Langmuir probe measurement of the bismuth plasma plume formed by a table-top extreme-ultraviolet pulsed laser


Properties of the plasma plume produced on a Bi target irradiated by a focused extreme-ultraviolet capillary-discharge laser beam were investigated. Langmuir probes were used to determine the electron temperature and the electron density, providing values of 1–3 eV and ~1013–1014 m−3, respectively. Although the temperatures seem to be comparable with values obtained in ablation plasmas produced by conventional lasers, the density is significantly lower. 

Up: schematic illustration of diagnostic arrangement with single (a) or double (b) Langmuir probe; 1 – solid metallic (Bi) target irradiatd by focused XUV laser; 2 – plasma spurt, 3 – electric conductive probe in ceramic facing, 4 – voltage source, 5 – digital oscilloscope with its own probe, 6 – galvanically isolated ground, d – probe-target distance, R – 2,28 MΩ oscilloscope probe resistivity. Below: Electron densities (left) and temperatures (right) in different distances from the target determined using the single Langmuir probe in desorption bismuth plasma.