A numerical study of vortex interactions for high- kappa superconductors

Abstract

The repulsive Lome force between two vortices in high-K superconductors with the vortices aligned along the direction of axial symmeuy was calculated by approximating the numerical intend by a set of polynomials to speed up the computations. Calculations were carried out ta simulate formation of hexagonal vortex lattice fiom a population of 4W initially randomly distributed vortices. Small domains with different alignments of vortices were found at the early stages and a single large domain with hexagonal order aligned with the edges emerged at lhe end. Also, the expansion of a vortex population was simulated and it kept its initial shap while it expanded isotopically outward into a larger area The force exerted on a displaced vortex io an otherwise prfect latlice was calculated and it was found to be aboul the same order of magnitude as the force between two isolated vortices, and about ten times stronger than the force exerted on an extra interstitial vortex.

Type II superconductivity

“…Asymptotic behavior at short distances ( Á Á Á Á Á Á Á ) is indicated. Both modified Bessel functions have the same large-distance asymptotic behavior (À À À À À À), as shown (Aktas, 1993). 371 Type II superconductivity core, where r{λ, as indicated in Fig.…”

“…Comparison with Fig. 9.19 shows that the current density exhibits more abrupt changes than the fields (Aktas, 1993). .21 Radial distribution of internal magnetic field in a superconducting rod of 1 mm radius for applied fields from 15 to 222 mT.…”

“…9.12 we plotted the distance dependence of these quantities for an isolated vortex. In this section, we will provide plots that were constructed from calculations of the position dependence of the field and the current density associated with densely packed vortices (carried out by Aktas, 1993;Aktas et al, 1994). The computations involved adding the contributions of the many overlapping vortices in the neighborhood of a particular vortex, as indicated in Figs.…”

“…9.15 and contains all the information on the fields and currents. Also shown are the current circulation around the vortices V and the midpoint M (Aktas et al, 1994). The previous few paragraphs described the internal magnetic field on a mesoscopic scale, with resolution over distances comparable with the penetration depth.…”

“…There are two regimes of flux motion, both of which involve dissipation (Palstra et al, 1988). The first is flux creep, when the pinning force dominates (Anderson, 1962), and the second flux flow, when the Lorentz force dominates (Kim et al, 1963;Tinkham, 1964).…”