Particle Trapping in a Large-amplitude Ion Acoustic Wave in the Presence of Interspecies Collisions

Trapping of particles in large-amplitude Ion Acoustic Waves is a ubiquitous process in the nonlinear evolution of many plasma instabilities such as Stimulated Brillouin Scattering (SBS), Collisionless Shocks, and Ion Streaming Instabilities. Recent work$^1$ has proposed that multi-species plasmas composed of heavy, high-Z and light low-Z ions can be used in ICF experiments to suppress the growth of potentially damaging levels of SBS without significant loss of the radiation drive in indirect-drive hohlraums. This suppression relies on the validity of using linear Landau damping of the IAW by the light ions. However, if the SBS-driven IAW can trap the light ions, the suppression of SBS could be reduced. Here, we present kinetic simulations with NIF-relevant plasma conditions that show the scattering of light ions on the heavy ions maintains the Maxwell-Boltzmann form of the ion distribution and thereby the linear Landau damping assumption. \\ $^1$ Berger,\textit{et al} PoP 26,012709(2019)