Optical Diagnostic Methods for Measuring Plasma Parameters in a Helicon Discharge

The article presents measurements of the plasma parameters of a helicon discharge using optical diagnostic methods on the PN-3 installation. The composition of the diagnostic complex is described. The methods for measuring plasma parameters, including emission spectroscopy and laser-induced fluorescence, and methods for processing measurement results are considered. The results of measurements of the plasma parameters of a helicon discharge using optical diagnostic methods are presented. The measurements are carried out in experiments to study the dependence of the parameters of the helicon discharge plasma on the value of magnetic induction and the magnetic field profile under the antenna. Argon is used as the working gas. The radial distribution of the electron temperature for different parts of the plasma column is measured by optical emission spectroscopy. The laser-induced fluorescence method using the 3d 2 G 9/2 and 4p 2 F 7/2 states to determine the local concentration of the singly charged Ar II ion is applied. On the basis of the results of the work, the optimal value of the magnetic field under the HF antenna, which was 900–1000 G, and the configuration of the magnetic field of the setup, a magnetic trap, are determined from the viewpoint of the plasma column profile and plasma density.