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Nuclear fusion is the reaction in which two or more nuclei combine together to form a new element with a higher atomic number (more protons in the nucleus). The energy released in fusion is related to E = mc 2 (Einstein’s famous energy-mass equation). On earth, the most likely fusion reaction is Deuterium–Tritium reaction. Deuterium and Tritium are both isotopes of hydrogen.
For a nuclear fusion reaction to occur, it is necessary to bring two nuclei so close that nuclear forces become active and glue the nuclei together. Nuclear forces are small-distance forces and have to act against the electrostatic forces where positively charged nuclei repel each other. This is the reason why nuclear fusion reactions occur mostly in high density, high temperature environment.
At very high temperatures, electrons are stripped from atomic nuclei to form a plasma (ionized gas). Under such conditions, the repulsive electrostatic forces that keep positively charged nuclei apart can be overcome, and the nuclei of select light elements can be brought together to fuse and form other elements. Nuclear fusion of light elements releases vast amounts of energy and is the fundamental energy-producing process in stars.
The goal of fusion research is to confine fusion ions at high enough temperatures and pressures, and for a long enough time to fuse. There are two main confinement approaches:
Sustained fusion reactions would produce vast amounts of clean energy with zero carbon emissions. For a given mass of fuel, the energy released from fusion would substantially exceed the energy released from fission (the neutron-induced splitting of heavy elements such as uranium) and would far exceed (by millions of times) the energy released in chemical reactions (e.g., the burning of coal, gas, or oil).
DID YOU KNOW?
In September 2013, scientists at the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory achieved the first step towards harnessing the power of the sun here on earth – they got more energy out of a fuel burn than was put into it. The achievement falls short of the NIF’s stated definition of “ignition”, which requires that the fuel burn release more energy than all of the energy used by the machine. To be clear, at this point they achieved a release of energy greater than that which the laser beams put into the fuel capsule.
Center for Nuclear Science and Technology Information of the American Nuclear Society
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