Browsing by Author "Langin, Thomas Karl"

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    Universality in the Equilibration of Quenched Yukawa One Component Plasmas
    (2016-02-15) Langin, Thomas Karl; Killian, Thomas C
    A Yukawa one-component plasma (OCP) is an idealized model in which particles interact through a 1/r potential with an additional exponential falloff with length scale 1/κ expressed in units of the average interparticle spacing. This model is used to approximately describe a wide range of physical systems, especially strongly coupled plasmas; i.e., those which have Γ≥1, where Γ is the ratio of the Coulomb interaction energy between neighboring particles to the kinetic energy per particle. All dynamics and physical properties in Yukawa OCPs are expected to be universal in κ when expressed in appropriate scaled units. We study a particularly clean realization of the Yukawa OCP, an ultracold neutral plasma (UNP) created by photoionization of an ultracold atomic gas. The rapid quench to a UNP results in an equilibration process known as Disorder Induced Heating (DIH). Even after DIH the plasma is strongly coupled, with Γ~3. During DIH, oscillations in 1/Γ (i.e. scaled Kinetic Energy) occurring at twice the plasma frequency, ω_{pi}, are observed, possibly indicating coupling to collective modes. Universality is demonstrated by showing that 1/Γ(t) curves taken at similar κ collapse onto the same curve when plotted vs. ω_{pi}t. We also compare our results to molecular dynamics (MD) simulations. The utility of the universality is shown by using the MD simulations to determine the density from experimental DIH measurements.