Distinguished role of the laser pulse temporal structure on deuteron acceleration

A comprehensive study was conducted to clarify the impact of the temporal shape of laser pulses on ion acceleration from ultrathin targets. The temporal structure of the pulses was set by changing their group delay dispersion and third order dispersion (TOD) independently, while the pulse energy and focal spot size were kept the same. We have found that the effect of pulse duration can be considerably larger than reported previously, making possible also switching between proton and deuteron acceleration. The TOD-induced post-pulses lead to an increase of efficiency by 50%, while the cutoff energy of the accelerated deuterons was at least doubled compared to that with transform-limited pulses. 2D PIC simulations and analytical considerations support the experimental findings, first of these kinds accounting for the effect of TOD, too. We believe that the performance of laser ion accelerators can be significantly enhanced by matching the dispersion values to the target characteristics.