Investigation of laser ablation plasma from thin graphite target

We have investigated the mechanism of a slow tail of low charge state ions in laser ablation plasma produced for highly charged ion generation such as C6+. In the previous experiments with different thickness of graphite sheets (3000 µm, 254 µm, 70 µm, and 25 µm), the low charge state tail was reduced only with the 25 µm sheet. To precisely investigate the phenomena further, we carefully studied the difference of charge states in laser produced plasma from 3000 µm, 25 µm and 17 µm graphite foils. The very similar reduction of the second peak for both 25 and 17 µm was observed. We confirmed that the reduction of total ion current measured by a faraday cup at the falling edge was contributed by C4+ and C5+.