Creating and studying ion acoustic waves in ultracold neutral plasmas

TL;DR

This paper demonstrates the creation and observation of ion acoustic waves in ultracold neutral plasmas, analyzing their damping behavior and effects of plasma expansion.

Contribution

It introduces a method to excite and measure ion acoustic waves in ultracold plasmas, and models their evolution considering plasma expansion effects.

Findings

Ion acoustic waves can be excited and observed in ultracold neutral plasmas.

The waves are weakly damped but experience faster damping than Landau damping predictions.

Plasma expansion significantly influences wave amplitude evolution.

Abstract

We excite ion acoustic waves in ultracold neutral plasmas by imprinting density modulations during plasma creation. Laser-induced fluorescence is used to observe the density and velocity perturbations created by the waves. The effect of expansion of the plasma on the evolution of the wave amplitude is described by treating the wave action as an adiabatic invariant. After accounting for this effect, we determine that the waves are weakly damped, but the damping is significantly faster than expected for Landau damping.