![]() ![]() It is practical to examine the kinetic energies of the products of nuclear fusion in the center of mass frame of reference. The proton fraction interacts by the electromagnetic force with the medium and converts its kinetic energy to thermal energy very quickly. The deuterium-deuterium fusion divides its output energy between neutrons and protons. That is problematic because it is harder to extract the energy from neutrons compared to charged particles. It seems that for power generation, the deuterium-tritium reaction is the most practical, but it provides most of the energy to the released neutron. ![]() It would have to be obtained by breeding the tritium from lithium.Ī large amount of energy is released by nuclear fusion reactions. The tritium part of the fuel is more problematic - there is no sizable natural source since tritium is radioactive with a halflife of about 10 years. Viewed as a potential fuel for a fusion reactor, a gallon of seawater could produce as much energy as 300 gallons of gasoline. This amounts to over 10 15 tons of deuterium. The deuterium part of the fuel does not pose a great problem because about 1 part in 5000 of the hydrogen in seawater is deuterium. Since the most practical nuclear fusion reaction for power generation seems to be the deuterium-tritium reaction, the sources of these fuels are important. The conceptual sketch below is grossly oversimplified since the engineering for handling liquid lithium is quite complex. With fast neutrons, tritium can be bred from the more abundant Li-7: While this constitutes a sizable supply, it is the limiting resource for the D-T process since the supply of deuterium fuel is virtually unlimited. Lithium-6 makes up 7.4% of natural lithium. This would occur if lithium were used as the coolant and heat transfer medium around the reaction chamber of a fusion reactor. The most promising source of tritium seems to be the breeding of tritium from lithium-6 by neutron bombardment with the reaction Or, omitting those constituents whose concentrations do not change:ĭeuterium-Tritium fusion is the most promising of the hydrogen fusion reactions, but no tritium occurs in nature since it has a 10 year half-life. The four fusion reactions which can occur with deuterium can be considered to form a deuterium cycle. In a deuterium-deuterium reactor, another reaction could also occur, creating a deuterium cycle: Of these the deuterium-tritium fusion appears to be the most promising and has been the subject of most experiments. These reactions are more promising than the proton-proton fusion of the stars for potential energy sources. Hydrogen fusion on the earth could make use of the reactions: Compare with fissionĮven though a lot of energy is required to overcome the Coulomb barrier and initiate hydrogen fusion, the energy yields are enough to encourage continued research. The deuterium fuel is abundant, but tritium must be either bred from lithium or gotten in the operation of the deuterium cycle. 80% of that energy yield is in the energy of the neutron, which is not as easily utilized as if it were carried by a charged particle. The reaction yields 17.6 MeV of energy but to achieve fusion one must penetrate the coulomb barrier with the aid of tunneling, requiring very high temperatures. The most promising of the hydrogen fusion reactions which make up the deuterium cycle is the fusion of deuterium and tritium. However, for the fueling of the stars, other fusion reactions will dominate. For elements heavier than iron, fission will yield energy.įor potential nuclear energy sources for the Earth, the deuterium-tritium fusion reaction contained by some kind of magnetic confinement seems the most likely path. If the combined nuclear mass is less than that of iron at the peak of the binding energy curve, then the nuclear particles will be more tightly bound than they were in the lighter nuclei, and that decrease in mass comes off in the form of energy according to the Einstein relationship. If light nuclei are forced together, they will fuse with a yield of energy because the mass of the combination will be less than the sum of the masses of the individual nuclei. ![]()
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