High-resolution imaging spectrograph for the ultra-soft X-ray range

An imaging (stigmatic) spectrograph composed of a flat grazing-incidence VLS grating and a focusing broadband normal-incidence multilayer mirror (Mo/Be, 111–138 Å Mo/Si, 125–250 Å), which determines the operating spectral range, is fabricated and tested. Line emission spectra of multiply charged ions excited in a laser plasma are obtained. The spectral resolution and spatial resolution of the device are limited by the cell size (13 μm) of the detector and amounted to ∼10³ and 26 μm, respectively. The stigmatism of the device makes it possible to use it for spectral diagnostics of plasma with a high spatial resolution. The device dimensions are about 1 m.