Thermonuclear reaction

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Thermonuclear reaction refers to a nuclear fusion , i.e. a fusion of lighter to heavier atomic nuclei , if it takes place with large amounts of substance and not just as a single nuclear reaction . Thermonuclear reactions are the main energy source of stars and important as the mechanism of nucleosynthesis .

Fusion reactions, starting from the lightest element hydrogen , are exothermic only up to the formation of iron (ie energy-supplying). Therefore this process can only produce elements down to iron, mainly helium , carbon , oxygen , neon , silicon and iron. Heavier elements can then be formed from these through neutron capture , either through the s-process (especially in red giants ) or the r-process (mainly in a supernova ).

In order for a reaction between two atomic nuclei to take place, they must come so close to each other that the short-range strong interaction exceeds the weaker, but long-range electromagnetic interaction , because the electromagnetic interaction causes the two positively charged nuclei to repel each other. In a thermonuclear reaction , the cores reacting with one another collide due to their thermal movement . Therefore, such a reaction only takes place at very high temperatures . Due to the tunnel effect , nuclei that do not come close enough can also fuse with a certain probability. This tunnel probability increases exponentially with temperature.

On earth, thermonuclear reactions occur in an uncontrolled manner in hydrogen bomb explosions . The first such event was the "George" experiment of US Operation Greenhouse in 1951 . Controlled thermonuclear reactions are to be used in future in nuclear fusion reactors .


  • Arnold Hanslmeier : Introduction to Astronomy and Astrophysics , Spektrum Akademischer Verlag, 2nd edition 2007, ISBN 978-3-8274-1846-3 , p. 331ff
  • Albrecht Unsöld , Bodo Baschek: The new cosmos. Introduction to astronomy and astrophysics , 7th edition, Springer-Verlag, Berlin-Heidelberg 2005

Individual evidence

  1. ^ Bernard L. Cohen: Concepts of Nuclear Physics . New York, etc .: McGraw-Hill, 1971, p. 401
  2. Kenneth W. Ford: Building the H Bomb - A Personal History. Singapore: World Scientific 2015, ISBN 978-9814632072 , page 147