Target Normal Sheath Acceleration at ultrahigh intensities: A theoretical parametric investigation

Ions can be effectively accelerated during the interaction of an ultra-intense ultra-short laser pulse irradiating a thin solid target via the so-called Target Normal Sheath Acceleration (TNSA) mechanism. One of the crucial issues at this stage of the research is how to predict the properties of the accelerated ions, both from a fundamental point of view and in the light of foreseen applications. Thus, it is desirable to have a simple but reliable description, to be used to extrapolate current results to regimes likely to be reached in the near future, thanks to developments in laser technology. In this work we theoretically investigated the maximum ion energy achieved in TNSA as a function of laser properties, with special focus to the ranges I_L (pulse intensity) 10^20 -10^22 W/cm^2 and E_L (pulse energy) 1-30 J, which appear to be the most interesting for future facilities. Particular attention will be devoted to elucidate the effective dependence of the maximum ion energy on the laser intensity for different combinations of laser parameters.