Drag Forces, Neutral Wind and Electric Conductivity Changes in the   Ionospheric E Region
  The neutrals in the Earth environment are in fact free and subjected to drag forces (by ions). In this study we show that drag or friction forces in the ionosphere-thermosphere system initiate changes in the plasma flow, neutral wind, and the conductivity, as well. Ions and electrons embedded in neutral wind field of velocity u acquire drifts perpendicular both to the initial neutral wind velocity and to the ambient magnetic field producing a perpendicular electric current. This perpendicular electric current is defined by a conductivity derived previously and the polarization electric field u x B. Self-consistently, the free neutrals acquires an additional neutral velocity component perpendicular to the initial neutral wind velocity u. The Pedersen and Hall currents wane within a specific time inversely proportional to neutral-ion collision frequency. These findings are relevant to a better understanding of electric current generation, distribution and closure in weakly ionized plasmas where charged particles (plasma) and neutrals are not bound (free) as the ionosphere and thermosphere in the Earth environment, the solar atmosphere-chromosphere region and even dusty plasmas. The theoretical results supposedly address to recent observations of meso-scale neutral wind rotation in the vicinity of auroral arcs (Kosch et al, 2010). 
Petko Nenovski
physics.space-ph astro-ph.SR physics.plasm-ph