Nuclear Fusion

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Nuclear Fusion in stars

 

 

 

Stars are powerhouses of energy that emit light that can be observed from thousands of light years away. The main sequence stars which compromise 90% of all stars are undergoing nuclear fusion. The most basic and most abundant element in the universe is Hydrogen, it is the fuel of the stars. Two hydrogen atoms are fused together becoming deuterium, or heavy hydrogen. Then the deuterium is fused with another hydrogen nuclei to form an isotope of Helium 3He. Two 3He nuclei then combine to become helium-4 a 4 proton alpha particle. This process is known as the proton-proton chain (pp-chain) and it produces a tremendous amount of energy in the form of gamma rays.

 

The proton-proton cycle is the nuclear fusion process that is dominant in stars that are similar to the earth in size. However stars that are larger than 1.3 times the sun use the carbon-nitrogen-oxygen (CNO) fusion reaction. The different processes stem from different temperatures. Smaller stars need a temperature of roughly four mega kelvins in order for pp-chains to occur. A temperature of fifteen mega kelvins is required for the CNO cycle and this cycle becomes dominate at seventeen mega kelvins.

 

The CNO cycle, like the pp-chain fuses 4 protons together and forms an alpha particle. The catalysts for the nuclear fusion are carbon, nitrogen, and oxygen isotopes. There are several stages in the CNO cycle which can be seen in (Name of picture). This series of nuclear fusion is the CNO 1 cycle. There are several different ways in which the CNO cycle undergoes nuclear fusion. The different CNO cycles stem from fusing different isotopes of carbon, nitrogen, and oxygen. Some will also use other elements for instance Fluorine is used in CNO-2 and CNO-3.

 

The nuclear fusion process converts lighter elements into heavier elements for the life of a star until iron is reached. Nuclear fusion no longer produces energy after iron is made. Once a star converts most of its fuel into iron it reaches the end of its life. Sufficiently large stars will supernova at this point. A supernova creates an immense amount of energy which allows higher order elements then iron to be produced such as gold and silver. These elements are then sent careening throughout space. Earth received its elements from this method of delivery.

Nuclear fusion is a powerful source of energy as evident by the tremendous energy produced by stars. Harnessing this power on earth has been an ongoing project for the past 60 years.