Modeling of vortex dynamics in HTSs with defects under the impact of pulsed magnetic field

Abstract

By means of the Monte Carlo method, a numerical study of the vortex system in a high-temperature superconductor under the impact of pulses of magnetic field has been conducted. Various shapes and amplitudes of pulses have been considered. Samples with random and regular distributions of three different numbers of defects have been compared from the viewpoint of efficiency of flux trapping. The low-temperature behavior of vortices and their penetration into samples have been shown to be independent of the pulse shape but strongly dependent of the type of pinning distribution. Saturating dependences of density of trapped magnetic flux on the pulse amplitude have been obtained. The samples with random pinning demonstrated higher efficiency of flux trapping at lower pulse amplitudes, and the samples with a triangular lattice of defects—at higher amplitudes. If the amplitude exceeded the saturation field of both samples, the trapped field was almost equal. The increasing number of defects has lead to an increase in trapped field within the considered range of concentrations.

Thermal behavior of flux jumps and influence of pulse-shape on the trapped field during pulsed magnetization of a high-temperature superconductor

“…The aim of this study is mostly to explore the effect of temperature on the flux jumps and TF. The computational model and method are the same as in [36,37], and their detailed description can be found in [37]. The essential features of the computational procedure and sample geometry are presented below.…”

“…The continuum-space MC method is a helpful tool for modeling the magnetization and current-carrying properties of HTSs in wide ranges of various parameters [36,37,[50][51][52][53][54][55][56][57][58][59]. Its undeniable advantage is the possibility of explicitly considering the behavior, various interactions, and phase states of a system with a varying number of vortices in continuous space.…”

“…Numerous studies of bulk superconductors and stacks of HTS-tapes [1,15,18,24,[26][27][28][29][30][31][32][33][34][35][36][37] are dedicated to the socalled flux jumps (or 'giant field leaps' as first introduced in [27]). These jumps occur at certain critical (or activation) fields and result in a rapid invasion of the magnetic flux into the superconducting samples.…”

“…The Monte Carlo (MC) method [48,49] can be of great use for this purpose because it takes into account the ambient temperature and the alternating external field while dealing with a grand canonical ensemble. This method has already proven its efficiency in studying the magnetic and transport properties of layered HTSs in wide ranges of temperatures, pinning parameters, magnetic fields, and transport currents [36,37,[50][51][52][53][54][55][56][57][58], both in 3D and 2D geometries. This technique also provides an opportunity of showing how an HTS behaves upon linear magnetization [36].…”

“…This technique also provides an opportunity of showing how an HTS behaves upon linear magnetization [36]. Lately, it has been shown in [36] that the activation field of flux jumps depends on the concentration and distribution of defects (random or periodic), and in [37]-that the shape and rise-time of the pulse does not impact the TF. However, both mentioned works only dealt with low temperatures.…”