Propagation characteristics of non-Gaussian laser beam in a plasma with density ramp using moment theory approach

2019 ◽  
Author(s):  
Nidhi Pathak ◽  
Paramjit Kaur ◽  
P. C. Agrawal ◽  
Sukhdeep Kaur
Keyword(s):  
Laser Beam ◽  
Theory Approach ◽  
Propagation Characteristics ◽  
Gaussian Laser Beam ◽  
Moment Theory ◽  
Non Gaussian

Enhanced Brillouin scattering of gaussian laser beam in collisional plasma: Moment theory approach

2014 ◽  
Vol 23 (01) ◽  
pp. 1450011 ◽  
Author(s):  
Keshav Walia
Keyword(s):  
Acoustic Wave ◽  
Laser Beam ◽  
Pump Beam ◽  
Brillouin Scattering ◽  
Scattered Wave ◽  
Theory Approach ◽  
Gaussian Laser Beam ◽  
Moment Theory ◽  
Ion Acoustic Wave ◽  
Ion Acoustic

In the present paper, enhanced Brillouin scattering of a gaussian laser beam in a collisional plasma has been investigated with the help of moment theory approach. The pump wave (ω0, k0) interacts with pre-excited ion-acoustic wave (ω, k), thereby generating a back-scattered wave (ω0 - ω, k0 - k). As a specific case, back scattering for which k ≃ 2k0 has been discussed. Due to nonuniform heating, collisional nonlinearity arises, which leads to redistribution of carriers. As a result background plasma density profile in a direction transverse to pump beam axis is modified. Consequently, the pump beam becomes self-focused and in turn leads focusing of ion-acoustic wave and back-scattered wave under appropriate conditions. It is further observed from the analysis that focusing of waves greatly enhances the SBS back-reflectivity.

scholarly journals Optical guiding of a laser beam in an axially nonuniform plasma channel

2010 ◽  
Vol 28 (2) ◽  
pp. 263-268 ◽  
Author(s):  
Arvinder Singh ◽  
Navpreet Singh
Keyword(s):  
Laser Beam ◽  
Plasma Channel ◽  
Theory Approach ◽  
Propagation Characteristics ◽  
Moment Theory ◽  
Nonuniform Plasma ◽  
Diffraction Phenomenon ◽  
The Moment ◽  
Preformed Plasma ◽  
Paraxial Ray

AbstractThe guiding of a laser beam in a plasma channel formed by a short laser prepulse is investigated. Due to the self defocusing of an ionizing short laser prepulse, the plasma channel formed is axially nonuniform. When a delayed second laser beam is allowed to propagate through such a preformed plasma channel, convergence and divergence of the beam is observed due to the relative competition of the refraction and diffraction phenomenon. We have solved the wave equation governing the propagation characteristics of an ionizing prepulse and a delayed pulse by the moment theory approach. Results have been compared with the paraxial ray model of Liu and Tripathi (1994). The moment theory predicts the propagation of guided laser beam over several Rayleigh lengths.

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.

scholarly journals Generalized Thermoelastic Functionally Graded on a Thin Slim Strip Non-Gaussian Laser Beam

Symmetry ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1094 ◽  
Author(s):  
Sayed M. Abo-Dahab ◽  
Ahmed E. Abouelregal ◽  
Marin Marin
Keyword(s):  
Laser Beam ◽  
Pulse Length ◽  
Generalized Thermoelasticity ◽  
Functionally Graded ◽  
Strong Impact ◽  
Problem Solution ◽  
Gaussian Laser Beam ◽  
Laser Parameters ◽  
Non Gaussian ◽  
The Impact

The present study utilizes the generalized thermoelasticity theory, with one thermal relaxation time (TR), to examine the thermoelastic problem of a functionally graded thin slim strip (TSS). The authors heated the plane surface bounding using a non-Gaussian laser beam with a pulse length of 2 ps. The material characteristics varied continually based on exponential functions. Moreover, the equations governing the generalized thermoelasticity for a functionally graded material (FGM) are recognized. The problem’s ideal solution was primarily obtained in the Laplace transform (LT) space. The LTs were converted numerically because of the considerable importance of the response in the transient state. For a hypothetical substance, the numerical procedures calculating the displacement, stress, temperature and strain were given. The analogous problem solution to an isotropic homogeneous material was provided by defining the parameter of non-homogeneity adequately. The obtained results were displayed using graphs to illustrate the extent to which non-homogeneity affected displacement, stress, temperature and strain. A comparison was been made between the present study and those previously obtained by others, when the new parameters vanish to show the impact of the non-homogeneity, TSS and laser parameters on the phenomenon. The results obtained indicate a significant strong impact of FGM, TSS and laser parameters.

scholarly journals Second harmonic generation of q-Gaussian laser beam in plasma channel created by ignitor heater technique

2019 ◽  
Vol 37 (2) ◽  
pp. 184-196 ◽  
Author(s):  
Naveen Gupta
Keyword(s):  
Second Harmonic Generation ◽  
Laser Beam ◽  
Harmonic Generation ◽  
Plasma Channel ◽  
Second Harmonic ◽  
Laser Beams ◽  
Theory Approach ◽  
Gaussian Laser Beam ◽  
Incident Laser ◽  
Pump Frequency

AbstractThis paper presents a scheme for second harmonic generation (SHG) of q-Gaussian laser beam in plasma channel created by ignitor heater technique. The ignitor beam creates plasma by tunnel ionization of air. The heater beam heats the plasma electrons and establishes a parabolic density profile. The third beam (q-Gaussian beam) is guided in this plasma channel under the combined effects of density nonuniformity of the plasma channel and relativistic mass nonlinearity of the plasma electrons. The propagation of q-Gaussian laser beam through the plasma channel excites an electron plasma wave at pump frequency that interacts with the incident laser beam to produce its second harmonics. The formulation is based on finding the numerical solution of the nonlinear Schrodinger wave equation for the fields of the incident laser beams with the help of moment theory approach. Particular emphasis is put on dynamical variations of the spot size of the laser beams and conversion efficiency of the second harmonics with distance of propagation.

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