Characterization of an imaging extreme-ultraviolet flat-field spectrometer and its application to extreme-ultraviolet emission profile measurement

The spatial imaging property of an extreme-ultraviolet (XUV) Bat-field spectrometer was studied using ray-tracing and measured experimentally. Under the condition that the spectrometer is stigmatic at 10 nm, ray-tracing simulations show that the spatial resolution is expected to be about 18 mum in the wavelength range from 2.5 nm to 30 nm. The measurement of the spatial resolution, using a wire as fiducial 20 mm away from the source position along the optical axis, was carried out for the CV resonance line (4.03 nm) and a spatial resolution of 70 mum was obtained. This value agrees well with the ray-tracing result for a source displaced 20 mm along the optical axis. Using the spatial imaging property of this spectrometer, the emission profiles of CV 1s(2)-1s3p (3.50 nm) and CVI L-beta (2.85 Nn) lines from a laser-produced carbon plasma were measured. The spatial imaging property and Abel inversion were applied to laser-produced carbon plasma spectra to deduce emission profiles.