V-Potential Double Layers and the Formation of Auroral Arcs

A simulation study of the electrostatic interaction of a field-aligned electron current sheet with ambient hot ions ($\frac{T_e}{T_i}\lesssim 0.6$) and a conducting boundary shows that a $V$-shaped potential double layer spontaneously develops and accelerates electrons to the ion thermal energy. It is proposed that this double-layer process is responsible for the aurora energy supply. Only as $\frac{T_e}{T_i}$ approaches unity, the potential exceeds $T_i$ via resistivity enhanced by wave trapping of electrons.