Nuclear fusion, also known as nuclear fusion, fusion reaction, fusion reaction or thermonuclear reaction, is a form of nuclear reaction in which two lighter nuclei combine to form a heavier nucleus and an extremely light nucleus (or particle).Atoms with small mass mainly refer todeuteriumUnder certain conditions (such as ultra-high temperature and high pressure), it can free extranuclear electronsNucleusThe two atomic nuclei can attract each other and collide with each other, so that the atomic nuclei can polymerize with each other and generate new atomic nuclei with heavier mass (such ashelium）Although the neutron mass is relatively large, because the neutron is not charged, it can also escape from the bondage of the atomic nucleus in the collision process and be released. The release of a large number of electrons and neutrons shows a huge energy release
Humans have been able to achieve uncontrolled nuclear fusion, that is, the explosion of hydrogen bombs.At present, scientists are working hard on controllable nuclear fusion, which may become the energy source in the future.
Nuclear fusion, that is, hydrogen nuclei (such as deuterium and tritium) combine to form heavier nuclei (such as helium), releasing huge energy.Because chemistry is a science that studies the properties, composition, structure and change laws of substances at the molecular and atomic levels, while nuclear fusion occurs at the nuclear level, so nuclear fusion is not a chemical change[1]。
Schematic Diagram of Nuclear Fusion
There is a huge amount of energy in the atomic nucleus. The change in the mass of the atomic nucleus (from one atomic nucleus to another) is often accompanied by the release or absorption of energy (mass energy equation).Nuclear fusion is the opposite form of nuclear reaction to nuclear fission, and in theory, nuclear fusion reaction will end in iron (Fe), because the atomic nucleus of iron is the most stable.
Nuclear fusion type
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Thermonuclear fusion
If thermonuclear fusion reaction is to be carried out, first of all, the temperature of the material must be increased (a high temperature of several million degrees or more) to separate the atomic nucleus and electrons. The material in this state is called plasma.Nuclear force is a very powerful force, but its range of force is only about 10 ^ - 15 meters. When protons and neutrons approach this range, nuclear force will play a role, so nuclear fusion reaction will occur[2]。
Cold fusion
Cold nuclear fusion refers to the hypothesis of nuclear fusion reaction at normal temperature and pressure.Cold nuclear fusion is different from "hot" nuclear fusion with high temperature and pressure in the interior of stars, thermonuclear weapons and experimental fusion reactors, and does not include normal temperature nuclear fusionμSub catalytic fusion.At present, there is no cold fusion theory or phenomenon accepted by the mainstream physics consensus.
Development of nuclear fusion
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In 1919, F. W. Aston found in his experiment that "the mass of helium-4 is about 1% less than the sum of the masses of the four hydrogen atoms that make up helium. According to Einstein's mass energy relationship, its mass difference is just equal to the energy released when four hydrogen nuclei converge into one helium-4. Rutherford also proved that nuclear reactions can occur when light nuclei with enough energy collide with each other almost at the same time[3]。
In 1920, Arthur Eddington, a British astronomer, argued in his book "Star Internal Structure" that stars, including the sun, are powered by nuclear fusion of hydrogen.
In 1929, Atkinson and Houtermans theoretically calculated the possibility of hydrogen atom fusing into helium at tens of millions of degrees of temperature, and believed that such nuclear fusion reaction might be carried out on the sun.
In 1934, Oliphant discovered the first D-D nuclear reaction.
In 1942, Schreiber and King first discovered the D-T nuclear reaction in Purdue University.
In 1951, the United States completed the first human nuclear fusion in a nuclear test.
In 1952, the United States conducted the first large-scale nuclear fusion in the hydrogen bomb test.
In 1967, China's first hydrogen bomb explosion test was completely successful over Lop Nur, Xinjiang in the western region.[1]
