Magnetic helicity tensor for an anisotropic turbulence

The evolution of the magnetic helicity tensor for a nonzero mean magnetic f ield and for large magnetic Reynolds numbers in an anisotropic turbulence i s studied. It is shown that the isotropic and anisotropic parts of the magn etic helicity tensor have different characteristic times of evolution. The time of variation of the isotropic part of the magnetic helicity tensor is much larger than the correlation time of the turbulent velocity field. The anisotropic part of the magnetic helicity tensor changes for the correlatio n time of the turbulent velocity field. The mean turbulent flux of the magn etic helicity is calculated as well. It is shown that even a small anisotro py of turbulence strongly modifies the flux of the magnetic helicity. It is demonstrated that the tensor of the magnetic part of the alpha effect for weakly inhomogeneous turbulence is determined only by the isotropic part of the magnetic helicity tensor.