Serviceability of using the carbon-graphite materials for inner elements of microwave diagnostic for large fusion devices

As an alternative to metal-made inner elements of MM and subMM diagnostics (antennae, reflectors, waveguides) we propose the elements fabricated of ca rbon-graphite materials (CGM). A comparative study of antennae and reflecto rs made of CGM and metal for 30-150 GHz in MM and for subMM ranges was carr ied out under the influence of pulsed plasma streams and heating up to 1000 degrees C. The effect of neutron irradiation on reflectivity at 337 mu m w as studied as well. The obtained data demonstrated that CGM can be used as material for fabricating the above mentioned inner diagnostic components in those large-scale fusion devices where similar materials are in use for th e first wall protection. The Fabry-Perot type resonator with spherical CGM- made mirrors showed rather good characteristics, and can be used for measur ing plasma properties in a divertor flow. (C) 1999 American Institute of Ph ysics. [S0034-6748(99)67401-9].