Evolution of electromagnetic soliton during laser-plasma interaction in an electron-positron-ion plasma having constant density gradient

Abstract

Laser propagation in an electron-positron-ion (EPI) plasma medium having a constant density
gradient is studied for the soliton evolution in the presence of a parallelly applied strong magnetic
field. In a nonlinear regime, laser-plasma interaction forms an electron density hill that moves
backward due to the density gradient. This hill localizes laser energy by the mechanism of
resonance absorption (ωl =ωpe) and remains stable for a longer period, qualifying for the evolution
of electromagnetic soliton. The position of the soliton from where it starts moving backward
depends on the slope of the linear density variation. If the slope increases, then the position of the
soliton is closer to the plasma boundary (x = 0). Another interesting property of the soliton is that
its height decreases, and width increases as the temperature of plasma species rises. We simulate
this phenomenon of electromagnetic soliton evolution in 1-D and 2-D by using Particle-In-Cell
(PIC) simulation using the EPOCH-4.17.10.