Abstract
We report the measurement of the linewidth and temporal coherence of a λ= 46.9 nm neon-like argon capillary discharge soft x-ray laser and its variation with plasma column length. A wavefront division interferometer was used to resolve the 3p 1S0-3s 1P1 laser line, resulting in a measured relative linewidths of λ/λ = 3-4 × 10 -5. The measurements do not observe saturation re-broadening as this clearly dominantly Doppler-broadened inhomogeneous line is amplified beyond the intensity corresponding to gain saturation. Model simulations indicate that this is the result of comparatively small collisional broadening that homogenizes the line profile to practically eliminate inhomogeneous saturation re-broadening. Collisional re-distribution is computed to only play a minor role in homogenizing the line profile.
