Characteristics of a radio-frequency cold atmospheric plasma jet produced with a hybrid cross-linear-field electrode configuration

Abstract

Cold atmospheric plasma (CAP) jet has wide applications in various fields including advanced materials synthesis and modifications, biomedicine, environmental protection and energy saving, etc. Appropriate control on the volume, temperature and chemically reactive species concentrations of the CAP jet is of great importance in actual applications. In this paper, an radio-frequency atmospheric-pressure glow discharge (RF-APGD) plasma generator with a hybrid cross-linear-field electrode configuration is proposed. The experimental results show that, with the aid of the copper mesh located at the downstream of the traditional co-axial-type plasma generator with a cross-field electrode configuration, a linear field between the inner powered electrode of the traditional plasma generator and the copper mesh can be established. This linerfield can, to some extent, enhance the discharges at the upstream of the copper mesh, resulting in small increments (all less than 12.5%) of the species emission intensities, electron excitation temperatures and gas temperatures by keeping other parameters being unchanged. And due to the intrinsic transparent and conducting features of the grounded copper mesh to the gas flowing, electric current and heat flux of the plasma plumes, a plasma region with higher concentrations of chemically reactive species and larger plasma plume diameters is obtained at the downstream of the grounded copper mesh on the same level of the gas temperature and electron excitation temperature compared to those of the plasma free jet. In addition, the charged particle number densities at the same downstream axial location of the grounded copper mesh decrease significantly compared to those of the plasma free jet. This means that the copper mesh is also, to some extent, helpful for separating the chemically reactive neutral species from the charged particles inside a plasma environment. The preceding results indicate that the cross-linear-field electrode configuration of the plasma generator is an effective approach for tuning the characteristics of the RF-APGD plasma jet in order to obtain an appropriate combination of the plasma jet properties with higher chemically reactive species concentrations, especially relative higher number densities of neutral species, larger plasma volumes and lower gas temperatures.

Influences of the inner diameter of the solid shielding tube on the characteristics of the radio-frequency cold atmospheric plasma jet

“…The generating and quenching chemical dynamics of various species in the RF-CAPs for the He-N 2 gas mixture discharges in open atmosphere are listed in table 1 [22,[58][59][60][61][62].…”

“…This is, in our opinion, due to the stronger mixing of the surrounding cold air with the main stream of the plasma jet beyond the shielding region. The rotational (T rot ) and vibrational (T vib ) temperatures in the plasma jet region are determined by comparing the simulated spectrum generated by varying the input parameters in the SPECAIR software to obtain a replica to the experimentally recorded nitrogen second positive system N 2 (C→B) (0-0) at 337.14 nm [22,66]. In this study, the ICCD spectrograph has a built-in 1800 l mm −1 grating, which corresponds to an optical resolution of 0.0351 nm, for recording the optical emission spectrum around 337 nm.…”

Applications of cold atmospheric plasmas (CAPs) in agriculture: a brief review and the novel development of a radio-frequency CAP jet generator for plant mutation

“…where I ij is the experimentally recorded emission intensity of the transition from level i to level j, k B is the Boltzmann constant, E ij and A ij are the energy difference and the Einstein coefficient for the spontaneous emission between the excited levels of i and j, λ ij is the corresponding wavelength of the emission line, g i is the statistical weight of the level i, which can be obtained from NIST [86]. This method has been widely employed by researchers when studying medium-and high-pressure plasmas [87][88][89]. Due to the similar variation trends of the electron temperature (T e ) and electron excitation temperature (T exc ) at higher operating pressures [85], we intend to use T exc to characterize the variation trend of T e , i.e.…”

Spatio-temporal evolution characteristics and pattern formation of a gas–liquid interfacial AC current argon discharge plasma with a deionized water electrode

“…However, exposition of discharge to ambient air gas suggests that the occurrence of O•is not only the result of H 2 O dissociation but also of O 2 [44,45]:…”