Length control of He atmospheric plasma jet plumes: Effects of discharge parameters and ambient air

Abstract

The effects of various discharge parameters and ambient gas on the length of He atmospheric plasma jet plumes expanding into the open air are studied. It is found that the voltage and width of the discharge-sustaining pulses exert significantly stronger effects on the plume length than the pulse frequency, gas flow rate, and nozzle diameter. This result is explained through detailed analysis of the I-V characteristics of the primary and secondary discharges which reveals the major role of the integrated total charges of the primary discharge in the plasma dynamics. The length of the jet plume can be significantly increased by guiding the propagating plume into a glass tube attached to the nozzle. This increase is attributed to elimination of the diffusion of surrounding air into the plasma plume, an absence which facilitates the propagation of the ionization front. These results are important for establishing a good level of understanding of the expansion dynamics and for enabling a high degree of control of atmospheric pressure plasmas in biomedical, materials synthesis and processing, environmental and other existing and emerging industrial applications.

Electrical, Thermal and Optical Parametric Study of Guided Ionization Waves Produced with a Compact μs-Pulsed DBD-Based Reactor

“…A time lag (ΔtGIWs) is established between the zero-crossing point of the positive current impulse and the rising voltage edge. The corresponding ΔtGIWs in the case of negative impulse is negligible under our experimental conditions, which is in agreement with other published works [16,23,42]. Hereafter, the results section will refer to the peak value (IPeak) of the positive current impulse, its corresponding accumulated charge (Qmain, obtained through integration of the current impulse over time), and the time lag ΔtGIWs (see Figure 3b for definition).…”

“…As it was previously mentioned, the tuning of V p does not affect the ∆t GIWs of the negative impulse, which is clearly demonstrated in the right frame of Figure 4. Identical behaviors were remarked in other studies, as well concerning linear-field [16] and single-electrode [42] setups. Jarrige et al [16] observed via ICCD measurements that the secondary discharge appeared in the DBD at the end of the voltage pulse, without any evident formation of a second plasma "bullet".…”

“…Tsat is measured herein under all of the experimental conditions, and it is plotted versus the system operating parameters (see results section). Besides, the length of the GIWs was measured similarly with [42] by using a high-definition DSLR camera (Nikon ® D3100, Nikon, Paris, France) and a calibrated paper ruler (use of metallic ruler was avoided to avoid possible perturbations on the dynamics of GIWs), which are placed perpendicularly (~100 cm away) and parallelly (20 cm away) to the plasma axis, respectively (see indicative snapshot in the lower frame of Figure 2). The emission intensities of various reactive species that were formed outside the reactor were identified/studied in a wide wavelength range (300-800 nm) via a high-resolution spectrometer (JOBIN YVON 1000 M, 1200 grooves/mm grating blazed at 500 nm, Horiba Scientific, Longjumeau, France), equipped with a CCD camera.…”

Chaos in atmospheric-pressure plasma jets

“…In any plasma jet system, the gas flow rate plays a key role in defining the physical characteristics of the discharge; parameters such as gas temperature and particle diffusion are all strongly influenced by the gas flow [39,40]. By introducing the gas flow rate as the second control parameter, it is possible to create a map of dynamical regimes in the plane of the two control parameters.…”

Electrical studies and plasma characterization of an atmospheric pressure plasma jet operated at low frequency

“…Stoffels et al developed a RF plasma jet called the "plasma needle," 10 which was extensively used in biomedical applications. 11 Among several other plasma jets that have been developed, [12][13][14][15][16] those which employ simple and nonexpensive voltage generators are attractive for biological or medical application not requiring a very strict control of the thermal load on the gas carrier. A comprehensive review, which gives a description of different plasma jet configurations and biomedical applications, was recently presented by Park et al 17 In particular, Li et al presented recently an atmospheric pressure jet driven by an a-c transformer operated at 50 Hz.…”