Nuclear Fusion

Binding Energy The mass of a nucleus is less than the sum of it constituent protons and neutrons. If we took the same number of protons and neutrons as in the nucleus we were trying to recreate, we would find the total mass of the individual protons and neutrons is greater than when they are arranged as a nucleus. This mass defect (Δm) is actually converted to energy released in fusing the individual protons and neutrons. This energy is called the binding energy.

Fusion Fusion occurs when small nuclei combine into larger nuclei and energy is released. Many stars, including our sun, is powered by fusing 4 hydrogen nuclei to make one helium nucleus. This fusion process is clean and a large amount of energy is released, which is why researchers here on Earth are trying to find ways to use fusion as an alternative energy source.

In another common fusion reaction, tritium is combined with deuterium, to form a helium nucleus and a neutron, along with the release of energy. The equation for this reaction is: Again, note that the sum of the atomic numbers on the reactant and product side must be equal. The same is true for mass numbers.

In 1939 Hans Bethe explained that this process occurs in the stars all over the universe but up to now we have not been able to successfully duplicate this process on earth despite over 50 years of trying. When deuterium and tritium are placed in the core of a reactor and heated to extremely high temperatures, plasma is produced. This plasma must be controlled and confined via strong magnetic fields. If this is achieved, fusion can occur. However, in 2004, a near breakthrough…

The Carbon-Nitrogen-Oxygen Cycle After one complete cycle, a large amount of energy is released. The final carbon-12 nucleus is identical to the original carbon-12 nucleus and is therefore available to start a new cycle. Proton fusion Β+ decay Proton fusion Proton fusion Β+ decay Proton fusion

Iron is believed to be the tenth most abundant element in the universe and the fourth most abundant in the Earth's crust. The graph of binding energies above shows that the Iron atom, situated in the middle of the periodic table, has the highest binding energy and hence is the most stable element. It neither splits nor fuses with other atoms in a nuclear reaction. It represents the dividing line between fission and fusion. The closer an element's mass number is to that of Iron the more stable it is and the less the likelihood that it will split or fuse with other atoms easily. The further an element is from Iron in the periodic table the less the binding energy holding it together, so that the elements at the extremes of the periodic table are the least stable and the most reactive.