Propagation of Ultra-Intense Laser Pulses in Near-critical Plasmas: Depletion Mechanisms and Effects of Radiation Reaction

TL;DR

This paper investigates how ultra-intense laser pulses propagate in near-critical plasmas, focusing on depletion mechanisms and radiation reaction effects, using advanced PIC simulations to explore highly nonlinear regimes for potential high-energy electron acceleration.

Contribution

It introduces a comprehensive PIC model to analyze stable laser propagation and energy transfer in highly nonlinear plasma regimes, highlighting new depletion mechanisms and guiding effects.

Findings

Stable laser propagation over long distances with external guiding.

Identification of new energy depletion mechanisms.

Efficient conversion of laser energy into high-energy electrons and photons.

Abstract

Although, for current laser pulse energies, the weakly nonlinear regime of LWFA is known to be the optimal for reaching the highest possible electron energies, the capabilities of upcoming large laser systems will provide the possibility of running highly nonlinear regimes of laser pulse propagation in underdense or near-critical plasmas. Using an extended particle-in-cell (PIC) model that takes into account all the relevant physics, we show that such regimes can be implemented with external guiding for a relatively long distance of propagation and allow for the stable transformation of laser energy into other types of energy, including the kinetic energy of a large number of high energy electrons and their incoherent emission of photons. This is despite the fact that the high intensity of the laser pulse triggers a number of new mechanisms of energy depletion, which we investigate systematically.