H_α line Doppler broadening in a glow discharge cathode region in the argon-hydrogen mixture

Spectral measurements of Doppler profiles of the hydrogen H_α spectral line in a glow direct current discharge in a mixture of 1% hydrogen in argon at pressures of 60, 120 and 180 Pa were performed. Solid and mesh cathodes were used. It is brought out that the line shapes are Gaussian with the width corresponding to the effective temperature of the excited atoms of 35-60 eV for emission from the cathode region. The line width does not change with the pressure and the distance from cathode in the region of negative glowing and increases slightly with the distance from the mesh cathode outside of the discharge gap. (paper)