| 1G | First generation HTS wires, formed by extrusion of BSCCO, coated with metal. |
| 2G | Second generation HTS wires, formed by depositing YBCO onto a metal substrate. |
| AC | Alternating current. Also ac. |
| Alpha channeling | A cooling technique that removes alpha particles from a fusion reactor while capturing their energy. |
| Ampere | Unit of electric current. Also Amp or A. |
| Anneal | To heat and then slowly cool a material to reduce brittleness. Annealing of ceramic superconductors usually follows sintering and is done in an oxygen-rich atmosphere to restore oxygen lost during calcination. The oxygen content of a ceramic superconductor is critical. For example, YBCO with 6.4 atoms of oxygen will not superconduct. But YBCO with 6.5 atoms will. (from superconductors.org) |
| ASD | Adjustable-speed drive |
| B | Magnetic Flux Density, also referred to as magnetic field. In Units of Teslas. Related to H via B = mH. |
| BCS theory | Theory developed to explain the properties of Type 1 superconductors by John Bardeen, Leon Cooper, and Robert Schrieffer. Key elements of the theory are Cooper Pairs of electrons. (from superconductors.org) |
| Bi-2212 | Bi2Sr2CaCu2Ox. Also known as BSCCO – 2212. See BSCCO. |
| Bi-2223 | (Bi, Pb)2Sr2Ca2Cu3Ox. Also known as BSCCO – 2223. See BSCCO. |
| Biaxially textured | Textured along two axes. |
| Borocarbides | Superconducting borocarbides are compounds containing both boron and carbon in combination with rare-earth and transition elements; some of which exhibit the unusual ability to return to a normal, non-superconductive state at temperatures below TC. (from superconductors.org) |
| BSCCO | HTS compound containing Bi, Sr, Ca, Cu, O, and typically including Pb for the best possible TC . Also known as Bi-2223 or (Bi,Pb)2Sr2Ca2Cu3O10,. Used in 1G HTS wires. |
| BSCCO-2223 | See Bi-2223 |
| Buffer | Material put in place between metal substrate and superconductor material to prevent contamination and provide texturing. |
| CCPPC | Continuous Columnar Pinning Centers. Type of pinning center produced by radiation damage, gives continuous columns of damage. See Flux Pinning. |
| Ceramics | Ceramic superconductors are inorganic compounds formed by reacting a metal with oxygen, nitrogen, carbon or silicon. Ceramics are typically hard, brittle, heat-resistant materials formed by a process known as solid-state reaction. (from superconductors.org) |
| Ceria | CeO2 Cerium oxide. Buffer material for HTS. See buffer. |
| chemical solution deposition | A technique for depositing thin films by dipping or spraying a substrate with a solution. |
| CIC | Cable-in-conduit. |
| closed-cycle refrigeration | Cooling system in which the cooling substance is recycled through the system and reused. |
| Coated conductor | A superconductor formeby depositing a superconducting film layer on a substrate. See thin film and thick film. |
| conductor | Conductors are materials that contain movable charges (electrons or holes) of electricity. When an electric potential difference is impressed across separate points on a conductor, the mobile charges within the conductor are forced to move, and an electric current between those points appears in accordance with Ohm's law. While many conductors are metallic, there are non-metallic conductors as well, including all plasmas. |
| Cooper pairs | Two electrons in a material that couple together as a result of interacting with the lattice. Main cause of superconductivity in BCS theory. |
| Critical current | Maximum current through a material that allows it to remain in the superconducting state. Also IC. |
| Critical fields | Minimum and maximum magnetic fields between which a material is superconducting. Also Hc1 (minimum) and Hc2 (maximum) |
| Critical temperature | Maximum temperature at which a material is superconducting. Also known as transition temperature. |
| CRT | Composite reaction textured |
| Cryocooler | Also see pulse tube cryocooler |
| Cryogenics | A branch of physics and engineering that studies and produces very low temperatures (below –150 °C, –238 °F or 123 K) and the behavior of materials at those temperatures. |
| Current density | Electrical current per cross-sectional area. Measured in Amps/m2. Also J. See JC. |
| CVD | Chemical vapor deposition, A method of forming dense structural parts or coatings using the decomposition of relatively high vapor pressure gases. |
| DAC | Diamond anvil cell, used to apply pressure to a sample in the laboratory, often to increase the TC of a superconductor. It is composed of 2 diamonds and a stainless steel gasket containing a small chamber full of fluid. Hydrostatic forces in excess of a million atmospheres can be brought to bear on a sample suspended within the fluid. |
| DC | Direct current |
| DC sputtering | A sputtering deposition in which direct current is applied to a cathode in a vacuum tube. Used for thin film deposition. |
| Defects | Nano-particles, dislocations, stacking faults, or columnar defects in the crystal structure that can increase HTS critical current. See Flux Pinning. |
| Diamagnetism | The ability of a material to repel a magnetic field. Superconductors exhibit strong diamagnetism below TC. In a few rare compounds, a material may become superconductive at a higher temperature than the point at which diamagnetism appears. But, as a rule, the onset of strong diamagnetism is one of the most reliable ways to ascertain when a material has become superconductive. (from superconductors.org) |
| Dilution refrigerator | Cryogenic device using helium to cool systems to micro-Kelvin temperatures. |
| Doping | A process of adding impurities to the crystal lattice of a semiconductor in order to control its properties. Some heavily-doped semiconductors are capable of superconductivity. |
| E-beam evaporation | Electron beam evaporation. Method by which a substance is vaporized by bombarding it with electrons. |
| Electropolishing | Sometimes called reverse electroplating, this is an electrochemical process which polishes a metal surface by removing a microscopic amount of material from the work piece. Used on some radio frequency particle accelerator cavities. |
| Expitaxial | A thin film with the same crystal structure as the substrate it was grown on. The property of superconductor materials to grow this way is used to get films with good grain alignment. |
| Ex-situ | "Out of place." In wire manufacturing, when the superconducting material is formed, then put into place. Compare In-situ. |
| Fault Current Limiter | Device to reduce a fault current in an electrical power system. |
| FCL | See fault current limiter |
| Flux lattice | Magnetic flux lines in a superconductor arrange themselves into a regular lattice. |
| Flux lines | Lines of magnetic flux inside a superconductor. Also known as vortices because the current spirals around them. These form a lattice structure, and flow through the material as the magnetic or electric field changes. The motion of flux lines dissipates energy and destroys the superconductor state. As the external magnetic field increases, the number of lines will increase, until the superconductor is full of them and the superconductor state is destroyed. |
| Flux Pinning | Preventing the movement of flux lines within a superconductor. This prevents destruction of superconductivity, and can be achieved by defects in the superconductor structure. |
| Flux Qubit | Micro-metre sized loops of superconducting metal interrupted by a number of Josephson junctions. Used to perform computations with qubits. |
| Fluxon | Quantized line of magnetic flux. |
| Four-point Probe | The most common method of determining the TC of a superconductor. Wires are attached to a material at four points with a conductive adhesive. Through two of these points a voltage is applied and, if the material is conductive, a current will flow. Then, if any resistance exists in the material, a voltage will appear across the other two points in accordance with Ohm’s law (voltage equals current times resistance). When the material enters a superconductive state, its resistance drops to zero and no voltage appears across the second set of points. By using the four-point method, instead of just two points, resistance in the adhesive and wires can be ignored; as the second set of points do not themselves conduct any current and can, therefore, only reflect what voltage exists across the body of the material. (from superconductors.org) |
| Free path length | Mean distance a electron will travel through a material without interacting. |
| FRP | Fiber-reinforced plastic |
| FWHM | Full width at half maximum |
| giant flux creep | Large thermal decay of current observed in high Tc superconductors (HTS). |
| Grain | Single crystal of superconductor material. |
| Grain Alignment | Orientation of grains to one another, less than 4o angle is best for superconductor. |
| Grain Boundary | Boundary between superconductor grains. |
| GZO | Gadolinium zirconium oxide, a buffering/texturing material used in some IBAD processes. |
| H | Henry. Magnetic field strength in units of Amps/meter. Related to B (magnetic flux density in teslas) via B = mH. |
| Hastelloy | Trade name of commercial Ni-based high temperature alloys. |
| Hc2 | Upper critical field. |
| High-Temperature Superconductors | High temperature superconductor – ceramic materials that superconduct with a Tc of 30 K or greater. Some examples are YBCO and BSCCO. Also known as HTS. |
| HOP | Operating magnetic field. |
| HTS | See High-temperature superconductors. |
| I | Current expressed in amps |
| I2R | Joule heating, the product of the current squared times the resistance of a conductor. |
| IBAD | Ion beam assisted deposition. A technique for depositing thin superconductor films. An ion beam is directed at an angle towards the substrate to grow textured buffer layers. |
| IC | See critical current. |
| Ic | Critical current of a superconductor, the maximum amount of current that can flow below a fixed electric field or resistivity criterion. |
| IFL | I = current, FL = full load. Full load current |
| Index value n | The n-value describes the relationship of the voltage drop across the wire to the applied current. (from amsuper.com) |
| In-situ | "In place." In wire manufacturing, when the precursors to the superconductor are put into place before being reacted to form the superconducting compound. Compare Ex-Situ. |
| IPP | Independent power producer |
| IR | Current times the resistance of a conductor; equals the voltage drop along the conductor. |
| Irreversibility line | The line which separates the mixed state region of the H-T plane of a type 2 superconductor into two regions, below which the critical current density has a finite value and turns to zero. |
| ISD | Inclined substrate deposition, Method for depositing a buffer onto a substrate at an angle in order to get good texturing. |
| I-V | Current-voltage |
| Jc | Critical current density. Maximum current density in a material that allows it to remain in the superconducting state. |
| JE | Engineering critical current – critical current density calculated for the entire wire, not just the superconductor material. Includes effects of buffers, substrate. |
| Josephson Junction | A thin layer of insulating material sandwiched between 2 superconducting layers. Electrons tunnel through this non-superconducting region via the Josephson effect. Key components in superconductor electronics and computing. (from superconductors.org) |
| Laser Ablation | |
| Large-grain HTS | HTS produced in relatively large thicknesses, composed of large crystals. JC is much lower than in thin film coated conductors, although it can be increased with the use of chemically-created pinning centers. Large grain HTS is frequently used to make permanent magnets. It is difficult to make long lengths of large grain HTS, and it is therefore not a candidate for power transmission. |
| LHC | Large Hadron Collider at CERN |
| LL | Load losses |
| Lorentz microsuperconductoropy | A simple method by which the domain walls of magnetic materials can be made visible in a qualitative fashion. |
| LPE | Liquid phase epitaxy |
| LTS | Low temperature superconductor, metallic materials with a TC of less than 30 K |
| Maglev | Magnetic levitation, i.e. for trains. Some use electromagnets, there are superconductor magnet prototypes. |
| Magnesium diboride | A cheap, "off-the-shelf" chemical compound that can be made into a superconductor. Magnesium diboride becomes superconducting at -234 °C (39K) - much higher than previously observed in relatively simple and readily available compounds, and between conventional LTS and HTS temperatures. Also MgB2. |
| Magnetic Field | |
| Magnetic Flux | |
| Magnetoencephalography | Imaging of the electromagnetic field of the brain. |
| MCP | Melt Cast Processed, |
| MEG | See Magnetoencephalography – imaging of the electromagnetic field of the brain. |
| Meissner effect | The Meissner effect is the effect by which a weak magnetic field decays rapidly to zero in the interior of a superconductor. The distance to which the field is active is known as the london penetration depth. This active exclusion of magnetic fields is distinct from perfect diamagnetism, as the magnetic field will be zero inside the superconductor regardless of what it was before the material became superconducting. The Meissner effect is one of the defining features of superconductivity, and its discovery served to establish that the onset of superconductivity is a phase transition. It was discovered by Walther Meißner and Robert Ochsenfeld in 1933. (wikipedia) |
| MFCL | Matrix fault current limiter. See Fault Current Limiter. |
| M-G | Motor-generator |
| MHD | Magnetohydrodynamic – Having to do with the study of magnetic fluids, i.e. plasma. |
| MILD | multiple-in-line-damage. See flux pinning. |
| MOCVD | Metallorganic Chemical Vapor Deposition, producing a thin film by depositing a precursor material evaporated onto a substrate. |
| MOD | Metal organic deposition. Precursor material deposited in liquid form onto substrate, baked to form YBCO. |
| MOV | Metal oxide varistor |
| MPMG | Melt powder melt growth |
| MRI | Magnetic resonance imaging. The body is exposed to a strong magnetic field, which aligns hydrogen atoms in the body's water and fat molecules. Radio frequency pulses make the atoms absorb and release energy that can be detected and displayed graphically by a computer. |
| multi-plume | A method for manufacturing superconducting materials where the superconductors are sprayed onto the metal substrate. |
| multi-turn | A method for manufacturing superconducting wire where the process is sped up by applying the superconducting material to multiple turns of the wire at the same time. |
| Naming superconductors | For cuprate superconductor. The scheme chosen uses four numbers. The first denotes the number of insulating layers between adjacent conducting blocks. The second represents the number of spacing layers between identical CuO2 blocks. The third gives the number of layers that separate adjacent CuO2 planes within the conducting block. And, the fourth is the number of CuO2planes within a conducting block. |
| Nano-structure | A nanostructure is an intermediate size between molecular and microscopic (micrometer-sized) structures. |
| Nd-422 | Nd4Ba2Cu2Ox |
| NLL | No-load loss |
| NMR | Nuclear magnetic resonance |
| NQR | Nitrogen nuclear quadrupole resonance. The use of the resonant frequency of atoms to determine the molecular structure of a material. |
| OD | Outer diameter |
| OPIT | Oxide-powder-in-tube process for manufacturing 1G wire. |
| PCS | Persistent current switch |
| PCS | Power conditioning system |
| perovskites | A family of Type 2 superconductor. These metal-oxide ceramics normally have a ratio of 2 metal atoms to every 3 oxygen atoms. |
| physical vapor deposition | A fabrication technique for depositing a thin film upon a substrate. A conventional physical vapor deposition (PVD) technique is sputtering. In the sputtering method, materials are bombarded with an ionized inert gas, such as argon, and are deposited onto the substrate.. |
| Pinning | See Flux Pinning |
| PIT | Powder in tube (conductor) |
| plasma | In physics and chemistry, plasma is typically an ionized gas, and is usually considered to be a distinct phase of matter in contrast to solids, liquids, and gases because of its unique properties. |
| PLD | See Pulsed laser deposition |
| Pulsed Laser Deposition | An efficient method to produce thin films by utilizing a technique called laser ablation. |
| Pulse Tube Cryocooler | A device which produces low temperatures. It is a closed system that uses an oscillating pressure at one end to generate an oscillating gas flow in the rest of the system. This gas flow can carry heat away from a low temperature point if the conditions are right. The prime advantage of Pulse Tube cryocoolers over Stirling cryocoolers is that they have no moving parts in the low temperature region. |
| p-YSZ | Polycrystalline yttrium-stabilized zirconia |
| QMG | Quench melt growth |
| Qubit | Quantum bit. A unit of data stored physically in a quantum system. |
| quatratran | quasiparticle trapping transistor - see supercurrent transistor |
| RABiTS | Rolling assisted biaxially textured substrates. Method for creating textured metal substrate for 2G wires by adding a buffer layer between the nickel substrate and YBCO, in order to prevent the texture of the YBCO from being destroyed during processing under oxidizing atmospheres. |
| RE | Rare earth element (such as La, Nd, Sm, Eu, Gd, etc.). Often added to superconductors to improve their flux pinning abilities. |
| RE-123 oxides | 123 compound formed with a rare earth instead of yttrium. See YBCO. |
| Reactive sputtering | A technique where a deposited film is formed by chemical reaction between the target material and a gas which is introduced into the vacuum chamber. Oxide and nitride films are often fabricated using reactive sputtering. The composition of the film can be controlled by varying the relative pressures of the inert and reactive gases. See thin film deposition. |
| Reel-to-reel | Continuous wire manufacturing. (Can theoretically handle any length wire.) |
| rf | Radio frequency |
| rms | Root mean square |
| RFSQ | Rapid Single Flux Quantum superconducting circuit. |
| SBCO | Sm-Ba-Cu-O compound. |
| SBIR | Small business innovative research program (From the US government.) |
| Self-epitaxial | A material that grows on itself with the same crystal structure. |
| Self-field | The self field is the magnetic field that is induced when there is finite current flowing in a wire. In the case of critical current measurements, the self field is the magnetic field that is induced in a straight piece of wire that is being measured. |
| SFCL | Superconducting Fault Current Limiter, |
| SFQ | Single flux quantum |
| Slot-die coating | A method of applying a liquid material to a substrate. In this process, liquid is forced out from a reservoir through a slot by pressure and transferred to a moving web. |
| SMES | Superconducting magnetic energy storage |
| sol-gel | A colloidal suspension that can be gelled to form a solid. The resulting porous gel then is chemically purified and fired at high temperatures into high purity oxide materials. The gel can be modified with a number of dopants to produce unique properties in the resultant glass unattainable by other means. It can be used in ceramics manufacturing processes, as an investment casting material, or as a means of producing very thin films of metal oxides for various purposes. |
| Spin coating | A procedure used to apply uniform thin films to flat substrates. An excess amount of solvent is placed on a substrate, which is then rotated at high speed in order to spread the fluid. Rotation is continued until the desired thickness of the film is achieved. The applied solvent is usually volatile, and evaporates as well as pouring off the edge of the substrate. |
| spray pyrolysis | Liquid droplets containing precursors are injected into a thermal reactor. The solvent evaporates and the precursors react to form the product. |
| SPTL | Superconducting power transmission line |
| Sputtering | A process whereby atoms in a solid target material are ejected into the gas phase due to bombardment of the material by energetic ions. It is commonly used for thin-film deposition and analytical techniques. |
| SQUID | Superconducting quantum interference device. A sensitive magnetic instrument usually used for medical diagnostics. |
| Substrate | The surface or base layer on which a superconducting thin film is grown. |
| Superconductivity | A state where a material exhibits no electrical resistance and excludes the inner magnetic field. |
| Superconductor | An element, inter-metallic alloy, or compound that will conduct electricity without resistance below a certain temperature. Once set in motion, current will flow forever in a closed loop of superconducting material. This applies only to direct current (DC) electricity and to finite amounts of current. All known superconductors are solids. superconductor can be classified into Type 1 and Type 2, and can be categorized further by their dimensionality. Most are 3-D, but some compounds, like surface-doped NaWO3 and some organic superconductors are 2-D. Li2CuO2 and single-walled carbon nano-tubes have shown rare 1-D superconductivity. In addition to repelling magnetic fields, enhanced thermal conductivity, higher optical reflectivity and reduced surface friction are also properties of superconductors. (from superconductors.org) |
| Superconductor | A material capable of displaying superconductivity. |
| Superconductor/PM | Superconductor/permanent magnet |
| SuperconductorFCL | Superconductive fault current limiter |
| supercurrent transistor | The superconducting transistor, or quatratran, is made of very thin layers of the superconductor niobium, insulation, and aluminum, which is a non-superconducting metal. When a voltage is applied to one of the superconducting layers, the increase in energy causes electrons from the aluminum layer to stream into a superconducting layer, causing a gain, or change in current, 70 times larger than the amount of current applied. |
| synchronous condenser | Fundamentally an AC synchronous motor that is not attached to any driven equipment. Its field is controlled by a voltage regulator to either generate or absorb reactive power as needed by the system. It operates at full leading power factor and puts VARs onto the network as required to support a system’s voltage or to maintain the system power factor at a specified level. The condenser’s installation and operation are identical to large electric motors. |
| T | 1. Tesla, a unit for magnetic flux density. 2. May also refer to temperature, as in TC |
| TC | See critical temperature. |
| TEM | Transmission electron microscope or microscopy |
| Tesla | Unit for magnetic flux density (B). Equal to one weber per square meter or one newton per ampere-meter. |
| Texturing | Crystal grain alignment – a textured buffer layer is used to grow an aligned superconductor layer. |
| TFA | Tri-flouro-acetate, a material used for MOD. |
| Thermal runaway | A condition in which the current for a fully charged nickel-cadmium battery rises out of proportion to the impressed-voltage level. This condition is caused when heat from oxygen recombination causes the battery's voltage to drop as it gets hot. |
| Thick Film Coated Conductor | 3 to 10 microns thick. A thick film coated conductor, say 7 microns thick would be expected to carry about 10 times the current carried by a thin film conductor, but it typically carries only a bit more current than thin film. Thin film coated conductor, about 1 micron thick, is the leading candidate for power transmission applications. It presently has Jc in the range of 1 to 2 Meg Amps per cm*2. A thin film tape, 1 cm wide and 1 micron thick might carry 100 Amps. |
| Thin Film Coated Conductor | Thin film coated conductor, about 1 micron thick, is the leading candidate for power transmission applications. It presently has Jc in the range of 1 to 2 Meg Amps per cm*2. A thin film tape, 1 cm wide and 1 micron thick might carry 100 Amps. |
| Thin Film Deposition | A method of fabricating ceramic superconductors to more precisely control the growth of the crystalline structure to eliminate grain boundaries and achieve a desired Tc. This can involve Pulsed-Laser Deposition (PLD) or Pulsed-Electron Deposition (PED) of the superconductor material onto a substrate. The substrate and possible buffer layers support the film and can increase the Jc of the HTS directly in contact with it. The part of the HTS nearest to the supporting layer carries high Jc. Further away from the support (less than a micron) Jc falls off very rapidly.A variation of this technique can be used to increase the Tc of a superconductor by growing it on a supporting material with a smaller interatomic spacing. The supporting material acts as a molecular "girdle" to compress the atomic lattice of the superconductor, thereby raising its transition temperature.Superconductive tape/wire is made using thin film deposition technology.(from superconductors.org) |
| Tl-1223 | (Tl, Pb)(Ba, Sr)2Ca2Cu3Ox |
| Tokamak | Fusion reactor design which uses a magnetic field to confine plasma to a closed torus. |
| Transport phenomena | Any of various mechanisms by which particles or quantities move from one place to another. Three common examples of transport phenomena are diffusion, convection, and radiation. |
| Type 1 superconductor | The Type 1 category of superconductors is mainly comprised of metals and metalloids that show some conductivity at room temperature. They require incredible cold to slow down molecular vibrations sufficiently to facilitate unimpeded electron flow in accordance with what is known as BCS theory. (from superconductors.org) |
| Type 2 superconductor | Also known as the "hard" superconductors. They have higher TC than Type 1 and their transition from a normal to a superconducting state is gradual across a region of "mixed state" behavior. This allows some penetration of external magnetic fields. All metallic compounds or alloys (except for vanadium, technetium and niobium), including the perovskites, BSCCO. |
| Ultra-capacitor | Sometimes called a supercapacitor, an ultra-capacitor is an electrochemical capacitor that has an unusually large amount of energy storage capability relative to its size. These are of particular interest for hybrid vehicles and as supplemental storage for battery electric vehicles. |
| Ultraconductor | Materials known as ultraconductors™ display room-temperature resistance many orders of magnitude lower than the best metallic conductors. Examples of these materials include oxidized atactic polypropylene (OAPP) and other polymers. Since ultraconductor™ is a colloquial term, these materials might better be described as "hyperconductors". The Meissner effect cannot be confirmed in them, but strong (giant) diamagnetism is in evidence. Some of them may actually find acceptance in high-current applications ahead of superconductors as a result of their low losses at ambient temperatures and pressures. |
| vapor-liquid-solid (VLS) process | A process for fabricating single crystal fibers such as silicon carbide with diameters ranging from 0.1-10 μm and lengths of 100 mm. |
| vortices | See flux lines. |
| XLPE | Cross-linked polyethylene (industry designation for dry insulated high voltage lines). |
| Y-123 | YBa2Cu3Ox (see also YBCO) |
| Y-211 | Y2BaCuO5 |
| YBCO | YBa2Cu3O7-d (also Y-123, YBCO-123, YBa2Cu3O7) A high temp superconductor material developed in 1991 by Fujikara. Used in 2G wires. |
| YSZ | Yttrium-stabilized zirconia. A buffering/texturing material used in some IBAD processes. |
| Z | Impedence (complex [ac] impedance of a circuit or component consisting of a resistive and a reactive part). |
