Energy

Fusion reactor

The fusion reactor works according to the opposite principle to the fission reactor. The fission reactor divides the nuclei of heavy atoms and the resulting heat is released in order to heat water and activate, through the water vapour, a turbine that produces electricity. Instead in the fusion reactor, light atoms (hydrogen isotopes deuterium and tritium) are united into a helium atom (fusion). The fusion frees a bit more energy than the fission and does not produce any radioactivity. In the fusion, only if two nuclei are located very close one to the other, the force of nuclear attraction melts them. The problem is that this force only act at very short distances, at thousand billion parts of a millimetre, and as the nuclei that are going to be melted are both positively charged, when they get closer, they tend to push back and do not melt due to another force, i.e. electrostatic repulsion, that acts on bigger distances and hamper the fusion. In order to break that barrier, the nuclei have to be in excitement state, at more than a hundred million degrees temperature, when atoms are detached from their electron “shell”. This is the condition when the fusion naturally occurs between light atoms. The extremely high temperature that is needed to fusion plasma (the ionised hot mixture of deuterium and tritium, hydrogen isotopes), i.e. several million degrees, has not allowed to build a fusion reactor at industrial level. Nevertheless, the research is continuing to make important progress and the objective seems to be approaching.