while being homogeneous in the toroidal and poloidal direction (i.e. $m=0$, $n=0$, where $m$ and $n$ are the toroidal and poloidal wave numbers in a toroidal geometry). Such structures are peculiar to turbulent systems since they are linearly stable and can only exist as a result of nonlinear wave interaction.

The importance of the zonal flows as a self-regulating mechanism for the turbulence and plasma transport is widely accepted. Only recently, however, experimental observations [@Fujisawa2007; @Fujisawa2008] and nonlinear electromagnetic simulations Ref.[@Thyagaraja2005; @Waltz2006; @Bruce] have highlighted that turbulence in fusion plasmas can also generate, together with the well documented zonal flows, zonal fields. These, similar to the zonal flows, are axisymmetric sheared band-like structures in the magnetic field. The zonal fields were predicted by several theoretical works, a detailed review of which can be found in Ref.[@Diamond2005]. In these works, zonal magnetic fields are shown to arise from finite $\beta$ (the ratio between the thermal and the magnetic pressure) drift-wave turbulence when electron inertia effects are included.

The radial oscillation of the zonal magnetic field is associated with zonal currents flowing in the direction of the confining magnetic field. These turbulence generated *current corrugations* perturb the $m=0$, $n=0$ component of the 