Coronal fast ignition by laser: Relativistic critical density increase and constraints on maximum laser wavelength

Abstract

The problem of the relativistic critical density increase under irradiation of a linearly polarized laser beam is analyzed and its relevance for fast ignition is shown. The corresponding cycle-averaged γ factor is determined from numerical simulations and from there an analytical expression is extracted for the mean relativistic critical density. The resulting maximum wavelengths for fast ignition are determined for two different models.