Ion emission from laser ablation of Cu and Cu98/Be2 alloy targets

The properties of pulse laser ablation of Cu and Cu98/Be2 materials are studied, and the differences in the emission of Cu ions are emphasized. The iodine high-power laser system PALS in Prague and a KrF laser were used to perform the experiments at the fundamental harmonics λ₀ = 1.315m and λ₀ = 248nm delivering energy up to 500J and 600mJ, respectively. Pure Cu and Cu98/Be2 alloy targets of 50, 500 and 1000μm 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 contrast to the incidental amount of carbon, oxygen and hydrogen impurities chemisorbed on target surfaces. It was approved that the emission of Cu ions driven by the KrF laser exhibits a higher gain from the Cu98/Be2 plasma in contrast to the Cu plasma. The ion emission induced by laser intensities near the threshold of fast ion generation is significantly affected by the emission of ionized impurities chemisorbed on a target surface and by repetitive outbursts of fast ions if generated. Under these conditions, the influence of the 2% Be admixture on the emission of Cu ions plays only a minor role.