The Research Of High Reflective Multilayer Mirrors For Ni-like Ta Soft X-Ray Laser

Multilayer mirrors, which permit the achievement of high normal incidence reflectivity in soft x-ray and EUV region, are the enabling technology for the significant improvements of optical imaging systems. These mirrors are now finding wide application in instrumentation for astronomy, microholography of biological samples, EUV lithography, synchrotron radiation, X-ray laser and so on. The high reflective mirrors for Ni-like Ta soft X-ray laser, working at 4.48nm, are the core elements in Ni-like Ta laser experiment and its application experiment. So the research on design, fabrication and measurement of 4.48nm high reflective mirrors is very important and meaningful.The high reflective mirrors for Ni-like Ta soft X-ray laser are periodical multilayers, whose layer thickness is small and the period number is large, which make them extremely difficult to fabricate. And the experimental reflectivity of prepared mirrors is much lower than the academic. Now, only the high reflective mirrors for Ni-like Ta soft X-ray laser made in a small number of countries like America, Germany and Japan meet the practical requirements. However, China hasn't do deep research on this kind of high reflective mirrors.In the thesis, the calculating method of reflectivity is discussed. According to the optical properties, the physical, chemical properties, and the film forming characteristics, Cr/C, Co/C and Cr/Sc are chosen as the material pairs. The reflective characteristics of multilayers made of different materials are compared. The multilayer structure parameters and peak reflectivity are yielded after the theoretical analysis. The effects of multilayer interface defects are dicussed based on D. Stearns dispersion theory.Cr/C, Co/C and Cr/Sc high reflective mirrors with different structures are fabricated by using DC magnetron sputtering methods. The deposition rates of different materials were accurately calibrated by using low angle X-ray reflectivity measurement. The fabricating parameters such as gas flux, bias voltage and sputtering...