Type1 Ion Phase Space

Vd = -0.4 Vth

A major difference of type 1 weak double layer movement between two component
 model and three component model is a life time of it.  The type 1 weak double 
layer crosses the region of the cold ion x-v phase space like an ion hole.  
In three component model, a type 1 weak double layre moves into the region of
 hot ion x-v phase space.
The size of the net potential jump across a weak double layer is difference 
between the two models, too.  A type 1 weak double layer has positive-nagative
-positive charge layers, and the negative charge is formed by rarefaction of 
the density of cold ions, which we look as an ion hole. The density of cold 
ions is smaller than in two component model,