Generation of ultrashort ion pulses in the keV range: Numerical simulations

Abstract

In order to gain a direct experimental access to the ultrafast dynamics induced by an impact of an energetic particle onto a solid surface, we set out to utilize a pump–probe technique using an ultrashort ion pulse as a stimulus (“pump”) in combination with a synchronized and time delayed analysis (“probe”). As a necessary prerequisite, we have recently developed a concept to generate ultrashort ion pulses with (sub-)picosecond temporal duration in the keV ion energy range which is interesting in many applications of ion–solid interactions. Here, we present further numerical simulations, where we focus on identifying pathways to decrease the space charge broadening of pulses containing more than one ion. As a result, we find that the influence of space charge can be significantly decreased using a defocused and properly shaped laser beam, thereby allowing to generate picosecond pulses containing up to ∼100 ions.