Plasmoid

A plasmoid is a coherent structure of plasma and magnetic fields. Plasmoids have been proposed to explain natural phenomena such as ball lightning, magnetic bubbles in the magnetosphere, and objects in cometary tails, in the solar wind, solar atmosphere, and in the heliospheric current sheet. Plasmoids produced in the laboratory include the compact toroids (similar to a vortex ring in low temperature fluid dynamics or hydrodynamics) field-reversed configurations, spheromaks, and filamentary variants in dense plasma focuses.

The word plasmoid was coined in 1956 by Winston H. Bostick (1916–1991) to mean a "plasma-magnetic entity":

The plasma is emitted not as an amorphous blob, but in the form of a torus. We shall take the liberty of calling this toroidal structure a plasmoid, a word which means plasma-magnetic entity. The word plasmoid will be employed as a generic term for all plasma-magnetic entities.

— Winston H. Bostick