Kinetic processes in the laser corona heated by a nanosecond iodine laser

Abstract

The behaviour of plasma electrons in a laser corona generated by focusing the first harmonic (λ = 1.315 µm) beam of the nanosecond iodine laser Asterix for a power density in the focal spot of 10¹⁶ Wcm⁻² is studied by solving a 1D Vlasov equation with a small collision term coupled to the Maxwell equations to describe the wave propagation and transformation in a long plasma corona. The temporal evolution of electron phase space is studied in detail with the aim to identify the mechanisms relevant for the wave properties. The dominant wave modes occurring in our model are both the backward and forward propagating Raman waves, each accompanied by a daughter electrostatic wave, which may strongly interact with the plasma electrons. Within the frame of our model we identify several mechanisms of wave transformation accompanying the propagation and the corresponding kinetic phenomena in the phase space. These are visualized by the behaviour of electron distribution function, evolution of electrostatic spectrum and of Raman reflection coefficient.