Dynamics, statistics and vortex crystals in the relaxation of 2D turbulence

Magnetically confined electron columns evolve in (r, theta) as essentially inviscid, incompressible 2D fluids with a single sign of vorticity. Turbule nt initial states with 50-100 vortices relax due to vortex merger and filam entation, in general agreement with a recent dynamical scaling theory. Howe ver, this relaxation sometimes halts when 3-20 vortices "anneal" into a fix ed pattern, or "vortex crystal." A new "regional maximum fluid entropy" the ory predicts the crystal patterns and background vorticity distribution, by assuming conservation of the robust flow invariants and preservation of th e intense vortices. However, simulations show that the character of the rel axed state generally depends strongly on initial conditions and dynamics.