Spheromak

A spheromak is a type of plasma configuration with a toroidal shape that contains closed, nested magnetic flux surfaces. Unlike tokamaks, another type of toroidal plasma device, a spheromak does not have a central column linking the hole in the torus. This absence simplifies the mechanical construction and allows for higher power density relative to its size.

Spheromaks are categorized as Compact Toroids (CTs), meaning they are toroidal plasmas confined by self-generated magnetic fields. The magnetic fields responsible for confinement are generated primarily by internal plasma currents, rather than external coils as in many other magnetic confinement fusion devices. The magnetic field configuration includes both toroidal and poloidal magnetic field components of roughly equal strength. This near-equal strength contributes to its stability compared to other CT configurations.

The formation of a spheromak typically involves a process called magnetic reconnection, where magnetic field lines break and reconnect, releasing energy and rearranging the magnetic topology. Several methods exist for spheromak formation, including coaxial plasma guns, inductive methods, and merging pre-formed plasmoids.

Research into spheromaks is ongoing as a potential pathway to controlled thermonuclear fusion. Their compact size and high power density offer potential advantages for fusion reactor designs. However, challenges remain in achieving stable, long-duration confinement and in scaling the technology to reactor-relevant parameters.