looks like your getting bubbles off the sharp edges that are the shortest path between the 2 poles
so the theory of Horvath is the shape gives the equal surface area on both plates? that's what I always thought but if the 8 points are the major contributors then the concave curves are lacking , being further distance.
I don't trust Meyers, Horvath or any patents.
Your demo is the first time I have ever seen a replication of the patent drawing, on that basis you are #1 in this area.
maybe the field has to relate to this shape ?
the visual of this cell is similar to the magnetron . Good for you , that is amazing dedication