On the Ar(1s₅) density distribution in a flow-driven DBD at intermediate pressure

Absolute densities of Ar(1s₅) metastable atoms have been measured temporally and spatially resolved in an intermediate-pressure dielectric barrier discharge using laser atomic absorption spectroscopy. Depending on the operating conditions, the maximum densities are in the range of $\mathrm{1...4}\times {10}^{17}{m}^{-3}$. The device under test is based on the Venturi-DBD concept, which allows an efficient investigation of the influence of different pressures. Furthermore, the effects of changes in the excitation frequencies and molecular admixtures on the Ar(1s₅) density and decay dynamics have been investigated. Moreover, they provide a variety of possible benchmark parameters for plasma-chemical models in argon. Due to the presence of the Ar(1s₅) state also for mixtures with low amounts of molecular gases, the generated data can be used to validate models considering nitrogen and oxygen. In the present investigation, an admixture of nitrogen has been used to determine the vibrational temperature of 1500...1900 K and the rotational temperature of 444 K experimentally. Measurements of the Ar(2p₁ $\to$ 1s₂) de-excitation allow tracking the spatiotemporal discharge development. (paper)