Flash coil figure 8 focality
When we use a round coil, induced electric fields flow in a concentric manner as shown at the left side of the figure 8 coil current flow picture.
The intensity of the electric fields increases in proportion to the radius of the coil.
In contrast, when we use a figure 8 coil the electric fields flow makes two vortices, as shown at the right side of the picture.
The two vortices merge at the center of the figure 8 thereby deliver localized, focussed stimulation because the field strength at the crossing of the wires inside the coil is higher than around the coil, as can been seen as the red color area.
Manufacturing of a Flash figure 8 coil is complicated as can be seen in the requirements of the isometric picture.
During manufacturing of a Flash figure 8 coil the internal wires do cross between the two parts of the coil.
After winding, both sides are then closed with special glue and placed inside a jig and heated inside an oven to dry for 48 hours.
This way the flexibility of both sides of the coil allow for placing the coil around the area to be treated.
At the overlapping area where the wires of both sides of the coil cross, the two vortices merge and create there the highest intensity of the PEMF pulse.