Comparison of atmospheric-pressure helium and argon plasmas generated by capacitively coupled radio-frequency discharge

Abstract

In this paper, the electrical discharge characteristics of plasmas generated in coaxial cylindrical electrodes capacitively powered by a radio-frequency power supply at atmospheric pressure are investigated with respect to helium and argon gases. The electrical discharge parameters, voltage ͑V͒, current ͑I͒, and power ͑P͒, are measured for both helium and argon plasmas, and the electron temperatures and electron densities for them are evaluated by means of the equivalent circuit model and the power balance equation. By comparison of the discharge characteristics of the helium and argon plasmas, it is found that the discrepant macroscopic characteristics of helium and argon plasma, viz., current and voltage characteristics and current and power characteristics, are owed to their own intrinsic microscopic parameters of the helium and argon atoms, such as the first excited energy, the ionization energy, the total cross section, and the atom mass. Furthermore, the influences of the additive gas, oxygen gas, on the electrical discharge characteristics are also investigated in the helium and argon plasmas, which are closely related to the electron temperature of plasmas.

From Submicrosecond- to Nanosecond-Pulsed Atmospheric-Pressure Plasmas

“…The mean electron energy increases rapidly as soon as the voltage is applied, reaching close to ∼10 eV. This is significantly higher than the mean electron energy observed in discharges that are sustained with continuous excitation (typical electron temperature for continuous excitation ∼1 eV [14], [21], [22]). Soon after the initial increase, the mean electron energy starts to drop as a result of the loss of energetic electrons to the anode [ Fig.…”

Physical Methods for Cleaning and Disinfection of Surfaces

“…Ekem et al [184], however, determined a lower reduction; approximately 7 min was necessary to obtain a similar reduction for B. stearothermophilus or B. subtilis spores. Uhm et al [185] demonstrated that, for spore inactivation, D-values of approximately 5 s can be reached with Ar/O 2 plasma, whereas for He/O 2 plasma, D-values are higher by a factor of 10-20 because of a reduced electron density [186]. For E. coli, Kelly-Winterberg et al [187] observed a significant influence of the attachment matrix on inactivation rate by OAUGDP; D-values for E. coli on glass, polypropylene, and agar were 70, 30, and 300 s, respectively.…”

Numerical Simulation on the Production of Reactive Oxygen Species in Atmospheric Pulse-Modulated RF Discharges with He/O2 Mixtures

“…[25,15] An optimal oxygen admixture of about 0.6%, at which the ground state atomic oxygen density could get the maximum value under a constant power or applied voltage condition, has been observed. [6,7,15] To investigate the influence of duty cycle and modulation frequency on the production of ROS, the oxygen admixture used in present study is fixed as 0.6%.…”