The last chapter introduced us to the two equations used to calculate plasma fields. It is clear that they work in a step wise alternating fashion which is sufficient for a rough simulation. The problem is that we never achieve sufficient resolution. That is because any disturbance will produce spiral waves that bore down to impossible resolutions.
Thus we progress with developing empirical results and developing limited equations to predict behavior.
Here we discuss sheaths in particular and double layers. Right now we want an intuitive understanding of possibilities.
The thermal aspect of temperature which is caused by large numbers of random collisions is not necessarily present, however, even if there has been sufficient energy input to strip electrons away from their nuclei. The electrons can be fast (energetic) while their (thermal) collision rates are low.
The sheath potential is analogous to the height of the hill.