Observation of MeV multicharged ions and hot electrons accelerated by a 65-fs laser pulse

The generation of fast particles (both ions and electrons) in a femtosecond laser-produced plasma has been studied experimentally and the possibility of applying particle-in-cell (PIC) codes to the description of the experime ntal results has been investigated. The energy distribution function of fas t ions has been measured directly by means of X-ray spectroscopy. It is sho wn that this diagnostic can also be used as an indirect method to measure f ast electrons inside the plasma. The hot electron distribution in the 0.1-2 MeV energy range was measured directly using a standard electron magnetic spectrometer. The comparison of the experimental results with the numerical simulations show: (1) the electromagnetic PIC-FC code can be successfully applied for simulating plasmas created by the interaction of femtosecond-la ser pulses with solid targets and (2) the existence of a transient populati on of hot electrons with a non-Maxwellian distribution typical of interacti on experiments with short-pulse lasers. (C) 2001 Elsevier Science Ltd. All rights reserved.