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Collective phenomena are central to our understanding of most forms of matter. In the case of plasmas, the presence of a rich spectrum of collective modes is a distinctive feature that separates this state of matter from a simple collection of charged particles. In ultracold neutral plasmas, which are orders of magnitude colder than any other neutral plasma and can be used to explore the physics of strongly coupled systems, little work has been done to study collective modes, especially modes involving ion degrees of freedom. In this talk I will describe the use of a new technique for creating controlled density perturbations to excite ion acoustic waves in an ultracold neutral plasma and measure their dispersion relation. This flexible technique for sculpting the density distribution will open new areas of plasma dynamics for experimental study, including the effects of strong coupling on dispersion relations and non-linear phenomena, instabilities, and perhaps shock waves in the ultracold regime.
This work is supported by the U.S. National Science Foundation, the Department of Energy, and David and Lucille Packard Foundation. |
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