We develop an integrated instrumental and computational package for the diagnosis of impurity content, Zeff profile, particle transport, and magnetohydrodynamics activity in magnetic fusion experiment plasmas. The package includes broadband filtered arrays of absolute (AXUV) photodiodes, a transmission grating imaging spectrometer measuring up to 20 chords across the discharge and having a few angstrom spectral resolution, together with an atomic physics database coupled with an impurity transport code. The atomic physics database is based on ab initio computations with the Hebrew University Lawrence Livermore atomic code. The package is designed for the diagnostic of sub-keV plasmas having predominantly low-Z impurities (C, B, and O) together with trace metals. A preliminary version is being tested on the National Spherical Torus Experiment spherical torus at the Princeton Plasma Physics Laboratory, using the ultrasoft x-ray imaging system and a grazing incidence spectrometer. Representative results from non-H-mode discharges are presented. © 2003 American Institute of Physics.