Electron plasma experiments to study driven 2D fluid-vortex dynamics.

Coherent vortex structures are ubiquitous in fluids and plasmas and are a common example of self-organized structures in nonlinear dynamical systems. The unique properties of magnetized, single-component electron plasmas have enabled a broad range of studies of two-dimensional (2D) fluid dynamics, including detailed studies of isolated vortex structures. Here, we describe an experimental system that exploits the fact that the boundary conditions on an electron plasma can be specified in the two dimensions perpendicular to the magnetic field by biasing azimuthal segments of a cylindrical confining electrode. This produces a variety of irrotational, time dependent, ExB flows, which advect the electron density. Further, use of non-neutral plasma manipulation techniques are shown to be capable of producing a wide variety of controlled initial conditions. Thus, by measuring the plasma density evolution, the response of the vorticity to an imposed flow can be studied with precision and control not possible in traditional fluids. The simplicity of these experiments means that we can study the effects of different externally imposed flows on a well-defined and repeatable initial vortex. This talk will give an overview of the experimental program at UCSD and highlight some recent studies including vortex response to a constant strain, ramped strain, and pulsed strain.