Comparisons of laboratory wavelength measurements with theoretical calculations for neon-like through lithium-like argon, sulfur and silicon

Atomic structure codes have a difficult time accurately calculating the wavelengths of many-electron ions without the benefit of laboratory measurements. This is especially true for wavelengths of lines in the extreme ultraviolet and soft X-ray regions. We are using the low-energy capability of the Livermore electron beam ion traps to compile a comprehensive catalog of astrophysically relevant emission lines in support of satellite X-ray observations. Our database includes wavelength measurements, relative intensities and line assignments, and is compared to a full set of calculations using the Hebrew University - Lawrence Livermore Atomic Code (HULLAC). Mean deviation of HULLAC calculations from our measured wavelength values is is highest for L-shell transitions of neon-like ions and lowest for lithium-like ions, ranging from a mean deviation of over 500 m Å for Si V to 12 mÅ in Ar XVI.