![]() In addition, ICCD images with an exposure time of 10 ms are provided for (d) in-phase and (e) out-of-phase voltage waveforms.įigure 2 shows the experimental setup of the two He plasma jets facing each other, called the anti-parallel alignment. (a) the anti-parallel two-jet alignment resulting in (b) a repulsive interaction with in-phase or (c) an attractive interaction for out-of-phase voltage waveforms at the two jets. However, except for this case, we used in-phase voltage waveforms. We also tested the out-of-phase case by applying two different power sources to the jets, as shown in Figs. The experiment was conducted by connecting one common power source to the two jets to ensure that the voltage phase of the two sources is the same. 2(a), the distance between the two jets was set to 20 mm, and when the two jets are aligned perpendicularly, the distance between the two endpoint centers is 10 mm. When the two jets are aligned horizontally facing one another, as shown in Fig. Two alignments of anti-parallel and perpendicular directions were tested. Experimental setup for the alignment of the two jets and Schlieren image measurement. ![]() The applied sinusoidal voltage of 3 to 4 kV was selected with a driving frequency of 20 kHz. The gas flow rate was varied from 1 to 2.5 standard liter per minute (SLM) at an interval of 0.5 SLM. The gas flow rate and applied voltage are the most critical variables in the experiment. The outer and inner diameters are 8 and 4 mm, respectively, and the distance from the grounded electrode covering the exterior dielectric to the high voltage electrode is 25 mm. We used the same plasma jet used in Tang et al. The diameter and focal length of the parabolic mirrors are 150 mm and 1.54 m, respectively. ![]() The driving frequency is fixed at 20 kHz for both the jets with the same phase. 4.įigure 1 shows the experimental setup used when measuring the Schlieren images of the interaction of two plasma jets it consists of two plasma jets, a power supply, two parabolic mirrors, a knife-edge, and a mass flow controller (MFC). Finally, conclusions are presented in Sec. 2, followed by the results for the variation of alignment, gas flow rate, and the applied voltage in Sec. The experimental setup and conditions are explained in Sec. Optical diagnostics were obtained with the Schlieren image method and an intensified charge-coupled device (ICCD). This study investigated the interaction of two APP jets using helium gas with different voltage driving methods. As the plasma jet emits bullet-like charges like a bullet in addition to gas flow mixed with radicals and excited states, the interaction of two plasma bullets propagating in opposite directions or to rectangular angles is a scientifically relevant phenomenon. However, the interactions of multiple plasma jets for different interaction angles have not been studied in detail so far. In contrast, the plasma jet arrays produce an intense and enhanced plasma jet, especially when the target surface is a conductor or biased. A lower applied voltage and a higher gas flow rate are more effective for a uniform onedimensional jet array. Deflection angles are larger in He jets than in Ar jets because He is lighter than Ar and the Ar jet array is more controllable and stable than the He jet array. Furthermore, the laminar flow length is reduced, and surface treatment remains insufficient. However, in this case, a strong repulsive force with each plasma plume is reported, resulting in diverse propagation trajectories. For this reason, there have been studies on using arrays or bundles of small plasma jets in parallel. However, the treatment area of a single plasma jet is limited to less than one square centimeter, which limits applications in the uniform treatment of large-area surfaces. In addition, the gas flow rate can be varied to change discharge characteristics. The breakdown voltage of plasma jets is much lower than that of air discharge, and their plasma bullets are faster than sound for delivering charges and chemical species to distant target surfaces. Īmong many electrode configurations of APPs, plasma jets are a popular tool for generating plasma plumes from tubes with Ar or He gas flow. The chemical interactions in APPs are being actively studied for the surface treatment of polymers. Thus, APPs are often used for surface treatment, processing of polymers, and biomedical applications. In addition, because APPs are not in equilibrium, they retain ambient gas temperature. Unlike low-pressure plasma reactors, atmospheric pressure plasmas (APPs) can generate reactive chemical species without a vacuum vessel and pumping equipment.
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