What is a Polywell Fusion Device?
Polywell was invented by the late Dr. Bussard in 1985. It is a unique approach to fusion that combines fusor or IEC (inertial electrostatic confinement, by Farnsworth, Hirsch, Elmore, Tuck, and Watson) with high beta magnetic cusp (by Grad and his team at New York University).
Polywell Fusion = Polyhedral Magnetic Fields (electron confinement) + Potential Well (ion acceleration and enhanced ion confinement)
The Polywell fusion device operates with a set of electromagnets (e.g., Polyhedral coils in a cube or dodecahedron configuration) generating a cusp magnetic field that traps energetic plasma particles at a high fuel pressure. When electron beams are injected, they create a potential well (i.e., a negative voltage in the central region) that accelerates fuel ions to 100 million degrees or higher for fusion reactions. The potential well also enhances the magnetic confinement of ions in a symbiotic relationship with the magnetic cusp.
In 2013, EMC2 became the first to demonstrate the confinement property of a high beta cusp device in experiments. EMC2 achieved this breakthrough by employing an innovative plasma start-up method with 700 MW of pulsed power. The results are published in a high-impact peer-reviewed journal ("High-Energy Electron Confinement in a Magnetic Cusp Configuration" - https://link.aps.org/doi/10.1103/PhysRevX.5.021024).
In 2019, EMC2 conducted first-ever first principles simulations resolving electron gyroradius scale to elucidate the scientific foundation of high beat cusp confinement utilizing ~ 200 million virtual particles. The results are published in a peer-review journal ("Discovery of an Electron Gyroradius Scale Current Layer: Its Relevance to Magnetic Fusion Energy, Earth's Magnetosphere, and Sunspots" - https://www.frontiersin.org/journals/astronomy-and-space-sciences/articles/10.3389/fspas.2019.00074).
Principles of fuel ion heating by potential well
To generate fusion reactions, fuel ions need to be accelerated to high energy to overcome repulsive electrical forces. In a fusor or IEC device, this can be achieved by physical grids or a virtual cathode (i.e. excess electrons in the device center as shown in the figure, also known as a potential well). In Polywell, electron beams are utilized to create a potential well inside the magnetic cusp that can heat fuel ions. This feat was achieved in 1995 and the results are published in a peer review journal ("Forming and maintaining a potential well in a quasispherical magnetic trap" - https://doi.org/10.1063/1.871103).
