A5060806510- Superconducting Materials and Applications
- Physics of Superconductivity and Magnetism
- Magnetic confinement fusion research
- HVDC Systems and Fault Protection
- Particle accelerators and beam dynamics
- Spacecraft and Cryogenic Technologies
- Hydrocarbon exploration and reservoir analysis
- Magnetic Properties and Applications
- Thermal Analysis in Power Transmission
- Geological and Geochemical Analysis
- Geological formations and processes
- Superconductivity in MgB2 and Alloys
- Heat Transfer and Boiling Studies
- Electromagnetic Launch and Propulsion Technology
- Paleontology and Stratigraphy of Fossils
- Magnetic properties of thin films
- Heat Transfer and Optimization
- Iron-based superconductors research
- Advanced Thermodynamic Systems and Engines
- Enhanced Oil Recovery Techniques
- Reservoir Engineering and Simulation Methods
- Magnetic Properties of Alloys
- Quantum, superfluid, helium dynamics
- CO2 Sequestration and Geologic Interactions
- Magnetic and transport properties of perovskites and related materials
Karlsruhe Institute of Technology
2018-2022
FZI Research Center for Information Technology
1994-2010
FIZ Karlsruhe – Leibniz Institute for Information Infrastructure
2006-2009
Slovak Academy of Sciences
2001
Institute of Electrical Engineering of the Slovak Academy of Sciences
1996
Virginia Tech
1994
Brookhaven National Laboratory
1981
RBCO (R = Y or rare earth element) coated conductors (CC) are the most promising HTS materials for future high field coils operated at moderately temperature (40-50 K). Coils planned second generation of fusion reactors (DEMO, "DEMOnstrator") and beyond. A ROEBEL bar concept a current (kA-class) low AC loss cable is suitable assembling technique in magnet windings due to flat rectangular cross section. The presented RACC-cable (RACC=ROEBEL assembled conductors) works with pre-shaping tapes...
Low AC loss high transport current HTS cables (>1 kA) are required for application in transformers, generators and considered future generations of fusion reactors coils. 2G coated conductors suitable candidates field at quite operation temperatures 50-77 K, which is crucial precondition economical cooling costs. As a feasibility study we present the first ROEBEL bar cable approx. 35 cm length made from industrial DyBCO conductor (THEVA GmbH, Germany). Meander shaped strands 4 mm width with...
The behavior of NbTi superconductors under dynamic mechanical stress was investigated. A training effect found in short-sample tests when the conductor strained a magnetic field and with transport current applied. Possible mechanisms are discussed which were proposed to explain short samples magnets. stress-induced microplastic as well an incomplete pseudoelastic detected by monitoring acoustic emission. experiments support hypothesis that or shape memory effects involving dislocation...
Research Article| August 01, 1994 Fluid inclusions as tectonothermobarometers: Relation between pressure-temperature history and reequilibration morphology during crustal thickening M. O. Vityk; Vityk 1Fluids Laboratory, Department of Geological Sciences, Virginia Polytechnic Institute State University, Blacksburg, 24061 Search for other works by this author on: GSW Google Scholar R. J. Bodnar; Bodnar C. S. Schmidt Geology (1994) 22 (8): 731–734....
Assembling coated conductors (CC) into flat ROEBEL bars (RACC-cable) is a practical method to reach high transport currents in low AC loss cable design which suitable for application windings. Electrical machinery as large transformers and generators/motors need few kA current. The aim of the presented work was demonstrating possibility strong increase current such RACC-cables. So far 1 achieved We present changed with 3-fold layered strands, an unchanged transposition pitch 18.8 cm finally...
Experiments were performed to study the cause for training phenomenon in superconducting magnets. Stress-strain curves of commercial superconductors taken with applied field and transport current. In experiments where samples strained a constant current below I <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</inf> , normal transition occured at successively higher stress levels. That means, behaviour short was found. low strain region distinct...
Unexpected periodic variations of the magnetic field were recently found along axes superconducting accelerator magnets. This modulation, which reduces quality magnets, shows a complex space and time dependence containing very long constants. We show in this article that variation rate dB/dt length cable induces superposed coupling currents flow over length. The these ‘‘supercurrents’’ for two-wire model is obtained by solution diffusion equation with diffusivity given parameters. existence...
Transient heat transfer from bare and coated copper surfaces to saturated liquid helium was measured with a time constant of ∼ 5 μsec. In another experiment recovery superconducting wire after temperature excursion studied. The results show large difference between surfaces, latter recover at higher surface fluxes. While the is smooth function excursion, that exhibits discontinuity, being for small disturbance.
Technical superconductors for 50-Hz application, operated at liquid-helium temperature, are designed very low ac losses. These losses cannot be measured calorimetrically on short samples of conductors with the conventional measuring techniques, but only coils wound several hundreds meters wire. We describe here development a technique which allows measurement resolution 10−8 W. The method is similar to thermal conductivity measurement. sample placed into vacuum vessel and connected via...
Low ac-loss HTS cables for transport currents well above 1 kA are required application in transformers and generators taken into consideration future generations of fusion reactor coils. Coated conductors (CC) suitable candidates high field at an operation temperature the range 50-77 K. Ac-field applications require with low ac-losses hence twisting individual strands. We solved this problem using Roebel technique. Short lengths bar were prepared from industrial DyBCO YBCO-CC. Meander shaped...
Since the discovery of superconductivity in MgB2 many efforts have been undertaken to improve current carrying capacity mono‐ or multifilament conductors. However, even though conductors can be produced geometries which easily allow twisting cabling, reduction ac losses has often played a minor role, technical superconductor applications like transformers, rotating machinery, and ramped magnets require with low AC losses. In this paper we present short cables together measured AC‐losses...
This study focusses on bleaching phenomena the pore scale in an Olenekian (Upper Buntsandstein) sandstone quarry.The area exposes a 10 m thick red body with up to cm sized, greyish white laminae sandstones.Analyses focus bleached and unbleached zones same sized samples.Bleached show larger grain size (by 27 μm), less compaction higher porosity 3 %).They also exhibit stronger cementation by all observed authigenic phases of quartz, illite, K feldspar minor extent dolomite.Calcu lated...
Unexpected periodic variations of the magnetic field were recently found along axis superconducting accellerator magnets, which reduces quality magnets. The modulation shows a complicated time dependence containing very long constants. In this letter it is shown that an inhomogeneous distribution dB/dt cable leads to superposed coupling currents flowing over lengths, can explain observed effects. solution diffusion equation allows one calculate space and hence amplitude modulation.
A prototype tokamak poloidal field coil of 3 m diameter was successfully tested. The designed to withstand typical transients like fast ramping, plasma controlling and disruptions. In order achieve these requirements, a low loss conductor developed. with its components according rules high voltage technology. realistic test the magnet requires at 23 kV current 15 kA, that means peak power 345 MW. Therefore, switching circuit used combined an additional lead middle winding. This allowed...