Experiments on pure electron plasmas have found that the decay of 2D t
urbulence can lead to spontaneous formation of ''vortex crystals,'' wh
ich are symmetric arrays of strong vortices within a background of wea
ker vorticity, in this paper we shaw that these vortex crystals can be
described as regional maximum fluid entropy states. The theory explai
ns the observed patterns of the vortex crystals as well as the vortici
ty distribution of the background.