scholarly journals Direct Electron Acceleration By An Intense Nonparaxial Cosh-Gaussian Laser Beam Driven Electron Plasma Wave in Plasma

2021 ◽  
Author(s):  
Gunjan Purohit ◽  
Bineet Gaur ◽  
Amita Raizada ◽  
Pradeep Kothiyal
Keyword(s):  
Laser Beam ◽  
Plasma Wave ◽  
Electron Acceleration ◽  
Electron Plasma ◽  
Acceleration Process ◽  
Gaussian Laser Beam ◽  
Plasma Parameters ◽  
Electron Plasma Wave ◽  
Self Focusing ◽  
Paraxial Ray

Abstract Excitation of electron plasma wave by an intense short laser pulse is relevant to electron acceleration process in laser plasma interactions. In this work, the self-focusing of an intense cosh-Gaussian laser beam in collissionless plasma have been studied in the non-paraxial region with relativistic and ponderomotive nonlinearities. Further, the effect of self-focusing of the cosh-Gaussian laser beam on the excitation of electron plasma wave and on subsequent electron acceleration has been investigated. Analytical expressions for the beam width parameter/intensity of cosh-Gaussian laser beam and the electron plasma wave have been established and solved numerically. The energy of the accelerated electrons has also been obtained. The strong self-focusing of the cosh-Gaussian laser beam in plasmas stimulates a large amplitude electron plasma wave, which further accelerates the electrons. The well-established laser and plasma parameters have been used in numerical computation. The results have been compared with paraxial ray approximation, Gaussian profile of laser beam and only with the relativistic nonlinearity. Numerical results suggest that the focusing of the cosh-Gaussian laser beam, the amplitude of electron plasma wave, and energy gain by electrons increases in non-paraxial region, when relativistic and ponderomotive nonlinearities are simultaneously operative. In addition, it has also been observed that the electron plasma wave is driven more efficiently by a cosh-Gaussian laser beam that accelerates plasma electrons to higher energies.

scholarly journals Effect of self-focused cosh Gaussian laser beam on the excitation of electron plasma wave and particle acceleration

2016 ◽  
Vol 34 (4) ◽  
pp. 621-630 ◽  
Author(s):  
B. Gaur ◽  
P. Rawat ◽  
G. Purohit
Keyword(s):  
Particle Acceleration ◽  
Laser Beam ◽  
Plasma Wave ◽  
Electron Plasma ◽  
The Self ◽  
Acceleration Process ◽  
Gaussian Laser Beam ◽  
Electron Plasma Wave ◽  
Self Focusing ◽  
Paraxial Ray

AbstractThis work presents an investigation of the self-focusing of a high-power laser beam having cosh Gaussian intensity profile in a collissionless plasma under weak relativistic-ponderomotove (RP) and only relativistic regimes and its effect on the excitation of electron plasma wave (EPW), and particle acceleration process. Nonlinear differential equations have been set up for the beam width and intensity of cosh Gaussian laser beam (CGLB) and EPW using the Wentzel-Kramers-Brillouin and paraxial-ray approximations as well as fluid equations. The numerical results are presented for different values of decentered parameter ‘b’ and intensity parameter ‘a’ of CGLB. Strong self-focusing is observed in RP regime as compared with only relativistic nonlinearity. Numerical analysis shows that these parameters play crucial role on the self-focusing of the CGLB and the excitation of EPW. It is also found that the intensity/amplitude of EPW increases with b and a. Further, nonlinear coupling between the CGLB and EPW leads to the acceleration of electrons. The intensity of EPW and energy gain by electrons is significantly affected by including the ponderomotive nonlinearity. The energy of the accelerated electrons is increased by increasing the value of ‘b’. The results are presented for typical laser and plasma parameters.

scholarly journals Electron plasma wave excitation by beating of two q-Gaussian laser beams in collisionless plasma

2016 ◽  
Vol 34 (2) ◽  
pp. 230-241 ◽  
Author(s):  
Arvinder Singh ◽  
Naveen Gupta
Keyword(s):  
Laser Beam ◽  
Plasma Wave ◽  
Electron Concentration ◽  
Collisionless Plasma ◽  
Electron Plasma ◽  
Spot Size ◽  
Laser Beams ◽  
Plasma Parameters ◽  
Electron Plasma Wave ◽  
Ponderomotive Nonlinearity

AbstractThis paper presents a scheme for excitation of an electron-plasma wave (EPW) by beating two q-Gaussian laser beams in an underdense plasma where ponderomotive nonlinearity is operative. Starting from nonlinear Schrödinger-type wave equation in Wentzel–Kramers–Brillouin (WKB) approximation, the coupled differential equations governing the evolution of spot size of laser beams with distance of propagation have been derived. The ponderomotive nonlinearity depends not only on the intensity of first laser beam, but also on that of second laser beam. Therefore, the dynamics of one laser beam affects that of other and hence, cross-focusing of the two laser beams takes place. Due to nonuniform intensity distribution along the wavefronts of the laser beams, the background electron concentration is modified. The amplitude of EPW, which depends on the background electron concentration, is thus nonlinearly coupled with the laser beams. The effects of ponderomotive nonlinearity and cross-focusing of the laser beams on excitation of EPW have been incorporated. Numerical simulations have been carried out to investigate the effect of laser and plasma parameters on cross-focusing of the two laser beams and further its effect on EPW excitation.

scholarly journals Beat wave excitation of electron plasma wave by coaxial cosh-Gaussian laser beams in collisional plasma

2015 ◽  
Vol 33 (4) ◽  
pp. 621-632 ◽  
Author(s):  
Arvinder Singh ◽  
Naveen Gupta
Keyword(s):  
Laser Beam ◽  
Plasma Wave ◽  
Electron Plasma ◽  
Spot Size ◽  
Collisional Plasma ◽  
Laser Beams ◽  
Theory Approach ◽  
Wave Excitation ◽  
Plasma Parameters ◽  
Electron Plasma Wave

AbstractThis paper presents a scheme for beat wave excitation of an electron plasma wave (EPW) by cross-focusing of two intense cosh-Gaussian (ChG) laser beams in an under dense collisional plasma. The plasma wave is generated on account of beating of two ChG laser beams of frequencies ω1 and ω2. Starting from Maxwell's equations, coupled differential equations governing the evolution of spot size of laser beams with distance of propagation have been derived by using Moment theory approach in Wentzel–Kramers–Brillouin approximation. The collisional nonlinearity depends not only on the intensity of first laser beam, but also on that of second laser beam. Therefore, dynamics of first laser beam affects that of other and hence cross-focusing of the two laser beams takes place. Numerical simulations have been carried out to investigate the effect of laser as well as plasma parameters on cross-focusing of laser beams and further its effect on power of excited EPW. It has been found that decentered parameters of the two laser beams have significant effect on power of EPW.

Study of optical guiding of the Hermite–Gaussian laser beam in preformed collisional parabolic plasma channel and second harmonic generation

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Jyoti Wadhwa ◽  
Arvinder Singh
Keyword(s):  
Second Harmonic Generation ◽  
Laser Beam ◽  
Plasma Wave ◽  
Harmonic Generation ◽  
Plasma Channel ◽  
Second Harmonic ◽  
Incident Beam ◽  
Electron Plasma ◽  
Gaussian Laser Beam ◽  
Electron Plasma Wave

Abstract In the present work, the scheme of optical guiding of the Hermite–Gaussian laser beam and the generation of second-harmonic 2ω radiation (ω being the frequency of incident beam) is presented in plasma having the preformed collisional plasma channel in which density variation is parabolic. The nonlinear coupling of excited electron plasma wave with the carrier or incident beam results in the production of second harmonics of the latter. The method of moments is used for finding the coupled differential equations for the beam diameter to study the dynamics of the Hermite–Gaussian laser beam in plasma under the effect of the collisional parabolic channel. For numerical simulations, the Runge–Kutta fourth-order numerical method is used. Standard perturbation theory gives the equation for excitation of electron plasma wave which further acts as the source term for the second harmonic generation. The numerical results show that the preformed plasma channel has a significant effect on the guiding as well as on the 2ω generation of the Hermite–Gaussian laser beam in plasma.

scholarly journals Stimulated Raman backscattering of filamented hollow Gaussian beams

2013 ◽  
Vol 31 (3) ◽  
pp. 387-394 ◽  
Author(s):  
Ram Kishor Singh ◽  
R.P. Sharma
Keyword(s):  
Raman Scattering ◽  
Gaussian Beam ◽  
Plasma Wave ◽  
Stimulated Raman Scattering ◽  
Collisionless Plasma ◽  
Electron Plasma ◽  
Electron Plasma Wave ◽  
Self Focusing ◽  
Paraxial Ray ◽  
Stimulated Raman

AbstractThis paper presents a model for excitation of electron plasma wave and resulting stimulated Raman scattering due to presence of a laser beam carrying null intensity in center (hollow Gaussian beam) in a collisionless plasma. We have studied the self-focusing of the hollow Gaussian beam and its effect on back stimulated Raman scattering process in the presence of ponderomotive nonlinearity. To understand the nature of propagation of the hollow Gaussian beam, electron plasma wave and back reflectivity, a paraxial-ray approximation has been invoked. It is predicted that self-focusing and back reflectivity reduces for higher order of hollow Gaussian beam.

EFFECT OF SELF-FOCUSING ON STIMULATED RAMAN SCATTERING BY A GAUSSIAN LASER BEAM IN COLLISIONAL PLASMA: MOMENT THEORY APPROACH

2013 ◽  
Vol 22 (03) ◽  
pp. 1350030 ◽  
Author(s):  
KESHAV WALIA ◽  
ARVINDER SINGH
Keyword(s):  
Laser Beam ◽  
Stimulated Raman Scattering ◽  
Electron Plasma ◽  
Collisional Plasma ◽  
Theory Approach ◽  
Gaussian Laser Beam ◽  
Moment Theory ◽  
Electron Plasma Wave ◽  
Beam Electron ◽  
Self Focusing

In the present paper, the effect of self-focusing on stimulated Raman scattering (SRS) process by a Gaussian laser beam in collisional plasma is investigated. Due to non-uniform heating, collisional nonlinearity arises, which leads to redistribution of carriers. As a result of which, background plasma density profile in a direction transverse to pump beam axis is modified. This modification affects the incident laser beam, electron plasma wave and back-scattered beam. Nonlinear differential equations for the beam width parameters of the main beam, electron plasma wave, back-scattered wave have been set up by taking full nonlinear part of the dielectric constant of collisional plasma with the help of moment theory approach and are solved numerically by Runge–Kutta method. It is observed from the analysis that focusing of waves greatly enhances the SRS reflectivity.

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