  Successful phenomenological models of pulsar wind nebulae assume efficient
dissipation of the Poynting flux of the magnetized electron-positron wind as
well as efficient acceleration of the pairs in the vicinity of the termination
shock, but how this is realized is not yet well understood. The present paper
suggests that the corrugation of the termination shock, at the onset of
non-linearity, may lead towards the desired phenomenology. Non-linear
corrugation of the termination shock would convert a fraction of order unity of
the incoming ordered magnetic field into downstream turbulence, slowing down
the flow to sub-relativistic velocities. The dissipation of turbulence would
further preheat the pair population on short length scales, close to
equipartition with the magnetic field, thereby reducing the initial high
magnetization to values of order unity. Furthermore, it is speculated that the
turbulence generated by the corrugation pattern may sustain a relativistic
Fermi process, accelerating particles close to the radiation reaction limit, as
observed in the Crab nebula. The required corrugation could be induced by the
fast magnetosonic modes of downstream nebular turbulence; but it could also be
produced by upstream turbulence, either carried by the wind or seeded in the
precursor by the accelerated particles themselves.
