User:Graham.Fountain/Polywell lead section

The polywell is a type of nuclear fusion reactor. It is one of a number of types of reactor, based on inertial electrostatic confinement, which use an electric field to accelerate charged ions and heat them to conditions suitable for nuclear fusion: as the positively charged ions, which are injected into the reactor, are accelerated by the electric field, their kinetic energy rises, and if they collide at the center they can fuse together to form new types of atomic nuclei and release energy. This electric field is generated in a polywell by trapping negatively charged electrons in a null at the center of a magnetic field. These trapped electrons then form a virtual cathode and create a negative voltage drop, or potential well. The magnetic field that traps the electons is generated by a set of electromagnets arranged in the shape of a polyhedron; hence, the name "polywell" from the contraction of "polyhedral" and "potential well". This is closely related to the magnetic mirror, the biconic cusp and the high beta fusion reactor.

The polywell was developed by the late Dr Robert Bussard and the company he founded in 1985, Energy/Matter Conversion Corporation, Inc. (EMC2), with funding from the Defense Threat Reduction Agency, DARPA, and the U.S. Navy. However, the first known proposal to combine this magnetic configuration with an electrostatic potential well in order to improve electron confinement was made by Oleg Lavrentiev in 1975. Bussard and EMC2 developed the polywell as an improvement on another inertial electrostatic confinement fusion reactor, the fusor. Fusors suffer from high conduction losses, because of the way the electic field is generated by a charged wire cage, which most of the ions accelerated towards the center fall into. Hence, no fusor has ever come close to break-even energy output. Whereas the polywell, which does not have this cage, is claimed to be capable of net power production, potentially from aneutronic fusion (without producing neutrons); in which case, it should require relatively low levels of biological shielding.