When a material is irradiated with a high-intensity laser pulse, its surface ionization generates electrons that are accelerated close to the speed of light by the ponderomotive force of the laser light, yet how electrons’ kinetic energy scales with laser power is still unclear. The authors experimentally clarify this relation and by modelling individual electron trajectories using numerical simulations identify two acceleration mechanisms for the generation of relativistic electrons related to the dependency of the electric and magnetic fields.
