Decrease in Intensity of Hg Lines near the Source in Weakly Ionized Mercury Gas Flow

Abstract

In a flowing mercury afterglow with d. c. discharge source, rapid decrease in intensity of Hg lines near the source are investigated. Both the axial intensity distribution along the flow downstream and the radial one are interpreted in connection with diffusion of electron to the wall and electron to the wall and electron attachment. The effective diffusion coefficient is found to be D_β,γ=2.7×10³⁄p(cm²/sec), which is close to the ambipolar diffusion coefficient under the experimental conditions i.e. n_e=5×10⁸/cm³ and T_e=2 eV.
As for the resonance line (6³P₁−6¹S₀), slow decrease in intensity as compared with decrease in intensity of lines emitted from the higher levels is taken to be due to the radiative imprisonment and in consequence the absorption coefficient of this line is obtained as 1.2×10⁻¹³n₀/cm and the quenching cross section of the state 6³P₁ due to the collisions with mercury atoms as ⟨σ⟩₁₀=0.048 Ų.