Laser Beam In Relativistic Plasma Research Articles

Enhanced self-focusing of Laguerre-Gaussian laser beam in relativistic plasma under exponential plasma density transition

In the current work, self-focusing of Laguerre-Gaussian laser beam under the influence of exponential plasma density transition in relativistic plasma is studied. It is observed that the spot size of laser beam shrinks as beam propagates into the plasma because of exponential plasma density ramp. The exponential plasma density ramp reduces the beam width parameter due to its slowly variation ramp profile. Also, with the rise in intensity of the laser beam, self-focusing enhances significantly. Our results in the present manuscript may be helpful in the field where strong self-focusing of the laser is required such as high-power laser driven fusion, explanation of devices involved in beam propagation in the various applications.

Generation of second harmonics of intense Hermite–Gaussian laser beam in relativistic plasma

AbstractIn this paper, the scheme of generation of second harmonics of incident electromagnetic wave having a Hermite–Gaussian intensity profile in an under dense relativistic plasma has been presented. The relativistic mass variation of electrons by the intense electric field of incident beam generates the density gradients in background plasma which further excites the electron plasma wave (EPW) at resonant frequency and coupling of the EPW with the incident beam results in the generation of second harmonics of incident beam. Propagation dynamics of the Hermite–Gaussian laser beam in plasma has been studied by the formulation of differential equation for the spot size of the laser beam with the help of method of moments. Numerical simulations have been carried out to solve the differential equation for the dimensionless beam width parameters. Solution of the nonlinear wave equation for the electric field vector of second harmonics of incident beam gives the expression for second-harmonic yield. It has been observed that second-harmonic yield is affected by the different modes of Hermite–Gaussian laser beam in relativistic plasma.

Self-focusing of q-Gaussian laser beam in relativistic plasma under the effect of light absorption

The dynamics of q-Gaussian laser has been studied analytically and using numerical methods by taking into account relativistic nonlinearity. A paraxial approach is employed to derive nonlinear differential equation for the beam width parameter under the effect of light absorption. Beam focusing has been found to depend on various parameters such as intensity, q-parameter and absorption levels. From the numerical simulations it has been observed that beam with higher q-value can be relativistically guided without much absorption up to several Rayleigh length.

Stimulated Raman scattering of gaussian laser beam in relativistic plasma

This paper presents an investigation of Stimulated Raman Scattering of gaussian laser beam in relativistic Plasma. The pump beam interacts with a pre-excited electron plasma wave and thereby generate a back-scattered wave. Due to intense laser beam, electron oscillatory velocity becomes comparable to the velocity of light, which modifies the background plasma density profile in a direction transverse to pump beam axis. The relativistic non-linearity due to increase in mass of the electrons effects the incident laser beam, electron plasma wave and back-scattered beam. We have set up the non-linear differential equations for the beam width parameters of the main beam, electron plasma wave, back-scattered wave and derived SRS back-reflectivity by taking full non-linear part of the dielectric constant of relativistic plasma with the help of moment theory approach. It is observed from the analysis that self-focusing of the pump beam greatly affects the SRS reflectivity, which plays a significant role in laser induced fusion.

Stimulated Brillouin Scattering of Gaussian Laser Beam in Relativistic Plasma

This paper presents an investigation of stimulated Brillouin scattering (SBS) of Gaussian laser beam in relativistic plasma. The pump beam interacts with a pre-excited ion-acoustic wave thereby generating a back-scattered wave. In the high intensity laser beam, electron oscillatory velocity becomes comparable to the velocity of light, which modifies the refractive index of plasma due to increase in the electron mass. This modification of refractive index affects the incident laser beam, ion-acoustic wave and back scattered beam. We have set up non-linear differential equations for the beam width parameters of the main beam, ion-acoustic wave, back-scattered wave and derived expression of SBS-reflectivity by taking full non-linear part of the dielectric constant of relativistic plasma with the help of moment theory approach. It is observed from the analysis that focusing of waves greatly affects the SBS reflectivity.

Dynamics of Gaussian spikes on Gaussian laser beam in relativistic plasma

AbstractIn the present paper, we have investigated the growth of a Gaussian perturbation superimposed on a Gaussian laser beam. The nonlinearity we have considered is of relativistic type. We have setup the nonlinear differential equations for beam width parameter of the main beam, growth and width of the laser spike by using the WKB and paraxial ray approximation. These are coupled ordinary differential equations and therefore these are simultaneously solved numerically using the Runge Kutta method. It has been observed from the analysis that self-focusing/defocusing of the main beam and the spike determine the growth dynamic of the spike.