Tokamak

Tokamak is a device used in nuclear fusion research for magnetic confinement of plasma. It is one of several types of magnetic confinement devices being developed to produce controlled thermonuclear fusion power. As of 2021, it is the leading candidate for a practical fusion reactor.

History

The tokamak was invented in the 1950s by Soviet physicists Igor Tamm and Andrei Sakharov, inspired by an original idea of Oleg Lavrentiev. The name is a Russian acronym for "toroidal chamber with magnetic coils".

Design and operation

A tokamak is essentially a torus, or doughnut-shaped vessel, in which a powerful magnetic field is used to confine a plasma of ions and electrons. The magnetic field is produced by a combination of external coils and a large current flowing in the plasma itself. The plasma is heated to temperatures of tens of millions of degrees, at which point the ions can overcome their mutual repulsion and fuse together, releasing a large amount of energy.

Major tokamaks

Several major tokamaks have been built around the world, including the Joint European Torus (JET) in the UK, the Tokamak Fusion Test Reactor (TFTR) in the US, and the T-15 in Russia. The largest and most ambitious tokamak project currently underway is the International Thermonuclear Experimental Reactor (ITER) in France, which is expected to be the first tokamak to produce a net gain in energy.

Challenges and criticism

Despite its promise, the tokamak approach to fusion power has faced several challenges. These include the difficulty of maintaining a stable plasma, the high cost of building and operating large tokamaks, and the problem of neutron radiation damage to the tokamak's structure. Some critics also argue that other approaches to fusion power, such as inertial confinement fusion or magnetic mirror devices, may be more promising.

See also

• Nuclear fusion
• Magnetic confinement fusion
• Inertial confinement fusion
• Magnetic mirror
• Plasma (physics)