Study of apparent effective ionization coefficient in CO2 and Ar gas mixtures

Abstract

Ar:CO2 gas mixtures have recently received research interest due to the possibly beneficial effects of Ar addition to CO2 for CO2 conversion using electrical discharges. For any gas discharge, knowledge of fundamental parameters, such as the effective ionization coefficient, is necessary to optimize the efficiency of the discharge for a particular application. The reduced apparent effective ionization coefficient αea/N is a measure of total ionization. αea/N is influenced by electron impact ionization, electron attachment and also by charge transfer reaction, Penning ionization, and photoionization. This study determined the αea/N of Ar:CO2 gas mixtures in the pressure range of 10–800 Torr and reduced electric field strength E/N range of 40–1200 Td utilizing a steady-state non-self-sustaining Townsend discharge. Experimental results were compared with calculations of Boltzmann equation solver BOLSIG+. Differences between measurements and calculations increased with decreasing CO2 content in the mixture down to 20%, and the differences were highest at low E/N values (below 150 Td). As the simple modification of the model, contribution of ionization of CO2 by Penning transfer from Ar* 3p53d excited states (13.86 eV) was added to the BOLSIG+ calculations, which resulted in good fit of the experimental measurements. Comparison of CO2 addition to Ar with the addition of O2 or N2 revealed that ionization of CO2 or O2 from Ar* 3p53d excited states influences ionization in Ar:CO2 and Ar:O2 mixtures but not in Ar:N2 mixtures, due to the different ionization energies of CO2, O2, and N2.

The production of reactive chlorine species (RCS) by argon and helium plasma jets and the sensitivity of liver cancer cell HepG2 to RCS and H2O2 treatment

“…However, the concentration of metastable atoms is also influenced by the electron concentration and energy, which depend on the O 2 content in the plasma gas. [ 41,42 ]…”

“…However, the concentration of metastable atoms is also influenced by the electron concentration and energy, which depend on the O 2 content in the plasma gas. [41,42] 3.2 | RCS production efficiency by Ar/O 2 and He/O 2 plasma jets RCS production presumes plasma treatment of the saline in the noncontact mode. The noncontact mode was more difficult to achieve in the case of the Ar/O 2 plasma jet.…”