Relativistic X-Ray Free Electron Lasers in the Quantum Regime

TL;DR

This paper develops a nonlinear quantum model for relativistic X-ray free electron lasers using a Klein-Gordon framework coupled with Maxwell-Poisson equations, highlighting quantum recoil effects and tunable scattering phenomena.

Contribution

It introduces a novel Klein-Gordon based nonlinear theory for quantum relativistic free electron lasers, deriving a general dispersion relation including large amplitude fields.

Findings

Quantum recoil effects significantly influence laser behavior.

Oblique scattering can be tuned by adjusting beam energy.

The model accounts for large amplitude electromagnetic wigglers.

Abstract

We present a nonlinear theory for relativistic X-ray free electron lasers in the quantum regime, using a collective Klein-Gordon (KG) equation (for relativistic electrons), which is coupled with the Maxwell-Poisson equations for the electromagnetic and electrostatic fields. In our model, an intense electromagnetic wave is used as a wiggler which interacts with a relativistic electron beam to produce coherent tunable radiation. The KG-Maxwell-Poisson model is used to derive a general nonlinear dispersion relation for parametric instabilities in three-space-dimensions, including an arbitrarily large amplitude electromagnetic wiggler field. The nonlinear dispersion relation reveals the importance of quantum recoil effects and oblique scattering of the radiation that can be tuned by varying the beam energy.