  We discuss the status of atomic physics in strong field. We focus on the
problem of electron-positron lines observed in heavy-ion collisions and on QED
effects, calculated in strong Coulomb fields, especially Delbr\"uck-scattering.
We discuss the similarities and differences between these effects and
channeling respectively beamstrahlung. We investigated the prospects for
photon-channeling, calculated channeling from first principles on the basis of
the Dirac equation, and determined the rate for electron-positron pair
production in the collision of two high-energy particle pulses.

High Energy Physics - Phenomenology;Nuclear Theory