Graphite as a structural material for the in-vessel components for plasma diagnostics in the millimeter and sub-millimeter ranges

The possibility to use the carbon-graphite materials (CGM) instead of metal s for fabrication of the in-vessel components for plasma diagnostics in the mm and sub-mm ranges on large-scale fusion devices was investigated. The r eflectivity of different kinds of CGMs (more than 20) was measured in the w avelength-range of 10 mum - 30 mm and was found to be only little below the values for metal analogues. The effects of surface roughness, pulsed plasm a impact, heating and neutron irradiation on the reflectivity of CGM-made r eflectors were analyzed. The role of graphite protection of the first wall in the energy balance in a fusion reactor was evaluated using the reflectiv ity data obtained. The working characteristics of antennae, waveguides and resonator fabricated of CGMs are presented as measured before and after pul sed plasma impact and/or heating up to 1000C. The CGM-made diagnostic components demonstrated much stronger resistance to pulsed power plasma impact than metal-made ones and at the same time reaso nable working characteristics. Therefore they can successfully replace the metallic components in cases when similar (i.e., CGM) materials are used fo r the first wall protection.