Time–space resolved distribution of oxygen metastable atoms in an axially symmetrical atmospheric pressure barrier discharge

Abstract

Tunable diode laser absorption spectroscopy is used as a non-invasive method for the diagnosis of a helium atmospheric pressure dielectric barrier discharge, containing oxygen as contaminant. The time evolution of the absorption coefficient corresponding to the oxygen metastable atoms on the 3 5 S 2 level is recorded as a function of the laser absorbing path, in the axial symmetrical electrode geometry. The bi-dimensional Abel transform is used to obtain local information on the space distribution of the metastable atoms in the discharge. The results show that the oxygen metastable atoms have distinct time-space dynamics, in relation to plasma kinetics involving helium high-energy species and to the marked role of the dielectric barrier.

Stimulation of wound healing by helium atmospheric pressure plasma treatment

“…The optical emission spectrum of the APPJ consists of the following atomic lines/molecular band: OH radical-at 308.9 nm as a result of H 2 O dissociation, N 2 -at 337 nm as dominant component of the ambient air, N + 2 -at 391 nm as helium metastable presence indicator, H α -at 656 nm, He-at 706 nm as working gas, O-at 777.4 nm as a result of H 2 O dissociation as well. The same spectra of the discharge, but with different intensities, were also reported by [28][29][30][31][32]. More precisely, at the 308.9 nm we can observe the emission band of the OH radical.…”

Argon metastables in HiPIMS: time-resolved tunable diode-laser diagnostics

“…The rapid changes during the pulsed plasma make it necessary to develop time-resolved diagnostic methods. The TD-LAS technique is usually employed for stationary plasmas [31] or time-averaged measurements in pulsed plasmas [32], but has been adapted in various ways to perform time-resolved measurements [21,22,24]. The method proposed in this paper uses the diode laser in its regular scanning mode, at very low scanning frequency (less than 0.2 Hz).…”

“…Although this technique is very efficient and easy to implement in continuous steady state discharges or time averaged measurements of plasma species [18,19,20], the pulsed regime raises additional problems due to the fast time variations [21]. Time resolved measurements of atomic species have been performed by locking the laser to a fixed wavelength (usually the resonance wavelength λ 0 ) [22,23]. Such time resolved measurements can easily give access to the general trend of the density evolution, but cannot give any information on the possible profile broadening.…”

DBD Surface Modification of Polymers in Relation to the Spatial Distribution of Reactive Oxygen Species

“…The complete results on the time-space dynamics of the oxygen metastable atoms, shown to relate to the plasma kinetics involving helium high energy species and to the marked role of the dielectric barrier, are presented elsewhere [20].…”