Analysis of applicability of triplet-state emission of molecular hydrogen for spectral diagnostics of a DC discharge

Abstract

The applicability of emission of the N³Λ_σ triplet states of molecular hydrogen for spectral diagnostics of the positive column of a dc glow discharge in hydrogen at translational gas temperatures of 360–600 K, specific absorbed powers of 0.8–4.25 W/cm, gas pressures of p = 0.3–15.0 Torr, reduced fields of E/N = 30–130 Td, and electron densities of n_e = 4.0 × 10⁹–6.5 × 10¹⁰ cm^–3 is analyzed by using an advanced level-based semi-empirical collisional−radiative model. It is found that secondary processes make the main contribution to the population and decay of the N³Λ_σ = a³Σ⁺_g, c³Π_u, g³Σ⁺_g, h³Σ⁺_g, and i³Π_g triplet states. The dipole-allowed transitions e³Σ⁺_g → a³Σ⁺_g, f³Σ⁺_g → a³Σ⁺_g, g³Σ⁺_g and k³Π_u → a³Σ⁺_g can be used for spectral diagnostics of a dc discharge within a simplified coronal model.