Localized absorption of laser energy in X-mode configuration of magnetized plasma

TL;DR

This paper demonstrates how tailoring plasma density profiles in magnetized plasma can localize laser energy absorption, effectively converting electromagnetic energy into ion kinetic energy at specific points, with potential applications in plasma heating.

Contribution

The study introduces a method to control localized laser energy absorption in plasma by manipulating the density profile, supported by Particle-In-Cell simulations.

Findings

Laser propagates inside plasma below lower hybrid resonance frequency.

Energy is absorbed at the resonance point where group velocity approaches zero.

Localized energy deposition can be achieved by density profile tailoring.

Abstract

The heating of ions via lower hybrid waves has been observed in several astrophysical as well as laboratory plasmas. We have conducted Particle-In-Cell simulations to demonstrate absorption of the incident laser pulse at a chosen localized point in the target by manipulating the plasma density profile. We show that a part of the incident laser propagates inside plasma target, when its frequency lies below the lower hybrid resonance frequency. Thereafter, as it experiences a negative density gradient, it approaches the resonance point where its group velocity approaches zero. This is where the electromagnetic energy prominently gets converted into electrostatic and eventually into kinetic energy of ions. Thus by tailoring the plasma density profile one can have the absorption of incident electromagnetic wave energy at a designated location inside the plasma. This may have importance in various applications where energy deposition/heating of plasma at a localized region is desirable.