Nuclear fusion
The joining together of two smaller atomic nuclei to produce a larger nucleus. Radiation is released when this happens. Nuclear fusion happens in stars like our Sun, and in hydrogen bombs. is when two small, light Nuclei is the plural of nucleus. The nucleus is the central part of an atom. It contains protons and neutrons, and has most of the mass of the atom. join together to make one heavier nucleus. Fusion reactions occur in stars where, for example, two hydrogen nuclei fuse together under high temperatures and pressure to form a nucleus of a helium Atoms of an element with the same number of protons and electrons but different numbers of neutrons..
There are a number of different nuclear fusion reactions happening in the Sun. The simplest is when four hydrogen nuclei become one helium nucleus.
\(4 _{1}^{1}\textrm{H} \rightarrow _{2}^{4}\textrm{He}\)
The combined mass of four hydrogen nuclei is 6.693 × 10-27 kilograms (kg). The mass of one helium nucleus is 6.645 × 10-27 kg. This means that there is a missing amount of mass equalling 0.048 × 10-27 kg.
The missing mass is converted to energy, which Spreads out from a source. Energy is transferred as a wave. away. This is seen happening in the Sun. In all Changes that occur in the nucleus of an atom. Eg due to radioactive decay, nuclear fission or nuclear fusion., a small amount of the mass changes to energy.
However, the issue with fusion is that it requires the fusing of nuclei, which are positive particles. As two nuclei approach each other, they will Objects that tend to push apart because of a force between them repel each other. because they have the same Property of matter that causes a force when near another charge. Charge comes in two forms, positive and negative. For example, a negative charge causes a repulsive force on a neighbouring negative charge.. The fusion of the nuclei has to happen under intense pressure and very high temperatures in order to force the nuclei together and overcome this electrostatic repulsion.
This need for a very high temperature and pressure makes it very difficult to build a practical and economic fusion power station. For fusion to occur at the lower pressures in a reactor on Earth, the temperature would need to be between 100 and 200 million degrees. Fusion has been successfully achieved by scientists at the JET experiment near Oxford but so far they have been unable to create a financially viable reactor.
Jonny Nelson introduces an animated explanation of fission and fusion