Magnetized Target Fusion with a Spherical Tokamak

Abstract

With good confinement and relatively high beta (up to 40%), the spherical tokamak could be a suitable magnetized target. To illustrate this potential, the theoretical fusion yield from compressing a spherical tokamak adiabatically to fusion conditions is calculated. While it is found that the large amount of energy stored in the compressed toroidal field constrains the potential energy gain, a system can be designed to produce significant useful output by directly recovering a large fraction of the compression energy. With 80% energy recovery, an example system using 140 MJ of pressurized gas to compress the spherical tokamak plasma within a 2 m radius liquid metal flux conserver can produce a fusion yield of 140 MJ and a net output of 40 MJ per pulse. At ~ 1 Hz this would produce 40 MW_electric.