Plasma heating by CO2-laser pulses for efficient multi-charged ion generation

CO2 laser-produced plasma ion component parameters were studied experimentally and numerically for aluminium and lead targets at peak laser intensity of 4 x 10(13) W cm(-2) and FWHM pulse duration of 15 ns. Angular dependences of ion number density, average velocity, and its spread were measured for different charge states by time-of-flight method. Ion charge state distribution shows high-charge and low-charge state groups. Ions in these groups have different average expansion velocity and longitudinal velocity spread. Angular distribution of high charge states is narrower than that of the low-charge state ion group, maximum yield of low charge states occurs at some angle from normal. For Al target the results show similar trends as for Pb target, but simulations have indicated that the effect of laser ponderomotive force is more pronounced in this case.