An empirical model of collective electrostatic effects for laser-beam channeling in long-scale-length relativistic plasmas

This work investigates the capability of ultraintense lasers with irradiance from 10(18) to 10(21) W cm(-2) to produce highly energetic electron beams from a Gaussian focus in a low-density plasma. A simple particle simulation code including a physical model of collective electrostatic effects in relativistic plasmas has been developed. Without electrostatic fields, free electrons escape from the Gaussian focal region of a 10-ps petawatt laser pulse very quickly, well before the laser field reaches its maximum amplitude. However, it has been demonstrated that the electrostatic field generated by the electron flow is able to strongly modify the range and direction of the laser-generated MeV electrons by allowing trapped electrons to experience much higher laser-intensity peaks along their trajectories. This modeling predicts some collimation but not enough to meet the requirements of fast ignition. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3622663]