Pre-activated magnetosphere generates negatively charged solitary potential area in the polar ionosphere. Those areas act as auroral driver and form twist motion of auroral sheet. We suggest that twist motion of the auroral sheet is analogous to the flapping motion of transmission belt in a factory driven by rotating line shaft. Non-uniform shear flows in the auroral sheet trigger flapping instabilities.

Negatively charged solitary potential areas (ion holes) are generated in collisional ionosphere by the incident energetic electrons. Those negative potential regions are ionospheric driver of discrete aurora. When the ion hole becomes sheet-like structure (auroral arc), shear flows develop in the sheet to form spirals.

Auroral spirals known as northern lights are a spectacular light show in the polar night sky. Internal processes in the polar ionosphere initiate northern lights by producing charge separations along the field lines. Parallel electric fields generated above the ionosphere by charge separations are steady-state electric fields. They occasionally discharge to produce northern lights, analogous to lightning flash in a thunderstorm.

Auroral spirals known as northern lights are a spectacular light show in the polar night sky. We show that auroral spirals are produced in the polar ionosphere by the internal processes that ensure quasi-neutral equilibrium of the polar ionosphere which is often violated during field line dipolarization. The internal driver produces spiral auroras in a manner different from the field line mapping scenario.

The ionosphere is a partly ionized medium above the atmosphere. Because of its anisotropic properties, the imposed electric fields from the magnetosphere produce space charge. Polarization electric fields induced in the ionosphere by this process generate ion drifts (Pedersen currents) and plasma evaporation along the field lines, thus achieving a quasi-neutral equilibrium of the ionosphere. The evaporation grows as a large-scale parallel potential structure in the magnetosphere.