Cross focusing of mixed mode operation in an extra dense plasma

1979 ◽  
Vol 57 (8) ◽  
pp. 1118-1123
Author(s):  
V. S. Soni ◽  
V. P. Nayyar
Keyword(s):  
Laser Beam ◽  
Critical Power ◽  
Dense Plasma ◽  
High Irradiance ◽  
Nonlinear Propagation ◽  
Power Laser ◽  
Self Focusing ◽  
Electron Density Gradient ◽  
Overdense Plasma ◽  
Degenerate Modes

This paper presents a study of the nonlinear propagation of a mixture of two degenerate modes (TEM00 and TEM10) of a high power laser beam in an extradense plasma. The high irradiance inhomogeneous laser beam creates an electron density gradient region in the overdense plasma (n > nc) through which the beam can propagate. The focusing effects have been studied for different power ratios of the two modes (TEM00 mode is considered to be stronger than theTEM10 mode). Self-focusing of the beam in x and y directions for critical power has been extensively studied.

scholarly journals Role of Density Profiles for the Nonlinear Propagation of Intense Laser Beam through Plasma Channel

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Sonu Sen ◽  
Meenu Asthana Varshney ◽  
Dinesh Varshney
Keyword(s):  
Laser Beam ◽  
Dielectric Function ◽  
Laser Plasma ◽  
Plasma Channel ◽  
Intense Laser ◽  
Nonlinear Propagation ◽  
Density Profiles ◽  
Laser Plasma Interaction ◽  
Self Focusing

In this work role of density profiles for the nonlinear propagation of intense laser beam through plasma channel is analyzed. By employing the expression for the dielectric function of different density profile plasma, a differential equation for beamwidth parameter is derived under WKB and paraxial approximation. The laser induces modifications of the dielectric function through nonlinearities. It is found that density profiles play vital role in laser-plasma interaction studies. To have numerical appreciation of the results the propagation equation for plasma is solved using the fourth order Runge-Kutta method for the initial plane wave front of the beam, using boundary conditions. The spot size of the laser beam decreases as the beam penetrates into the plasma and significantly adds self-focusing in plasma. This causes the laser beam to become more focused by reduction of diffraction effect, which is an important phenomenon in inertial confinement fusion and also for the understanding of self-focusing of laser pulses. Numerical computations are presented and discussed in the form of graphs for typical parameters of laser-plasma interaction.

Relativistic cross-focusing of extraordinary and ordinary modes in a magnetoactive plasma

2013 ◽  
Vol 79 (5) ◽  
pp. 953-961 ◽  
Author(s):  
MEENU ASTHANA VARSHNEY ◽  
SHALINI SHUKLA ◽  
SONU SEN ◽  
DINESH VARSHNEY
Keyword(s):  
Magnetic Field ◽  
Laser Beam ◽  
Magnetoactive Plasma ◽  
Plasma Parameters ◽  
Self Focusing ◽  
Second Mode ◽  
Polarized Beam ◽  
Set Up ◽  
Overdense Plasma ◽  
The Magnetic Field

AbstractThis paper presents the effect of self-focusing on a circularly polarized beam propagating along the static magnetic field when the extraordinary and ordinary modes are present simultaneously for relativistic intensities. The nonlinearity in the dielectric function arises on account of the relativistic variation of mass, which leads to the mutual coupling of the two modes that support the self-focusing of each other. The propagation and focusing of the first mode affects the propagation and focusing of the second mode. The fact that the two modes are laser-intensity dependent leads to cross-focusing. Dynamics of one laser beam affects the dynamics of the second laser beam. When both the beams or modes are strong, the nonlinearities introduced by the relativistic effect in the presence of the magnetic field are additive in nature, such that one beam can undergo oscillatory self-focusing and other beam simultaneously defocusing and vice versa. The dynamical equation governing the cross-focusing has been set up and a numerical solution has been presented for typical relativistic laser–plasma parameters from a slightly underdense to overdense plasma.

scholarly journals Excitation of an upper hybrid wave by a high power laser beam in plasma

2008 ◽  
Vol 26 (1) ◽  
pp. 61-68 ◽  
Author(s):  
G. Purohit ◽  
P.K. Chauhan ◽  
R.P. Sharma
Keyword(s):  
Magnetic Field ◽  
Laser Beam ◽  
Static Magnetic Field ◽  
Electron Concentration ◽  
Pump Laser ◽  
Electron Mass ◽  
Nonlinear Coupling ◽  
Hybrid Wave ◽  
Power Laser ◽  
Self Focusing

AbstractIn the present investigation, the excitation of an upper hybrid wave (UHW) in a hot collisionless magneto-plasma by a relativistic laser beam propagating perpendicular to the static magnetic field and having its electric vector polarized along the direction of the static magnetic field (ordinary mode) is presented. Due to nonuniform intensity distribution of pump laser, the background electron concentration is modified. The amplitude of the UHW, which depends on the background electron concentration, is thus nonlinearly coupled with the laser beam. The effect of nonlinear coupling between the pump laser and UHW is studied. The effect of the relativistic electron mass nonlinearity and the relativistic self-focusing of the pump laser on the excitation of the UHW have been incorporated. The dynamics of the excitation of the UHW in different power domains of the laser beam is accordingly modified. It has been seen that the effect of changing the strength of the static magnetic field on the nonlinear coupling and the dynamics of the excitation of the UHW is significant. The focusing behavior of the UHW may find its relevance in the heating of plasmas near the upper hybrid resonance.

Focusing of an Intense Relativistic Electron Beam by a Hollow Conical Laser Beam

1975 ◽  
Vol 30 (8) ◽  
pp. 976-980
Author(s):  
F. Winterberg
Keyword(s):  
Laser Beam ◽  
Relativistic Electron ◽  
Radiation Pressure ◽  
Relativistic Electron Beam ◽  
Laser Light ◽  
Electron Beams ◽  
The Self ◽  
Intense Laser ◽  
Power Laser ◽  
Self Focusing

Abstract Estimates suggest that the nonlinear transverse radiation pressure produced within a plasma by a convergent annular high power laser beam may lead to the focusing of an intense relativistic electron down to a radius of ~10-4 cm. The transverse radiation pressure results from the dielectric property of a plasma in conjunction with the phenomena of the self-focusing of intense laser light. The tightly focused electron beams would make possible the release of thermonuclear energy by micro-explosions.

scholarly journals Relativistic interaction of rippled laser beams with plasmas

2000 ◽  
Vol 18 (3) ◽  
pp. 399-403 ◽  
Author(s):  
M.V. ASTHANA ◽  
A. GIULIETTI ◽  
D. GIULIETTI ◽  
L.A. GIZZI ◽  
M.S. SODHA
Keyword(s):  
Laser Beam ◽  
Critical Power ◽  
Radial Dependence ◽  
Main Beam ◽  
Gaussian Laser Beam ◽  
Self Focusing ◽  
Relativistic Interaction ◽  
Saturation Effects ◽  
Paraxial Ray ◽  
Initial Power

An investigation of the growth of a radially symmetrical ripple, superimposed on a Gaussian laser beam in a plasma is presented. Based on WKB and paraxial ray approximation the phenomenon of relativistic self-focusing (RSF) is analytically investigated. The differential equation for beamwidth parameter of rippled laser beam is evaluated. The ripple gets focused when the initial power of the ripple is greater than the critical power for focusing. The focusing is found to be considerably affected by the power of the main beam and the phase angle between the electric vectors of the main beam and the ripple. At higher intensities the saturation effects of nonlinearity become predominant, making the nonlinear refractive index in the paraxial region have slower radial dependence, and thus the ripple extract relatively less energy from its neighborhood. The case of magnetized plasmas is also preliminarily discussed.

Self-focusing of cosh-Gaussian laser beam in collisional plasma: effect of nonlinear absorption

2021 ◽  
Author(s):  
Naveen Gupta ◽  
Sandeep Kumar ◽  
A Gnaneshwaran ◽  
Sanjeev Kumar ◽  
Suman Choudhry
Keyword(s):  
Laser Beam ◽  
Nonlinear Absorption ◽  
Collisional Plasma ◽  
Gaussian Laser Beam ◽  
Self Focusing ◽  
Plasma Effect
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