Theory of relativistic radiation reflection from plasmas

TL;DR

This paper develops a theoretical framework for understanding how intense laser radiation reflects off plasma surfaces, explaining the formation of electron sheets and deriving equations to predict reflection behavior under various conditions.

Contribution

It introduces the relativistic electronic spring (RES) model, providing a new analytical approach to plasma-radiation interactions at relativistic intensities.

Findings

RES model accurately predicts plasma electron sheet formation

Theory matches PIC simulation results for plasma dynamics

Applicable to plasma heating and high-harmonic generation studies

Abstract

We consider the reflection of relativistically strong radiation from plasma and identify the physical origin of the electrons' tendency to form a thin sheet, which maintains its localisation throughout its motion. Thereby we justify the principle of the relativistic electronic spring (RES) proposed in [A. Gonoskov et al. PRE 84, 046403 (2011)]. Using the RES principle we derive a closed set of differential equations that describe the reflection of radiation with arbitrary variation of polarization and intensity from plasma with arbitrary density profile for arbitrary angle of incidence. PIC simulations show that the theory captures the essence of the plasma dynamics. In particular, it can be applied for the studies of plasma heating and surface high-harmonic generation with intense lasers.