Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

Target densities near the critical plasma density are of great interest for the laser-ion acceleration community, as new and interesting acceleration mechanisms can occur at these densities due to the effect of relativistically induced transparency.
Designing and builing near-critical densitiy targets with closely defined parameters has thus been the goal of much recent and ongoing target development.
Here, we present our approach for a density tailored near-critical target, that utilizes controlled preexpansion of a cryogenic hydrogen jet target used at the Draco laser facility at Helmholtz-Zentrum Dresden-Rossendorf (HZDR).
The cylindrical solid hydrogen jet target is irradiated with pump laser pulses in the range of 10¹² to10¹⁸ W/cm². The expansion of the emerging plasma cloud is studied over several tens of picoseconds by means of high resolution two-color off-harmonic optical probing.
At high pump laser intensities, a simple toy model of the radial density profile of the expanding jet target is applied to estimate the evolution of the plasma density during the expansion process.
We show, how the expansion process can be directly influenced by controlling intensity and temporal shape of the pump laser pulses.