Determination of N-atom Density in High Ar- 𝐍𝟐 Gas Pressure Microwave Afterglow | Chapter 18 | Plasmas Afterglows with N2 for Surface Treatments synthesis 2024

100 to 760 Torr (atmospheric gas pressure). The determination of N -atoms density in high-pressure Ar − N2 microwave afterglow is revisited. First, it is observed that pure pink afterglows are mainly obtained at high pressures up to atmospheric gas pressure, which is an aN+N factor of N + N recombination near 0. Second, there is an uncertainty in the range k = 10⁻¹¹ −10⁻¹² cm³ s⁻¹ on the k-rate coefficient of the reaction 𝑁₂,𝑣 > 13+𝑁₂(𝐴) → 𝑁₂(𝐵,𝑣′)+𝑁₂ which dominates the pink afterglow An enhancement of the 𝑁₂(𝐵,𝑣′ = 8)/𝑁2(𝐵,11) density ratio is observed up to the atmospheric gas pressure. It was interpreted by a reduction of the quenching of the 𝑁₂(𝐵,𝑣′ = 8) by Ar. Values of the 𝑁 +𝑁 recombination rates were determined when 𝑎𝑁+𝑁 > 0.1. It was found a large uncertainty depending on the N₂( B,v′ = 11) quenching rates found in the literature. It is estimated a decrease in the N + N recombination rates by 0.6 in the Ar− 2% N₂ in comparison to pure N2 afterglow. The determination of N-atoms density in high-pressure Ar- xN₂ microwave afterglow is revisited. First, it is confirmed that pure pink afterglows are mainly observed at high

 

Author (s) Details

André Ricard
LAPLACE, Université de Toulouse, CNRS, INPT, UPS, 118 route de Narbonne, 31062 Toulouse Cedex 9, France.

 

Jayr Amorim
Department Fisica, Inst. Tec. Aeronautica 12228-900, Sao Jose dos Campos, Brazil.

 

Please see the book here:- https://doi.org/10.9734/bpi/mono/978-93-49473-93-5/CH18

Effect of O2 into N2 Afterglows in RF and Corona Discharges | Chapter 17 | Plasmas Afterglows with N2 for Surface Treatments synthesis 2024

The afterglows in N² −O₂ gas mixtures have been previously described: N− atoms titration by NO [A − 1], oxygen in impurity in N₂ at reduced gas pressure and at atmospheric gas pressure. The N and O-atoms density versus the O₂ percent from 1 to 4% into N₂ in HF flowing afterglow (at 7 Torr, 0.5 slpm, 150 W) was strongly decreasing for N-atoms from 15 to 210¹⁴ cm⁻³ and kept a nearly constant value for O-atoms density: 7-9 10¹⁴ cm⁻³, a value which is higher than the N-atom density in the range 2 − 10%O₂ into N₂. In RF afterglows, it was studied the effect of O-atoms and O₂ molecules when O₂ was introduced into N₂ before or after the plasma (8 Torr, 1 slpm, 100 W ). It is concluded that a quenching of N₂ active species by O-atoms more effective than with O₂ in the early and late afterglows. At N₂ the atmospheric gas pressure of Corona Plasmas with O2 impurity, it has been measured the density of the N₂O¹ S excimer equal to about 10¹² cm⁻³, largely less than the N and N₂ (A) densities: (5-7) 10¹⁴ cm⁻³.

 

Author (s) Details

André Ricard
LAPLACE, Université de Toulouse, CNRS, INPT, UPS, 118 route de Narbonne, 31062 Toulouse Cedex 9, France.

 

Anne-Marie Pointu
LPGP, Université de Paris-Saclay, 91405 Orsay, France.

 

Soo-Ghee Oh
Department Energy System Res., Ajou University, Suwon 16499, Korea.

 

Please see the book here:- https://doi.org/10.9734/bpi/mono/978-93-49473-93-5/CH17

Microwave Cavities Generated Active Species in Plasmas | Chapter 3 | Plasmas Afterglows with N2 for Surface Treatments synthesis 2024

Microwave plasma sources are described from low Ar gas pressure (< 1 Torr) to high gas pressures (> 10 Torr up to the atmospheric gas pressure) in N2 and Ar. At low gas pressure, the plasma diameter is over 1 cm, typically 2.6 cm and at high gas pressure, it needs discharge tubes < 1cm, down to 0.1 cm. The microwave plasmas have been studied from low to atmospheric gas pressure in rare gases (mainly Ar) and gas mixtures containing N2. At low gas pressure, it is found the surface wave plasmas, produced by patented launchers Surfatron and Surfaguide, which were developed by Michel Moisan in the Plasmas Lab. of the Montreal Univ. in 1975 [1] (see note). At high gas pressure from a few Torr up to the atmospheric gas pressure, the SW plasmas Surfatron at low power and Surfaguide at high power are still operating. It is also given the results obtained by a resonant cavity in N₂ − xO₂ with 𝑥 = 0−20%. It is presently reported the detection of plasma active species obtained by optical spectroscopy. The main used frequency was 2450 MHz. The plasma power could vary from a few Watts (surfatron) up to a few 103 Watts (Surfaguide, resonant cavity). The plasma can be produced in a static gas flow, mainly at low gas pressure and up to several liters per minute (slpm) at high gas pressures. The optical spectroscopy was set up first to obtain the spatial distribution of radiative species, mainly in Ar gas at low gas pressure in the perspective to characterize the SW plasmas. Then the radial distribution of Ar metastable density was obtained by resonant optical absorption. At medium (a few Torr) up to the atmospheric gas pressure, flowing HF plasmas (resonant cavity) and SW plasmas were produced in gas mixtures with N₂ to produce N -atoms and other active species such as N2 metastable molecules and N₂ +ions which are studied inside the plasma and in afterglow conditions. It discusses the kinetics reactions relating the 𝑁₂(𝑋,𝑣),𝑁₂(𝐴,𝑣′),𝑁₂(𝐵,𝑣′),𝑁₂(𝐶,𝑣′),𝑁₂ + (𝑋,𝑣′) and N₂ + (𝐵,𝑣′) interfering in the radiative emissions of N₂ (𝐵,𝑣′),𝑁₂(𝐶,𝑣′) and N₂ +(𝐵,𝑣′) states. At atmospheric gas pressure, the plasmas are mainly in Ar dominant gas, easier to ionize. In these conditions, the plasmas are characterized by the electron density and the gas temperature which will be reported for specific microwave plasmas sources. Depending on plasma parameters such as powers, flow rates and exit tube diameters, the plasmas were more and less near the Local Thermodynamic Equilibrium (LTE) as demonstrated in Montreal Univ., Lisbon IST and Cordoba Univ. The conclusion was that the N₂ excited states are mainly produced from the N2 ground state by electron collisions in a resonant microwave cavity. It was estimated that the LTE was nearly reached in a 100 Torr, 300-500 W N₂ plasma in a quartz tube of i.d.10 mm. with equality of vibrational and rotational temperatures.

 

Author (s) Details

 

André Ricard

LAPLACE, Université de Toulouse, CNRS, INPT, UPS, 118 route de Narbonne, 31062 Toulouse Cedex 9, France.

Please see the book here:- https://doi.org/10.9734/bpi/mono/978-93-49473-93-5/CH3