A new class of instruments for x-ray spectroscopy has emerged, especially for imaging x-ray spectroscopy, comprising fast spectrographs with spherical crystals, transmission diffraction grating-obscurae, and multilayer Fresnel lenses. These instruments significantly extend the capabilities of experimental spectroscopy of high temperature plasmas. In this paper we show that the use of these instruments in the atomic spectroscopy of multiply charged ions greatly improves the accuracy of measurements of x-ray spectral line wavelengths, and makes possible the study of previously unobserved low-intensity spectral transitions. In addition, their use in plasma diagnostics yields information about oneand two-dimensional spatial parameter distributions both of nonuniform plasma microsystems (e.g., micropinches, or dense regions of a laser plasma) and extended plasma sources in regions of low luminosity (e.g., freely expanding laser plasmas at large distances from the target). We present here the results of our experimental and theoretical studies of the radiative properties of real plasma objects (i.e., X pinch, Z pinch with composite loading, and plasmas produced by laser pulses with nanosecond and subpicosecond durations). 63 1995 American Institute of Physics.