Nonlinear simulation of electromagnetic current diffusive interchange mode turbulence

The model equation for the electrostatic current diffusive interchange mode turbulence is extended for both electrostatic and electromagnetic turbulence. Not only E × B convective nonlinearity but also the electromagnetic nonlinearity which is related to the parallel flow are incorporated into the model equation. The two-dimensional nonlinear simulation of the electromagnetic current diffusive interchange mode is performed based on the extended fluid model. Two cases are investigated. In the first case, we neglect the terms ∂A/∂t and ∇_∥p_e in Ohm's law, but retain the electromagnetic nonlinearity. This case corresponds to a simple extension of previous work. It is found that the electromagnetic nonlinearity gives rise to the normal cascade and higher saturation of the fluctuating energy. In the second case, we retain ∂A/∂t and ∇_∥p_e terms as well. In this case, the turbulent level develops higher than that in the electrostatic limit, and the strong oscillatory behaviour of the fluctuating energy is observed. The strong inverse cascade is observed, which overcomes the normal cascade due to the electromagnetic nonlinearity. The quasi-linear effect and the system size effect on the saturation level are also discussed in the context of the second model.