Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

Laser-driven ion acceleration promises to provide a compact solution for demanding applications like particle therapy, proton radiography or inertial confinement research. Controlling the particle beam parameters to achieve these goals is currently pushing the frontier of laser driven particle accelerators.

The performance of the plasma acceleration is strongly dependent on the complex pre-plasma formation process at the target front surface which is determined by the temporal intensity contrast. Particularly low-density targets require an enhanced temporal contrast to remain overcritical until the main pulse arrives. Plasma mirror setups have proven to significantly improve the temporal contrast by reducing pre-pulse intensity and steepening the rising edge of the main laser pulse, enabling the investigation of laser proton acceleration and proton energy scaling using ultra-thin targets.

We present new experimental results on the interaction of the DRACO Petawatt ultra-short pulse laser with ultra-thin foil targets. Efficient and on-demand contrast cleaning established through a re-collimating plasma mirror setup facilitated thickness scans from the µm range down to several tens of nm. The combination of a complex set of diagnostics, consisting of proton detectors in target normal, laser forward and laser backward axis, laser pulse transmission and reflection diagnostics as well as detection of front surface electrons, delivered concrete indicators for the acceleration conditions. Furthermore, tremendous progress has been achieved by successfully implementing a novel laser contrast diagnostic by means of self-referenced spectral interferometry with extended time excursion (SRSI-ETE), allowing to characterize the temporal contrast in the experimental area on a single-shot base with unprecedented dynamic and temporal range.