6 research outputs found
Surface Influence on Flux Penetration into HTS Bulks
The influence of surface treatment on AC loss in melt-processed quasi-single
crystal HTS was investigated with resonance oscillations technique. We have
found that amplitude dependencies of AC loss on magnetic field amplitude become
rather complicated after surface polishing. The experimental data show well
distinguished dynamic crossover from absence of barrier at low rates of field
variation to its appearence at higher rates. An explaination of such a dynamic
surface barrier appearance based on consideration of along surface vortex
propagation was suggested.Comment: 2 pages with 1 EPS figure, to be presented at LT2
Determination of critical current density in melt-processed HTS bulks from levitation force measurements
A simple approach to describe the levitation force measurements on
melt-processed HTS bulks was developed. A couple of methods to determine the
critical current density were introduced. The averaged -plane
values for the field parallel to this plane were determined. The first and
second levitation force hysteresis loops calculated with these values
coincide remarkably well with the experimental data.Comment: 10 pages (tex), 2 figures (in jpeg
Temperature dependence of trapped magnetic field in MgB2 bulk superconductor
Based on DC magnetization measurements, the temperature dependencies of the
trapped magnetic field have been calculated for two MgB2 samples prepared by
two different techniques: the high-pressure sintering and the hot pressing.
Experimentally measured trapped field values for the first sample coincide
remarkably well with calculated ones in the whole temperature range. This
proves, from one side, the validity of the introduced calculation approach, and
demonstrates, from another side, the great prospects of the hot pressing
technology for large scale superconducting applications of the MgB2.Comment: 3 pages, 3 figures, submitted to AP
Thermobaric Effect on Melt-Textured MBaCuO (M = Y, Nd)
The effect of a short (10-30 min) thermobaric action (in the 1-5 GPa pressure
and 700-1300C temperature range) on the structure, superconductive and
mechanical properties of melt-textured-MBaCuO (M=Y, Nd) or
MT-MBCO have been studied. The existence has been established of
pressure-temperature--time conditions (2 GPa, 800C for 30 min and
900-950C for 15 min for MT-YBCO; 5 GPa, 850-900C for 15 min for
MT-NdBCO) the treatment under which allows superconductive properties of the
materials (because of the contact with zirconia and high pressure) to be
preserved or improved, mechanical characteristics increased and the materials
condensed.Comment: 2 pages (tex), 2 figures (eps), to be presented at LT2