focuses on the effect of ponderomotive force on shocks produced by the intense laser. We show that the ponderomotive force can significantly modify the strength and shape of shock waves, providing insight into the underlying physics of shock waves in relativistic degenerate plasmas which may help to better understand experimental observations in this regime.

Collision off-axis position dependence of relativistic nonlinear Thomson inverse scattering of an excited electron in a tightly focused circular polarized laser pulse

This paper presents a novel view of the impact of electron collision off-axis positions on the dynamic properties and relativistic nonlinear Thomson inverse scattering of excited electrons within tightly focused, circularly polarized laser pulses of varying intensities. We examine the effects of the transverse ponderomotive force, specifically how the deviation angle and speed of electron motion are affected by the initial off-axis position of the electron and the peak amplitude of the laser pulse. When the laser pulse intensity is low, an increase in the electron’s initial off-axis distance results in reduced spatial radiation power, improved collimation, super-continuum phenomena generation, red-shifting of the spectrum’s harmonic peak, and significant symmetry in the radiation radial direction. However, in contradiction to conventional understandings, when the laser pulse intensity is relatively high, the properties of the relativistic nonlinear Thomson inverse scattering of the electron deviate from the central axis, changing direction in opposition to the aforementioned effects. After reaching a peak, these properties then shift again, aligning with the previous direction. The complex interplay of these effects suggests a greater nuance and intricacy in the relationship between laser pulse intensity, electron position, and scattering properties than previously thought.

On radiation dynamics in plasma relativistic microwave amplifier at the edge of electron beam pulse

We consider dynamics of radiation of a plasma microwave amplifier on a surface wave at the leading edge of the relativistic electron beam pulse. It has been shown that depending on the electron density of the plasma, different modes of operation of the amplifier are possible. At low plasma density, there is an early activation of the amplifier with large gain at the leading edge of the electron beam pulse and a significant decrease in the amplification of the signal when the electron energy reaches a plateau. With a higher plasma density, a later activation takes place with an almost constant output amplitude. The effect of ponderomotive force on plasmas was discussed.

Laguerre–Gaussian laser beam guiding and its second harmonics in plasma having density ramp

This paper presents the optical guiding of a laser beam in plasma by using a preformed plasma channel. The density ramp in plasma density due to the plasma pressure has also been considered. The effect of ponderomotive force has been taken into account which originates due to the intensity gradient present in the laser beam. This force produces a plasma gradient by expelling plasma electrons from a high-field to a low-field region, providing heavy ions remain immobile. Plasma oscillations result from a gradient in plasma density that excites an electron plasma wave. The equation governing the plasma wave excitation has been found by using linear perturbation theory. An in-phase mixing of an incident laser beam with this plasma wave generates its second harmonics. Laguerre–Gaussian laser profile has been used for harmonic production. Moment theory has been used to obtain a differential equation for beam waist, which has been solved numerically by Runge–Kutta's fourth-order method. The effect of different modes of Laguerre–Gaussian profile, beam intensity, plasma density, channel depth, and slope of density ramp has been explored.

Stimulated Raman scattering of self-focused elliptical q-Gaussian laser beam in plasma with axial density ramp: effect of ponderomotive force

Stimulated Raman scattering of self-focused elliptical q-Gaussian laser beam in plasma with axial density ramp: effect of ponderomotive force

Stimulated Raman scattering of self focused elliptical q-Gaussian laser beam in plasma with axial temperture ramp: effect of ponderomotive force

The phenomenon of stimulated Raman scattering (SRS) of elliptical q-Gaussian laser beams interacting nonlinearly with underdense plasmas has been investigated theoretically. Using variational theory semi analytical solutions of the coupled nonlinear wave equations for the three waves (pump, EPW and scattered) have been obtained under W.K.B approximation technique. The equations so obtained have been solved numerically to envision the effects of laser as well as plasma parameters on the dynamics of pump beam and further its effect on the power of scattered wave. It has been observed that power of the scattered wave is significantly affected by the self focusing effect of pump beam.

Nonlinear interaction of elliptical q-Gaussian laser beams with plasmas with axial density ramp: effect of ponderomotive force

Theoretical investigation on optical self action effects of intense q-Gaussian laser beams interacting with collisionless plasmas with axial density ramp has been presented. Emphasis are put on investigating the dynamics of beam width and axial phase of the laser beam. Effect of the ellipticity of the cross section of the laser beam also has been incorporated. Using variational theory based on Lagrangian formulation nonlinear partial differential equation (P.D.E) governing the evolution of beam amplitude has been reduced to a set of coupled ordinary differential equations for the beam widths of the laser beam along the transverse directions. The evolution equation for the axial phase of the laser beam has been obtained by the Fourier transform of the amplitude structure of the laser beam from coordinate space to \((k_x, k_y)\) space. The differential equations so obtained have been solved numerically to envision the effect of laser-plasma parameters on the propagation dynamics of the laser beam.

Research progress of ultrabright <i>γ</i>-ray radiation and electron-positron pair production driven by extremely intense laser fields

The advent of high-power ultra-short ultra-intense laser pulses opens up the new frontiers of relativistic nonlinear optics, high-field physics, laser-driven inertial confined fusion, etc. In recent years, with the construction of high power laser facilities at a multi-petawatt (PW) level and above, the interaction between laser and matter enters into a new realm of high field physics, where extremely rich nonlinear physics is involved. In addition to classical nonlinear physics involving wave-particle interactions, relativistic effects, and ponderomotive force effects, the quantum electrodynamic (QED) effects occur, such as radiation reaction force, electron-positron pair production, strong γ-ray radiation, QED cascades, and vacuum polarization. This paper presents a brief overview of electron-positron pair creation and bright γ-ray emission driven by the extremely intense laser fields.

Absorption of Electromagnetic Waves in Non-Dispersive Plasma due to Effect of Ponderomotive Force

The absorption coefficient of electromagnetic wave propagating through overdense absorbing plasma is calculated by using Fresnel’s formula. Also, the force acting per unit volume of the electron fluid is calculated along z direction. The Fresnel’s formula is reduced in terms of conductivity and angular frequency so that nature of absorption coefficient with respect to conductivity of plasma and angular frequency of wave is studied, with the assumption that conductivity and angular frequency are two independent terms. By keeping conductivity of plasma constant, it is seen that the absorption coefficient is increased with increase in angular frequency and also absorption coefficient has the lowest value for the highest value of conductivity. At constant angular frequency of incidence, the absorption coefficient is decreased with increase in conductivity and also absorption coefficient has the highest value of angular frequency of incidence. Also the nature of force on the plasma is studied by considering that the conductivity of plasma is very large with compare to angular frequency of incident laser. The expression of absorption coefficient is separated into real and imaginary parts, and then plots are studied with respect to these parts. It is found that in both cases, the force on plasma is existed for short in time and distance, and then damps exponentially. Also, the variation of potential with distance is cleared that the potential is shielded within multiple distance of Debye length.

Nonlinear vortex solution for perturbations in the Earth's ionosphere

Abstract. There is much observational evidence of different fine structures in the ionosphere and magnetosphere of the Earth. Such structures are created and evolve as a perturbation of the ionosphere's parameters. Instead of dealing with a number of linear waves, we propose to investigate and follow up the perturbations in the ionosphere by dynamics of soliton structure. Apart from the fact that this is a more accurate solution, the advantage of soliton solution is its localization in space and time as a consequence of the balance between nonlinearity and dispersion. The existence of such a structure is driven by the properties of the medium. We derive the necessary condition for having a nonlinear soliton wave, taking the vortex shape as a description of the ionosphere parameter perturbation. We employ a magnetohydrodynamical description for the ionosphere in plane geometry, including rotational effects, magnetic field effects via ponderomotive force, and pressure and gravitational potential effects, treating the problem self-consistently and nonlinearly. In addition, we consider compressible perturbation. As a result, we have found that Coriolis force and magnetic force on the one hand and pressure and gravity on the other hand determine dispersive properties. Dispersion at higher latitudes is mainly driven by rotation, while near the Equator, within the E and F layers of the ionosphere, the magnetic field modifies the soliton solution. Also, a very general description of the ionosphere results in the conclusion that the unperturbed thickness of the ionosphere layer cannot be taken as an ad hoc assumption: it is rather a consequence of equilibrium property, which is shown in this calculation.

Theoretical Study of Absorption of Light Due to Effect of Ponderomotive Force

Absorption of light due to effect of ponder motive force in laser plasma interaction which has seen that the nonlinear interaction results from rigorous application of the ponder motive force description based on Lorentz’s theory. The deduced equation of motion is more general than that of the two–fluid model of the plasma and that used in the theory of microwave interaction with plasma. As might be expected, the forces are only in the direction of lower plasma densities and tangential forces vanish only with the general equation of two–fluid model. This result has been verified up to the third order in the spatial variation of the electron density. In addition it is seen that the collision frequency decreases continuously with the increase in temperature. From these results, it is concluded that the absorption coefficient decreases continuously with the increase in temperature. Furthermore, this work describes the variation of the absorption coefficient with laser light frequency and shows that the absorption coefficient depends on the frequency of light.

Nonlinear effect of microwave longitudinal ponderomotive force on the dynamics and energy of an externally injected electron in an inhomogeneous plasma-filled circular and elliptical cylinder waveguides

ABSTRACT Dynamics and energy of an externally injected single electron in inhomogeneous plasma-filled circular and elliptical cylinder waveguides in the electromagnetic fields of wave mode, particularly paying attention to the effect of the longitudinal ponderomotive force is studied. It is shown that by considering this effect in the background plasma the electron energy gain during its movement in the waveguide is changed. Here it is considered two cases for two different background electron densities in the absence of the microwave field including the constant density and linear density profile. We employe the fourth-order Runge–Kutta method for simulating the injected electron momentum and energy equations and the nonlinear wave equation obtained from Maxwell's equations for the mode in the considered configurations. Effect of the longitudinal ponderomotive force acting on the plasma electrons in the balance with the pressure gradient force on the kinetic and total energy of the externally injected electron during its motion in the waveguide is graphically presented.

Hydrodynamic Modeling of Spin-Polarized Edge Magnetoplasmons

A novel method, the so-called magneto-optical interaction, is gaining increasing interest for realizing the localization of the electromagnetic radiation to subwavelength scales and enhancement of the local electric fields. We investigate spin-polarized edge magnetoplasmons based on the spin-dependent quantum hydrodynamic model, in a bounded two-dimensional electron gas with perpendicular magnetic field and an electromagnetic wave. The effects of the Fermi pressure associated with Pauli exclusion principle and quantum force due to the Bohm potential, and the effect of the spin-induced ponderomotive force, are taken into consideration. Full spin-polarized edge state exists at the boundary of the two-dimensional electron gas. Spin rotation occurs due to the magneto-optical kerr effect. The existence of the electromagnetic field could reduce the spin amplitude and increase the spin rotation time, since their magnitude oscillates between positive and negative values and hinders the spin precession.

Ponderomotive force induced nonlinear interaction between powerful terahertz waves and plasmas

We have investigated the ponderomotive force induced nonlinear interaction between terahertz (THz) wave and plasmas. The effects of ponderomotive force on the THz beam-width and spatial electric intensity distribution are investigated in different incident THz wave frequencies. It is observed that ponderomotive force can make THz beam focusing, and the higher the THz wave frequency, the more stable the focusing effect will be. The characteristics of THz beam will also be affected by plasma density. This unique nonlinear interaction may be exploited in novel THz driven optical modulators and switches.

Investigation of optical properties of an overdense magnetized plasma lens in the interaction with high-intensity Gaussian laser pulses

Self-focusing of a high-intensity circularly polarized Gaussian laser pulse by an overdense magnetized thin plasma lens is numerically investigated. The quasi-static axial magnetic field can be produced by inverse Faraday effect (IFE) mechanism in laser–plasma interaction. It has been shown that the inclusion of self-transparency, ponderomotive force, and magnetic field effects significantly affect the self-focusing properties. When the strength of the magnetic field increases, the self-focusing property is enhanced for the right and is weakened for the left-handed circularly polarized laser pulse. The ponderomotive force repels electrons from the axis and drives electron cavitation and as a result further lowers the plasma frequency. When the influence of the ponderomotive force is taken into account, self-focusing for both polarizations is strongly affected. The clear difference between the effects of the right- and left-handed circularly polarized pulses may lead us to use them for different experimental applications.

Effect of inertial ponderomotive force and self-focusing of the fundamental pulse on generation of second harmonic in magnetic plasma

In this paper, nonlinear propagation of the intense ultra short pulses through under dense plasmas are investigated analytically. Using paraxial theory, the beam width parameter is evaluated as a function of the propagation distance. The effect of the inertial ponderomotive force, ρm(u→⋅∇→) u→, on intensity of the second harmonic pulse and self focusing of laser pulse are considered. It is shown that the second harmonic amplitude depends on the propagation distance periodically. It is shown that the inertial ponderomotive force affects efficiency of the second harmonic generation, but it does not affect beam width parameter of the second harmonic wave.

Effect of tilted electrostatic field on the Kelvin–Helmholtz instability in a liquid dielectric and gas flow

The effect of surface ponderomotive forces on the Kelvin–Helmholtz instability is studied in the linear formulation based on the equations and boundary conditions of the electrostatics and fluid dynamics of an ideal incompressible fluid. Conditions to be satisfied by the values of determining parameters of the problem for the transition of an unstable flow in zero electric field into a stable regime after the application of a horizontal electric field have been written in the form of inequalities. It has been shown that, at the stability bound, the wavelength of the most instable mode is independent of the ponderomotive forces. In case of a liquid with large permittivity a stable flow regime exists for which the stability condition only differs in small dimensionless values from the stability condition for the charged surface of a quiescent liquid conductor in contact with a gas at rest.