Numerical study of the magnetic electron drift vortex mode turbulence in a nonuniform magnetoplasma

Abstract

A simulation study of the magnetic electron drift vortex (MEDV) mode turbulence in a magnetoplasma in the presence of inhomogeneities in the plasma temperature and density, as well as in the external magnetic field, is presented. The study shows that the influence of the magnetic field inhomogeneity is to suppress streamer-like structures observed in previous simulation studies without background magnetic fields. The MEDV mode turbulence exhibits non-universal (non-Kolmogorov type) spectra for different sets of the plasma parameters. In the presence of an inhomogeneous magnetic field, the spectrum changes to a 7/3 power law, which is flatter than without magnetic field gradients. The relevance of this work to laser-produced plasmas in the laboratory is briefly mentioned.

Two Dimensional Inhomogeneous Magnetic Electron Drift Modes

“…We have adapted the nonlinear fluid code that was developed to study the evolution of MEDV modes in [23] in the presence of equilibrium electron density and temperature gradients, to also include a background gradient in the magnetic field [24]. Consequently, the energy stored in these gradients excite linear as well as nonlinear instabilities in a different manner, than that described in [23], because the nonlinear mode coupling interactions are significantly modified by the presence of both plasma and magnetic field gradients.…”

“…Evolution of anisotropic mode structures as described by kx and ky mode averaged over the entire turbulent spectrum in inhomogeneous MEDV turbulence. Initially, kx = ky. Progressive development of anisotropy kx > ky is ascribed to the presence of background gradients in magnetic and temperature fields for which the anisotropy angle 0 = tan Ref [24]). …”

“…In this paper, we report a simulation study of the MEDV mode turbulence in the presence of gradients in the equilibrium electron temperature and electron density, as well as in the background magnetic field [24]. We concentrate our study on the magnetic field effect and its influence on the spectral properties of the MEDV mode turbulence.…”

“…Our major results are also pubhshed in Ref. [24]. The MEDV mode turbulence involve a competition between nonlinear zonal flows [25], which we define as nonlinear MEDV modes with a finite scale in the direction of the equilibrium plasma density and temperature gradients, and streamers that have a finite scale perpendicular to the plasma gradients.…”

“…The saturated structures in B, T, V^B and B -V^B are shown in the figure.The numerical resolution is 256^, box dimension is 2n x 2ji, and the parameters used are a = + 1 and KB =0.5. (After Ref[24]). …”