Quasi-optical spectral system for submm-wave radiometry of turbulent plasma

We present the results of experimental development of the original multichannel quasi-optical radiometric system intended for fast-response spectral measurements of 210-530 GHz-emission from hot and turbulent plasma at the GOL-3 nuclear fusion plasma facility. The system employs a scheme with quasi-optical demultiplexing of the input radiation beam onto separate spatial channels with subsequent frequency filtering by quasi-optical metal mesh filters and spectral signal detection by calibrated Shottky-diode-based receivers. Experimental realization and testing is considered by the example of a four-channel system incorporating anisotropic-mesh-based band-pass filters with polarization-sensitive transmission bands (FWHM 35-50 GHz) that allows us to use only two hardware filters for selecting four spectral bands.