# Transverse instability in the "light sail" ion acceleration

## TL;DR

This paper develops a 3D theoretical model of transverse instability in laser-driven ion acceleration, revealing electron-ion coupling as the main driver, and aligns with simulation results, offering insights for instability mitigation.

## Contribution

A novel 3D theory of transverse instability in light sail ion acceleration, emphasizing electron-ion coupling over Rayleigh-Taylor effects, supported by simulation validation.

## Key findings

- Electron-ion coupling drives the instability's linear stage.
- The spectral structure and growth rate match 3D PIC simulations.
- Target destruction is caused by rapid plasma heating from the instability.

## Abstract

Acceleration of ultrathin plasma foils by laser radiation pressure promises compact alternatives to the conventional ion accelerators. It was shown, that a major showstopper for such schemes is a strong transverse instability, which develops the surface ripples, and is often attributed to the Rayleigh-Taylor (RT) type. However, simulations indicate, that these perturbations develop the features, that cannot be consistently explained by the RT mechanism. Here we develop a three-dimensional (3D) theory of this instability, which shows that its linear stage is mainly driven by strong electron-ion coupling, while the RT contribution is actually weak. Our model provides the instability spectral structure and its growth rate, that agrees with the large scale 3D particle-in-cell simulations. Numerical modeling shows, that target destruction results from a rapid plasma heating induced by the instability field. Possible paths to instability mitigation are discussed.