Effect of pulse polarity on the temporal and spatial emission of an atmospheric pressure helium plasma jet

Abstract

A single needle-electrode plasma jet driven by a home-made microsecond pulse power supply is studied. The electrical characteristics and optical emissions of the plasma jets driven by positive-and negative-polarity pulses are compared. With the same magnitude of applied voltage, the plasma jet driven by positive pulses shows a higher discharge current, a higher optical emission intensity and travels to a longer distance. The temporal-spatially resolved He (706.5 nm), N 2 (337.1 nm) and + N 2 (391.4 nm) emissions behave differently in the plasma jets driven by different polarity pulses: They appear to be discrete emission packets in the positive plasma jet, but continuous emission in the negative plasma jet (under the time resolution in this study). The emission front propagates at a faster speed in the positive plasma jet than in the negative plasma jet. The different behavior of the plasma jets is attributed to the electric field distribution under different polarity pulses.

Investigation of mode interconversion for interfacial pattern formation through plasma–surface interaction

“…Notably, particularly the band of OH (A) is also expressed as the second diffraction band around 618 nm. These radical species are mainly generated by high‐energy electron excitation and the penning ionization process . The distinct structures of the spectra of He(2 1 P–4 1 F) and He (2 1 P–4 1 D) are shown in Figure b, which would be of use to analyze the electric field distribution from tube end to ITO surface for the two types of mode patterns in the study below.…”

“…For He APPJ admixed with N 2 , more N 2 + (B) is generated through N 2 ‐electron reactions and the penning ionization reaction between metastable He(2s 1 S 0 ) (energy levels of 20.62 eV) and He(2s 3 S 1 ) (energy levels of 19.82 eV) . A small addition of N 2 can promote penning ionization, which reduces the initial discharge voltage, while a large number of N 2 molecules as the doping ratio increases can weaken penning ionization and enhance the breakdown voltage due to the high‐vibration dynamic diatomic structure of the N 2 molecule . However, superfluous N 2 also depletes the N 2 + (B) quantity that causes less N 2 + (B) formation.…”

Atmospheric‐pressure pulsed discharges and plasmas: mechanism, characteristics and applications

“…Experimental research showed that the APPJs are typically composed of discrete plasma bullets, which propagates with velocities on the order of 10 4 –10 6 m/s [52, 53]. Wang et al [54] investigated the spatial and temporal distribution of N 2 , N 2 + , O and He emission in a pulse‐driven helium plasma jet. The N 2 and N 2 + emission plume travelled at a faster speed and located in the plume front while He and O emission travelled at a slower speed and only located in the nozzle exit.…”

Aqueous Gold Nanoparticles Generated by AC and Pulse-Power-Driven Plasma Jet

“…A plasma jet, generated in open air rather than in confined chambers, can be used for direct treatment without the limitation of the object’s size [19]. However, the treatment area of single plasma is small (less than 1 cm 2 ) due to its inherent structure [20]. One convenient method is to form a jet array by grouping a number of individual plasma jets units together.…”