Impact of ion mobility on nonlinear Compton scattering of an ultra-intense laser pulse in a plasma

TL;DR

This paper explores how plasma ion mobility influences nonlinear Compton scattering in ultra-intense laser fields, revealing significant modifications to photon emission rates due to plasma dispersion effects even without electrons present.

Contribution

It demonstrates that ion plasma dispersion can alter nonlinear QED processes, showing both suppression and enhancement of photon emission rates in high-intensity laser interactions.

Findings

Ion plasma can suppress photon emission by about 10% at intermediate intensities.

Ion plasma can enhance photon emission by about 10% at high intensities.

Effects occur even in electron-free plasma due to ion response as a dispersive medium.

Abstract

We demonstrate that the nontrivial dispersion of a plasma driven by a high-intensity laser pulse qualitatively affects fundamental nonperturbative QED processes triggered by the laser pulse even in the case that no electrons remain in the interaction volume, e.g., due to ponderomotive expulsion. In the electron-free case this plasma effect is mediated by the response current of the residual ions as a dispersive effect on the laser propagation. The residual ions hence act as an effective background to the propagating electromagnetic laser field. We demonstrate that this has an impact on the fundamental nonlinear QED process of photon emission by an electron upon absorption of a large number of laser photons, called nonlinear Compton scattering. In two exemplary cases we find the ion plasma to suppress and enhance the photon emission rate by approximately $10\%$ for an intermediate and high laser intensity, respectively. The latter enhancement has no classical analog.