Parametric amplification of laser-driven acceleration in a plasma channel

Abstract

Two-dimensional particle-in-cell simulations are presented for a laser-irradiated solid-density target with and without an underdense preplasma. It is shown that an underdense preplasma can generate an energetic electron tail in addition to the warm electrons generated at the critical surface. Preplasma electrons are accelerated in a quasi-static positively charged channel formed by the laser. At ultra-relativistic laser intensities (a0=10), the acceleration mechanism is not sensitive to the laser polarization. An energetic tail with energies significantly exceeding the energy expected for a single electron in a vacuum is present in simulations with s and p-polarized beams. This suggests that the mechanism of parametric amplification of laser-driven electron acceleration is a likely explanation for the observed phenomenon. © 2012 American Institute of Physics.