Universality of flux creep in superconductors with arbitrary shape and current-voltage law

The nonlinear and nonlocal diffusion equation for the relaxing current density J(r, t) in long superconductors of arbitrary cross section in a constant perpendicular magnetic field B-a is solved exactly by separation of variables in the electric field E(r, t) = f(r)g(t). This solution includes the limiting cases of longitudinal and transverse geometries and applies to the current-voltage laws E proportional to J(n) ranging from Ohmic (n = 1) to Bean-like (n --> infinity) behavior. The electric field profile f(r) weakly depends on n and becomes universal for n exceeding approximate to 5. At large times t one finds E proportional to 1/t(n/n-1)) and J proportional to 1/t(1/(n-1)) for n > 1, and E proportional to J proportional to exp(-t/tau(0)) for n = 1. The contour lines of the creeping E(r, t) coincide with the field lines of B(r, t) in the remanent state B-a = 0.