Ion Wakes: Modeling Dust Plasma Interactions>
Lorin Swint Matthews, Ph.D.
Professor, Department of Physics, Baylor University
The interaction of an object within a streaming fluid is a phenomenon widely encountered in physics, spanning a range of
length scales, from the familiar meter- to cm-sized wakes observed behind rocks in flowing streams (Fig. 1a), the kilometerslong
wakes observed in cloud patterns as air flows past ocean islands (Fig. 1b), to the wakes produced in the bow shock of
a speeding neutron star covering distances on the order of a parsecs (Fig. 1c). Plasma, a gas consisting of electrons, ions,
and neutral molecules, can also be considered as a fluid. When plasma is moving with respect to an immersed object (such
as a micron-sized dust grain), the object becomes charged and the trajectories of the ions in the plasma are altered as they
flow past the charged body. Depending on flow velocity and the magnitude of the perturbing potential, ions can be focused
into a region downstream of the object, creating an ion wakefield (Fig. 1d). Here we report results of coupled numerical
models of the plasma discharge, ion wakefield and particle interactions in ground-based lab experiments and in microgravity
experiments onboard the ISS.
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