An extended locally constant field approximation for nonlinear Compton scattering

Understand

The locally constant field approximation (LCFA) has to date underpinned the numerical simulation of quantum processes in laser-plasma physics and astrophysics, but its validity has recently been questioned in the parameter regime of current laser experiments.

• While improvements are needed, literature corrections to the LCFA show inherent problems.
• Using nonlinear Compton scattering in laser fields to illustrate, we show here how to overcome the problems in LCFA corrections.
• We derive an "LCFA+" which, comparing with the full QED result, shows an improvement over the LCFA across the whole photon emission spectrum.