In the movie, the red and green dots represent the simulation electrons and ions, respectively. For these particle quantities, the vertical axis is particle velocity along the background magnetic field, with the relative vertical scales between the electrons and ions defined so that the same vertical spread in the electrons and ions mean the two species have the same temperature.
The remaining curves plot, vs. distance along the background magnetic field:
| the electric potential (time averaged) | (yellow) |
| the parallel electric field | (orange) |
| the charge density produced by parallel particle motion | (pink) |
| the perpendicular wave magnetic field | (blue) |
| the charge density produced by perpendicular ion polarization drift | (lavendar) |
A number of interesting features appear in this simulation. First, note the formation of a strong disturbance about 1/6 of the distance across the system from the left boundary. This disturbance is a cluster of double layers, driven by the leftward electron drift associated with the Alfvén wave. Later, another large double layer appears at the extreme right of the system, driven by the rightward traveling electrons. Other weaker double layers driven by rightward traveling electrons are visible just to the left of this double layer. Each double layer is accompanied by a characteristic spike in the electric potential ( in yellow). The potential drops abruptly from left to right for the case of double layers driven by leftward traveling electrons and rises left-to-right when driven by rightward traveling electrons.
Also note that these rightward traveling electrons are accelerated by the Alfvén wave and later steepen up into a significant front racing from left to right, most obvious in the center of the system, at the top of the movie frame, late in the simulation. These electrons are trapped in and are essentially surfing on the rightward-propagating Alfvén wave, identifiable as the rightward progression of all the field quantities graphed in the bottom half of the movie frame. It is this population of electrons which can potentially travel downward along the Earth's magnetic field lines (to the right in our simulation) to produce the Aurora Borealis.
