Field-reversed configuration

A fusion approach using a self-contained, elongated ring of plasma held mostly by magnetic fields from its own internal currents.

• Currents circulating in the plasma create a closed magnetic 'bubble'; outside coils only need to position and compress it.
• It can be formed at one end and pushed along, so machines can be straight and simpler than a tokamak's closed ring.
• Helion collides two such rings and compresses them, aiming to recover electricity directly from the plasma's expansion, with no steam turbine.
• These plasmas have historically been short-lived and prone to instability, and no such device has yet shown net energy gain.