Particle-in-Cell Analysis of Relativistic Transparency Thresholds.

High-intensity lasers capable of accelerating electrons to relativistic speeds alter the optical properties of a plasma through the phenomenon of relativistic transparency. This phenomenon critically influences the laser-plasma energy coupling efficiency and thus must be taken into consideration when choosing parameters for various applications (laser-plasma acceleration, for example). Here we employ 1D particle-in-cell simulations of a high-intensity pulse incident onto a uniform plasma pre-heated to a relativistic temperature. We want to test different combinations of laser-intensity and plasma temperature and study their contributions to relativistic transparency through absorption and reflectivity analyses.