Nuclear fusion

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The hydrogen deuterium-tritium (D-T) fusion reaction is being used to make Fusion power.
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The hydrogen deuterium-tritium (D-T) fusion reaction is being used to make Fusion power.

Fusion is the process of making a single heavy nucleus (part of an atom) from two lighter nuclei (atoms). Although the nucleus (atom) that is created by this process is heavier than either of the starting nuclei (atoms), it is not as heavy as the combined (joined) original weight of the starting nuclei (atoms). This lost mass is converted (changed) in to lots of energy (heat and light). Einstein's famous E=mc2 equation (maths) describes the relationship between mass (called m in physics), energy (called E), and c2 which stands for the speed of light multiplied by itself. c2 and the speed of light are called constants because they do not change, this is a very important idea used in modern physics, with fusion it describes how much energy will be made from the joining of atoms.

Fusion is found in the middle of stars like the Sun where hydrogen (the lightest atom) and then helium (the second lightest atom) are fused (joined) together to make energy. This energy reaches us on Earth as sun light and heat and helps all life to survive (live) by making plants grow, and warming the oceans to make clouds and the weather.

Not all elements can be joined; the heavier the element is, the less easily it can be joined with another. After fusion produces an atom of Iron (a metal) no energy is released in the reaction anymore. This is what causes stars to die. They join all of their atoms together to make heavier atoms of different types, until they start to make Iron. After they start to make Iron using fusion, they cannot make heat and light as easily as before and begin to cool down and eventually die. However, it takes a very long time for stars to die, much longer than the age of the Earth.

Fusion is important for people to understand. Now that we know about nuclear fusion we can change how our nuclear (uses atoms) power stations work. Currently nuclear power stations split heavy atoms up to make energy using something called fission, this is the opposite of fusion and does not produce as much energy. The heavy atoms needed for nuclear power plants today are hard to find and have to be mined from the ground, costing lots of money. With fusion power only Hydrogen (deuterium and tritium isotopes) is needed and this can be made from water (heavy water) from the sea or a lake using electrolysis (electricity). Since water is everywhere we use it to make lots more power for far less money. Fusion seems an ideal energy source for the near future, as conventional (commonly used) energy sources such as oil and petrol are depleted.

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