Early time striation structuring in ionized barium clouds due to the presence of BaO flow

Model calculations of the interaction of a diffusing BaO cloud with an infinite conductivity Ba+ plasma cloud have been performed. This diffusing neutral cloud initially structures the ion cloud preferentially at long wavelengths for values of the ionized cloud radius ρ0, neutral cloud Gaussian radius a, and separation rι between ionized and neutral cloud centers such that ρ0rι/a² ≲ 1. In the plane perpendicular to the ambient magnetic field B the phase of the distortions in the Ba+ cloud is such as to produce ‘dimplings’ of the field line integrated isodensity Ba+ contour at radius ρ0, i.e., to produce displacements radially inward toward the field line integrated Ba+ cloud center at both points where the line passing through the two cloud centers intersects the circle of radius ρ0 centered at the origin of the Ba+ cloud. The amplitude of the displacements is greatest for ρ0/a ≈ 1, rι/a ≈ 1. The inward displacements can be as large as 0.015a. For ρ0 = a this could result in dimplelike displacements of characteristic size ρ0 in times of ∼4ρ0/Vdr, where Vdr is the magnitude of the relative ion-neutral drift velocity in the striating region. Computer simulation results supporting these ideas are shown. Moreover, the theoretical model and attendant numerical results are in general agreement with observations of a 144-km Ba cloud released in the Secede test program.