Self-focusing of a high-intensity laser in a collisional plasma under weak relativistic-ponderomotive nonlinearity

Abstract

Self-focusing a laser beam in collisional plasma is investigated under the weak relativistic-ponderomotive nonlinearity. In this case, the plasma equilibrium density is modified and it causes generation of the nonlinearity due to the Ohmic heating of electrons, collisions, and the weak relativistic-ponderomotive force during the interaction of the laser beam with the plasma. Our theoretical and simulation results show that a significant nonlinearity in laser self-focusing can occur under the weak relativistic-ponderomotive regime for some appropriate simulation parameters

Nonlinear interaction of elliptical q-Gaussian laser beams with plasmas with axial density ramp: effect of ponderomotive force

“…Plasmas can produce self focusing of laser beams mainly through three mechanisms. These mechanisms are (1) Relativistic self focusing [13,14] (2) Ponderomotive Self focusing [15][16][17] (3) nonlinear Ohmic heating [18,19]. In relativistic mechanism modification in optical properties of plasma occurs without any modification in electron density whereas in the remaining two mechanisms this modification occurs via redistribution of plasma electrons.…”

The simultaneous effect of the temperature and density gradient on the relativistic self-focusing of the Gaussian laser beam in an under-dens plasma

“…The necessity for the self-focusing is that the laser beam is sufficiently powerful and intense to propagate considerable distance without divergence. In most cases, laser self-focusing of the laser beam inside the plasma is as ponderomotive self-focusing (PSF) and a relativistic selffocusing (RSF) [14][15][16][17]. Ponderomotive selffocusing (PSF) is caused by the ponderomotive force, which pushes electrons away from the region where the laser beam is more intense, therefore increasing the refractive index and inducing a focusing effect.…”

Temporal characteristics of relativistic stimulated Brillouin scattering of a laser in plasmas

“…There have been many theoretical and numerical works on SBS in recent decades in which SBS is usually treated as an isolated process. Several studies [22][23][24][25][26][27][28][29][30][31][32][33] have been conducted, including the issues of linear and nonlinear behavior of SBS, such as the effect of ion trapping on SBS, pulse amplification and compression by SBS, SBS reflectivity in the case of a spatially smoothed laser beam interacting with an inhomogeneous plasma, suppression of SBS by stronger Landau damping in multiple ion species hohlraum plasmas, and SBS in the strong coupling regime. Lan et al [34] experimentally demonstrated laser-plasma instabilities in a gas-filled spherical hohlraum at a laser injection angle of 55 degrees for ignition.…”