Investigation of Ultra-fast Ablative Capillary Discharges as Possible Sources for Amplified Spontaneous Emission in the VUV and XUV

Practical applications of XUV and soft X-ray lasers as, e.g., X-ray microscopy or holography depend on a successful realization of low-cost, table-top size laser systems for these spectral ranges. In order to avoid large and expensive pump lasers, fast capillary discharges are investigated as an alternative approach to XUV and soft X-ray lasing. Such devices are relatively simple and combine a favourable geometry for lasing with sufficiently hot and highly ionized plasmas. In capillary discharges the plasma is produced by a short rise-time current pulse through a small capillary in a solid insulator. One way of operation is to fill the capillary with the gas of interest. The other way which was preferred by us is to evacuate the capillary, cause ignition by a sliding discharge process and investigate the plasma established by ablation from the capillary wall. Meanwhile another approach is being experimentally tested: The plasma production by a plasma focus device, the plasma of which being expanding through a nozzle, thus achieving adiabatic expansion and probable inversion of relevant population densities.