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
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
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
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
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
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.