New crystal spectrograph designs and their application to plasma diagnostics (invited)

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Abstract
A special crystal monolith was fabricated for absolute measurements of x‐ray wavelength. It consists of two flat quartz plates, accurately cut relative to reflecting net planes, with a fixed distance between them. Absolute wavelengths (i.e., without use of reference lines) of L‐shell laser produced spectra of Cu, Ge, As, etc. have been measured in the 7.5–8.5 Å with an accuracy of Δλ/λ=10−5. Our Johann type x‐ray spectrometer with a cylindrically bent quartz has been used to reveal line coincidences necessary for photopumping processes. In this scheme source‐size influences are smaller, therefore, line profiles have been measured at a spectrometer resolution better than 5000. Because of its focusing in the sagittal plane, a von Hámos type x‐ray spectrometer has been used to detect the small x‐ray emission of subpicosecond laser‐produced plasmas (E=2 mJ, t=100 fs). X‐ray spectra of Al both Kα, Kβ lines and Heα‐resonance line with its satellites. Finally, a multichannel x‐ray microscope has been designed and fabricated. It consists of several two‐dimensionally bent crystals where each of them images one x‐ray line emitted by a laser‐produced plasma. The spatial resolution of x‐ray line images is about 5 μm, and the width of the spectral ranges is Δλ/λ=10−4 to 10−2. Thus, the spatial distribution of ions radiating in selected x‐ray lines have been found being of interest in the study of population inversions.