Proton-Proton Chain for Fusion Reaction


           


This sequence of events shows the proton-proton chain which is a fusion reaction in the core of Sun-like stars producing helium from hydrogen.
  1. Two protons collide with enough energy to overcome the Coulomb repulsion between them causing them to stick together forming a deuterium nucleus (one proton and one neutron). In the process one proton is converted to a neutron and one neutrino and one positron are released.
  2. The positron collides with an electron. Thus annihilating each other and producing two gamma rays.
  3. The neutrino passes through the star and escapes into space. (Neutrinos rarely interact with matter and pass through most objects undetected.)
  4. The newly formed deuterium nucleus then collides with another proton forming helium-3 (a nucleus with two protons and one neutron). This reaction releases a gamma ray.
  5. The final reaction is the collsion of two helium-3 nuclei creating a helium-4 nucleus (two protons and two neutrons) and releasing two protons.
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