Shear-limited test particle diffusion in 2-dimensional plasmas

Shear reduction of 2D point vortex diffusion

“…We derive the results of our statistical theory for self diffusion, and compare these results to molecular dynamics and vortex-in-cell simulations. For comparision to ion experiments, see the paper by Anderegg et al in this Proceedings [9]. We find that the simulations agree with our theory provided that s is negative (i.e.…”

“…Under such conditions, these E x B drifts are the main cause of collisional diffusion, dominating over the classical diffusion [8] caused by velocity-scattering collisions. Using laser "tagging" techniques, ion experiments have directly measured the test-particle diffusion, and show quantitative correspondence with the present theory [9]. Electron experiments in the 2D regime have established that the bulk viscosity is strongly enhanced as the shear is reduced [10], but the theory of this (closely related) transport coefficient is not yet complete.…”

“…The particle kinetic velocity V does not appear in present theory of 2D E x B drift collisions of charged rods, but it does appear in the analogous 3D theory of "long-range" or "E x B drift" collisions between charged particles. Indeed, theory and experiments [9] show that diffusion in the 2D regime is enhanced over diffusion in the 3D regime by the factor Nb, specifically D 3 D/D 2 D -0.47Nb. Moreover, experiments on viscosity in the 2D regime [10] show essentially the same enhancement.…”