X-ray microscopy of laser-produced plasmas with the use of bent crystals

Abstract

X-ray spectroscopical and microscopical methods are used for the determination of the spectral and spatial distribution of X-ray intensity of laser-produced plasmas. The use of Bragg reflections of two-dimensionally bent crystals enables the X-ray microscopical imaging in narrow spectral ranges (Δλ/λ = 10−4 to 10−2) with wavelengths 0.1 nm < λ > 2.6 nm. It is possible to adapt, in the X-ray microscope, the distances, magnification, position, and width of the spectral window to the special conditions of the laser facility. Manufacturing and testing of the two-dimensionally bent crystals requires a great deal of effort. It was demonstrated that a spatial resolution of about 5 μm was achieved, and that the experimentally determined reflectivity was found to be in close agreement with the dynamical theory of X-ray interferences. Due to high luminosity of the X-ray microscope, in experiments with laser-produced plasmas it was necessary to attenuate the radiation with aperture-limiting diaphragms or filters down to 0.01–1% of the original intensity in the case of a magnification of about one. Emission of the resonance line W 1–2, the intercombination line of helium-like ions, and Lyman alpha line were imaged simultaneously with a three-channel microscope. Such images form the foundation for establishing the Ne(r), Tz(r) maps.