Search

Spectroscopy methods were used for studying the dynamics of neutral plasma component in current sheets formed in two-dimensional (2D) and three-dimensional (3D) magnetic configurations during discharge in helium. It has been ascertained that when the current sheet is formed in the 2D magnetic field, flows of fast suprathermal helium atoms appear in it, which are directed along the current sheet width (the largest of the sheet transverse dimensions). It is shown that helium atoms can acquire the directed energy Wx due to the resonance charge exchange of accelerated ions in the current sheet plasma. The energy of directed motion of helium atoms can reach Wx ≈ (480 ± 120) eV, which is ~20 times higher than the temperature of helium atoms Ta ≈ (20 ± 2) eV at the same times. During the current sheet formation in the 3D magnetic configuration, fast helium atoms were not observed. [ABSTRACT FROM AUTHOR]

Abstract—The results of measuring the plasma density in those areas of the current sheet where helium atoms are predominantly localized are presented. The measurements were carried out based on the analysis of the profiles of neutral helium spectral lines of 447 and 492 nm using a new method—determination of the half-width at the half-height of the red wing of the spectral line. This method has a number of advantages over classical methods in conditions of a large dynamic range of changes in plasma density and interferences from spectral lines of impurities. The application of this method made it possible for the first time to determine the concentration of electrons in various regions of the current sheet, as well as at different configurations of the magnetic field and the values of the initial pressure of helium at which the current sheet is formed. The results obtained are in qualitative agreement with the electron concentration measurements based on the analysis of the profiles of the spectral lines of the helium ion, but differ somewhat from them quantitatively, due to the localization of the helium ions and atoms in different regions of the current sheet. [ABSTRACT FROM AUTHOR]