Experimental study of channel formation by 30 ps intense laser pulses in near-critical, mm-scale plasmas

We will present results, obtained at the VULCAN laser (RAL, UK), of an experiment investigating channel creation in deuterium gasjets at different plasma densities (from 10$^{18} $cm$^{-3}$ up to 10$^{20}$cm$^{-3}$) using laser pulses with parameters of Fast Ignitor relevance (T$\approx$30ps, I$\approx$10$^{18}$ W/cm$^2$) and a range of diagnostics including optical and proton probing. For densities up to few times 10$^{18}$cm$^{-3}$, smooth and several mm long , strongly evacuated channels with sharp walls are created. For higher densities, the interaction appears to be more chaotic, with possible indication of unstable explosion of the channel walls. Soliton-like features are also observed in the channel vicinities.