Transport of Energy by Ultra-Intense Laser-Generated Electrons in Nail-Wire Targets*

Understanding the transport of energy by relativistic fast electrons produced in petawatt (10$^{15}$ W) laser matter interactions is one of the key challenges in fast ignition of ICF. A simple and small target (nail-wire) was designed to investigate aspects of this transport. Nail-wire targets were irradiated using the Vulcan Petawatt Laser (0.8 ps, 3x10$^{20}$ W/cm$^{-2})$ at the Rutherford Appleton Laboratory. A Cu K$\alpha $ spherically bent crystal imager, a Highly Ordered Pyrolytic Graphite (HOPG) Spectrometer, and Single Photon Counting CCD were employed to give absolute K$\alpha $ measurements. The penetration of hot electrons via the nail head into the bulk of the wire has been determined from the K$\alpha $ data. XUV images (68 and 256 eV) indicate heating of a thin surface layer of the targets. A comparison of experimental results with the PIC/hybrid simulations using both LSP and e-PLAS will be presented at the meeting.