Many-body collision contributions to electron momentum damping rates in a plasma influenced by electron strong coupling

TL;DR

This study uses numerical simulations to identify many-body collisions involving bound electrons as the main reason for faster electron plasma oscillation damping in strongly coupled ultracold plasmas, beyond two-body collision predictions.

Contribution

It demonstrates that many-body collisions significantly enhance electron momentum damping rates, providing a new understanding of collision dynamics in strongly coupled plasmas.

Findings

Many-body collisions cause increased damping rates.

Bound electrons contribute to collision effects.

Simulation results match experimental observations.

Abstract

Experimental studies of electron-ion collision rates in an ultracold neutral plasma (UNP) can be conducted through measuring the rate of electron plasma oscillation damping. For sufficiently cold and dense conditions where strong coupling influences are important, the measured damping rate was faster by 37\% than theoretical expectations [W. Chen, C. Witte, and J. Roberts, Phys. Rev. E \textbf{96}, 013203 (2017)]. We have conducted a series of numerical simulations to isolate the primary source of this difference. By analyzing the distribution of electron velocity changes due to collisions in a molecular dynamics simulation, examining the trajectory of electrons with high deflection angle in such simulations, and examining the oscillation damping rate while varying the ratio of two-body to three-body electron-ion collision rates, we have found that the difference is consistent with the effect due to many-body collisions leading to bound electrons. This has implications for other electron-ion collision related transport properties in addition to electron oscillation damping.