Sigma Pi Sigma Lecture
"Making a Plasma Act Like a Crystal"

 Dr. John Goree
Department of Physics, University of Iowa

Wednesday, April 16, 2003 at 7:00 pm
Science Building Room 102
Augustana College, Rock Island, Illinois

Parking is available in Lot H, just north of the building. You may enter on the ground floor at either the north or south entrance. The lecture hall is at the south end of the building. There is handicap parking at the north entrance.

In this interdisciplinary talk, it is explained how a dusty plasma is an ionized gas containing small particles of solid matter, which require a large negative electric charge.  These particles repel one another, yet they are confined so they can't escape.  As their motion is cooled, they arrange themselves in a lattice, similar to the cells in a crystalline lattice.  This so-called "plasma crystal" behaves completely unlike other plasma; in fact, it behaves like normal solid matter.  Experiments are described that show a melting/freezing phase transition and other kinds of solid state behavior.

What distinguishes a plasma crystal from normal solid matter is that the "atoms" are actually micron-sized plastic micro spheres that are big enough to image directly using a video camera as they move about.  The presentation includes videos, easily understood photos, and other audience-friendly images.  An interdisciplinary approach is taken, drawing from the fields of seismology, fluid mechanics, and condensed matter in addition to plasma physics.  Results are shown from experiments performed in labs on Earth and on the International Space Station.