Spheromak

A spheromak is an arrangement of plasma formed into a toroidal shape similar to a smoke ring. It contains large internal electric currents and their associated magnetic fields arranged so the magnetohydrodynamic forces within it are nearly balanced, producing confinement times of microseconds without any need for external field coils. Spheromaks belong to a class of plasma configurations called compact toroids, distinct from the externally coiled tokamak and stellarator designs. A spheromak can be created and sustained using magnetic flux injection, an approach that leads to a variant configuration called a dynomak.