XUV spectroscopy for space (SOLAR-C/EUVST) and laboratory applications

The field of the extreme ultraviolet (XUV) spectroscopy is a hot topic in both astrophysics and high energy physics. The atmosphere absorption of the UV radiation makes the development of satellite-based mission UV-oriented one of the most active sector of the space observations. At the same time, the study of physical phenomena based on ultrashort XUV and soft X-ray pulses gives a strong impulse in the development of XUV spectrometers and monochromators, in order to ensure the observation and selection of the proper wavelength. In this Thesis, three XUV applications are described, covering both the field of astronomical observations and the field of laboratory applications. The XUV region of the electromagnetic spectrum is critical for the understanding of key physical processes happening in the solar atmosphere. As a result, the Japan-led mission with an international participation SOLAR-C/EUVST will provide an insight of the solar atmosphere and of the instabilities happening in the outer layer of the Sun, giving a novel insight into the atmospheric activity of our star. The first contributions in this Thesis describes the work performed in the realization and analysis of the optical coating for the Slit Assembly, the Italian contribution to SOLAR-C. The selection of the suitable materials is described and the theoretical models are presented. Then, the campaign measurements of the first samples of the coating is presented, giving a complete characterization of the optical performance of the coating. The contribution ends with the description of the first calibration and measurement activities performed onto the first Slit Assembly prototypes. The second contribution relates to the applications of XUV spectroscopy in the field of laboratory equipment, especially for low-cost tabletop experiment: an active grating. The design of this low-cost optical element is presented and its optical performance are described. The system can be installed as part of a monochromator for the spectral selection and focalization of ultrafast XUV pulses. The third contribution is the description of the calibration and commissioning activities of the COmpact SPectrometer COSP. COSP is a grating spectrometer for Free Electron Laser (FEL) applications, in which COSP would achieve medium resolution in a wide spectral range. The instrument has been characterized in terms of spectral response at several endstations of the Elettra Sincrotrone Trieste and FEL FERMI facility.