Speaker
Description
The acceleration of heavy ions with mass number of ~200-class by high intensity femtosecond laser pulse is still challenging because of the too small knowledge of the ionization mechanisms which strongly couple to the dynamics of the plasma and determine the acceleration efficiency especially at the relativistically induced transparency (RIT) phase where efficient acceleration takes place. The issue arises from the fact that the information of dominant ionization mechanism in the plasma is always clarified by state-of-the-art PIC simulations which are backed up by a limited set of experimental investigations.
Aiming at improving the situation, we carried out both simultaneous measurements of accelerated ions, transmitted laser energy, and plasma parameters by X-ray spectroscopy, by scanning the gold target thickness to cover a wide range of plasma densities which includes the transition phase to RIT and demonstrated over 10 MeV/u gold ions with ~70+ charge at the RIT phase. State-of-the-art simulations, which make use of the measured temporal pulse conditions and are backed up by a large set of diagnostics, demonstrate that the collisional ionization process cannot be neglected for the generation of high-energy highly charged gold ions through a large range of plasma parameters even within the RIT phase.
