Theory of plasma wakes driven by Compton scattering

Photon bursts with a wavelength smaller than the plasma inter-particle distance can drive plasma wakes via Compton scattering. Such wakes are likely to be formed in astrophysical environments where abundant energetic photons are produced. We present here a complete one dimensional theory of this fundamental process, which is compared with the results of PIC simulations enriched with a Compton module. We take into account several parameters such the length of the photon driver, the initial energy density (number density and frequency), and the plasma magnetization. A special focus is also dedicated to the difference with other drivers (laser / particle beam) that excite plasma modes via their effective ponderomotive force. Our results show that Langmuir and extraordinary modes are driven efficiently when the photon energy density lies above a certain threshold. The interaction of photon bursts with magnetized plasmas is of distinguished interest as the generated extraordinary modes can convert into pure electromagnetic waves at the plasma/vacuum boundary.

This work was supported by the European Research Council (ERC-2015-AdG Grant 695088).