EVOLUTION OF LOW-FREQUENCY BARRIER DISCHARGE PLASMA RADIATION IN LOW-PRESSURE NEON. ION RADIATION SPECTRUM

Emission of low-frequency barrier discharge plasma in neon at a pressure of 1.4–1.7 Torr formed by transitions between excited states of the Ne⁺ ion is studied in the wavelength range of 290–450 nm using kinetic spectroscopy methods. The difference in the relative intensities of ion lines at different stages of the plasma evolution is discussed: from direct excitation with ionization from the ground state of the atom by electron impact in the active stage (discharge), followed by a transition to the recombination afterglow as the electron temperature relaxes. The latter is due to the collisional-radiative recombination of doubly charged Ne²⁺ ions with electrons, creating at a density of the latter of [e]≈10¹¹ cm⁻³ the population flux of some Ne⁺* levels comparable to excitation by electrons at the stage of the plasma creation. A significant number of ion lines corresponding to transitions from states with the principal quantum number n = 3 contain an intermediate stage, the explanation of which is based on the experimentally confirmed hypothesis that the long-lived neon atoms in metastable states participate in their excitation. In contrast, the spectral lines of transitions from excited states of the Ne⁺* ion of 2s²2p⁴(³P₂)4f configurations do not have this stage.

dielectric barrier discharge, ion lines, electron impact excitation, afterglow, collisional-radiative recombination