On the electron beam loading in radiation-friction dominated regime of direct laser acceleration

We study beam loading of electrons accelerated via the process of direct laser acceleration under the conditions of preformed plasma channels irradiated by ultra-intense laser pulses using analytical methods and particle-incell simulations in quasi-cylindrical geometry. We find the rates at which the electrons populate the beam for multi-petawatt peak power laser drivers. We show that the majority of accelerated electrons originate at the interface between the channel interior and channel wall and outline the underlying physical mechanism.