scholarly journals Correlating Metastable-Atom Density, Reduced Electric Field, and Electron Energy Distribution in the Initiation, Transient, and Post-Transient Stages of a Pulsed Argon Discharge

2017 ◽  
Author(s):  
James B. Franek
Keyword(s):  
Electric Field ◽  
Energy Distribution ◽  
Electron Energy ◽  
Metastable Atom ◽  
Electron Energy Distribution ◽  
Atom Density ◽  
Argon Discharge

scholarly journals A Computationally Assisted Ar I Emission Line Ratio Technique to Infer Electron Energy Distribution and Determine Other Plasma Parameters in Pulsed Low-Temperature Plasma

Plasma ◽  
2019 ◽  
Vol 2 (1) ◽  
pp. 65-76 ◽  
Author(s):  
James Franek ◽  
Samuel Nogami ◽  
Mark Koepke ◽  
Vladimir Demidov ◽  
Edward Barnat
Keyword(s):  
Electric Field ◽  
Energy Distribution ◽  
Emission Line ◽  
Electron Density ◽  
Electron Energy ◽  
Metastable Atom ◽  
Line Ratio ◽  
Electron Energy Distribution ◽  
Atom Density ◽  
Argon Discharge

In the post-transient stage of a 1-Torr pulsed argon discharge, a computationally assisted diagnostic technique is demonstrated for either inferring the electron energy distribution function (EEDF) if the metastable-atom density is known (i.e., measured) or quantitatively determining the metastable-atom density if the EEDF is known. This technique, which can be extended to be applicable to the initial and transient stages of the discharge, is based on the sensitivity of both emission line ratio values to metastable-atom density, on the EEDF, and on correlating the measurements of metastable-atom density, electron density, reduced electric field, and the ratio of emission line pairs (420.1–419.8 nm or 420.1–425.9 nm) for a given expression of the EEDF, as evidenced by the quantitative agreement between the observed emission line ratio and the predicted emission line ratio. Temporal measurement of electron density, metastable-atom density, and reduced electric field are then used to infer the transient behavior of the excitation rates describing electron-atom collision-induced excitation in the pulsed positive column. The changing nature of the EEDF, as it starts off being Druyvesteyn and becomes more Maxwellian later with the increasing electron density, is key to interpreting the correlation and explaining the temporal behavior of the emission line ratio in all stages of the discharge. Similar inferences of electron density and reduced electric field based on readily available diagnostic signatures may also be afforded by this model.

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