Proton radiography of cylindrical laser-driven implosions

We report on the results of a recent experiment at the Rutherford Appleton Laboratory investigating fast electron propagation in cylindrically compressed targets; a subject of interest for fast ignition. This experiment was performed within the framework of the road map of HiPER (the European High Power laser Energy Research facility Project). Protons accelerated by a ps-laser pulse are used to radiograph a 220 µm diameter, imploded with ~200 J of laser light (1 ns λ = 0.53 µm) in four symmetrically incident beams. Results are also compared with those from hard x-ray radiography. Detailed comparison with 2D radiation hydrodyamics simulations is performed with the aid of a Monte Carlo code adapted to describe plasma effects. Finally, a simple analytical model is developed to estimate the performance of proton radiography for given implosion conditions.