Flux creep simulations online

### Mission

Flux creep phenomenon is a basic one for understanding many features of vortex behaviour in HTSC. Unfortunately, analytical results are available for a very limited number of flux creep problems. In most cases the only efficient tool to describe the vortex behavior is numerical simulations. This site presents videos obtained by flux creep simulations, namely, the time evolution of flux density, current density and electric field spatial distributions as well as magnetization hysteresis loops obtained under various external conditions.

### Videos

(as animated GIF files)
 Complete set of movies for B(x), J(x), E(x) and M(Ba) Thin strip in perpendicular field swept with a constant rate: Uc/kT = 3     Uc/kT = 5     Uc/kT = 11     Uc/kT = 33 Long slab in parallel field swept with a constant rate: Uc/kT = 3     Uc/kT = 11     Uc/kT = 33 Thin strip in ac applied field, Uc/kT = 5 Comparative analysis

### Basic expressions

For simulations we use Maxwell equation  dB/dt = - dE/dx,   the electric field  E = vB,   the velocity of the thermally activated vortex motion   v = vc exp[ -U(j) / kT ].
The current dependence of the pinning energy is usually taken in logariphmic form,   U = Uc ln( j / jc ),   which leads to E ~ jn, with n = Uc / kT.
The relation between the current density and flux density is j = dB/dx for the parallel geometry, or the inverted Biot-Savart law for the perpendicular geometry.

 Superconductivity Group at Oslo Univ.    HTS Group at Ioffe Institute Updated: 14.10.00,   Maintained by D. Shantsev