Plasma wakes driven by Compton scattering: nonlinear regime and electron acceleration

Plasma wakes can be generated with a large variety of drivers such as particle or light beams. The light beam sees the plasma as a dielectric medium and excites plasma modes via its ponderomotive force. It has been recently shown that there is an alternative to ponderomotive drivers [1]. Photons with a wavelength smaller than the plasma inter-particle distance only interact with the electrons of the plasma through Compton scattering. A photon burst exerts a piston force on the electron of the plasma which can lead to plasma wakes. We focus on this fundamental process for different photon frequencies, photon flux, and plasma magnetization. The analytical findings are in very good agreement with the simulations performed with the particle-in-cell code OSIRIS coupled to a Compton scattering module [2]. For low photon energy densities, the amplitude of the wakes remains linear, and one observes the generation of Langmuir and extraordinary modes. For extreme photon energy densities, the amplitude of the wake becomes non-linear and becomes analogous to the blowout of the regime observed with intense lasers [3]. We will highlight the typical mechanisms that eventually limit electron acceleration in these wakes such as phase velocity of the wake, dephasing, driver collimation, and driver depletion.