Instability of a Thin Conducting Foil Accelerated by a Finite Wavelength Intense Laser

TL;DR

This paper develops a theoretical model for RT-like instability in thin foils accelerated by intense lasers, incorporating finite wavelength effects, revealing how diffraction influences growth rates and polarization impacts the instability.

Contribution

It introduces a novel model accounting for finite wavelength effects and diffraction in laser-driven RT-like instabilities, enhancing understanding of their behavior in high-intensity laser applications.

Findings

Growth rate peaks near laser wavenumber

Diffraction significantly alters instability growth

Polarization affects instability characteristics

Abstract

We derive a theoretical model for the Rayleigh-Taylor (RT)-like instability for a thin foil accelerated by an intense laser, taking into account finite wavelength effects in the laser wave field. The latter leads to the diffraction of the electromagnetic wave off the periodic structures arising from the instability of the foil, which significantly modifies the growth rate of the RT-like instability when the perturbations on the foil have wavenumbers comparable to or larger than the laser wavenumber. In particular, the growth rate has a local maximum at a perturbation wavenumber approximately equal to the laser wavenumber. The standard RT instability, arising from a pressure difference between the two sides of a foil, is approximately recovered for perturbation wavenumbers smaller than the laser wavenumber. Differences in the results for circular and linear polarization of the laser light are pointed out. The model has significance to radiation pressure acceleration of thin foils and to laser-driven inertial confinement fusion schemes, where RT-like instabilities are significant obstacles.