Advanced experimental and theoretical analysis of defect evolution and structural disordering in optical and dielectric materials for fusion applications (AETA)

Project coordinator: Dr. phys. Anatoli Popov

Duration: 2019-2020

Important part of the fusion reactors are functional optical and dielectric materials to be used as diagnostic windows, lenses, fibers, cables and in some other monitoring equipment. Thus it is of fundamental importance, to understand, control and predict their radiation damage under intensive neutron/gamma radiation environment. Most used in the past years methods to control radiation damage in insulating optical/dielectric materials are based on the traditional X ray diffraction, microscopy and optical spectroscopy. The latter approach proved particularly useful to study a simple primary radiation defects in simple oxides. However, this approach is quite limited and cannot be applied e.g. to the interstitial oxygen ions (which are complementary to the electron F-type centers and serve as hole component of the Frenkel pairs) and/or at high radiation fluencies where optical absorption is saturated, and the individual bands overlap.

In this experimental-theoretical project, we suggest to apply in combination with more traditional optical absorption and luminescence, a set of additional magnetic resonance and vibrational spectroscopic methods (EPR and Raman, IR and neutron scattering) in order to monitor the development of the radiation damage in several functional materials - diamond (used in diagnostics and as high power microwave transmission window for plasma stabilization), Al2O3 (sapphire), MgAl2O4 spinel, which are attractive candidates for diagnostics/optical windows. Of great importance is also to determine a specific role of impurities (Mn, Fe, Cr, Ti).

Special attention will be paid to the RAMAN spectroscopy, which is rapidly developing in recent years, especially with combination with calculations of the defect vibrational properties based on the state of the art first principles calculations with hybrid exchange-correlation functionals.