14 research outputs found
Critical current density and trapped field in HTS with asymmetric magnetization loops
Applications of the extended critical state model are considered. The trapped
magnetic field, the penetration field and the field dependence of the critical
current density are analysed. The critical current density and the trapped
field in superconducting grains depend on the grain size. Asymmetry of the
hysteresis curves relative to the M = 0 axis is related to the scale of the
current circulation.Comment: 5 pages, 4 figures, presented in the 9th International Workshop on
Processing and Applications of Superconducting (RE)BCO Large Grain Materials
(PASREG 2015
Magnetic flux trapping in porous superconductors
The magnetization of superconducting samples is influenced by their porosity.
In addition to structural modifications and improved cooling, the presence of
pores also plays a role in trapping magnetic flux. Pores have an impact on the
irreversibility field, the full penetration field, and the remnant
magnetization. Generally, as porosity increases, these parameters tend to
decrease. However, in the case of mesoscopic samples or samples with low
critical current densities, increased porosity can actually enhance the
trapping of magnetic flux.Comment: 9 pages, 3 figure
Computation of current-voltage characteristics of weak links
Simplified model for current-voltage characteristics of weak links is
suggested. It is based on approach which considers Andreev reflections as
responsible for the dissipative current through the metallic Josephson
junction. The model allows to calculate current-voltage characteristics of weak
links (superconductor - normal metal - superconductor junctions, microbridges,
superconducting nanowires) for different thicknesses of the normal layer at
different temperatures. The current-voltage characteristics of tin microbridges
at different temperatures were computed.Comment: 11 pages, 5 figure
Microstructural Parameters for Modelling of Superconducting Foams
Superconducting YBa2Cu3Oy (YBCO) foams were prepared using commercial open-cell,
polyurethane foams as starting material to form ceramic Y2BaCuO5 foams which are then converted
into superconducting YBCO by using the infiltration growth process. For modelling the superconducting and mechanical properties of the foam samples, a Kelvin-type cell may be employed as a first
approach as reported in the literature for pure polyurethane foams. The results of a first modelling
attempt in this direction are presented concerning an estimation of the possible trapped fields (TFs)
and are compared to experimental results at 77 K. This simple modelling revealed already useful
information concerning the best suited foam structure to realize large TF values, but it also became
obvious that for various other parameters like magnetostriction, mechanical strength, percolative
current flow and the details of the TF distribution, a refined model of a superconducting foam sample
incorporating the real sample structure must be considered. Thus, a proper description of the specific
microstructure of the superconducting YBCO foams is required. To obtain a set of reliable data, YBCO
foam samples were investigated using optical microscopy, scanning electron microscopy and electron
backscatter diffraction (EBSD). A variety of parameters including the size and shape of the cells
and windows, the length and shape of the foam struts or ligaments and the respective intersection
angles were determined to better describe the real foam structure. The investigation of the foam
microstructures revealed not only the differences to the original polymer foams used as base material,
but also provided further insights to the infiltration growth process via the large amount of internal
surface in a foam sample
ΠΠ½Π°Π»ΠΈΠ· ΠΏΠ΅ΡΠ΅Π»Ρ Π½Π°ΠΌΠ°Π³Π½ΠΈΡΠ΅Π½Π½ΠΎΡΡΠΈ ΡΠ²Π΅ΡΡ ΠΏΡΠΎΠ²ΠΎΠ΄Π½ΠΈΠΊΠΎΠ²
The critical state model and the extended critical state model are described to analyse a magnetization
hysteresis and to find superconductor parameters. We discuss how geometric sizes and form influence on magnetization hysteresis, critical current and trapped fluxΠΠΏΠΈΡΠ°Π½ΠΎ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π½ΠΈΠ΅ ΠΌΠΎΠ΄Π΅Π»ΠΈ ΠΊΡΠΈΡΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΡΠΎΡΡΠΎΡΠ½ΠΈΡ ΠΈ ΡΠ°ΡΡΠΈΡΠ΅Π½Π½ΠΎΠΉ ΠΌΠΎΠ΄Π΅Π»ΠΈ ΠΊΡΠΈΡΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΡΠΎΡΡΠΎΡΠ½ΠΈΡ Π΄Π»Ρ ΠΎΠΏΡΠ΅Π΄Π΅Π»Π΅Π½ΠΈΡ ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΠΎΠ² ΡΠ²Π΅ΡΡ
ΠΏΡΠΎΠ²ΠΎΠ΄Π½ΠΈΠΊΠΎΠ² ΠΈΠ· ΠΈΠ·ΠΌΠ΅ΡΠ΅Π½Π½ΡΡ
ΠΏΠ΅ΡΠ΅Π»Ρ Π½Π°ΠΌΠ°Π³Π½ΠΈΡΠ΅Π½Π½ΠΎΡΡΠΈ. ΠΠ±ΡΡΠΆΠ΄Π°Π΅ΡΡΡ Π²Π»ΠΈΡΠ½ΠΈΠ΅ Π³Π΅ΠΎΠΌΠ΅ΡΡΠΈΡΠ΅ΡΠΊΠΈΡ
ΡΠ°Π·ΠΌΠ΅ΡΠΎΠ² ΠΈ ΡΠΎΡΠΌΡ ΠΎΠ±ΡΠ°Π·ΡΠΎΠ² Π½Π° Π²ΠΈΠ΄ ΠΏΠ΅ΡΠ΅Π»Ρ Π½Π°ΠΌΠ°Π³Π½ΠΈΡΠ΅Π½Π½ΠΎΡΡΠΈ, ΠΊΡΠΈΡΠΈΡΠ΅ΡΠΊΠΈΠΉ ΡΠΎΠΊ ΠΈ Π·Π°ΠΌΠΎΡΠΎΠΆΠ΅Π½Π½ΠΎΠ΅ ΠΌΠ°Π³Π½ΠΈΡΠ½ΠΎΠ΅ ΠΏΠΎΠ»
ΠΠ½Π°Π»ΠΈΠ· ΠΏΠ΅ΡΠ΅Π»Ρ Π½Π°ΠΌΠ°Π³Π½ΠΈΡΠ΅Π½Π½ΠΎΡΡΠΈ ΡΠ²Π΅ΡΡ ΠΏΡΠΎΠ²ΠΎΠ΄Π½ΠΈΠΊΠΎΠ²
The critical state model and the extended critical state model are described to analyse a magnetization
hysteresis and to find superconductor parameters. We discuss how geometric sizes and form influence on magnetization hysteresis, critical current and trapped fluxΠΠΏΠΈΡΠ°Π½ΠΎ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π½ΠΈΠ΅ ΠΌΠΎΠ΄Π΅Π»ΠΈ ΠΊΡΠΈΡΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΡΠΎΡΡΠΎΡΠ½ΠΈΡ ΠΈ ΡΠ°ΡΡΠΈΡΠ΅Π½Π½ΠΎΠΉ ΠΌΠΎΠ΄Π΅Π»ΠΈ ΠΊΡΠΈΡΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΡΠΎΡΡΠΎΡΠ½ΠΈΡ Π΄Π»Ρ ΠΎΠΏΡΠ΅Π΄Π΅Π»Π΅Π½ΠΈΡ ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΠΎΠ² ΡΠ²Π΅ΡΡ
ΠΏΡΠΎΠ²ΠΎΠ΄Π½ΠΈΠΊΠΎΠ² ΠΈΠ· ΠΈΠ·ΠΌΠ΅ΡΠ΅Π½Π½ΡΡ
ΠΏΠ΅ΡΠ΅Π»Ρ Π½Π°ΠΌΠ°Π³Π½ΠΈΡΠ΅Π½Π½ΠΎΡΡΠΈ. ΠΠ±ΡΡΠΆΠ΄Π°Π΅ΡΡΡ Π²Π»ΠΈΡΠ½ΠΈΠ΅ Π³Π΅ΠΎΠΌΠ΅ΡΡΠΈΡΠ΅ΡΠΊΠΈΡ
ΡΠ°Π·ΠΌΠ΅ΡΠΎΠ² ΠΈ ΡΠΎΡΠΌΡ ΠΎΠ±ΡΠ°Π·ΡΠΎΠ² Π½Π° Π²ΠΈΠ΄ ΠΏΠ΅ΡΠ΅Π»Ρ Π½Π°ΠΌΠ°Π³Π½ΠΈΡΠ΅Π½Π½ΠΎΡΡΠΈ, ΠΊΡΠΈΡΠΈΡΠ΅ΡΠΊΠΈΠΉ ΡΠΎΠΊ ΠΈ Π·Π°ΠΌΠΎΡΠΎΠΆΠ΅Π½Π½ΠΎΠ΅ ΠΌΠ°Π³Π½ΠΈΡΠ½ΠΎΠ΅ ΠΏΠΎΠ»