Wavelength measurement of the Ni-like soft-x-ray lasing lines and comparison to the atomic-physics calculation

A flat-field grazing-incidence spectrometer is used to measure the lasing spectra that include Nd (Z=60) through Ta (Z=73), recorded on a backside-illumination-type CCD detector, where Z is the atomic number. In the spectra from Nd through Ta plasmas, precision wavelengths of the lasing lines are determined with the well-known Al (Z=13) lines as reference lines recorded on the same CCD detector. The measured wavelengths are compared with the result of the relativistic atomic-physics calculations.