Nuclear Fusion

It is a nuclear process, where energy is produced by smashing together light atoms. It is the opposite reaction of fission, where heavy isotopes are split apart. Fusion is the process by which the sun and other stars generate light and heat.  It’s most easily achieved on Earth by combining two isotopes of hydrogen: deuterium and tritium. Hydrogen is the lightest of all the elements, being made up of a single proton and a electron. Deuterium has an extra neutron in its nucleus; it can replace one of the hydrogen atoms in H₂0 to make what is called “heavy water.” Tritium has two extra neutrons, and is therefore three times as heavy as hydrogen. In a fusion cycle, tritium and deuterium are combined and result in the formation of helium, the next heaviest element in the Periodic Table, and the release of a free neutron.

Deuterium is found one part per 6,500 in ordinary seawater, and is therefore globally available, eliminating the problem of unequal geographical distribution of fuel resources. This means that there will be fuel for fusion as long as there is water on the planet.

What is Fusion Power?

Let’s take look at a fusion reaction. You can see that as deuterium and tritium fuse together, their component parts are recombined into a helium atom and a fast neutron. As the two heavy isotopes are reassembled into a helium atom, you have ‘extra’ mass leftover which is converted into the kinetic energy of the neutron, according to Einstein’s formula: E=mc2.

For a nuclear fusion reaction to occur, it is necessary to bring two nuclei so close that nuclear forces become active and glue the nuclei together. Nuclear forces are small-distance forces and have to act against the electrostatic forces where positively charged nuclei repel each other. This is the reason nuclear fusion reactions occur mostly in high density, high temperature environment.  At very high temperatures, electrons are stripped from atomic nuclei to form a plasma (ionized gas). Under such conditions, the repulsive electrostatic forces that keep positively charged nuclei apart can be overcome, and the nuclei of select light elements can be brought together to fuse and form other elements. Nuclear fusion of light elements releases vast amounts of energy and is the fundamental energy-producing process in stars.  The goal of fusion research is to confine fusion ions at high enough temperatures and pressures and for a long enough time to fuse.

The light and heat from stars, such as the Sun, is made by a process known as nuclear fusion.   Fusion happens when two lightweight atoms. are forced together to form a heavier one, and a lot of energy is produced as a result. However, fusion can only occur at the incredibly high temperatures and pressures found at the centre of stars. All chemical elements in the universe heavier than Hydrogen and Helium were created in stars through nuclear fusion. At the end of the star's lifetime, these heavy elements can be re-distributed into space and nearby gas clouds or nebula, and so form the building blocks for future generations of stars.

This means that you, and everything around you, must be made of "stardust".

Nuclear fusion occurs in stars

Scientists are trying to find a way to make nuclear fusion power stations, since they would be much cleaner to run than our current nuclear fission power stations and they would produce a lot of energy. However, this is very difficult to do on Earth because you have to make the "fuel" very hot and squeeze it down into a tiny space to get fusion to work.