A family of Johann configuration curved crystal spectrometers has been designed to share the basic engineering features of compactness, modularity, facility of alignment and focus, and incorporation of solid-state charge coupled device detector arrays. These detectors have intrinsically low noise, useful energy resolution, two-dimensional position sensitivity, and readout modes that are programmable. The spectrometers, although relatively compact, with a Rowland circle diameter in the range 0.5-2 m, can still have sufficient resolving power, dispersion, and throughput to be invaluable in high resolution studies of atomic and plasma sources. This article discusses the basic design features and performance of these doubly dispersive spectrometers and illustrates their versatility by applications to studies of a wide range of laboratory x-ray sources such as line emission from highly ionized atoms in the extended plasmas of Tokamaks and nearly point plasmas produced by focused laser irradiation of solids and in beam-foil experiments and electron beam ion traps.

Abstract. The inclusion of collisional rates for He-like Fe and Ca ions is discussed with reference to the analysis of solar flare Fe  and Ca  line emission, particularly from the Yohkoh Bragg Crystal Spectrometer (BCS). The new data are a slight improvement on calculations presently used in the BCS analysis software in that the discrepancy in the Fe  y and z line intensities (observed larger than predicted) is reduced. Values of electron temperature from satellite-to-resonance line ratios are slightly reduced (by up to 1 MK) for a given observed ratio. The new atomic data will be incorporated in the Yohkoh BCS databases. The data should also be of interest for the analysis of high-resolution, non-solar spectra expected from the Constellation-X and Astro-E space missions. A comparison is made of a tokamak S  spectrum with a synthetic spectrum using atomic data in the existing software and the agreement is found to be good, so validating these data for particularly high-n satellite wavelengths close to the S  resonance line. An error in a data file used for analyzing BCS Fe  spectra is corrected, so permitting analysis of these spectra.

The equilibrium state in tokamak core plasmas has been studied using the relative intensities of resonance x-ray lines, for example Ly ␣ ͑H-like͒, ''w'' ͑He-like͒, and ''q'' ͑Li-like͒ from test ions such as Ar ϩ15 , Ar ϩ16 , and Ar ϩ17. A full spatial analysis involves comparison of the line intensities with ion diffusion calculations, including relevant atomic rates. A zero-dimensional model using a global ion loss rate approximation has also been demonstrated by comparison with the data collected from a Johann configuration spectrometer with a charged coupled device ͑CCD͒ detector. Since the lines are nearly monoenergetic, their intensities are independent of the instrument sensitivity and are directly proportional to the ion abundances. This method has recently been applied to Ar in the Oxford electron beam ion trap ͑EBIT͒ with a beam energy in the range 3-10 keV. Taking into account the cross sections for monoenergetic electron collisions and polarization effects, model calculations agree with the observed line ratios at 4.1 keV beam energy. This work will be expanded to provide nomograms of ionization state versus line intensity ratios as a function of EBIT beam energy.

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