Thanks for a layman-lucid explanation. Does the Polywell design also fit into the overall fusion research picture as yet another design that might one day contribute parts of itself to the final working design as the Max Planck director suggested would happen with the tokamak and stellarator designs?
The polywell is an interesting concept, but it is extremely different from every other confinement mechanism, so it's hard to see how the ideas could be incorporated. To be precise, there are two "shapes" of "electromagnetic fields": curl-free (electric (unless magnetic monopoles exist)) and divergence-free (magnetic or electric), and each kind of field lends itself to a different kind of degree of symmetry in a confinement mechanism. Specifically, a divergence-free field cannot admit a spherical confinement because of Green's theorem, whereas a curl-free field requires a very unrealistic charge configuration to generate a toroidal confinement.
Tokamaks use a combination of divergence-free magnetic fields and divergence-free electric fields to make a donut. Stellarators use only magnetic fields to make a twisted donut. The polywell uses curl-free electric fields generated by an electron gun to make a sphere. There are other variants of inertial electrostatic confinement fusion, including that currently under development by Lockheed Martin, but it's generally received less attention.
