A streamer behavior evolution during an applied voltage cycle in helium and argon atmospheric pressure plasma jets fed by DBD

Abstract

The study describes the behavior of plasma streamer discharges in helium and argon atmospheric pressure plasma jets fed by dielectric barrier discharge with the specific AC voltage waveform, which has hundred-kHz oscillations deviated from the zero level. The equivalent electrical and gas feeding conditions for producing both helium and argon jets have been provided. The plasma jet in helium is shown to have a diffusive structure and is formed by guided ionization waves, whereas an argon plasma jet is formed by numerous filaments which can have several branches on their ends. Repetitive stepwise plasma bullet formation has been observed in He plasma jet, whereas random and stochastic branching of the streamer has been recorded in Ar plasma jet. Both types of streamers have an approximately equal maximum of their length but significantly differ with the lifetime: they exist for about 1 and almost 8 μs in the argon and helium plasma jets, correspondingly.

Electrodeless atmospheric secondary induced ionization jet (EASII-jet): Dynamics and properties of a transferred helium plasma source

“…The luminous volume of light is characteristic of the IW front resulting from the space charge ahead of it, inducing an intense transient EF of values typically ranging from 10 kV/cm to 20 kV/cm in this type of discharge 12,13,24,30 . The propagation velocity of the guided IW is (2.2 ± 0.2) × 10 7 cm/s in agreement with experimental and theoretical values reported in the literature 11,23,24,31 . The total discharge current is recorded by placing the current monitor sensor around the anode electrode.…”

“…This usual precaution enhances the stabilization of the IW propagation within the He plume expanding out of the primary tube and being subject to the buoyancy force 22 . After ignition of the discharge near the needle electrode, the IW is propagating within the primary tube 23 . At the outlet, the IW exits the tube and is guided by the He flow bounded by the surrounding air and flowing over several cm resembling a plasma plume 23,24 .…”

“…After ignition of the discharge near the needle electrode, the IW is propagating within the primary tube 23 . At the outlet, the IW exits the tube and is guided by the He flow bounded by the surrounding air and flowing over several cm resembling a plasma plume 23,24 . This region of interest is labeled part i in figure 1.…”

Variation in guided streamer propagation along a DBD plasma jet by tailoring the applied voltage waveform

“…23 For a helium APPJ, a stepwise propagation of a guided streamer was observed in our recent works. 24,25 This phenomenon was realized with a power supply that generated an output voltage signal that consisted of a superposition of microsecond bipolar square pulses and oscillating signals. The numerical calculations 26 showed the possibility of a stepwise scenario for streamer propagation with the corresponding modulation of the nanosecond-pulsed applied voltage.…”

“…The value of the gas flow was selected such that the flow was laminar and the length of the plasma jet was maximal. 24,25,28 The jet was sustained in ambient air at an air temperature of 20 C and a relative humidity of 48%.…”