Finite Larmor radius effects and velocity correlations in two-dimensionalelectrostatic plasma turbulence

Abstract

Low-frequency electrostatic turbulence in low-{beta} plasmas is studied in two spatial dimensions by direct numerical simulations. In this limit the guiding center velocity in the direction perpendicular to a homogeneous magnetic field is in a first approximation the {bold {ital E}}{times}{bold {ital B}}{sub 0}/B{sub 0}{sup 2} velocity. The electron Larmor radius can safely be set to zero for most relevant conditions, but the ion dynamics are noticeably influenced by their finite Larmor radius. In the present study we use a fluid model where these effects are included by a simple filtering operation. The equilibrium spectra are investigated and compared with known analytical results. Particular attention is given to the finite Larmor radius effect for the turbulent diffusion of charged particles across magnetic field lines. The integral time scale and the micro time scale associated with the velocity correlations for the turbulent flow are discussed with attention to their dependence on the finite Larmor radius corrections. Finally, the numerical code is generalized to a hybrid model, which incorporates many ion species with different Larmor radii simultaneously present in the flow. {copyright} {ital 1997} {ital The American Physical Society}