THE STRUCTURE OF A EQUILIBRIUM MAGNETOTAIL

Considering the presence of the plasma sheet and the plasma mantle,we obtain a two-dimensional self-consistent equilibrium model of the magnetoteil based on the Vlasov equation.The model is characterized by an equilibrium state.The pressure is assumed to be isotropic.The gradients parallel to the tail are assumed to be much smaller than the perpendicular one.Our model is of two-dimensions,the gradients in y-direction are neglected.Our model includes a number of dominant structural elements: (1) the plasma sheet,a region of hot plasma; (2) the closed field lines inside the plasma sheet; (3) the tail lobe,regions of dilute plasma between plasma sheet and magnetopause; (4) the plasma mantle,regions of magnetosheath-like plasma inside and adjacent to the magnetopause; (5) magnetopause,the boundary of the magnetosphere; (6) the flaring magnetotail.We have discussed the influence of the presence of the plasma mantle on the equilibrium model of the magnetotail.The model tells that the presence of the plasma mantle makes the magnetotail more "tail" like.So it overcomes partly,at least,the difficulty in Birn's model.