  The interaction of intense femtosecond laser pulses with atomic Argon
clusters has been investigated by using nano-plasma model. Based on the dynamic
simulations, ionization process, heating and expansion of a cluster after
irradiation by femtosecond laser pulses at intensities up to 2*1017 Wcm-2 are
studied. The analytical calculation provides ionization ratefor different
mechanisms and time evolution of the density of electrons for different pulse
shapes. In this approach the strong dependence of laser intensity, pulse
duration and laser shape on the electron energy, the electron density and the
cluster size are presented using the intense chirped laser pulses. Based on the
presented theoretical modifications, the effect of chirped laser pulse on the
complex dynamical process of the interaction is studied. It is found that the
energy of electrons and the radius of cluster for the negatively chirped
pulsesare improved up to 20% in comparison to the unchirped and positively
chirped pulses.
