The interaction of high-intensity laser pulses with homo-nuclear aluminum clusters carried out by
2D3V UMPIC code has been investigated. The qualitative picture of the ion acceleration depends
on the strength of the laser field and the cluster radius. In this study, the radius of the cluster and
the laser dimensionless amplitude has been changed, and the effect of laser polarization on ion
acceleration by these variations has been considered. Increasing cluster radius (from 10 to 200
nm), simulations show transferred laser energy to the ions increases for both linear and circular
polarization, but the magnitude of this growth for circular polarization is larger than that of linear
polarization in a given laser intensity. Also, the effect of laser dimensionless amplitude on ion
acceleration has been studied for both laser polarizaton. Simulation reveals that aluminum ions
cut-off energy and their energy spread increase rapidly up to a0~2.5, and then saturate at larger
amplitudes, for both polarizations. However, by increasing laser amplitude (a0>5), energy spread
of linear polarization is less than that of circular polarization.