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Superconducting Wire
Superconducting wires are electrical wires made of superconductive material. When cooled below their transition temperatures, they have zero electrical resistance. Most commonly, conventional superconductors such as niobium-titanium are used, but high-temperature superconductors such as YBCO are entering the market. Superconducting wire's advantages over copper or aluminum include higher maximum current densities and zero power dissipation. Its disadvantages include the cost of refrigeration of the wires to superconducting temperatures (often requiring cryogens such as liquid nitrogen or liquid helium), the danger of the wire quenching (a sudden loss of superconductivity), the inferior mechanical properties of some superconductors, and the cost of wire materials and construction. Its main application is in superconducting magnets, which are used in scientific and medical equipment where high magnetic fields are necessary. Important parameters The construction and operating ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Current Density
In electromagnetism, current density is the amount of charge per unit time that flows through a unit area of a chosen cross section. The current density vector is defined as a vector whose magnitude is the electric current per cross-sectional area at a given point in space, its direction being that of the motion of the positive charges at this point. In SI base units, the electric current density is measured in amperes per square metre. Definition Assume that ''A'' (SI unit: m2) is a small surface centred at a given point ''M'' and orthogonal to the motion of the charges at ''M''. If ''I'' (SI unit: A) is the electric current flowing through ''A'', then electric current density ''j'' at ''M'' is given by the limit: :j = \lim_ \frac = \left.\frac \_, with surface ''A'' remaining centered at ''M'' and orthogonal to the motion of the charges during the limit process. The current density vector j is the vector whose magnitude is the electric current density, and whose dire ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iron Pnictide
Iron-based superconductors (FeSC) are iron-containing chemical compounds whose superconducting properties were discovered in 2006. In 2008, led by recently discovered iron pnictide compounds (originally known as oxypnictides), they were in the first stages of experimentation and implementation. (Previously most high-temperature superconductors were cuprates and being based on layers of copper and oxygen sandwiched between other substances (La, Ba, Hg)). This new type of superconductors is based instead on conducting layers of iron and a pnictide (chemical elements in group 15 of the periodic table, here typically arsenic (As) and phosphorus (P)) and seems to show promise as the next generation of high temperature superconductors."Iron Exposed as High-Temperature Superconductor" Scie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cuprate Superconductor
Cuprate superconductors are a family of high-temperature superconducting materials made of layers of copper oxides (CuO2) alternating with layers of other metal oxides, which act as charge reservoirs. At ambient pressure, cuprate superconductors are the highest temperature superconductors known. However, the mechanism by which superconductivity occurs is still not understood. History The first cuprate superconductor was found in 1986 in the non-stoichiometric cuprate lanthanum barium copper oxide by IBM researchers Georg Bednorz and Karl Alex Müller. The critical temperature for this material was 35K, well above the previous record of 23 K. The discovery led to a sharp increase in research on the cuprates, resulting in thousands of publications between 1986 and 2001. Bednorz and Müller were awarded the Nobel Prize in Physics in 1987, only a year after their discovery. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnesium Diboride
Magnesium diboride is the inorganic compound with the formula MgB2. It is a dark gray, water-insoluble solid. The compound has attracted attention because it becomes superconductor, superconducting at 39 K (−234 °C). In terms of its composition, MgB2 differs strikingly from most low-temperature superconductors, which feature mainly transition metals. Its superconducting mechanism is primarily described by BCS theory. Superconductivity Magnesium diboride's superconducting properties were discovered in 2001. Its critical temperature#Superconductivity, critical temperature (''T''c) of is the highest amongst conventional superconductors. Among conventional (BCS theory, phonon-mediated) superconductors, it is unusual. Its electronic structure is such that there exist two types of electrons at the Fermi level with widely differing behaviours, one of them (Sigma bond, sigma-bonding) being much more strongly superconducting than the other (Pi bond, pi-bonding). This is at ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extrusion Process
Extrusion is a process used to create objects of a fixed cross-sectional profile by pushing material through a die of the desired cross-section. Its two main advantages over other manufacturing processes are its ability to create very complex cross-sections; and to work materials that are brittle, because the material encounters only compressive and shear stresses. It also creates excellent surface finish and gives considerable freedom of form in the design process. Drawing is a similar process, using the tensile strength of the material to pull it through the die. It limits the amount of change that can be performed in one step, so it is limited to simpler shapes, and multiple stages are usually needed. Drawing is the main way to produce wire. Metal bars and tubes are also often drawn. Extrusion may be continuous (theoretically producing indefinitely long material) or semi-continuous (producing many pieces). It can be done with hot or cold material. Commonly extruded materials ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pit Process
Pit or PIT may refer to: Structure * Ball pit, a recreation structure * Casino pit, the part of a casino which holds gaming tables * Trapping pit, pits used for hunting * Pit (motor racing), an area of a racetrack where pit stops are conducted * Trading pit, a part of a trading floor where open outcry takes place * Pit cave, a natural cave containing a vertical shaft * Mine (mining) ** Open-pit mine, surface extraction of rock or minerals ** Coal mine or pit Science and technology * Pit, an excavation on metallic surface caused by pitting corrosion * Pit, one of many indentations used to store data on a compact disc * Pit, a seed inside a fruit; for example a cherry pit * Pit (nuclear weapon), the core of an implosion weapon * Powered industrial truck, a US legal term * Programmable interval timer, a computing device * Pulsed inductive thruster, a device used in spacecraft propulsion * Pit (botany), a part of plant cell walls which allows the exchange of fluids * Pyrena, the hard ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
BSCCO
Bismuth strontium calcium copper oxide (BSCCO, pronounced ''bisko''), is a type of cuprate superconductor having the generalized chemical formula Bi2 Sr2 Ca''n''−1 Cu''n'' O2''n''+4+''x'', with ''n'' = 2 being the most commonly studied compound (though ''n'' = 1 and ''n'' = 3 have also received significant attention). Discovered as a general class in 1988, BSCCO was the first high-temperature superconductor which did not contain a rare-earth element. It is a cuprate superconductor, an important category of high-temperature superconductors sharing a two-dimensional layered (perovskite) structure (see figure at right) with superconductivity taking place in a copper-oxide plane. BSCCO and YBCO are the most studied cuprate superconductors. Specific types of BSCCO are usually referred to using the sequence of the numbers of the metallic ions. Thus Bi-2201 is the ''n'' = 1 compound ( Bi2 Sr2 Cu O6+''x''), Bi-2212 is the ''n'' = 2 compound ( Bi2 Sr2 C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High-temperature Superconductivity
High-temperature superconductors (abbreviated high-c or HTS) are defined as materials that behave as superconductors at temperatures above , the boiling point of liquid nitrogen. The adjective "high temperature" is only in respect to previously known superconductors, which function at even colder temperatures close to absolute zero. In absolute terms, these "high temperatures" are still far below ambient, and therefore require cooling. The first high-temperature superconductor was discovered in 1986, by IBM researchers Bednorz and Müller, who were awarded the Nobel Prize in Physics in 1987 "for their important break-through in the discovery of superconductivity in ceramic materials". Most high-c materials are type-II superconductors. The major advantage of high-temperature superconductors is that they can be cooled by using liquid nitrogen, as opposed to the previously known superconductors which require expensive and hard-to-handle coolants, primarily liquid helium. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vanadium–gallium
Vanadium–gallium (V3Ga) is a superconducting alloy of vanadium and gallium. It is often used for the high field insert coils of superconducting electromagnets. Vanadium–gallium tape is used in the highest field magnets (magnetic fields of 17.5 teslas). The structure of the superconducting A15 phase of V3Ga is similar to that of the more common Nb3Sn and Nb3Ti. In conditions where the magnetic field is higher than 8 Tesla and the temperature is higher than 4.2 Kelvin, Nb3Sn and V3Ga see use. The main property of V3Ga that makes it so useful is that it can be used in magnetic fields up to about 18 Tesla, while Nb3Sn can only be used in fields up to about 15 Tesla.Reed, Richard P. Clark, Alan F. (1983). Materials at Low Temperatures – 13.9.3.2 Filament Diameter. ASM International. Retrieved from https://app.knovel.com/hotlink/pdf/id:kt00AEBP4A/materials-at-low-temperatures/filament-diameter The high field characteristics can be improved by doping with high-Z elemen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wire Drawing
Wire drawing is a metalworking process used to reduce the cross-section of a wire by pulling the wire through a single, or series of, drawing die(s). There are many applications for wire drawing, including electrical wiring, cables, tension-loaded structural components, springs, paper clips, spokes for wheels, and stringed musical instruments. Although similar in process, drawing is different from extrusion, because in drawing the wire is pulled, rather than pushed, through the die. Drawing is usually performed at room temperature, thus classified as a cold working process, but it may be performed at elevated temperatures for large wires to reduce forces. Process The wire drawing process is quite simple in concept. The wire is prepared by shrinking the beginning of it, by hammering, filing, rolling or swaging, so that it will fit through the die; the wire is then pulled through the die. As the wire is pulled through the die, its volume remains the same, so as the diameter de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
