Mgb2 Superconducting Wires
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Mgb2 Superconducting Wires Basics And Applications
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Author : Rene Flukiger
language : en
Publisher: World Scientific
Release Date : 2016-08-10
Mgb2 Superconducting Wires Basics And Applications written by Rene Flukiger and has been published by World Scientific this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016-08-10 with Technology & Engineering categories.
The compendium gives a complete overview of the properties of MgB2 (Magnesium Diboride), a superconducting compound with a transition temperature of Tc = 39K, from the fundamental properties to the fabrication of multifilamentary wires and to the presentation of various applications. Written by eminent researchers in the field, this indispensable volume not only discusses superconducting properties of MgB2 compounds, but also describes known preparation methods of thin films and of bulk samples obtained under high pressure methods.A unique selling point of the book is the detailed coverage of various applications based on MgB2, starting with MRI magnets and high current cables, cooled by Helium (He) vapor. High current cables cooled by liquid hydrogen are also highlighted as an interesting alternative due to the shrinking He reserves on earth. Other pertinent subjects comprise permanent magnets, ultrafine wires for space applications and wind generator projects.
Mgb2 Superconducting Wires
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Author : Rene Flukiger
language : en
Publisher: World Scientific Series in Applications of Superconductivity and Related Phenomena
Release Date : 2016
Mgb2 Superconducting Wires written by Rene Flukiger and has been published by World Scientific Series in Applications of Superconductivity and Related Phenomena this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with Electric wire categories.
The compendium gives a complete overview of the properties of MgB2 (Magnesium Diboride), a superconducting compound with a transition temperature of Tc = 39K, from the fundamental properties to the fabrication of multifilamentary wires and to the presentation of various applications. Written by eminent researchers in the field, this indispensable volume not only discusses superconducting properties of MgB2 compounds, but also describes known preparation methods of thin films and of bulk samples obtained under high pressure methods. A unique selling point of the book is the detailed coverage of various applications based on MgB2, starting with MRI magnets and high current cables, cooled by Helium (He) vapor. High current cables cooled by liquid hydrogen are also highlighted as an interesting alternative due to the shrinking He reserves on earth. Other pertinent subjects comprise permanent magnets, ultrafine wires for space applications and wind generator projects.
Study Of Cu Sheathed Mgb2 Superconducting Wires
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Author : Prashant Gijavanekar
language : en
Publisher:
Release Date : 2005
Study Of Cu Sheathed Mgb2 Superconducting Wires written by Prashant Gijavanekar and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005 with Magnesium diboride categories.
Enhancement Of Connectivity And Flux Pinning In Mgb2 Superconducting Bulks And Wires
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Author : Lin Lü
language : en
Publisher:
Release Date : 2009
Enhancement Of Connectivity And Flux Pinning In Mgb2 Superconducting Bulks And Wires written by Lin Lü and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with Flux pinning categories.
Fabrication Of Chemically Doped High Upper Critical Field Magnesium Diboride Superconducting Wires
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Author :
language : en
Publisher:
Release Date : 2005
Fabrication Of Chemically Doped High Upper Critical Field Magnesium Diboride Superconducting Wires written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005 with categories.
Controlled chemical doping of magnesium diboride (MgB2) has been shown to substantially improve its superconducting properties to the levels required for high field magnets, but the doping is difficult to accomplish through the usual route of solid state reaction and diffusion. Further, superconducting cables of MgB2 are difficult to fabricate because of the friable nature of the material. In this Phase I STTR project, doped and undoped boron fibers were made by chemical vapor deposition (CVD). Several>100m long batches of doped and undoped fiber were made by CVD codeposition of boron plus dopants. Bundles of these fibers infiltrated with liquid magnesium and subsequently converted to MgB2 to form Mg-MgB2 metal matrix composites. In a parallel path, doped boron nano-sized powder was produced by a plasma synthesis technique, reacted with magnesium to produce doped MgB2 superconducting ceramic bodies. The doped powder was also fabricated into superconducting wires several meters long. The doped boron fibers and powders made in this program were fabricated into fiber-metal composites and powder-metal composites by a liquid metal infiltration technique. The kinetics of the reaction between boron fiber and magnesium metal was investigated in fiber-metal composites. It was found that the presence of dopants had significantly slowed the reaction between magnesium and boron. The superconducting properties were measured for MgB2 fibers and MgB2 powders made by liquid metal infiltration. Properties of MgB2 products (Jc, Hc2) from Phase I are among the highest reported to date for MgB2 bulk superconductors. Chemically doped MgB2 superconducting magnets can perform at least as well as NbTi and NbSn3 in high magnetic fields and still offer an improvement over the latter two in terms of operating temperature. These characteristics make doped MgB2 an effective material for high magnetic field applications, such as magnetic confined fusion, and medical MRI devices. Developing fusion as an energy source will dramatically reduce energy costs, global warming, and radioactive waste. Cheaper and more efficient medical MRI devices could lower examination costs, find potential health problems earlier, and thus also benefit society as a whole. Other potential commercial applications for this material are devices for the generation and storage of electrical power, thus lowering the cost of delivered electricity.
Superconducting Wires And Thin Films Of Mgb2 For Electric Devices
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Author : Israel Felner
language : en
Publisher:
Release Date : 2006
Superconducting Wires And Thin Films Of Mgb2 For Electric Devices written by Israel Felner and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006 with categories.
Optimisation Of Hysteretic Losses In High Temperature Superconducting Wires
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Author : Krueger, Philipp
language : en
Publisher: KIT Scientific Publishing
Release Date : 2014-05-15
Optimisation Of Hysteretic Losses In High Temperature Superconducting Wires written by Krueger, Philipp and has been published by KIT Scientific Publishing this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014-05-15 with Science categories.
Hysteretic loss optimisations through numerical simulation and subsequent experimental confirmation in transport current and background field measurements: ferromagnetic shielding and topological geometry optimisation is used to reduce energy dissipation in HTS coated conductor geometries. Single tapes and coil geometries are investigated. A 3D model capable of taking into account contact resistances is also presented for the Twisted Stacked Tape Conductor cable.
Connectivity Doping And Anisotropy In Highly Dense Magnesium Diboride Mgb2
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Author : Guangze Li
language : en
Publisher:
Release Date : 2015
Connectivity Doping And Anisotropy In Highly Dense Magnesium Diboride Mgb2 written by Guangze Li and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
Magnesium diboride (MgB2) is a superconducting material which can be potentially used in many applications such as magnetic resonance imaging system (MRI), wind turbine generators and high energy physics facilities. The major advantages of MgB2 over other superconductors include its relatively high critical temperature of about 39 K, its low cost of raw materials, its simple crystal structure, and its round multifilament form when in the form of superconducting wires. Over the past fourteen years, much effort has been made to develop MgB2 wires with excellent superconducting properties, particularly the critical current density Jc. However, this research has been limited by technical difficulties such as high porosity and weak connectivity in MgB2, relatively small flux pinning strength, low upper critical field Bc2 and relatively high anisotropy. The goal of this dissertation is to understand the relationship between superconducting properties, microstructure, and reaction mechanisms in MgB2. In particular, the influences of connectivity, Bc2, anisotropy and flux pinning were investigated in terms of the effects of these variables on the Jcs and n-values of MgB2 superconducting wires (n-value is a parameter which indicates the sharpness of resistive V-I transition). The n-values of traditional "Powder in Tube (PIT)" processed MgB2 wires were improved by optimizing precursor species after the identification of microstructural defects such as so-called "sausaging problems". Also, it was found that "high porosity and weak connectivity" was one of the most critical issues which limited the Jc performance in typical MgB2. To overcome this problem, highly dense, well-connected MgB2 conductors were successfully fabricated by adopting an innovative "Advanced Internal Magnesium Infiltration (AIMI)" process. A careful study on the reaction kinetics together with the microstructural evidence demonstrated how the MgB2 layer was formed as the infiltration process proceeded. As a result, it is possible to control the MgB2 layer growth in the AIMI-processed MgB2 wires. The best AIMI wires, with improved density and connectivity, accomplished an outstanding layer Jc, which was 1.0 × 105 A/cm2 at 4.2 K and 10 T, nearly 10 times higher than the Jcs of PIT wires. The engineering Je of AIMI wires, namely the critical current over the whole cross-sectional area in the wire, achieved 1.7 × 104 A/cm2 at 4.2 K, 10 T, 200 % higher than those of PIT wires. Finally, two promising dopants, Dy2O3 and O, were engineered to incorporate with MgB2. Dy2O3 nanopowders, co-doped with C in AIMI wires, enhanced the Jc performance at elevated temperatures such as 20 K. Oxygen, on the other hand, doped into MgB2 thin films through a newly-developed O2 annealing process, improved Bc2 to 14 T at 21 K. Both of the doping studies were helpful to understand the superconducting nature of MgB2.
High Energy Milled Ex Situ Mgb2 For Tapes And Wires
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Author : Anna Kario
language : en
Publisher: Cuvillier Verlag
Release Date : 2011-05-02
High Energy Milled Ex Situ Mgb2 For Tapes And Wires written by Anna Kario and has been published by Cuvillier Verlag this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011-05-02 with Technology & Engineering categories.
1. The optimum solution for the difficulties during conductor deformation was to use the ex situ precursor powder which is not sensitive to heat treatments in the range of temperatures needed for the working stress release of the sheath metal. Two different ex situ powders are studied: homemade ex situ (based on mechanically alloyed in situ powder) and commercial powder with reduced crystallite size achieved by high energy ball milling. 2. As the first approach, ex situ powder is prepared using mechanical alloying. A detailed phase analysis shown secondary phases, such as MgO and MgB4+x. A high critical current density for unsintered tapes and wires was obtained. It is observed that non of the applied final heat treatments of the conductors improve their superconducting properties. It is assumed that, heat treatments influence the crystallite size which is explained by MgO at the grain boundaries blocking grain growth. Additional milling or chemical treatment of the powder to clean the grains is needed to accomplish a smaller particle size. However, if medium Jc values are sufficient, the MA in-ex situ powder is an interesting precursor powder for conductors needed for the react & wind method of superconducting coil preparation, because the final heat treatment of a such a conductor is not needed. 3. As the second approach, commercially available ex situ powder was milled to reduce grain size. The average crystallite size of the powder is reduced by ball milling drastically from 47 nm to 15 nm, however, this powder is highly reactive. Powders after 2 h or longer milling times exposed to air react rapidly with oxygen and create up to 40 wt% of secondary phases, like MgB4+x and MgO. This reaction can be avoided by using exclusively a protective atmosphere for the sample preparation. Ex situ MgB2 stability examination via the decomposition behaviour. 4. The decomposition of MgB2 to Mg and higher borides at high annealing temperatures is observed in bulks and conductors. The temperature of the MgB2 decomposition decreases with increasing milling time. Unfortunately, the decomposition takes place at temperatures which are in the same range as the temperature needed for ex situ sintering. With increasing milling time, the crystallite size decreases and more powder is decomposed. It was found that an increased grain connection due to the milling and a decreased crystallite size play a larger role in increasing Jc than secondary phases. The milling process creates fresh reaction surfaces without a MgO layer for an improved grain connectivity. 5. The high reactivity of the powder caused by the high energy ball milling might be reduced by carbon addition. Carbon is successfully introduced into the lattice, as proved by a change in the lattice parameter, a decrease of Tc, an increase of the upper critical field and a change of the Jc dependence on applied field. The carbon substitution in the lattice is accomplished via high energy ball milling. 6. The best Jc results ( Jc=104 A/cm2 at 12.4 T) are obtained for the tape with the 20 h milled powder with 5 wt% of carbon addition. The precursor powder is well deformable: the 2 m long conductor was prepared using a combination of swaging, drawing and rolling with the help of intermediate heat treatments. Such additional heat treatments do not influence the precursor powder. Furthermore the carbon addition to the tape precursor increases the decomposition temperature of the powder, decreases its reactivity and improves the Jc(H) dependence of the tape in comparison to the tape with undoped precursor. The tapes prepared from that powder do not show a Jc anisotropy in respect to the field direction. The ex situ powder was used as superconducting diffusion barrier for copper sheathed conductors to prevent reaction between filament and sheath. 7. In addition, ex situ powder is used as a chemical barrier in Glidcop® in situ wires, substituting Nb or Ti which are commonly used. It is proved that the wire deformation by drawing with the powder barrier is possible. The effectiveness of the barrier in preventing a reaction between the Glidcop® sheath and the in situ MgB2 in wires heat treated both under ambient pressure and under high gas pressure was studied. It is found that this barrier is effective in preventing diffusion between Mg and Cu in the sheath only in the case of high pressure sintering. This novel technique allows to get relatively high values of the engineering critical current density Je (Je=104 A/cm2 at 5.3 T) because a high superconductor filling factor of 50% can be achieved. This is usually very challenging in powder-in-tube composite conductors with a diffusion barrier. Homepage IFW Dresden
Electromechanical Properties Of Superconducting Mgb2 Wire
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Author : Mina Hanna
language : en
Publisher:
Release Date : 2005
Electromechanical Properties Of Superconducting Mgb2 Wire written by Mina Hanna and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005 with High temperature superconductors categories.