Dependence on the scattering angle of the electron temperature and electron density in Thomson-scattering measurements on an atmospheric-pressure plasma jet

2000 ◽  
Vol 61 (2) ◽  
pp. 1920-1924 ◽  
Author(s):  
S. C. Snyder ◽  
D. M. Crawford ◽  
J. R. Fincke
Keyword(s):  
Electron Temperature ◽  
Electron Density ◽  
Atmospheric Pressure ◽  
Atmospheric Pressure Plasma ◽  
Plasma Jet ◽  
Thomson Scattering ◽  
Atmospheric Pressure Plasma Jet ◽  
Scattering Angle ◽  
Pressure Plasma ◽  
Scattering Measurements

scholarly journals Laser-induced photodetachment of negative oxygen ions in the spatial afterglow of an atmospheric pressure plasma jet

2022 ◽  
Author(s):  
Tim Jacobus Adrianus Staps ◽  
Tim Jacobus Maria Donders ◽  
Bart Platier ◽  
J Beckers
Keyword(s):  
Electron Density ◽  
Atmospheric Pressure ◽  
Atmospheric Pressure Plasma ◽  
Negative Ions ◽  
Plasma Jet ◽  
Ambient Air ◽  
Microwave Cavity ◽  
Oxygen Mixture ◽  
Atmospheric Pressure Plasma Jet ◽  
Pressure Plasma

Abstract Negative ions are an important constituent of the spatial afterglow of atmospheric pressure plasmas, where the fundamental plasma-substrate interactions take place that are vital for applications such as biomedicine, material synthesis, and ambient air treatment. In this work, we use laser-induced photodetachment to liberate electrons from negative ions in the afterglow region of an atmospheric pressure plasma jet interacting with an argon-oxygen mixture, and microwave cavity resonance spectroscopy (MCRS) to detect the photodetached electrons. This diagnostic technique allows for the determination of the electron density and the effective collision frequency before, during and after the laser pulse was shot through the measurement volume with nanosecond time resolution. From a laser saturation study, it is concluded that O− is the dominant negative ion in the afterglow. Moreover, the decay of the photodetached electron density is found to be dominantly driven by the (re)formation of O− by dissociative attachment of electrons with O2. As a consequence, we identified the species and process responsible for the formation of negative ions in the spatial afterglow in our experiment.

Influence of different O2/H2O ratios on He atmospheric pressure plasma jet impinging on a dielectric surface

2021 ◽  
Author(s):  
Jie Liu ◽  
Lijun Wang ◽  
Xin Lin ◽  
Runming Zhang
Keyword(s):  
Electron Density ◽  
Atmospheric Pressure ◽  
Atmospheric Pressure Plasma ◽  
Plasma Jet ◽  
Dielectric Surface ◽  
Ionization Wave ◽  
Electron Collision ◽  
Recombination Reaction ◽  
Atmospheric Pressure Plasma Jet ◽  
Pressure Plasma

Abstract A two dimensional (2D) axisymmetric fluid model is built to investigate the effect of different O2 and H2O admixture on the plasma dynamics and the distribution of reactive species in He atmospheric pressure plasma jet (APPJ). The increase of O2: H2O ratio slows down both the intensity and the propagation speed of ionization wave. Due to the decrease of both H2O ionization rate and H2O Penning ionization as well as the stronger electronegativity of O2, the increase of O2: H2O ratio results in a significant reduction of electron density in the APPJ, which restricts the occurrence of electron collision ionization reactions and inhibits the propagation of plasma. The excitation energy loss of O2 is not the reason for the weakening of the plasma ionization wave. The densities of O2+, O- and O2- increase with the rise of O2 admixture while H2O+ decreases due to the decrease of electron density and H2O concentration. OH- density is affected by both the increase of O- and the decrease of H2O so it shows peak in the case of O2: H2O=7:3. O is mainly produced by the excitation reactions and the electron recombination reaction (e + O2+ → 2O), which is directly related to the O2 concentration. OH is mainly produced by e + H2O → e + H + OH so the OH density decreases due to the decrease of electron density and H2O concentration with the increase of O2: H2O ratio. On the dielectric surface when the propagation of streamer extinguishes, O flux shows an upward trend while the OH flux decreases, and the propagation distance of O and OH decreases with the increase of O2: H2O ratio.

scholarly journals High-Accuracy Surface Topography Manufacturing for Continuous Phase Plates Using an Atmospheric Pressure Plasma Jet

Micromachines ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 683
Author(s):  
Huiliang Jin ◽  
Caixue Tang ◽  
Haibo Li ◽  
Yuanhang Zhang ◽  
Yaguo Li
Keyword(s):  
Surface Topography ◽  
Atmospheric Pressure ◽  
High Efficiency ◽  
Atmospheric Pressure Plasma ◽  
Plasma Jet ◽  
Continuous Phase ◽  
High Accuracy ◽  
Phase Plate ◽  
Atmospheric Pressure Plasma Jet ◽  
Pressure Plasma

The continuous phase plate (CPP) is the vital diffractive optical element involved in laser beam shaping and smoothing in high-power laser systems. The high gradients, small spatial periods, and complex features make it difficult to achieve high accuracy when manufacturing such systems. A high-accuracy and high-efficiency surface topography manufacturing method for CPP is presented in this paper. The atmospheric pressure plasma jet (APPJ) system is presented and the removal characteristics are studied to obtain the optimal processing parameters. An optimized iterative algorithm based on the dwell point matrix and a fast Fourier transform (FFT) is proposed to improve the accuracy and efficiency in the dwell time calculation process. A 120 mm × 120 mm CPP surface topography with a 1326.2 nm peak-to-valley (PV) value is fabricated with four iteration steps after approximately 1.6 h of plasma processing. The residual figure error between the prescribed surface topography and plasma-processed surface topography is 28.08 nm root mean square (RMS). The far-field distribution characteristic of the plasma-fabricated surface is analyzed, for which the energy radius deviation is 11 μm at 90% encircled energy. The experimental results demonstrates the potential of the APPJ approach for the manufacturing of complex surface topographies.

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