Fusion, or synthesis, is the process of combining two or more distinct entities into a new whole.
Fusion may also refer to:
Nuclear physics is the field of physics that studies atomic nuclei and their constituents and interactions, in addition to the study of other forms of nuclear matter.
Nuclear fusion is a reaction in which two or more atomic nuclei, usually deuterium and tritium, combine to form one or more different atomic nuclei and subatomic particles. The difference in mass between the reactants and products is manifested as either the release or absorption of energy. This difference in mass arises due to the difference in nuclear binding energy between the atomic nuclei before and after the reaction. Nuclear fusion is the process that powers active or main-sequence stars and other high-magnitude stars, where large amounts of energy are released.
The proton–proton chain, also commonly referred to as the p–p chain, is one of two known sets of nuclear fusion reactions by which stars convert hydrogen to helium. It dominates in stars with masses less than or equal to that of the Sun, whereas the CNO cycle, the other known reaction, is suggested by theoretical models to dominate in stars with masses greater than about 1.3 solar masses.
Stellar evolution is the process by which a star changes over the course of time. Depending on the mass of the star, its lifetime can range from a few million years for the most massive to trillions of years for the least massive, which is considerably longer than the current age of the universe. The table shows the lifetimes of stars as a function of their masses. All stars are formed from collapsing clouds of gas and dust, often called nebulae or molecular clouds. Over the course of millions of years, these protostars settle down into a state of equilibrium, becoming what is known as a main-sequence star.
A fusor is a device that uses an electric field to heat ions to a temperature in which they undergo nuclear fusion. The machine induces a voltage between two metal cages, inside a vacuum. Positive ions fall down this voltage drop, building up speed. If they collide in the center, they can fuse. This is one kind of an inertial electrostatic confinement device – a branch of fusion research.
The triple-alpha process is a set of nuclear fusion reactions by which three helium-4 nuclei are transformed into carbon.
Nuclear technology is technology that involves the nuclear reactions of atomic nuclei. Among the notable nuclear technologies are nuclear reactors, nuclear medicine and nuclear weapons. It is also used, among other things, in smoke detectors and gun sights.
Muon-catalyzed fusion is a process allowing nuclear fusion to take place at temperatures significantly lower than the temperatures required for thermonuclear fusion, even at room temperature or lower. It is one of the few known ways of catalyzing nuclear fusion reactions.
Karyogamy is the final step in the process of fusing together two haploid eukaryotic cells, and refers specifically to the fusion of the two nuclei. Before karyogamy, each haploid cell has one complete copy of the organism's genome. In order for karyogamy to occur, the cell membrane and cytoplasm of each cell must fuse with the other in a process known as plasmogamy. Once within the joined cell membrane, the nuclei are referred to as pronuclei. Once the cell membranes, cytoplasm, and pronuclei fuse, the resulting single cell is diploid, containing two copies of the genome. This diploid cell, called a zygote or zygospore can then enter meiosis, or continue to divide by mitosis. Mammalian fertilization uses a comparable process to combine haploid sperm and egg cells (gametes) to create a diploid fertilized egg.
The endosperm is a tissue produced inside the seeds of most of the flowering plants following double fertilization. It is triploid in most species, which may be auxin-driven. It surrounds the embryo and provides nutrition in the form of starch, though it can also contain oils and protein. This can make endosperm a source of nutrition in animal diet. For example, wheat endosperm is ground into flour for bread, while barley endosperm is the main source of sugars for beer production. Other examples of endosperm that forms the bulk of the edible portion are coconut "meat" and coconut "water", and corn. Some plants, such as orchids, lack endosperm in their seeds.
A heterokaryon is a multinucleate cell that contains genetically different nuclei. Heterokaryotic and heterokaryosis are derived terms. This is a special type of syncytium. This can occur naturally, such as in the mycelium of fungi during sexual reproduction, or artificially as formed by the experimental fusion of two genetically different cells, as e.g., in hybridoma technology.
A thermonuclear weapon, fusion weapon or hydrogen bomb is a second-generation nuclear weapon design. Its greater sophistication affords it vastly greater destructive power than first-generation nuclear bombs, a more compact size, a lower mass, or a combination of these benefits. Characteristics of nuclear fusion reactions make possible the use of non-fissile depleted uranium as the weapon's main fuel, thus allowing more efficient use of scarce fissile material such as uranium-235 or plutonium-239. The first full-scale thermonuclear test was carried out by the United States in 1952; the concept has since been employed by most of the world's nuclear powers in the design of their weapons.
Nuclear binding energy in experimental physics is the minimum energy that is required to disassemble the nucleus of an atom into its constituent protons and neutrons, known collectively as nucleons. The binding energy for stable nuclei is always a positive number, as the nucleus must gain energy for the nucleons to move apart from each other. Nucleons are attracted to each other by the strong nuclear force. In theoretical nuclear physics, the nuclear binding energy is considered a negative number. In this context it represents the energy of the nucleus relative to the energy of the constituent nucleons when they are infinitely far apart. Both the experimental and theoretical views are equivalent, with slightly different emphasis on what the binding energy means.
Cytopathic effect or cytopathogenic effect refers to structural changes in host cells that are caused by viral invasion. The infecting virus causes lysis of the host cell or when the cell dies without lysis due to an inability to replicate. Both of these effects occur due to CPEs. If a virus causes these morphological changes in the host cell, it is said to be cytopathogenic. Common examples of CPE include rounding of the infected cell, fusion with adjacent cells to form syncytia, and the appearance of nuclear or cytoplasmic inclusion bodies.
The iron peak is a local maximum in the vicinity of Fe on the graph of the abundances of the chemical elements.
Cell fusion is an important cellular process in which several uninucleate cells combine to form a multinucleate cell, known as a syncytium. Cell fusion occurs during differentiation of myoblasts, osteoclasts and trophoblasts, during embryogenesis, and morphogenesis. Cell fusion is a necessary event in the maturation of cells so that they maintain their specific functions throughout growth.
A fuel is any material that can be made to react with other substances so that it releases energy as thermal energy or to be used for work. The concept was originally applied solely to those materials capable of releasing chemical energy but has since also been applied to other sources of heat energy, such as nuclear energy.
Nuclear computation is a type of computation which allows threads to either spawn new threads or converge many threads to one. The aim of nuclear computation is to take advantage of threading abilities of modern multi-core processors where the trend is to increase their hardware ability to compute more threads then their earlier generation processors.
Colliding beam fusion (CBF), or colliding beam fusion reactor (CBFR), is a class of fusion power concepts that are based on two or more intersecting beams of fusion fuel ions that are independently accelerated to fusion energies using a variety of particle accelerator designs or other means. One of the beams may be replaced by a static target, in which case the approach is termed accelerator based fusion or beam-target fusion, but the physics is the same as colliding beams.
Deuterium–tritium fusion is a type of nuclear fusion in which one deuterium nucleus fuses with one tritium nucleus, giving one helium nucleus, one free neutron, and 17.6 MeV of energy. It is the best known fusion reaction for fusion devices.
