RESUMO
The focusing properties of very large (≈33 × 33 cm2) spherically and toroidally curved crystals with a radius of curvature of ≈10 m were determined numerically with an x-ray tracing code and are compared to those of cylindrically bent crystals. Large spherically and toroidally curved crystals are of interest for the diagnostic of future large tokamak fusion experiments and possibly for other extended x-ray sources. Compared with cylindrically bent crystals-which are now widely used for the plasma diagnostic in tokamak experiments, in particular, for Doppler-broadening measurements to determine the central ion temperature-2D-curved crystal spectrometers can provide a significant enhancement of the intensity due to the additional focusing of the sagittal rays.