Weibel-mediated filamentary structures observed in the ICF context

TL;DR

This paper demonstrates how Weibel-mediated filamentary structures develop in laser-irradiated plasma plumes, explaining experimental magnetic fluctuation data through theoretical and particle-in-cell modeling.

Contribution

It provides the first detailed analysis of Weibel filament formation in expanding plasma plumes in the ICF context, supported by modeling and experimental data.

Findings

Electron pressure anisotropy drives filament growth during plasma expansion.

Self-generated magnetic fluctuations match experimental observations.

Filament wavelength and amplitude estimates align with data from OMEGA and Laser Megajoule.

Abstract

In light of novel and past experimental results, we demonstrate how Weibel-mediated filamentary structures can develop in the expanding plasma plume of a laser-irradiated foil. The transverse ballistic cooling that occurs during the quasi-spherical plasma expansion naturally drives an electron pressure anisotropy, resulting in the growth of electron current filaments. This effect competes with electron-ion Coulomb collisions which tend to isotropize the electron distribution function. Based on theoretical and particle-in-cell modeling, we provide estimates of the dominant wavelength and amplitude of the self-generated magnetic fluctuations, which are found to explain experimental data obtained at the OMEGA and Laser Megajoule facilities.