A tokamak uses magnetic fields to trap superhot plasma inside a ring-shaped chamber to enable nuclear fusion. While scientists have studied this process for a long time, engineering challenges remain. Currently, no tokamak has generated net energy for commercial power, as holding the plasma away from walls is very difficult.
A tokamak uses magnetic fields to confine superhot plasma to enable nuclear fusion; despite advances in research, engineering challenges remain, and no tokamak has generated net energy for commercial power
A tokamak is a device that uses magnetic fields to trap very hot plasma inside a ring-shaped vacuum chamber. Plasma, a fourth state of matter, is a gas whose atoms have been stripped of their electrons, leaving free electrons and charged nuclei. The word comes from a Russian acronym describing a toroidal (ring-shaped) chamber with magnetic coils. The best-known fusion energy project in the world, the International Thermonuclear Experimental Reactor (ITER), uses this design.
Nuclear energy today comes almost entirely from fission, the controlled chain reaction of uranium atoms, but fusion has always been theoretically possible and a subject of consistent long-term investigation by scientists. When light atomic nuclei such as deuterium and tritium, two isotopes of hydrogen and the best-studied candidates, join, they form helium and a fast neutron. But even this simple merger requires temperatures hotter than the sun's core, which no earthly material can contain. In physics, this is called the problem of containment. Contact with a wall would also cool the plasma and contaminate it with impurities. Plasma, being made of charged particles, can be steered by magnetic fields, and a tokamak uses that property to hold it away from the walls long enough for fusion to occur.