The DONUT experiment in the ONU plasma laboratory is a world-class facility for studying dusty plasma.

My research is focused on the physics of dusty (complex) plasma, particularly normal modes, chaotic dynamics, nonlinear waves and phase transitions. Interesting, high-quality, original research is performed by myself and Dr. Theisen in collaboration with ONU students using the Dusty ONU experimenT (DONUT). Our results are reported in leading journals such as Physics of Plasmas, Journal of Physics D: Applied Physics, and Review of Scientific Instruments. There are many interesting projects for students interested in working on experiment, simulation, or theory of dusty plasma. ONU students have coauthored six refereed publications describing experiments performed on DONUT.

Research results from DONUT were presented in an invited talk at the 53rd Annual Meeting of the American Physical Society Division of Plasma Physics in November 2011.

Experimental work from the DONUT experiment on melting in two dimensions [T. E. Sheridan, Phys. Plasmas 15, 103702 (2008)] was recognized in the Physics Update section of the December 2008 issue of Physics Today. The American Institute of Physics, which publishes Physics Today, says: "Physics Today is the most-frequently cited magazine in multidisciplinary physics, reaching more than 120,000 scientists and engineers at university, government, and industrial labs in 151 countries."

What is plasma?
Plasma is a gas consisting of positive particles (ions) and negative particles (electrons) in nearly equal amounts. There may also be a neutral (i.e., not electrically charged) gas component. A plasma is different from a neutral gas because the electrons and ions interact through long-range electromagnetic forces, rather than through short-range "bumping-into-each-other" forces. Consequently, each charged particle in the plasma simultaneously interacts with a large number of other charged particles. Because of this long range interaction, the physics of plasmas is richer than that of ordinary gases.

What is dusty plasma?
Dusty plasma is a system of microscopic "dust" particles that float in a normal plasma. Dust particles in plasma typically collect electrons faster than positive ions, and so acquire a negative charge. The dust particles are confined by the electric fields in the plasma, and form a system with interesting and unique properties. In many cases, a dusty plasma acts like a classical condensed matter (solid state) system.


Large disk of dust of ~4000 dust particles in the DONUT experiment in the center of a confining ring. The particles are illuminated by a red diode laser.


Electron micrograph of dust particles used to make dusty plasma (from