Investigations of materials for windows of the fusion reactor diagnostic systems

Plasma diagnostic and fusion reactor control systems will need windows which transparency is unchanged under irradiation. To choose suitable window material for the visible light and to define the influence of irradiation on its properties, the investigations in different countries have been performed. In this paper the main results of the study are summarized. It is demonstrated that quartz glass KU-1 with the largest content of (OH) is the best of three types of quartz glass with different hydroxyl content, sapphire. spine] and cerium glass after gamma and neutron irradiation. Investigations of quartz glass KU-1 have shown that it may be used for diagnostic systems in the fusion reactor. It is suitable for spectral region from similar to300 to 2000 nm. The best window location is behind the dog-leg channels to guard it against the neutral atom fluxes, which can damage its surface and increase diffusion reflection.