Turbulent diffusion in two-dimensional, strongly magnetized plasmas

Abstract

Particle diffusion is investigated in a strictly two-dimensional collisionless guiding-centre model for a strongly magnetized plasma. An analytical expression is presented for the entire time variation of the mean square test-particle displacement in the limit of low-frequency, strongly turbulent, electric field fluctuations. The analysis relies on an explicit integral expression for the Lagrangian autocorrelation function in terms of the Eulerian wavenumber spectrum and a time-varying weight function. Bohm diffusion is discussed by means of a simple model spectrum. The analysis applies for turbulent transport associated with electrostatic convective cells, magnetostatic cells and drift wave turbulence with the assumption of local homogeneity and isotropy in two dimensions.