Ion charge state and energy distributions of laser produced plasma from pure metals and their alloy.

A high intensity highly charged laser ion source has been studied at the Institute of Modern Physics for the last few years. In order to investigate the processes of plasma heating and expansion of laser produced plasma, the charge state and energy distributions of the ions from pure copper, silver, and copper-silver alloy, in which the atom number ratio between copper and silver is 2:3, were measured with a 90° cylindrical electrostatic ion analyzer. It was shown that the yields of highly charged copper ions from the pure copper target are higher compared with those of the alloy target. In contrast, higher yields of highly charged silver ions were obtained from the copper-silver alloy target. Moreover, the ion energy distributions were derived from the time-of-flight spectra for the ions with different ion charge states and compared between the pure metal and alloy targets.