No abstract

Optical emission spectroscopy is used for the determination of hydrogen molecule rotational T rot and vibrational T vib and translational temperature T tr . The experiment was carried out using copper or titanium hollow cathode discharges operated in pure hydrogen. The rotational temperature of excited electron energy levels is determined from Fulcher-α diagonal bands (d 3 u → a 3 + g electronic transition, P-, Q-and R-branches), which were later used to derive the rovibronic temperature of the hydrogen molecule ground state, which is assumed equal to T tr . The vibrational temperature T vib is determined for the same electronic transition (Q-branch with ν = 2,3; ν = 0). For all temperatures the radial temperature distribution is reported.

The presented results are concerned with the shape of the Balmer alpha line emitted from a low pressure dc glow discharge with stainless steel (SS) and titanium (Ti) hollow cathode (HC) with D2 or Ar∕D2∕H2 gas mixture. The analysis indicates that the line profile represents a convolution of three Gaussian profiles resulting from different collision excitation processes. The average energy of excited deuterium atoms determined from the width of the broadest Gaussian is about 86eV in both HCs. In Ar∕D2∕H2 gas mixtures, the energies are in the range from 33eVto47eV, but with much larger contribution of this Gaussian to the Balmer alpha profile. In discharges with hydrogen isotopes, the energy derived from the medium-width Gaussian is in the range from 4eVto6eV, while in gas mixtures it is between 1eV and 2eV. The width of the narrowest Gaussian slightly exceeds the instrumental broadening and it is always below 0.5eV.

We report the results of an Ar I and Ne I line shape study in an abnormal glow discharge operating in argon and neon. The spectral lines were observed along the axis of a cylindrical glow discharge parallel (side-on) and perpendicular (end-on) to the cathode surface. The side-on spectra show spectral line shifting and sometimes simultaneous shifting and splitting in the cathode fall region of the glow discharge. The results of the measured line shift with available data for the dc Stark effect are used for measurement of electric field strength in the cathode fall region of the glow discharge. Electron temperatures of 2860 K and 4770 K in the negative glow region of argon and neon discharges, respectively, were determined from the relative intensities of Ar I or Ne I lines using the Boltzmann plot technique. An electron number density of ≈10 20 m −3 (±25%) in the negative glow region of the argon discharge was determined from the widths of two plasma-broadened Ar I lines using theoretical Stark broadening data. The end-on recorded line profiles show 10-40% larger half-widths than the side-on recorded line profiles from the negative glow. This effect is a result of the superposition of line emission in the cathode fall region under the influence of the dc Stark effect on the line profile from the negative glow.

We report the results of five Ne i line shapes study in an abnormal Grimm-type glow discharge operating in neon.