Bianisotropic-critical-state model to study flux cutting in type-II superconductors at parallel geometry

Abstract

A critical-state model is postulated that incorporates, for the first time, the structural anisotropy and flux-line cutting effect in a type-II superconductor. The model is constructed starting from the theoretical scheme of Romero-Salazar and Pérez-Rodríguez to study the anisotropy induced by flux cutting. Here, numerical calculations of the magnetic induction and static magnetization are presented for samples under an alternating magnetic field, orthogonal to a static dc-bias one. The interplay of the two anisotropies is analysed by comparing the numerical results with available experimental data for an yttrium barium copper oxide (YBCO) plate, and a vanadium–titanium (VTi) strip, subjected to a slowly oscillating field in the presence of a static field .

Thermomagnetic stability in isotropic type-II superconductors under multicomponent magnetic fields

“…There remains the challenging to consider an anisotropic critical state model [3,7], both thermal and conductive properties of the heat capacity C(T, H), as well as other sample geometry [14].…”

Critical states of a superconducting slab subjected to tension and bending

“…c The flux-cutting or pinning mechanism determines two critical current density components, J J c =   and J J c = ^^ [6,7], which are parallel and perpendicular to the magnetic induction intensity B, respectively. The flux vortex begins to move when the Lorentz force f J B L = ^exceeds the average pinning force f J B, p c…”

“…Both of J c and yield stress exhibit a variety of nonlinear electromagnetic constitutive relations. The constitutive relation can be introduced into the electrodynamic equation [6] to construct the governing equation of the time-varying electromagnetic field (critical-state evolution). As a result, a numerical theoretical method coming from the generalized variational principle [5,30] can solve the evolution of critical states in any direction.…”