Proposal for soft-x-ray and XUV lasers in capillary discharges.

Capillary plasmas with large length-to-diameter ratios (1ld > 100) are proposed as amplification media for soft-xray and XUV radiation by direct discharge excitation. The capillary geometry provides a small volume and an adequate resistance for ohmic heating. Heat conduction to the capillary walls provides rapid cooling of the plasma during the decay of the excitation pulse, resulting in a large recombination rate and a population inversion. A timedependent collisional-radiative model of the capillary plasma predicts gains of the order of 5 cm1 in the 18.2-nm