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Experiments on 2D Vortex Patterns in a Malmberg-Penning Trap with a Photocathode

Experiments on 2D Vortex Patterns in a Malmberg-Penning Trap with a Photocathode by Daniel Richard Durkin Doctor of Philosophy in Physics University of California at Berkeley Professor Joel Fajans, Chair The equations governing the evolution of a strongly magnetized pure electron system are analogous to those of an ideal 2D °uid; electron density is analogous to °uid vorticity. Therefore, we can study 2D vortex dynamics with pure electron systems in a Malmberg-Penning trap. We generate our electron systems with a photocathode, as opposed to the traditional thermionic sources. The photocathode provides increased control over the initial electron pro ̄le, permitting us to perform previously inaccessible °uid-type experiments. The following results on the stability of 2D vortex patterns are presented here: 1. The stability of N vortices arranged in a ring. 2. The stability of N vortices arranged in a ring with a central vortex. 3. The stability of more complicated vortex patterns. The electron pro ̄le injected by an equipotential cathode is also investigated. Professor Joel Fajans Dissertation Committee Chair