The mean energy of a decaying magnetic field in MHD‐turbulence

Abstract

Abstract A magnetic field which is contained in a turbulent, electrically conducting fluid is supposed to decay. The decay time of the mean energy of the fluctuating part of the magnetic field – in contrast with the energy of the mean field – is shown to be determined by the molecular magnetic diffusivity and the correlation length of the turbulence. The investigation is carried out for weak magnetic fields in homogeneous isotropic mirror‐symmetric turbulence and in the framework of the second‐order correlations approximation.