Stimulated Raman scattering in the relativistic regime in near-critical plasmas

TL;DR

This paper investigates how high-intensity short laser pulses interact with near-critical plasmas, revealing that stimulated Raman scattering in the relativistic regime significantly enhances energy transfer and ion acceleration, as shown by PIC simulations.

Contribution

It demonstrates the critical role of stimulated Raman scattering in relativistic regimes for efficient laser energy transfer in near-critical plasmas, supported by detailed PIC simulation analysis.

Findings

Plasma absorption reaches 68% of laser energy.

Efficient electron heating throughout the plasma.

Enhanced ion acceleration at plasma edges and cavities.

Abstract

Interaction of a high intensity short laser pulse with near-critical plasmas allows to achieve extremely high coupling efficiency and transfer laser energy to energetic ions. One dimensional Particle-In-Cell (PIC) simulations are considered to detail the processes involved in the energy transfer. A confrontation of the numerical results with the theory highlights a key role played by the process of stimulated Raman scattering in the relativistic regime. The interaction of a 1 ps laser pulse (I $\sim$ 6.10$^{18}$ W.cm$^2$) with an under-critical (0.5 $n_c$) homogeneous plasma leads to a very high plasma absorption reaching 68 % of the laser pulse energy. This permits a homogeneous electron heating all along the plasma and an efficient ion acceleration at the plasma edges and in cavities.