Photon acceleration in superluminous and accelerated ionization fronts

The interaction of an electromagnetic wave packet with a superluminous ionization front is described here using the Hamiltonian theory of photon acceleration. We also describe the interaction with accelerated ionization fronts. The different qualitative photon trajectories are presented for both cases. The frequency up-shift is also derived. It is shown that a proper tailoring of the ionization front velocity can lead to higher frequency up-shifts than in constant velocity ionization fronts