Probe-assisted study of the erosion plume upon the ablation of tantalum in vacuum by the 308-nm excimer laser radiation

A Langmuir probe was used to study the erosion plume produced during the ablation of a tantalum target in vacuum by radiation from an excimer laser at 308 nm. The spatial and temporal dependences of the electron and ion currents of the probe were obtained in real time. The electron temperature of different regions of the plume at different distances from the target was measured for the first time from a series of dependences of the electron probe current on the probe voltage. The nonuniformity of the electron temperature and its lowering in different plume regions with increasing expansion time were determined. The ion density in the plume was determined at different distances from the target.