Proton radiography of laser-driven imploding target in cylindrical geometry

Abstract

An experiment was done at the Rutherford Appleton Laboratory (Vulcan laser petawatt laser) to study fast electron propagation in cylindrically
\ncompressed targets, a subject of interest for fast ignition. This was performed in the framework of the experimental road map of HiPER (the European high
\npower laser energy research facility project). In the experiment, protons accelerated by a picosecond-laser pulse were used to radiograph a 220 μm
\ndiameter cylinder (20 μm wall, filled with low density foam), imploded with ∼ 200 J of green laser light in four symmetrically
\nincident beams of pulse length 1 ns. Point projection proton backlighting was used to get the compression history and the stagnation time. Results are also
\ncompared to those from hard x-ray radiography. Detailed comparison with two-dimensional numerical hydrosimulations has been done using a Monte Carlo
\ncode adapted to describe multiple scattering and plasma effects. Finally we develop a simple analytical model to estimate the performance of proton radiography
\nfor given implosion conditions.