Effect of laser ripple on the beat wave excitation and particle acceleration

2007 ◽  
Vol 73 (1) ◽  
pp. 117-130 ◽  
Author(s):  
P. K. CHAUHAN ◽  
S. T. MAHMOUD ◽  
R. P. SHARMA ◽  
H. D. PANDEY
Keyword(s):  
Particle Acceleration ◽  
Laser Beam ◽  
Plasma Wave ◽  
Electron Plasma ◽  
Laser Beams ◽  
Wave Excitation ◽  
Mass Variation ◽  
Excitation Process ◽  
Electron Plasma Wave ◽  
Relativistic Mass

Abstract.This paper presents the effect of ripple on the plasma wave excitation process and acceleration of electrons in a laser produced plasma. The plasma wave is generated by the beating of two coaxial lasers of frequencies ω1 and ω2, such that ω1-ω2≅ωp. One of the main laser beams also has intensity spikes. The nonlinearity due to the relativistic mass variation depends not only on the intensity of one laser beam but also on the second laser beam. Therefore the behavior of the first laser beam affects the second laser beam, hence cross-focusing takes place. Owing to the interaction of ripple and the main laser beams, the ripple grows inside the plasma. The behavior of the ripple in the plasma affects the excitation of the electron plasma wave as well as the electron acceleration. The amplitude of the electron plasma wave and the electron energy are calculated, in the presence of ripple.

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.

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.

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