The role of collisions and strong coupling in ultracold plasmas
  Ultracold plasmas are formed by photo-exciting clouds of cold atoms and molecules near the ionization threshold. They explore a new region of plasma physics and display effects of strong coupling, which is characterized by a ratio of Coulomb energy to kinetic energy that is greater than unity. Collisions of many types play a role in the creation, equilibration, and expansion of these systems. 
J. Castro, P. McQuillen, H. Gao and T. C. Killian
physics.plasm-ph physics.atom-ph