Title: Experimental study of mini-magnetosphere,
Abstract: Magnetosphere at ion kinetic scales, or mini-magnetosphere, possesses unusual
features as predicted by numerical simulations. However, there are practically
no data on the subject from space observations and the data which are available
are far too incomplete. In the present work we describe results of laboratory
experiment on interaction of plasma flow with magnetic dipole with parameters
such that ion inertia length is smaller than a size of observed magnetosphere.
A detailed structure of non-coplanar or out-of-plane component of magnetic
field has been obtained in meridian plane. Independence of this component on
dipole moment reversal, as was reported in previous work, has been verified. In
the tail distinct lobes and central current sheet have been observed. It was
found that lobe regions adjacent to boundary layer are dominated by
non-coplanar component of magnetic field. Tail-ward oriented electric current
in plasma associated with that component appears to be equal to ion current in
the frontal part of magnetosphere and in the tail current sheet implying that
electrons are stationary in those regions while ions flow by. Obtained data
strongly support the proposed model of mini-magnetosphere based on two-fluid
effects as described by the Hall term.