  New laser facilities will reach intensities of $10^{23} \textrm{W cm}^{-2}$.
This advance enables novel experimental setups in the study of laser-plasma
interaction. In these setups with extreme fields quantum electrodynamic (QED)
effects like photon emission via non-linear Compton scattering and
Breit-Wheeler pair production become important.
  We study high-intensity lasers grazing the surface of a solid-state target by
two-dimensional particle-in-cell simulations with QED effects included. The two
laser beams collide at the target surface at a grazing angle. Due to the fields
near the target surface electrons are extracted and accelerated. Finally, the
extracted electrons collide with the counter-propagating laser, which triggers
many QED effects and leads to a QED cascade under a sufficient laser intensity.
Here, the processes are studied for various laser intensities and angles of
incidence and finally compared to a seeded vacuum cascade. Our results show
that the proposed target can yield many order of magnitude more secondary
particles and develop a QED cascade at lower laser intensities than the seeded
vacuum alone.
