With the continuing development of laser systems, new important and so-far unexplored fields of research related to interaction of ultra-intense laser beams with matter are opening. At intensities of the order of 10²² W=cm², electrons may be accelerated in the electromagnetic field of the laser wave and achieve such a high energy that they can enter the regime affected by the radiation reaction. Due to the non-linear Thomson and Compton scattering the accelerated electrons emit photons. The interaction of emitted photons with the laser field may result in effective generation of electron-positron pairs by means of the Breit-Wheeler process. In this work we study the influence of laser pulse polarization on gamma-ray generation during interaction of two colliding and tightly focused laser pulses with a low density target composed of electrons. This paper focuses on evolution of electron trajectories and key parameters χ_e (probability of photon emission) and χ_γ(probability of pair generation) in the laser field. These interactions are studied using 2D PIC simulations. It is shown that in the case of circularly polarized and tightly focused laser beams, electrons are not following circular trajectories at the magnetic node of the standing wave established in the focus, which leads to lowering the radiation emission efficiency.

Date Published: 1 May 2015
PDF: 7 pages
Proc. SPIE 9515, Research Using Extreme Light: Entering New Frontiers with Petawatt-Class Lasers II, 95150M (1 May 2015); doi: 10.1117/12.2178756

Published in SPIE Proceedings Vol. 9515:
Research Using Extreme Light: Entering New Frontiers with Petawatt-Class Lasers II
Georg Korn; Luis O. Silva, Editor(s)