"Dynamics of electron plasma vortices subject to external strain flows," by Noah Hurst (UC San Diego)

Thursday, May 9, 2019 - 12:30pm to 1:30pm
Plasma Seminars

The ExB drift dynamics of non-neutral pure electron plasmas in a Penning-Malmberg trap apparatus, under certain conditions, are isomorphic to those of a two-dimensional (2D) ideal (inviscid, incompressible) fluid. Here, the plasma is confined radially due to a strong, applied magnetic field, and confined axially due to applied electrostatic potentials. The plasma density in the plane perpendicular to the field plays the role of the fluid vorticity. In this way, 2D vortex dynamics can be studied experimentally in a way that closely approximates the ideal fluid equations. Presented here is a novel method to subject electron plasma vortices to external flows in the laboratory by adjusting the boundary conditions in 2D. The experimental data show that external strain flows can perturb or destabilize the vortices, depending on the strain-to-vorticity ratio. Furthermore, when the strain rate is varied in time, a variety of interesting nonlinear behavior is observed. Transient strain pulses are used to generate electron vorticity filaments and study the resulting Kelvin-Helmholtz instability. Adiabatic vortex behavior is observed in response to ramped strain, and turbulent behavior is observed when the strain rate is varied periodically. The results are compared to theoretical models when possible and to other experimental and numerical work.

Event Attachments: 
BaPSF Auditorium, Rehab Building Room 15-70