Achievement of the saturation limit and double pass amplification in a discharge pumped soft X-ray amplifier

Previously we have reported the demonstration of large soft X-ray amplification by collisional excitation of neon-like argon in the plasma column of a fast compressional capillary discharge. Herein we report the generation of laser pulse energies up to 30 /spl mu/J at 46.9 nm in the plasma column of such a discharge, and the first clear demonstration of gain saturation of a table-top soft X-ray amplifier. Single pass amplification experiments yielded laser pulse energies up to 6 /spl mu/J. Greater energies were obtained by using an iridium mirror.