Ultracold Plasmas and Other Oxymorons

Dr. Scott Bergeson
Department of Physics and Astronomy
Brigham Young University

We often think of plasmas at high temperatures, like the Solar Corona (T = 10,000K) or fusion plasmas (T = 100,000,000K). But some plasmas exist at low temperatures, like the interstellar medium (T = 2.7K). We make even colder plasmas (T = 0.001K) using laser-cooled atoms. This system is far from equilibrium but relaxes on very short time scales.

In general, the plasma evolution can be predicted using a hydrodynamical model with a little atomic physics thrown in. And a number of unbelievably complicated experiments that were intended to find "new physics" ended with the resigned admission that the theory is right after all. But some recent data from our lab appears to lie outside the standard cold plasma model.

I will give an overview of this field, try to explain why it is interesting, and present a few unsolved puzzles from our lab.