Effect of rippled laser beam on excitation of ion acoustic wave

Pramana ◽  
2000 ◽  
Vol 55 (5-6) ◽  
pp. 803-811 ◽  
Author(s):  
Nareshpal Singh Saini ◽  
Tarsem Singh Gill
Keyword(s):  
Acoustic Wave ◽  
Laser Beam ◽  
Ion Acoustic Wave ◽  
Ion Acoustic

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 Effect of self-focused rippled laser beam on the excitation of ion acoustic wave in relativistic ponderomotive regime

2014 ◽  
Vol 32 (4) ◽  
pp. 557-568 ◽  
Author(s):  
Rakhi Gauniyal ◽  
Prashant Chauhan ◽  
Priyanka Rawat ◽  
Gunjan Purohit
Keyword(s):  
Acoustic Wave ◽  
Laser Beam ◽  
Collisionless Plasma ◽  
Plasma Parameters ◽  
Power Flux ◽  
Ion Acoustic Wave ◽  
Coupled Equations ◽  
Increase With Increase ◽  
Ion Acoustic ◽  
Paraxial Ray

AbstractThis paper presents an investigation of self-focusing of intense Gaussian rippled laser beam in collisionless plasma by including the nonlinearity associated with the relativistic mass and the ponderomotive force and its effects on the excitation of ion acoustic wave. The growth of ripple, riding on an intense Gaussian laser beam in plasma and its coupling with ion acoustic wave has also been studied. Modified coupled equations for main laser beam, growth of laser ripple in plasma, rippled laser beam, beam width, and density perturbation associated with ion acoustic wave are derived using Wentzel-Kramers-Brillouin and paraxial ray approximation. These coupled equations are solved analytically and numerically to study the laser intensity in plasma and the variation of amplitude of the ion acoustic wave for various established laser and plasma parameters. From numerical computation, it is observed that both nonlinearities significantly affected the dynamics of the growth of laser ripple in plasma, propagation of rippled laser beam as well as ion acoustic wave in plasma at high laser power flux. The growth of laser ripple increase with increase in the intensity of laser beam and due to the contribution of growth rate, intensity profile of rippled laser beam and ion acoustic wave modified accordingly.

scholarly journals Stimulated Brillouin backscattering of hollow Gaussian laser beam in collisionless plasma under relativistic–ponderomotive regime

2016 ◽  
Vol 35 (1) ◽  
pp. 81-91 ◽  
Author(s):  
R. Gauniyal ◽  
N. Ahmad ◽  
P. Rawat ◽  
B. Gaur ◽  
S.T. Mahmoud ◽  
...  
Keyword(s):  
Acoustic Wave ◽  
Laser Beam ◽  
Collisionless Plasma ◽  
Main Beam ◽  
Theory Approach ◽  
Gaussian Laser Beam ◽  
Ion Acoustic Wave ◽  
Coupled Equations ◽  
Ion Acoustic ◽  
Stimulated Brillouin

AbstractStimulated Brillouin backscattering of an intense hollow Gaussian laser beam (HGLB) from collisionless plasma has been investigated under relativistic–ponderomotive regime. The main feature of considered hollow Gaussian laser beam is having the same power at different beam orders with null intensity at the center. Backscattered radiation is generated due to nonlinear interaction between main beam (pump beam) with pre-excited ion acoustic wave (IAW). Modified coupled equations has been set up for the beam width parameters of the main beam, ion-acoustic wave, back-scattered wave, and back reflectivity of stimulated Brillouin scattering (SBS) with the help of the Wentzel–Kramers–Brillouin approximation, fluid equations and paraxial theory approach. These coupled equations are solved analytically and numerically to study the laser intensity in the plasma, the variation of amplitude of the excited IAW and back reflectivity of SBS. The back reflectivity of SBS is found to be highly sensitive to the order of the HGLB, intensity of main laser beam, and plasma density for typical laser and plasma parameters. The focusing of main laser beam (hollow Gaussian) and IAW significantly affected the back reflectivity of SBS. The results show that the self-focusing and back reflectivity is enhanced for higher order modes of HGLB.

Studies of ion-acoustic wave properties by pulsed CO2 laser scattering

1979 ◽  
Vol 22 (1) ◽  
pp. 110 ◽  
Author(s):  
R. L. Watterson ◽  
A. L. Peratt ◽  
H. Derfler
Keyword(s):  
Acoustic Wave ◽  
Co2 Laser ◽  
Laser Scattering ◽  
Ion Acoustic Wave ◽  
Ion Acoustic ◽  
Pulsed Co2 Laser ◽  
Wave Properties
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