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As an alternative to metal-made inner elements of MM and subMM diagnostics (antennae, reflectors, waveguides) we propose the elements fabricated of carbon–graphite materials (CGM). A comparative study of antennae and reflectors made of CGM and metal for 30–150 GHz in MM and for subMM ranges was carried out under the influence of pulsed plasma streams and heating up to 1000 °C. The effect of neutron irradiation on reflectivity at 337 μm was 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 the first wall protection. The Fabry–Perot type resonator with spherical CGM-made mirrors showed rather good characteristics, and can be used for measuring plasma properties in a divertor flow.

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The possibility to use the carbon-graphite materials (CGM) instead of metals 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 reflectivity of different kinds of CGMs (more than 20) was measured in the wavelength range of 10 pm-30mm and was found to be only little below the values for metal analogues. The effects of surface roughness, pulsed plasma impact, heating and neutron irradiation on the retlectivity of CGM-made reflectors were analyzed. The role of graphite protection of the first wall in the energy balance in a fusion reactor was evaluated using the reflectivity data obtained. The working characteristics of antennae, waveguides and resonator fabricated of CGMs are presented as measured before and after pulsed plasma impact and/or heating up to 1 oooc.The CGM-made diagnostic components demonstrated much stronger resistance to pulsed power plasma impact than metal-made ones and at the same time reasonable working characteristics. Therefore they can successfully replace the metallic components in cases when similar (h., CGM) materials are used for the first wall protection.

A modified method of dual polarization single line microwave backscattering is proposed for correlation and spectral studies of density fluctuations in plasma with known geometry of magnetic field (stellarator with low β plasma, reflex discharge). Simultaneous launching of microwaves of both ordinary (O) and extraordinary (X) polarization via the same antenna has an advantage for correlation measurements of fluctuations in adjacent plasma layers because a procedure of separation of reflected waves is simplified.