Plasma Wave Generation in a Self-Focused Channel of a Relativistically Intense Laser Pulse

Abstract

Evidence for self-channeling of a relativistically intense laser pulse in an underdense plasma is presented through Schlieren and $90\ifmmode^\circ\else\textdegree\fi{}$ Thomson sidescatter images. Using collective Thomson scattering of a probe beam, we observe that relativistically propagating plasma waves are excited over the entire length of the channel, up to 12 Rayleigh lengths $(\ensuremath{\approx}4\mathrm{mm})$. From the wave amplitude, the intensity inside the channel is estimated to be $\ensuremath{\sim}{10}^{18}\mathrm{W}/\mathrm{cm}{}^{2}$.