Download Fusion - School

Fusion
demonstrate an understanding that the Sun’s energy is generated by nuclear fusion reactions at its core, converting hydrogen into
helium
Nuclear fusion is where the nuclei of small atoms fuse together to form larger nuclei. This is how all
atoms, other than Hydrogen, are made. All atoms are created by the fusion of smaller atoms inside
stars. When the star explodes these heavy atoms are dispersed into space. They may go on to form
planets such as the Earth. Every atom inside your body originated from nuclear fusion inside a star
(except any hydrogen of course). Fusion happens in the core of the Sun where the the temperature is
about 15 million K.
The most common fusion reaction inside our Sun is the fusion of Hydrogen into Helium.
The cycle below is called the proton proton chain which is the most common fusion reaction which
takes place in the Sun. You do not need to learn it.
Mass to Energy
The mass of the products of this reaction are slightly less than the mass of what we started with. The
energy from the reaction comes from the conversion of mass into energy. The total mass of the Sun
actually gets less by 400,000 tons a second. Despite this it has been calculated that the Sun will last
for a few more billion years.
Larger hotter stars such as blue giants do not last anywhere near as long.
Teams of scientists across the world are working very hard on trying to recreate nuclear fusion on a
commercial scale in a fusion reactor. If they are successful we could have a virtually renewable and
environmentally friendly source of huge amounts of energy. The difficulty is recreating the very high
temperatures necessary for fusion to take place.