Kinetic Analysis of Chlorofluorocarbon Discharges

1984 ◽  
Vol 38 ◽  
Author(s):  
Herbert H. Sawin ◽  
Akimichi Yokozeki ◽  
Aaron J. Owens ◽  
Kenneth D. Allen
Keyword(s):  
Electron Impact ◽  
Etching Rate ◽  
Threshold Energy ◽  
Electron Attachment ◽  
Impedance Analysis ◽  
Average Electron Energy ◽  
Electrode Surfaces ◽  
Positive Ions ◽  
Rate Limiting Step ◽  
Average Electron

AbstractThe fundamental plasma kinetics of chlorofluorocarbon discharges have been studied experimentally and modeled. Electrical impedance analysis of the plasma discharge during the etching process was used to estimate the average electron energy and the electron concentration. Assuming the electron-impact generation of reactant species is the rate limiting step, the etching rate of polysilicon etching was modeled using a simplified expression for the electron-impact rate coefficient for dissociation and the experimentally estimated electron densities and electron energies. Dissociative electron attachment should play a significant role in the production of etchant species at low electron energies. The lower threshold energy and the larger cross-section (σ) for dissociative attachment of chlorofluorocarbons (σmax,∼6×10-18 cm2 at ∼ 3 eV for CF3Cl) in coomprpsanrtison to that of fluorocarbons (σmax ∼0.8×10-18 cm2 at ∼7 eV for CF4 ), increases the significance of this machanism in chlorofluorocarbon discharges. In addition, the production of appreciable concentrations of C1- could influence the transport of positive ions to the electrode surfaces.

Numerical Simulation of Leakage Current on Conductive Insulator Surface

2019 ◽  
Vol 8 (4) ◽  
pp. 9487-9492
Keyword(s):  
Numerical Simulation ◽  
Electric Field ◽  
Leakage Current ◽  
Method Of Lines ◽  
Electron Attachment ◽  
Negative Ions ◽  
Conduction Current ◽  
Insulator Surface ◽  
Finite Difference Approximations ◽  
Positive Ions

The outdoor insulator is commonly exposed to environmental pollution. The presence of water like raindrops and dew on the contaminant surface can lead to surface degradation due to leakage current. However, the physical process of this phenomenon is not well understood. Hence, in this study we develop a mathematical model of leakage current on the outdoor insulator surface using the Nernst Planck theory which accounts for the charge transport between the electrodes (negative and positive electrode) and charge generation mechanism. Meanwhile the electric field obeys Poisson’s equation. Method of Lines technique is used to solve the model numerically in which it converts the PDE into a system of ODEs by Finite Difference Approximations. The numerical simulation compares reasonably well with the experimental conduction current. The findings from the simulation shows that the conduction current is affected by the electric field distribution and charge concentration. The rise of the conduction current is due to the distribution of positive ion while the dominancy of electron attachment with neutral molecule and recombination with positive ions has caused a significant reduction of electron and increment of negative ions.

Electron impact excitation of positive ions

1970 ◽  
Vol 266 (1175) ◽  
pp. 225-279 ◽  
Keyword(s):  
Electron Impact ◽  
Cross Sections ◽  
Nuclear Charge ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
Positive Ions ◽  
Relativistic Coulomb ◽  
Hydrogenic Ions

Non-relativistic Coulomb-Born-Oppenheimer reactance matrices and cross-sections are given for all transitions between the Is, 2s and 2p states in He+ and in hydrogen-like ions of large nuclear charge. From these results some cross-sections for intercombination transitions in highly charged non-hydrogenic ions are estimated.

All that is known about Mars discrete aurorae so far

2021 ◽  
Author(s):  
Lauriane Soret ◽  
Zachariah Milby ◽  
Jean-Claude Gérard ◽  
Nick Schneider ◽  
Sonal Jain ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Emission Layer ◽  
Atmospheric Effect ◽  
Average Electron Energy ◽  
Mars Express ◽  
Spatially Correlated ◽  
Auroral Emissions ◽  
Average Electron ◽  
First Time ◽  
Imaging Spectrograph

<p>The discrete aurorae on Mars were discovered with the SPICAM spectrograph on board Mars Express. Now, they have been analyzed in detail using the much more sensitive MAVEN/IUVS imaging spectrograph.</p><p>This presentation gives a summary of the very latest results obtained by Schneider et al. and Soret et al. on this topic.</p><p>The main conclusions are the following:</p><ul><li>the number of auroral event detections has considerably increased since the Mars Express observations;</li> <li>many detections have been made outside of the Southern crustal magnetic field structures;</li> <li>the MUV spectrum shows the same emissions as those observed in the dayglow, with similar intensity ratios;</li> <li>the Vegard-Kaplan bands of N<sub>2</sub> have been observed for the first time in the Martian aurora;</li> <li>the CO Cameron and the CO<sub>2</sub><sup>+</sup> UVD emissions occur at the same altitude;</li> <li>the OI emission at 297.2 nm has been analyzed;</li> <li>the CO Cameron/CO<sub>2</sub><sup>+</sup> UVD ratio is quasi-constant;</li> <li>intensities are higher in B-field regions;</li> <li>auroral emissions are more frequent in the pre-midnight sector;</li> <li>the altitude of the emission layer is independent of local time and presence or absence of a crustal magnetic field;</li> <li>the altitude of the emission layer varies moderately with season (atmospheric effect);</li> <li>the events are spatially correlated with an increase in the flux of energetic electrons simultaneously measured by the MAVEN/SWEA (Solar Wind Electron Analyzer) detectors;</li> <li>the peak altitude of the emission is in good agreement with that expected from the average electron energy.</li> </ul>

Continuum Modeling of Charged Particle Transport: RF Breakdown and Discharges of SF6

1986 ◽  
Vol 68 ◽  
Author(s):  
Brian E. Thompson ◽  
Herbert H. Sawun ◽  
Aaron Owens
Keyword(s):  
Electric Fields ◽  
Electron Attachment ◽  
Negative Ions ◽  
Rate Coefficients ◽  
Rf Discharge ◽  
Continuity Equations ◽  
Positive Ions ◽  
Discharge Model ◽  
Rf Breakdown ◽  
Charged Particle Transport

AbstractContinuity equations for the concentration of electrons, positive ions, and negative ions were constructed and solved to predict rf breakdown voltages and the electrical properties of SF, discharges.These balances for the three types of charged species include terms for convection (electric field-driven fluxes), diffusion, and reactions (ionization, electron attachment, and negative-positive ion recombination).The mobilities, diffusivities, and reaction rate coefficients necessary for the rf discharge model are based on reported measurements and calculations of these parameters in dc electric fields.The electric fields developed in the rf discharge are calculated from Poisson's equation and applied voltage conditions.Predictions based on this model are compared with measured rf breakdown characteristics of SF6.

Energetics of the Ionization and Fragmentation of Phosphorus Trifluoride by Electron Impact

1975 ◽  
Vol 53 (6) ◽  
pp. 933-938 ◽  
Author(s):  
David F. Torgerson ◽  
John B. Westmore
Keyword(s):  
Mass Spectrum ◽  
Electron Impact ◽  
Ionization Efficiency ◽  
Negative Ion ◽  
Efficiency Curve ◽  
Group V ◽  
Fragmentation Pathways ◽  
Ion Fragmentation ◽  
Positive Ions ◽  
Significant Intensity

Relative intensities and appearance potentials of several positive ions in the mass spectrum of PF3 are reported as well as an ionization efficiency curve for F−, the only negative ion of significant intensity. Probable ion fragmentation pathways are proposed, together with heats of formation of some positive ions, and ionization potentials for PF3, PF2·, and PF. The results are compared with available data for other Group V halides.

21S excitation of heliumlike ions

1983 ◽  
Vol 61 (7) ◽  
pp. 981-987 ◽  
Author(s):  
C. S. Singh ◽  
R. Srivastava ◽  
D. K. Rai
Keyword(s):  
Electron Impact ◽  
Cross Sections ◽  
Threshold Energy ◽  
Total Cross Sections ◽  
Variable Charge ◽  
Near Threshold

The variable charge, Coulomb-projected Born (VCCPB) approximation is applied to the calculation of cross sections for electron impact 11S–21S excitation in heliumlike ions (3 ≤ Z ≤ 8 and Si12+, Ca18+, and Fe24+). Differential and total cross sections have been reported for incident energies ranging from near threshold to five times threshold energy and are compared with other available theoretical estimates.

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