Toward saturation of a discharge-pumped soft x-ray amplifier

Operation of a discharge-pumped 46.9 nm Ne-like Ar amplifier at gain length products up to gl approximately equal to 14 is reported. The laser line intensity is observed to increase exponentially for plasma column lengths up to 15 cm, above which it is observed to saturate. The saturation behavior is discussed. Results of the parameterization of the discharge pumped amplifier and the measurement of the soft x-ray laser pulsewidth also are reported. The use of an axial magnetic field, that limits the maximum plasma compression and decreases the density gradients, is observed to cause a moderate increase of the soft x-ray laser intensity and a beam profile that is more Gaussian.