What is nuclear fusion?

Above - An illustration demonstrating fusion at work.

Nuclear fusion reactions have been releasing massive amounts of energy in our galaxy for billions of years. This is a process where, in the extreme conditions of space, two very light atoms combine to form another larger atom while releasing enormous energy from the nuclear forces of the fusing nuclei. This is the same process by which a star such as our sun produces its solar energy. Whenever we feel the warmth of the sun, and when we can see by its natural light, we are observing the products of nuclear fusion in the galaxy.

When a star is created, it initially consists of hydrogen and helium formed from the “Big Bang”, the process that created our universe.

For more information about the Big Bang theory, go to:
http://map.gsfc.nasa.gov/m_uni/uni_101bb1.html

Hydrogen isotopes collide into the star and fuse, forming a helium nucleus (helium has a higher atomic mass than hydrogen). Later, the helium nuclei collide and form even heavier elements. These reactions continue until the nuclei reach the atomic mass of iron (56) after which it is energetically unfavourable for fusion to produce higher, heavier masses. Then, the star has almost reached the end of its life. Some stars keep shrinking until they become a cooling ember made up of iron. However, if a star is very large, sometimes there can be a tremendous, violent, brilliant explosion.

During this explosion, the star will suddenly expand and produce more energy in a very short time than the energy produced by the sun during a person’s lifetime. When this happens, we say that the star has become a “supernova”. Some of the elements that we find on earth (such as lead, gold and silver) were the products of a supernova explosion. The iron element that we find all through the earth (and also in the earth’s centre) is the result of supernova explosions and dead stars.

For more information about supernovae, go to:
http://imagine.gsfc.nasa.gov/docs/science/know_l2/supernovae.html

Scientists have been producing fusion reactions for about 60 years. Unfortunately, the enormous amounts of energy released have been uncontrollable and the only application of nuclear fusion has been in the destructive hydrogen bomb. Today, we are trying to develop more peaceful uses of fusion energy. When used for mankind’s benefit, the power from nuclear fusion offers an almost unlimited source of energy for future generations. But fusion power also presents many scientific and engineering challenges because extremely high temperatures are required to start the reaction. Hydrogen isotopes, particularly deuterium (found in seawater) and tritium, are the most popular fuels under investigation. However, nuclear fusion research is only in the experimental stage. Due to the cost and the complexity, international cooperation is the only way forward. The challenge is to prove that nuclear fusion power can produce useful energy.

For more information about nuclear fusion, go to:
http://www.jet.efda.org/pages/fusion-basics.html

Next Section >> What is nuclear fission?

^ back to top ^