Fusion Energy
Magnetic fusion confinement with tokamaks and stellarators By Wolfgang Picot
T
he first fusion reactions in a laboratory were achieved in 1934 — a major breakthrough at the time. Today, however, achieving a fusion reaction is not particularly difficult: in 2018, a twelve-year-old entered the Guinness World Records as the youngest person to successfully create a fusion experiment at home. Unfortunately, such experiments produce bursts lasting just fractions of seconds, and achieving and sustaining these fusion reactions for prolonged periods remains a major challenge. Only by developing a steady and reliable way of producing fusion power can fusion become a commercially viable energy source.
How a tokamak works: The electric field induced by a transformer drives a current (big red arrows) through the plasma column. This generates a poloidal magnetic field that bends the plasma current into a circle (green vertical circle). Bending the column into a circle prevents leakage and doing this inside a doughnutshaped vessel creates a vacuum. The other magnetic field going around the length of the doughnut is referred to as toroidal (green horizontal circle). The combination of these two fields creates a three-dimensional curve, like a helix (shown in black), in which the plasma is highly confined.
6 | IAEA Bulletin, May 2021
Fusion power Fusion power exploits energy released from the ‘fusion’ of light atomic nuclei. When two such particles merge, the resulting nucleus is slightly lighter than the sum of the originals. The difference, rather than disappearing, is converted into energy. Amazingly, this tiny loss of mass translates into a tremendous amount of energy that makes the pursuit of fusion energy highly worthwhile. There are three states of matter: solid, liquid and gas. If a gas is subjected to very high temperatures, it becomes a plasma. In plasma, electrons are stripped from the atoms. An atom with no electrons orbiting around the nucleus is said to be ionized and is called an
