Download or read book Role of Metallurgy in the Thermal Conductivity of Superconducting Niobium written by Saravan Kumar Chandrasekaran and published by . This book was released on 2013 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Investigation of the Thermal Transport in Superconducting Niobium and Tantalum written by Peng Xu and published by . This book was released on 2019 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt: Superconducting radio frequency (SRF) cavities fabricated from bulk high purity niobium (Nb) are increasingly used for particle accelerators to achieve continuous operation. Even in the superconducting regime, residual resistance and small imperfections on the RF surface can dissipate energy and cause local heating that leads to cavity quench. Large values of thermal conductivity can mitigate local temperature excursions and prevent cavity quench, thus improving cavity performance. Understanding thermal transport in bulk and thin film superconducting Nb may guide thermal design of current and next generation SRF cavities.The thermal conductivity of metals is composed of electronic and lattice (phonon) components. In normal conductors, the electronic component dominates, and in superconducting metals, as the temperature drops below the critical temperature, phonons become increasingly important carriers of thermal energy. A widely used model of thermal conductivity in superconductors omits explicit accounting of the effect of dislocations, which result from deformation. Here, this model is extended by accounting for the effects of phonons scattered by dislocations independent from boundary scattering. This extended model agrees better with measurements of thermal conductivity in deformed Nb samples, especially at temperatures T less than 3 K. An apparent threshold of dislocation density Nd is found to be Nd = O(1012) m−2 for Nb and when applied to tantalum (Ta), it is Nd = O(1011) m−2. There is little contribution to the thermal conductivity when the dislocation density is less than this threshold. This model can also be used to estimatethe dislocation density by fitting measured values of thermal conductivity.Examination of thermal conductivity data for superconducting Nb shows that there is often a local maximum, a so-called phonon peak, kpp. The temperature at which this kpp occurs Tpp is between 1.72 K and 2.35 K and shifts for samples after deformation. It is well known that the magnitude of kpp decreases as the material is deformed, and hence with increasing Nd. Less cited is that Tpp increases with increasing Nd. This may affect the operating temperature of an SRF cavity. At a certain level deformation (i.e., 4.7% deformation for a residual resistivity ratio RRR = 185), the phonon peak disappears. More deformation is needed for higher RRR, (i.e., greater purity).The models discussed above require estimating several parameters from thermal conductivity measurements and may be best suited to explaining the relative importance of the several scattering mechanisms. For predicting thermal conductivity from basic material variables, the Boltzmann transport equation (BTE) is solved by two methods to predict the lattice component of thermal conductivity. One method uses a substitution of variables from frequency to wavevector in the Callaway model to include the nonlinear phonon dispersion relationship for the longitudinal acoustic (LA) and transverse acoustic (TA) phonon polarizations. This model incorporates a relaxation time approximation using Matthiessen's rule to consider phonon scattering by electrons, boundaries, and dislocations. Another method to predict the lattice thermal conductivity uses an energy-based, variance-reduced Monte Carlo (MC) solution to the BTE for phonons. The MC solution allows more general consideration of the individual scattering mechanisms. It may also be generalized for more complex geometries. The MC solution technique was first verified by comparing the predicted thermal conductivity in bulk Si and Si nanowires with experimental results. Both solutions of the BTE for the lattice thermal conductivity of undeformed and deformed superconducting Nb agreed well with experimental values. The MC model was also used to demonstrate that interstitial impurities must be near saturation to change the lattice thermal conductivity of Nb. The MC solution was also effective in predicting the lattice thermal conductivity of superconducting Ta, with the appropriate change in dispersion relation and other material parameters.
Download or read book Thermal Conductivity and Thermal Effects in Superconducting Niobium written by Syed Mohammad Wasim and published by . This book was released on 1970 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Design and Fabrication of a High temperature High vacuum Furnace to Heat Treat Niobium for Superconducting Radio Frequency Cavities written by Saravan Kumar Chandrasekaran and published by . This book was released on 2010 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Applied Superconductivity Metallurgy and Physics of Titanium Alloys written by E.W. Collings and published by Springer Science & Business Media. This book was released on 1986-01-31 with total page 868 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scope and Purpose Although conductors based on the Al5 intermetallic compound Nb Sn 3 possess desirable high-field superconducting properties, manufacturing and handling difficulties, coupled with the tendency of their critical current densities to degrade rapidly under stress, have generally restricted their use to fairly straightforward, usually small-scale solenoidal-magnet applica tions. Likewise the Al5 compound VGa, which has a wider critical strain 3 window than NbSn but a uniformly lower upper critical field, has not 3 entered widespread service. Strain has been found to have no measurable influence on either the critical fields or the critical current densities of compound superconductors with BI and Cl5 crystal structures, but as yet they are still in the research and development stages. On the other hand, conductors using the binary alloy Ti-Nb or multi component alloys based on it, because of their relative ease of manufacture, excellent mechanical properties, and relatively low strain sensitivities, are now being pressed into service in numerous large-scale devices. Such conductors are being wound into magnets for use in energy storage, energy conversion (i. e. , generators and motors), and high-energy particle detectors and beam-handling magnets. of cold-rolled or drawn Ti-Nb-alloy wire for superconducting The use magnet applications was first proposed in 1961. During the ensuing ten years, while progress was being made in the development of Cu-clad filamentary-Ti-Nb-alloy conductors, Ti-Nb and other Ti-base binary transi tion-metal (TM) alloys were being employed as model systems in the fundamental study of type-II superconductivity.
Download or read book Thermal Conductivity of Superconducting Niobium written by Byron Keith Moore and published by . This book was released on 1971 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Thermal Conductivity of Superconducting Niobium from 0 03k to 4k written by Stephen Carroll Smith and published by . This book was released on 1971 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Applied Superconductivity Metallurgy and Physics of Titanium Alloys written by E.W. Collings and published by Springer. This book was released on 1986-03-31 with total page 736 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Thermal Conductivity of Superconducting Niobium written by Jon Ross Carlson and published by . This book was released on 1968 with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Ultrahigh Vacuum Heat Treatment and Superconducting Properties of Niobium written by John Alexander Timoshenko and published by . This book was released on 1964 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Metallurgy of Superconducting Materials written by Thomas Luhman and published by . This book was released on 1979 with total page 488 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Summaries of the UDAEC Basic Research Programs in Metallurgy Solid State Physics and Ceramics written by and published by . This book was released on 1965 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Thermal Transport and Thermal magnetic Breakdown in Superconducting Cavities Made of High Thermal Conductivity Niobium written by Kathleen Rempel Krafft and published by . This book was released on 1983 with total page 408 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1976 with total page 612 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Applied Superconductivity Metallurgy and Physics of Titanium Alloys written by E.W. Collings and published by Springer. This book was released on 1986-01-31 with total page 854 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scope and Purpose Although conductors based on the Al5 intermetallic compound Nb Sn 3 possess desirable high-field superconducting properties, manufacturing and handling difficulties, coupled with the tendency of their critical current densities to degrade rapidly under stress, have generally restricted their use to fairly straightforward, usually small-scale solenoidal-magnet applica tions. Likewise the Al5 compound VGa, which has a wider critical strain 3 window than NbSn but a uniformly lower upper critical field, has not 3 entered widespread service. Strain has been found to have no measurable influence on either the critical fields or the critical current densities of compound superconductors with BI and Cl5 crystal structures, but as yet they are still in the research and development stages. On the other hand, conductors using the binary alloy Ti-Nb or multi component alloys based on it, because of their relative ease of manufacture, excellent mechanical properties, and relatively low strain sensitivities, are now being pressed into service in numerous large-scale devices. Such conductors are being wound into magnets for use in energy storage, energy conversion (i. e. , generators and motors), and high-energy particle detectors and beam-handling magnets. of cold-rolled or drawn Ti-Nb-alloy wire for superconducting The use magnet applications was first proposed in 1961. During the ensuing ten years, while progress was being made in the development of Cu-clad filamentary-Ti-Nb-alloy conductors, Ti-Nb and other Ti-base binary transi tion-metal (TM) alloys were being employed as model systems in the fundamental study of type-II superconductivity.
Download or read book Superconductor Materials Science Metallurgy Fabrication and Applications written by Simon Foner and published by Springer. This book was released on 1981-10 with total page 1008 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book encompasses the science, measurement, fabrica tion, and use of superconducting materials in large scale and small scale technologies. The present book is in some sense a continuation and completion of a series of two earlier books based on NA TO Advanced Study Institutes held over the last decade. The first book in the series entitled Superconducting Machines ~nd Devices: Large Systems Appli cations edited by S. Foner and B. B. Schwartz (1974) represented a compilation of all the applications of superconducting technology. The second book entitled Superconductor Applications: Squids and Machines, edited by B. B. Schwartz and S. Foner (1977) reviewed small scale applications and up-dated the large scale applications of superconductiv ity at that time. These two books are both introductions and advanced reference volumes for almost all aspects of the applications of super conductivity. The growth of applied superconductivity has mushroomed in the decade of the 1970's. Technologies which were discussed in the beginning of the 1970's are now beyond the prototype stage. Materials development and performance in operating systems is the basis of the continued applications and economic viability of super conducting technology. In this book, a complete review of all materials technology is presented by leading authorities who were instrumental in the development of superconducting materials technology. The present book is based on the NATO Advanced Study vi PREFACE Institute entitled Superconducting Materials: Science and Technology which was held from August 20 to August 30, 1980 in Sintra, Portugal.
Download or read book The NBS Alloy Data Center written by Gesina C. Carter and published by . This book was released on 1968 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Alloy Data Center, part of the National Standard Reference Data System, has two primary functions. One is to stimulate cooperation and coordination among the existing data centers in the area of the physical properties of well characterized alloys. The final data generated by these centers for publication should be consistent with one another where correlation or possible overlap exists. The other purpose is the collection (from publications as well as private communications), evaluation, and publication of data in some areas where special competence exists in the Alloy Physics Section. Of interest to the center are metals, semimetals, intermetallic compounds, and alloys. Excluded are those materials which have ill-defined constitutions and heat treatments. An automated system was developed to meet the bibliographic needs of the center. This system will be described as well as the specific properties of interest. The system presently contains a complete annotated file dealing with NMR Knight shift measurements. The soft X-ray spectroscopy compilation is being kept up-to-date with the same system. (Author).
