Speaker
Description
With the trend towards higher repetition rate laser systems for applications, there is a demand for new, high repetition rate target solutions. This talk will look at efforts to develop shaped, thin, near-critical density gas targets for radiation pressure driven ion acceleration experiments using the high power, $\mathrm{10.6}{\mu m}$ $\mathrm{CO_2}$ laser at Brookhaven National Laboratory. By suitably shaping a gas target, a ps laser pulse was used to first form a transient plasma grating structure in an underdense density ramp. Subsequently, protons were accelerated from the near-critical density plasma grating elements to multi-MeV energies, with few percent energy spreads with modest $\mathrm{\sim10^{15}\,Wcm^{-2}}$ laser intensities. The measured proton energies were more than twice that predicted by the hole-boring scaling, $E_i = 4I/n_cc$. Multiple spectral features were observed on a significant fraction of shots. These results will be discussed, along with some future directions.
