Analysis of the Possibility of Measuring the Electron Plasma Density of the T-15MD Tokamak by Probing with Electromagnetic Waves of the Submillimeter Range

Abstract

The passage of probing beams of the submillimeter range in the T-15MD tokamak chamber along various chords is considered in this paper. Microwave generators with submillimeter radiation and HCN lasers with a radiation wavelength of λ = 337 μm are widely used in interferometers in many plasma systems as sources of probing beams. The possibility of using a solid-state microwave generator and an HCN laser in the form of probing radiation sources with wavelengths λ = 915 and 337 μm, respectively, for measuring the electron concentration in the T-15MD tokamak plasma is considered. The paper does not present full-fledged designs of T-15MD tokamak interferometers but examines the passage of the probing beams in the vacuum chamber in order to determine the influence of refraction. Schematic diagrams of interferometers with indicated wavelengths are also presented and discussed, and the results of calculations of the relative error of the phase shift due to deviation of the probe beam are presented. A design of emitting and receiving antennas is proposed. Introducing and receiving the probe beam is carried out through the T-15MD tokamak equatorial pipe and through the upper and lower pipes. In the probing channels passing through the equatorial pipe, the beams are reflected from the mirror fixed on the inner wall of the vacuum chamber. The possibility of measuring the main plasma parameter—the average electron density—when probing with electromagnetic radiation with a wavelength of λ = 915 μm, as well as the possibility of multichannel phase measurement when probing a plasma cord with electromagnetic radiation with a wavelength of λ = 337 μm, in the T-15MD tokamak is shown.