Mitigation of Laser-Plasma Instabilities in Inertial Confinement Fusion using Structured Foam Plasmas

Laser-plasma instabilities (LPIs), such as stimulated Raman scattering (SRS) and stimulated Brillouin scattering (SBS), hinder inertial confinement fusion (ICF) by redirecting laser energy and causing unwanted electron preheat. Mitigating these instabilities is essential for achieving the compression and ignition conditions necessary for fusion. One approach involves disrupting the coherent coupling required for LPI growth, either through broadband laser sources or spatially incoherent plasmas.

In this work, we present particle-in-cell (PIC) simulations of laser interaction with spatially inhomogeneous plasmas derived from foam targets. We examine two distinct foam architectures, stochastic Voronoi foams and periodic log-pile foams, and evaluate their impact on LPI growth under realistic ICF conditions. Key parameters such as foam density, porosity, and randomness are varied to assess their influence on the LPIs. Our simulations reveal that spatial incoherence introduced by foam-based plasmas leads to a substantial reduction in the growth of SRS. Furthermore, we provide an analytical modeling of electromagnetic wave damping in stochastic foams, offering further insight into the mechanisms by which structural disorder inhibits instability development.