Ultra high energy density plasmas generated by highly relativistic laser nanowire interactions*

The interaction of high aspect ratio, ordered nanowire arrays with clean, ultrashort laser pulses of relativistic intensity provides a unique combination of nearly complete optical absorption and increased light penetration into near solid density matter. Previous experiments have shown that irradiation of Ni and Au nanowires at intensities of 5x10$^{\mathrm{18}}$Wcm$^{\mathrm{-2}}$ generate multi-keV, near solid density plasmas in which the ionization state reaches Ni$^{\mathrm{+26}}$ and Au$^{\mathrm{+52}}$ charge states$^{\mathrm{1\thinspace }}$at depths of 5$\mu $m$^{\mathrm{\thinspace }}$suggesting the creation of volumetrically heated matter$^{\mathrm{2}}$. Here we present the first results of the irradiation of Ag nanowire arrays with highly relativistic laser pulses of intensities up to 5x10$^{\mathrm{21}}$Wcm$^{\mathrm{-2}}$. Time integrated x-ray spectra show the presence of He-like and Li-like emission. Results of experiments conducted with a variety of different nanowire diameters will be presented and compared to three dimensional particle in cell (3D-PIC) simulations. $^{\mathrm{1}}$Purvis et al Nature Photonics 7, 769 (2013).~$^{\mathrm{2}}$Bargsten et al Sci. Advances Vol. 3 No. 1 (2017)