Abstract
The paper presents the results of spectroscopic measurements of plasma discharges at the KTM tokamak. The measurements were carried out during the June 2021 campaign, which plasma discharges were obtained with a plasma current from 120 kA to 150 kA and a duration of ~250 ms.In connection with the design changes inside the vacuum chamber of the tokamak, special attention is paid to the study of the elemental composition of the plasma and the analysis of impurities and the ways of their entry is carried out. Impurities in plasma directly affect radiation losses. Optical spectroscopy (OS) is one of the main methods for studying the penetration of impurities into plasma.An Avaspec-ULS2048CL-EVO-RS-BB spectrometer was used to determine the emission spectrum of the KTM tokamak plasma. The time evolution of the hydrogen lines was measured using the diagnostics of a Hα-Dα monitor equipped with narrow-band interference filters (FWHM 1 nm).Based on the measured emission spectrum, it was found that in the hydrogen plasma of the KTM tokamak, in addition to the presence of a working gas, there were also impurities of carbon, oxygen, nitrogen and argon (C, O, N, Ar) in various ionization states.