Nonlinear electron-magnetohydrodynamic simulations of three dimensional current shear instability

摘要

This paper deals with detailed nonlinear electron-magnetohydrodynamic simulations of a three dimensional current shear driven instability in slab geometry. The simulations show the development of the instability in the current shear layer in the linear regime leading to the generation of electromagnetic turbulence in the nonlinear regime. The electromagnetic turbulence is first generated in the unstable shear layer and then spreads into the stable regions. The turbulence spectrum shows a new kind of anisotropy in which power transfer towards shorter scales occurs preferentially in the direction perpendicular to the electron flow. Results of the present three dimensional simulations of the current shear instability are compared with those of our earlier two dimensional simulations of sausage instability. It is found that the flattening of the mean velocity profile and thus reduction in the electron current due to generation of electromagnetic turbulence in the three dimensional case is more effective as compared to that in the two dimensional case.