O 2 ( Δ 1 ) production in He∕O2 mixtures in flowing low pressure plasmas

Abstract

Chemical oxygen-iodine lasers (COIL) are attractive for diverse industrial applications because they are capable of high efficiency, high power operation, and because the 1.315 m wavelength can be transmitted through fiber optics and couples efficiently with most metals. Conventional COILs are pumped with O 2 ͑ 1 ⌬͒ that is generated by reaction of Cl 2 in a basic H 2 O 2 solution. Current trends in pumping COILs involve producing the O 2 ͑ 1 ⌬͒ in electric discharges, thereby circumventing the hazards, complexity, and weight associated with pumping and storing caustic liquids. In this work, we have investigated the scaling of O 2 ͑ 1 ⌬͒ yields with specific energy deposition in He/ O 2 mixtures in flowing radio frequency (rf) discharges at pressures of a few to tens of Torr using a global plasma kinetics model. We found that O 2 ͑ 1 ⌬͒ yield increases nearly linearly with specific energy deposition in O 2 molecules up to a few eV per molecule, with yields peaking around 30% by 5 -8 eV. Further increases in specific energy deposition serve only to increase O 2 dissociation and gas heating, thereby reducing the O 2 ͑ 1 ⌬͒ yield. We also found that variations in peak yields at a given specific energy deposition are caused by secondary effects resulting from dilution, pressure, and power level. We show that these secondary effects alter the O 2 ͑ 1 ⌬͒ yield by shifting the O 2 ͑ 1 ⌺͒ /O 2 ͑ 1 ⌬͒ ratio.

Electron collisions with atoms, ions, molecules, and surfaces: Fundamental science empowering advances in technology

“…11. These results were produced with a global kinetics, collisional-radiative model (41), in which conservation equations for the densities of the charged and neutral species, electron temperature, gas temperature, and laser optical fluxes are integrated in time while accounting for transport in the form of diffusion to surfaces and/or plug flow. Rate and transport coefficients for electron impact processes were obtained from solutions of Boltzmann's equation for the electron energy distribution with FSD for cross sections as input.…”

Surface Characteristics of Polyethylene Terephthalate (PET) Film Exposed to Active Oxygen Species Generated via Ultraviolet (UV) Lights Irradiation in High and Low Humidity Conditions

“…Generation mechanisms of these active oxygen species have already been reported as follows [11][12][13][14][15][16]. Firstly, an oxygen molecule is decomposed into two ground-state oxygen atoms by irradiation with 185 nm UV light.…”

“…It is known that active oxygen species such as excited singlet oxygen [O( 1 D)], ozone (O 3 ), hydroxyl radicals (OH*), and hydrogen peroxide (H 2 O 2 ) have long lifetime or high oxidization abilities [8][9][10][11][12][13][14][15][16]. Generation mechanisms of these active oxygen species have already been reported as follows [11][12][13][14][15][16].…”

“…In the generation process, many kinds of active oxygen species, e.g., ozone, excited state singlet oxygen atom and molecule, hydroxyl radical, hydrogen peroxide, and hydroperoxide, are generated and decomposed [8][9][10][11][12][13][14][15][16]. Since generation process is based on the decomposition of oxygen and water molecules and the oxidation abilities of these active oxygen species are different, the control of humidity environment is important for controlling the surface modification.…”

Plasma Assisted Low Temperature Combustion

“…In addition, a heat loss term to account for conduction losses to the wall is added to the energy equation [33]. The low temperature kinetic model used here is a combination of the newly developed high pressure kinetic mechanism (HP-Mech) [34] and plasma reactions collected primarily from [35][36][37][38]. HP-Mech includes pressure dependence of reaction rates for all unimolecular reactions and can be applied from low pressure to high pressure conditions.…”