  We consider a new mechanism for damping the oscillations of a mature neutron
star. The new dissipation channel arises if superfluid vortices are forced to
cut through superconducting fluxtubes. This mechanism is interesting because
the oscillation modes need to exceed a critical amplitude in order for it to
operate. Once it acts the effect is very strong (and nonlinear) leading to
efficient damping. The upshot of this is that modes are unlikely to ever evolve
far beyond the critical amplitude. We consider the effect of this new
dissipation channel on the r-modes, that may be driven unstable by the emission
of gravitational waves. Our estimates show that the fluxtube cutting leads to a
saturation threshold for the instability that can be smaller than that of other
proposed mechanisms. This suggests that the idea may be of direct astrophysical
relevance.
