CAREER: Transport Phenomena in Ultracold Neutral Plasmas

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This Faculty Early Career Development (CAREER) Program award supports a fundamental theoretical investigation of the transport properties of ultracold neutral plasmas. Ultracold plasmas are a novel state of matter because the low temperature causes constituent particles, electrons and ions, to be strongly coupled. This medium has fundamentally different properties than traditional plasmas, analogous to the ways in which liquids differ from gases. Strongly coupled plasmas arise in several disciplines influencing energy, security and fundamental physics research. Examples include dense plasmas found in inertial confinement fusion experiments, intense laser-material interaction studies, sonoluminescing microbubbles, as well as astrophysical objects such as white dwarfs and giant planet interiors. Ultracold plasmas provide a unique window to view this physics because they can be accurately measured using lasers. This enables detailed tests of theoretical models. In addition to the theoretical research, a complimentary outreach program will introduce the public to plasma physics through an interactive "What is Plasma" demonstration. This will be an integral part of a larger exhibit on the history of space science at the University of Iowa (UI) to be displayed by the UI Natural History Museum, and later as a traveling exhibit in the UI Mobile Museum. Ultracold plasmas are formed by laser-induced ionization of trapped ultracold atoms, resulting in a charge-neutral mixture of cold ions and electrons. Advances provided by this project are statistical mechanical theory and molecular dynamics simulations capable of accounting for both components of the plasma. Theory and simulations in this relatively new field have focused on one-component models, treating the plasma as a single fluid. The new advances address two-component physics that will become increasingly important as experiments strive for lower temperatures. The particular processes that will be emphasized are equation of state, mutual diffusion, viscosity and energy relaxation rates. The project will focus on understanding how various microphysics processes affect macroscopic transport, including the opposite sign of electron and ion charge, the nonequilibrium nature of electrons and ions, and the dynamic dielectric response of the plasma. The results will provide insights into the fundamental physics of strongly coupled plasmas, contributing to several frontier research fields.