Flux pinning is desirable in hightemperature ceramic superconductors to prevent flux creep, which can create a pseudo resistance and depress both critical current density and critical field. Processing, flux pinning and application of bisrcacuo. Superconductors formed by powder metallurgy have a matrix of niobiumtitanium alloy with discrete pinning centers distributed therein which are formed of a compatible metal. Theories on the summation of randomly directed individual pinning forces to estimate the pinning force density are described based on the historical understanding of the pinning phenomena. Flux pinning in superconducting nbti wires with nb. Flux pinning in superconductors wiley online library.
Role of flux pinning in high temperature superconductors. Meissner effect science from scratch short video from imperial college london about the meissner effect and levitating trains of the future. Flux pinning in superconductors springer series in solidstate sciences matsushita, teruo on. This provides the stability of a levitating magnet. Fluxpinning is desirable in hightemperature ceramic superconductors in order to prevent fluxcreep, which can create a pseudoresistance and depress jc and hc. Pdf magnetooptical studies of flux pinning in high. Extrinsic twodimensional flux pinning centers, via grapheneencapsulated boron powder as precursors, have been introduced into mgb2 superconductors by means of in situ and diffusion sintering methods. High field flux pinning and the upper critical field of nbti superconductors article pdf available in ieee transactions on applied superconductivity 72. The influence of the flux pinning on the vortex phase diagram in high tc superconductors is discussed, and the dependencies of the irreversibility field are also described on other quantities such as anisotropy of superconductor, specimen size and electric field strength. Expressions for flux pinning in type ii superconductors are derived from considerations of the nature of the interaction between individual flux lines and pinning centres, and of the geometry of the pinning centres.
The condensation energy interaction known for normal precipitates or grain boundaries and the kinetic energy interaction proposed. The nonsuperconducting inclusions act as pinning centers in the superconductor, increasing the critical current thereof. Type i1 superconductors permit limited flux penetration in the form of flux quanta or fluxoids. Because of this, flux pinning turns out to be a highly complex phenomenon. Flux pinning by nano particles embedded in polycrystalline y.
The magnetization curve is reversible for an ideal superconductor. Inhomogeneities always exist in real superconducting materials. When they move, the flux line lattice fll dissipates energy and the superconductor eventually goes normal. Us5226947a niobiumtitanium superconductors produced by. Introduction to superconductivity video about type 1 superconductors. Flux pinning by platinum and rhodium in high temperature superconductors platinum additions to ybco thick films improve critical current densities and superconducting properties by j. The artificial pinning centers in the nbti matrix are reduced in size by processing steps to sizes on the order of the coherence length, typically in the range of 1 to 10 nm. Lichtenberger iowa state university follow this and additional works at. Thus, the threshold problem was actually resolved and it was shown that the pinning loss is of a hysteresis nature even for very weak pinning centers. Us5430008a method and composition for improving flux. Observed pinning force density is compared with the predictions of the larkinovchinnikov theory and the coherent potential approximation theory. Flux pinning mechanisms in type ii superconductors. The flux pinning enhancement of type ii superconductors with defects have been studied in both copperoxide high and lowtemperature superconductor materials 3,4,14. Pdf we study magnetic flux interacting with arrays of pinning sites aps placed on vertices of hyperbolic tesselations ht.
Magnetic flux motion and flux pinning in superconductors. Degradation of a hightemperature superconductor s properties due to flux creep is a limiting factor in the use of these superconductors. The condensation energy interaction known for normal precipitates or grain boundaries and the kinetic energy interaction. Flux pinning mechanisms in graphene doped mgb 2 superconductors k. Pinning the motion of its magnetic field lines also means stopping the motion of the magnet. Similarly, in superconducting electronic devices and bulk superconductors used as permanent magnets, the prevention of flux motion through pinning is critical in. Flux pinning is only possible when there are defects in the crystalline structure of the superconductor usually resulting from grain boundaries or impurities. Sanders a dissertation submitted to the graduate faculty in partial fulfillment of the. Experimenting with a superconducting levitation train. Addition of nanoparticle dispersions to enhance flux pinning. Flux pinning in superconductors springer series in solid.
To understand the origin of the difference in behavior requires a microscopic description of the. Pdf magnetic flux pinning in superconductors with hyperbolic. If the data for voids and dislocation loops are plotted as q. Flux pinning in superconductors springer series in solidstate sciences. Degradation of a hightemperature superconductors properties due to flux creep is a limiting factor in the use of these superconductors. Flux pinning in superconductors teruo matsushita springer. Magnetic flux motion and flux pinning in superconductors by steven c. The condensation energy interaction known for normal precipitates or grain boundaries and the kinetic energy interaction proposed for artificial nb pins in nbti, etc. This demonstration with high temperature superconductors indicates that they are of. Kiuchi department of computer science and electronics, kyushu institute of technology, 6804 kawazu, iizuka 820, japan abstract the flux pinning properties in high temperature superconductors are strongly influenced by ther. Pdf high field flux pinning and the upper critical field.
Langhorn school of metallurgy and materials, university of birmingham screen printed thick film technology is recognised as an inexpensive and. The statistical theory clarified that the nonzero pinning force. Pdf high field flux pinning and the upper critical field of. Flux pinning is desirable in hightemperature ceramic superconductors to prevent flux creep, which can create a pseudoresistance and depress both critical current density and critical field. Magnetic ilux motion and flux pinning in superconductors sanders, steven castle, ph. Carbon can be considered as the most successful dopant for enhancing h c2, as it causes strong. Extrinsic twodimensional flux pinning centers in mgb2. Fluxpinning is only possible when there are defects in the crystalline structure of the superconductor usually resulting from grain boundaries or impurities. Flux pinning in superconductors 4 summation theories on pinning force density. Flux pinning is the phenomenon where a superconductor is pinned in space above a magnet. Uniform graphene encapsulation of the boron powders was achieved by the hydrothermal method with highly dispersed graphene oxide as the precursor.
Langhorn school of metallurgy and materials, university of birmingham screen printed thick film technology is recognised as an inexpensive and effective means for the production of. R 0transition temperaturesb is a state variablemeissner effectenergy gap giaeverbcs model. Flux pinning in superconductors wimbush major reference. Editorial full text access special issue on processing, flux pinning, and application of bisrcacuo hightemperature superconductors. Aug 18, 2008 flux pinning in irradiated superconductors having either dislocation. The setup enables to test parameters like stability, speed, and safety, of the superconducting train for various gaps ranging between 1 mm to 15 mm between the. High field flux pinning and the upper critical field of nbti superconductors. Second magnetization peak effect, vortex dynamics and flux. The main motivation for using type ii superconductors in these materials the. The book deals with the flux pinning mechanisms and properties and the electromagnetic phenomena caused by the flux pinning common for metallic, hightemperature and mgb2 superconductors. Magnetic relaxation, flux pinning and critical currents in superconductors karl s. Summation curves for flux pinning in superconductors.
Flux pinning in superconductors teruo matsushita springer 201112 517 pages english pdf. Flux pinning is desirable in hightemperature ceramic superconductors in order to prevent flux creep, which can create a pseudoresistance and depress jc and hc. The book covers the flux pinning mechanisms and properties and the electromagnetic phenomena caused by the flux pinning common for metallic, hightc and mgb 2 superconductors. The elementary interaction force fp can be accurately computed for such defects if their size is known from transmission electron microscopy. Expressions for fluxpinning in type ii superconductors are derived from considerations of the nature of the interaction between individual fluxlines and pinningcentres, and of the geometry of the pinningcentres. Method and composition for improving flux pinning and critical current in. Teruo matsushita flux pinning in superconductors 2006.
Data exist for a range of defects for which fp varies by over a factor of 104. Fietz and webb first demonstrated in dilute nb alloys that the peak in f p scales as h c 2 t 2. Method and composition for improving flux pinning and critical current in superconductors. The book covers the flux pinning mechanisms and properties and the electromagnetic phenomena caused by the flux pinning common for metallic, hightc and mgb2 superconductors. Flux pinning on nanosized defects and critical current in htc. Magnetooptical studies of flux pinning in hightemperature superconductors article pdf available in international journal of materials research formerly zeitschrift fuer metallkunde. Pdf fundamental electromagnetic phenomena in superconductors. Flux pinning by platinum and rhodium in high temperature. Addition of nanoparticle dispersions to enhance flux. Scaling laws for flux pinning in hard superconductors.
However, because of its extreme importance for the technical applications of the cuprate superconductors, the subject of flux pinning has recently attracted a large amount of research and development. Feb 18, 20 70046 superconductor meissner effect and flux pinning tute v0434h. The intergranular josephson vortex pinning is found to be. The possibility of flux line dislocations flds and fld dipole participating in this plastic shear process may be important for weaker pinning materials where the pin spacing is large but for hard superconductors, where line pins are likely to be closely spaced, the chances of finding an fld source between pins is negligible. Teruo matsushita flux pinning in superconductors 2006 springer. Fluxpinninginduced stress and magnetostriction in bulk. Aug 19, 2004 the flux pinning enhancement of type ii superconductors with defects have been studied in both copperoxide high and lowtemperature superconductor materials 3,4,14. Note that flux pinning can only occur in typeii superconductors. Expressions for fluxpinning in type ii superconductors are derived from considerations of the nature of the interaction between individual fluxlines and pinningcentres, and of. Magnetic relaxation, flux pinning and critical currents in. The book covers the flux pinning mechanisms and properties and the electromagnetic. Flux pinning in irradiated superconductors having either dislocation.
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