Ion Emission from Laser Ablation of Cu and Cu98/Be2 alloys Targets

The properties of pulse laser ablation of Cu and Cu98/Be2 materials are studied and the differences in emission of Cu ions are emphasized. The iodine high-power laser system PALS and a KrF laser were used to perform the experiments at the fundamental harmonics λ = 1.315 µm and  = 248 nm delivering energy up to 500 J and 600 mJ, respectively. Pure Cu and Cu98/Be2 alloy targets of 50 µm, 500 µm and 1000 µm in thickness were ablated to measure the influence of the Be admixture on the emission of Cu ions. The alloy Cu98/Be2 was chosen due to the well defined amount of a beryllium admixture in the plasma in contrary to the incidental amount of carbon, oxygen and hydrogen impurities chemisorbed on target surfaces of Cu and Cu98/Be2 samples. It was approved that the emission of Cu ions driven by the KrF laser exhibits a higher gain from the Cu98/Be2 plasma in contrary to the Cu plasma. The fast ion emission induced by laser intensities near the threshold value is significantly affected by the emission of ionized impurities chemisorbed on the target surface and by repetitive outbursts of fast generated ions. Under these conditions the influence of the 2% Be admixture on the emission of Cu ions plays only a minor role.