Suppression of stimulated Raman scattering due to localization of electron plasma wave in laser beam filaments

2009 ◽  
Vol 16 (3) ◽  
pp. 032301 ◽  
Author(s):  
Prerana Sharma ◽  
R. P. Sharma
Keyword(s):  
Raman Scattering ◽  
Laser Beam ◽  
Plasma Wave ◽  
Stimulated Raman Scattering ◽  
Electron Plasma ◽  
Electron Plasma Wave ◽  
Stimulated Raman

Filamentation of laser beam and suppression of stimulated Raman scattering due to localization of electron plasma wave

2011 ◽  
Vol 78 (1) ◽  
pp. 55-63 ◽  
Author(s):  
GUNJAN PUROHIT ◽  
PRERANA SHARMA ◽  
R. P. SHARMA
Keyword(s):  
Analytical Solution ◽  
Raman Scattering ◽  
Laser Beam ◽  
Plasma Wave ◽  
Stimulated Raman Scattering ◽  
Electron Plasma ◽  
Nonlinear Coupling ◽  
Electron Plasma Wave ◽  
Unmagnetized Plasma ◽  
Stimulated Raman

AbstractThis paper presents the effect of laser beam filamentation on the localization of electron plasma wave (EPW) and stimulated Raman scattering (SRS) in unmagnetized plasma when relativistic and ponderomotive nonlinearities are operative. The splitted profile of the laser beam is obtained due to uneven focusing of the off-axial rays. The semi-analytical solution of the nonlinearly coupled EPW equation in the presence of laser beam filaments has been found. It is observed that due to this nonlinear coupling between these two waves, localization of EPW takes place. Stimulated Raman scattering of this EPW is studied and back reflectivity has been calculated. Further, the localization of EPW affects the eigenfrequency and damping of plasma wave. The new enhanced damping of the plasma wave has been calculated and it is found that the SRS process gets suppressed due to the localization of plasma wave in laser beam filamentary structures.

Suppression of stimulated Raman scattering at ultra relativistic laser power: Effect of localization

2010 ◽  
Vol 77 (3) ◽  
pp. 293-306
Author(s):  
RUCHIKA GUPTA ◽  
PRERANA SHARMA ◽  
R. P. SHARMA ◽  
M. RAFAT
Keyword(s):  
Raman Scattering ◽  
Laser Beam ◽  
Plasma Wave ◽  
Stimulated Raman Scattering ◽  
Power Laser ◽  
Plasma Parameters ◽  
Power Flux ◽  
Electron Plasma Wave ◽  
Power Effect ◽  
Stimulated Raman

AbstractThe filamentation of the high-power laser beam is investigated by taking off axial contribution when relativistic nonlinearity is considered. The effect of filamentation of the laser beam is studied on the localization of the electron plasma wave (EPW) and on the stimulated Raman scattering (SRS). The semi-analytical solution of the nonlinearly coupled EPW equation in the presence of laser beam filaments has been found. It is observed that due to this nonlinear coupling between two waves, localization of EPW takes place. This localization of EPW affects the Eigen frequency and damping of plasma wave. The new enhanced damping of the plasma wave has been calculated and it is found that the SRS process gets suppressed due to the localization of plasma wave in laser beam filamentary structures. For typical laser beam and plasma parameters with wavelength λ (=1064 nm), power flux (=1018 W cm−2) and plasma density n/ncr (=0.2); the SRS back reflectivity is found to be suppressed by a factor of approximately 8%.

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.

scholarly journals Enhanced Raman scattering of a rippled laser beam in a magnetized collisional plasma

2004 ◽  
Vol 22 (1) ◽  
pp. 35-40 ◽  
Author(s):  
NARESHPAL SINGH SAINI ◽  
TARSEM SINGH GILL
Keyword(s):  
Raman Scattering ◽  
Laser Beam ◽  
Plasma Wave ◽  
Scattered Wave ◽  
Electron Plasma ◽  
Main Beam ◽  
Stimulated Scattering ◽  
Electron Plasma Wave ◽  
Scattered Power ◽  
Enhanced Raman Scattering

In the laser–plasma interaction experiments, self-focusing and filamentation affect quite a large number of other parametric processes including stimulated scattering processes. Nonlinearity considered in the present problem is the collisional type. The coupling between the main beam, ripple, and excited electron plasma wave is strong. Authors have investigated the growing interaction of a rippled laser beam with an electron plasma wave leading to enhanced Raman scattering. An expression for scattered power is derived and the effect of the externally applied magnetic field on the enhancement of scattered power is observed. From computational results, it is observed that the effect of increased intensity of the main beam leads to suppression of power associated with the Raman scattered wave.

scholarly journals Stimulated Raman scattering of ultra intense hollow Gaussian beam in relativistic plasma

2015 ◽  
Vol 33 (3) ◽  
pp. 489-498 ◽  
Author(s):  
Prerana Sharma
Keyword(s):  
Raman Scattering ◽  
Laser Beam ◽  
Gaussian Beam ◽  
Plasma Wave ◽  
Stimulated Raman Scattering ◽  
Collisionless Plasma ◽  
Vital Role ◽  
Higher Order ◽  
Gaussian Laser Beam ◽  
Stimulated Raman

AbstractEffect of relativistic nonlinearity on stimulated Raman scattering (SRS) of laser beam propagating carrying null intensity in center [hollow Gaussian beam (HGB)] is studied in collisionless plasma. The construction of the equations is done employing the fluid theory which is developed with partial differential equation and Maxwell's equations. The phenomenon of SRS is shown along with the excitation of seed plasma wave considering relativistic nonlinearity. The power of plasma wave is observed for higher order of HGB. The Raman back reflectivity is studied numerically for various orders of hollow Gaussian laser beam (HGLB) and the numerical analysis shows that these parameters play vital role on reflectivity characteristics. It is observed that the Raman back reflectivity is less for the higher order of HGLB.

scholarly journals Nonstationarity of stimulated Raman scattering in a homogeneous plasma slab

1993 ◽  
Vol 11 (1) ◽  
pp. 227-239 ◽  
Author(s):  
M. S. Jovanović ◽  
M. M. Škorić
Keyword(s):  
Plasma Wave ◽  
Stimulated Raman Scattering ◽  
Electron Plasma ◽  
Linear Wave ◽  
Wave Damping ◽  
Electron Plasma Wave ◽  
Homogeneous Plasma ◽  
Maximum Reflectivity ◽  
Plasma Slab ◽  
Stimulated Raman

Nonstationarity of stimulated Raman backscattering in a finite homogeneous plasma slab is examined. Slowly varying envelope equations are analyzed taking into account a damping and a convection of an electron plasma wave, with a nonzero source boundary condition assumed. The linear analysis method is used for examination of stability of saturated stationary amplitude solutions. When linear wave damping is sufficiently small or absent, these solutions are spatially periodic and appear linearly unstable to small perturbations. However, a direct numerical simulation of the backscattering process in a lossless case shows that the system tends to quasistationary state with maximum reflectivity (R → 1). If the electron plasma wave damping exceeds a certain critical value, a spatially aperiodic solution raises and the Raman backscattering process becomes stable.

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