Magnetic bottle

A magnetic mirror is a type of magnetic confinement device, used in physics experiments to trap high temperature plasma using magnetic fields. The mirror was one of the earliest major approaches to fusion power, along with the stellarator and z-pinch machines.

In a magnetic mirror, a configuration of electromagnets is used to create an area with increasing density of magnetic field lines at either end of the confinement area. Particles approaching the ends experience an increasing force that eventually causes them to reverse direction and return to the confinement area. This mirror effect will only occur for particles within a limited range of velocities and angles of approach.

The magnetic mirror was one of the major approaches to magnetic confinement fusion from the 1960s into the 1980s. Large experimental magnetic mirror machines have been developed to confine hot deuterium plasma as a possible approach to fusion power, since the plasma is too hot for any solid container. The largest such machine was the Mirror Fusion Test Facility (MFTF) completed in 1986 at Lawrence Livermore Laboratory in the US. The approach has since seen less development, in favor of the tokamak, but mirror research continues today in countries like Russia.

The concept of magnetic-mirror plasma confinement was proposed in mid-1950s independently by Gersh Budker at the Kurchatov Institute, Russia and Richard F. Post at the Lawrence Livermore National Laboratory. The first small-scale open magnetic plasma trap machine ("probkotron") was built in 1959 at the Budker Institute of Nuclear Physics in Novosibirsk, Russia.

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