Papers by Youri Viouchkov
IEEE Transactions on Applied Superconductivity, 2016
Superconductor Science and Technology, 2010
IEEE Transactions on Applied Superconductivity, 2000
Insulation in a high field superconducting magnet plays a critical role. For high field magnets u... more Insulation in a high field superconducting magnet plays a critical role. For high field magnets using coated conductor, insulation faces a few special challenges. In order to maximize the engineering current density, the conductor insulation has to be very thin (e.g. $<12.5\ \mu{\rm m}$). In addition to required mechanical and dielectric integrity under high stresses at cryogenic temperatures, the temperature
IEEE Transactions on Appiled Superconductivity, 2001
Superconducting coil windings are subject to complex strain states due to fabrication and operati... more Superconducting coil windings are subject to complex strain states due to fabrication and operation, particularly when wound in a complex geometry. Although there has been significant study of the effects of longitudinal tension and bending on Ag/Bi-Sr-Ca-Cu-O conductors, there has been little attention to the effects of longitudinal compression. Here we report a method to apply pure longitudinal compression on tape conductors without bending or buckling. Measurements on short Bi-2223 samples include stress-strain relationships at room temperature and 77 K, and the effects of compression on Ic
IEEE Transactions on Appiled Superconductivity, 2001
We report the combination of two separately developed materials processing technologies which tog... more We report the combination of two separately developed materials processing technologies which together have made possible the production of single phase fibers of (Hg,Re)Ba-Ca-Cu-O ((Hg,Re)-1223). These fibers have shown Tc values of 132 K, irreversibility fields of 2.3 T at 77 K and Ic values as high as 10 A and 40 A at 77 and 4.2 K, respectively. One salient use of these fibers is their application to the HTS section of a resistive/superconducting hybrid current lead. Such an application offers greater system cooling efficiencies and the ability to operate in higher magnetic fields than current leads based upon the more commonly used Y-Ba-Cu-O (123) and Bi-Sr-Ca-Cu-O (2223) compounds
IEEE Transactions on Appiled Superconductivity, 2000
ABSTRACT Mechanical properties of Bi2Sr2CaCu2 Ox (Bi-2212) superconducting tapes at room temperat... more ABSTRACT Mechanical properties of Bi2Sr2CaCu2 Ox (Bi-2212) superconducting tapes at room temperatures were studied to define critical parameters limiting their use for high field insert magnets. This investigation was dedicated to stress-strain effects and mechanical interactions between the ceramic and metal matrix due to thermal cycling. A model of mechanical behavior during thermal cycling of Ag-sheathed Bi-2212 tapes is proposed
IEEE Transactions on Appiled Superconductivity, 1999
ABSTRACT The critical current of the tapes prepared using continuous processing is significantly ... more ABSTRACT The critical current of the tapes prepared using continuous processing is significantly enhanced and processing time reduced, compared with that of traditional processing. The effect of conductor pulling speed on the microstructure, phase purity and therefore critical current of the tape is investigated using ESEM, XRD and DC transport measurements.
IEEE Transactions on Applied Superconductivity, 2000
The National High Magnetic Field Laboratory is developing several powered magnets employing novel... more The National High Magnetic Field Laboratory is developing several powered magnets employing novel configurations for use in photon and neutron scattering experiments. First is a split resistive magnet being built for Far-Infrared Scattering at the NHMFL in Tallahassee. This magnet has spurred the development of the novel Split Florida-Helix (SFH) technology. High-field test coils of the SFH concept have been
IEEE Transactions on Applied Superconductivity, 2000
ABSTRACT The National High Magnetic Field Laboratory (NHMFL) has several resistive solenoid magne... more ABSTRACT The National High Magnetic Field Laboratory (NHMFL) has several resistive solenoid magnet projects underway presently, including upgrade of four existing magnets, design of the conical bore insert for the Helmholtz Center Berlin (HZB), design of insert coils of the Series-Connected-Hybrid (SCH) for NHMFL and design of resistive split magnet. The upgrades and the design of the conical bore insert are discussed in detail while other programs are presented briefly.
IEEE Transactions on Applied Superconductivity, 2000
Development of high-field magnets using high temperature superconductors (HTS) is a core activity... more Development of high-field magnets using high temperature superconductors (HTS) is a core activity at the NHMFL. Magnet technology based on both YBCO-coated tape conductors and Bi-2212 round wires is being pursued. Two specific projects are underway. The first is a user magnet with a 17 T YBCO coil set which, inside an LTS outsert, will generate a combined field of 32 T. The second is a 7 T Bi2212 demonstration coil set to be operated in a large bore resistive magnet to generate a combined magnetic field of 25 T. Owing to the substantial technological differences of the two conductor types, each project faces different conductor and magnet technology challenges. Two small coils have been tested in a 38-mm cold bore cryostat inserted in a 31 T resistive magnet: a Bi2212 round-wire layerwound insert coil that generated 1.1 T for a total of 32.1 T and a YBCO double-pancake insert that generated 2.8 T for a total central field of 33.8 T. Four larger layer-wound coils have been manufactured and tested in a 20 T, 186-mm cold bore resistive magnet: a sizeable Bi-2212 coil and three thin large-diameter YBCO coils. The test results are discussed. The current densities and stress levels that these coils tolerate underpin our conviction that > 30 T all-superconducting magnets are viable.
IEEE Transactions on Applied Superconductivity, 2000
Abstract The National High Magnetic Field Laboratory is constructing a 32 T all superconducting m... more Abstract The National High Magnetic Field Laboratory is constructing a 32 T all superconducting magnet. The high field insert coil, which produces about 17 T field, will be made of YBCO coated conductor. Due to the limited available coated conductor piece ...
Applied Physics Letters, 2011
To explore the limits of layer wound (RE)Ba2Cu3O7-x (REBCO, RE = Rare Earth) coils in a high magn... more To explore the limits of layer wound (RE)Ba2Cu3O7-x (REBCO, RE = Rare Earth) coils in a high magnetic field environment > 30 T, a series of small insert coils have been built and characterized in background fields. One of the coils repeatedly reached 35.4 T using a single ~100 m length of REBCO tape wet wound with epoxy and nested in a 31 T background magnet. The coil was quenched safely several times without degradation. Contributing to the success of this coil was the introduction of a thin polyester film that surrounded the conductor. This approach introduces a weak circumferential plane in the coil pack that prevents conductor delamination that has caused degradation of several epoxy impregnated coils previously made by this and other groups.
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Papers by Youri Viouchkov