scholarly journals Excitation of nonlinear ion acoustic wave and stimulated Brillouin scattering of hollow Gaussian beam in relativistic plasma

2017 ◽  
Vol 35 (2) ◽  
pp. 226-233 ◽  
Author(s):  
P. Sharma
Keyword(s):  
Differential Equation ◽  
Acoustic Wave ◽  
Gaussian Beam ◽  
Brillouin Scattering ◽  
Collisionless Plasma ◽  
Stimulated Brillouin Scattering ◽  
Beam Width ◽  
Ion Acoustic Wave ◽  
Ion Acoustic ◽  
Stimulated Brillouin

AbstractIn the present work, excitation of nonlinear ion acoustic wave (IAW) in collisionless plasma by laser beam having null intensity at the center is examined considering relativistic nonlinearity. The differential equation for beam-width parameter is determined considering relativistic nonlinearity using the paraxial and Wentzel–Kramers–Brillouin approximations by the parabolic equation method. The propagation features of the IAW are found to be modified due to the nonlinearity present in the system. The hollow Gaussian beam (HGB) gets nonlinearly coupled with the seed IAW, results in excitation of nonlinear IAW. The interaction of nonlinear IAW with pump beam demonstrated stimulated Brillouin scattering (SBS) of HGB. It is found that the power of IAW and power of SBS is affected with the order of HGB. The power of IAW and backscattered power of SBS is determined analytically and numerically for various orders of HGB. It is found that the power of IAW and the backscattering is diminished for higher order of HGB.

scholarly journals Stimulated Brillouin backscattering of filamented hollow Gaussian beams

2013 ◽  
Vol 31 (4) ◽  
pp. 689-696 ◽  
Author(s):  
R.P. Sharma ◽  
Ram Kishor Singh
Keyword(s):  
Acoustic Wave ◽  
Gaussian Beam ◽  
Brillouin Scattering ◽  
Collisionless Plasma ◽  
Stimulated Brillouin Scattering ◽  
Ion Acoustic Wave ◽  
Ion Acoustic ◽  
Paraxial Ray ◽  
Stimulated Brillouin ◽  
Plasma Coupling

AbstractThis paper presents an investigation for excitation of ion acoustic wave and resulting stimulated Brillouin scattering in a collisionless plasma due to presence of a laser beam carrying null intensity at center (hollow Gaussian beam). In presence of ponderomotive nonlinearity, the pump beam get focused and affects the back stimulated Brillouin scattering process. To understand the nature of laser plasma coupling, a paraxial-ray approximation has been invoked for the propagation of the hollow Gaussian beam, ion acoustic wave, and stimulated Brillouin scattering. It is observed from the result that self-focusing and back reflectivity reduces for higher order of hollow Gaussian beam.

scholarly journals Stimulated Brillouin backscattering of a ring-rippled laser beam in collisionless plasma

2015 ◽  
Vol 33 (3) ◽  
pp. 499-509 ◽  
Author(s):  
Gunjan Purohit ◽  
Priyanka Rawat
Keyword(s):  
Laser Beam ◽  
Narrow Range ◽  
Brillouin Scattering ◽  
Collisionless Plasma ◽  
Plasma Parameters ◽  
Ion Acoustic Wave ◽  
Coupled Equations ◽  
Ion Acoustic ◽  
Paraxial Ray ◽  
Stimulated Brillouin

AbstractThe effect of the propagation of a ring-rippled laser beam in the presence of relativistic and ponderomotive non-linearities on the excitation of ion-acoustic wave (IAW) and resulting stimulated Brillouin backscattering in collisionless plasma at relativistic powers is studied. To understand the nature of propagation of the ring ripple-like instability, a paraxial-ray approach has been invoked in which all the relevant parameters correspond to a narrow range around the irradiance maximum of the ring ripple. Modified coupled equations for growth of ring ripple in the plasma, generations of IAW and back-stimulated Brillouin scattering (SBS) are derived from fluid equations. These coupled equations are solved analytically and numerically to study the intensity of ring-rippled laser beam and excited IAW as well as back reflectivity of SBS in the plasma for various established laser and plasma parameters. It is found that the back reflectivity of SBS is enhanced due to the strong coupling between ring-rippled laser beam and the excited IAW. The results also show that the back reflectivity of SBS reduce for higher intensity of the laser beam.

scholarly journals Controlled beat-wave Brillouin scattering in the ionosphere

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
B. Eliasson ◽  
A. Senior ◽  
M. Rietveld ◽  
A. D. R. Phelps ◽  
R. A. Cairns ◽  
...  
Keyword(s):  
Acoustic Wave ◽  
Ionospheric Plasma ◽  
Brillouin Scattering ◽  
Scale Model ◽  
Plasma Parameters ◽  
Ion Acoustic Wave ◽  
Electromagnetic Pump ◽  
Pump And Probe ◽  
Ion Acoustic ◽  
Stimulated Brillouin

AbstractStimulated Brillouin scattering experiments in the ionospheric plasma using a single electromagnetic pump wave have previously been observed to generate an electromagnetic sideband wave, emitted by the plasma, together with an ion- acoustic wave. Here we report results of a controlled, pump and probe beat-wave driven Brillouin scattering experiment, in which an ion-acoustic wave generated by the beating of electromagnetic pump and probe waves, results in electromagnetic sideband waves that are recorded on the ground. The experiment used the EISCAT facility in northern Norway, which has several high power electromagnetic wave transmitters and receivers in the radio frequency range. An electromagnetic pump consisting of large amplitude radio waves with ordinary (O) or extraordinary (X) mode polarization was injected into the overhead ionosphere, along with a less powerful probe wave, and radio sideband emissions observed on the ground clearly show stimulated Brillouin emissions at frequencies agreeing with, and changing with, the pump and probe frequencies. The experiment was simulated using a numerical full-scale model which clearly supports the interpretation of the experimental results. Such controlled beat-wave experiments demonstrate a way of remotely investigating the ionospheric plasma parameters.

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.

scholarly journals Suppression of stimulated Brillouin scattering in laser beam hot spots

2009 ◽  
Vol 27 (4) ◽  
pp. 619-627 ◽  
Author(s):  
R.P. Sharma ◽  
Prerana Sharma ◽  
Shivani Rajput ◽  
A.K. Bhardwaj
Keyword(s):  
Laser Beam ◽  
Brillouin Scattering ◽  
Collisionless Plasma ◽  
Stimulated Brillouin Scattering ◽  
Landau Damping ◽  
Beam Radius ◽  
Plasma Parameters ◽  
Power Flux ◽  
Ion Acoustic Wave ◽  
Stimulated Brillouin

AbstractIn this article, filamentation of a high power laser beam in hot collisionless plasma is investigated considering the ponderomotive nonlinearity. We have studied the effect of self focusing (filamentation) of the laser beam on the localization of ion acoustic wave (IAW) and on stimulated Brillouin scattering (SBS) process. The nonlinear coupling between the laser beam and IAW results in the modification of the Eigen frequency of IAW; consequently, enhanced Landau damping of IAW and a modified mismatch factor in SBS process occur. Due to enhanced Landau damping, there is a reduction in the intensity of IAW wave, and the SBS process gets suppressed. For the typical laser plasma parameters: the laser power flux = 1016 W/cm2, laser beam radius (r0) = 12 µm, n/ncr = 0.11, and (Te/Ti) = 10, the SBS reflectivity is found to be suppressed approximately by 10%.

scholarly journals Demonstrating the saturation of stimulated Brillouin scattering by ion acoustic decay using fully kinetic simulations

2015 ◽  
Vol 22 (9) ◽  
pp. 092116 ◽  
Author(s):  
T. Chapman ◽  
B. J. Winjum ◽  
S. Brunner ◽  
R. L. Berger ◽  
J. W. Banks
Keyword(s):  
Brillouin Scattering ◽  
Stimulated Brillouin Scattering ◽  
Ion Acoustic ◽  
Stimulated Brillouin
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