Early time properties of ultracold neutral plasmas

Abstract

We present simulations of some of the early time properties of ultracold neutral plasmas. We focus on three aspects of this system. First, we study the earliest electron dynamics when the initial temperature of the electrons would place them in the strongly coupled regime. We focus on times out to ∼10 plasma periods of the electron but also present results out to ∼85 plasma periods. In particular, we study how the formation of Rydberg atoms leads to heating and how the mass of the ion could enter the dynamics. Second, we study how the ions behave when the electrons are at high temperatures by comparing simulations that treat the electrons as a fluid and simulations that simultaneously include the electrons and ions. For light ions, the electron–ion scattering transfers substantial energy from the electrons to the ions. Finally, we study the ion motion at early times and at low temperatures where the electron evolution and ion motion could be at comparable time scales. This allows a test of electron–ion scattering when the electron plasma is nearly strongly coupled and we find that the recent values for the electron–ion scattering rate underestimate the ion heating in our calculations.