Ey. Klimenko et al., ANISOTROPIC PINNING IN MACROSCOPIC ELECTRODYNAMICS OF SUPERCONDUCTORS, Journal of experimental and theoretical physics, 85(3), 1997, pp. 573-587
Anisotropy of critical currents and electric fields in superconductors
with strong pinning has been ascribed in the macroscopic model to fea
tures of the material equation system relating the electric field to t
he current density in a superconductor. The anisotropy of the pinning
proper is described by an operator relating the pinning force density
to the vectors of magnetic induction and Lorentz force. In the approxi
mation of an extended critical state model, a feasible expression of t
his operator is given in the form of an algorithm based on the concept
of a collective anisotropic potential well containing fluxoids. The c
urrent-carrying capacity of a strongly anisotropic niobium-titanium fo
il as a function of the orientation of the current density and applied
field with respect to the principal axes of the material has been inv
estigated in detail. Given measurements of the transverse electric fie
lds in the foil under magnetic fields normal to the foil plane, we can
plot cross sections of surfaces describing the pinning force density
in the space of magnetic induction and Lorentz force. (C) 1997 America
n Institute of Physics. [S1063-7761(97)01909-4].