Excitation of helical shape argon atmospheric pressure plasma jet using RF pulse modulation

TL;DR

This paper demonstrates the generation of a helical argon plasma jet at atmospheric pressure using RF pulse modulation, revealing unique structural and chemical properties relevant for plasma applications.

Contribution

It introduces a novel helical plasma jet structure driven by pulse modulated RF power and explores its formation mechanisms and chemical implications.

Findings

Helical structure observed in open air, differing from conventional shapes.

Pulse modulation influences the formation and characteristics of the helical jet.

Enhanced reactive oxygen and nitrogen species due to the helical structure.

Abstract

The article reports the excitation of a helical argon atmospheric pressure plasma jet using a pulse modulated 13.56 MHz radiofrequency (RF) power source. This helical structure is observed in open ambient air which is far different from the conventional conical shape. This helical structure originates due to the periodic pressure variation in the discharge region caused by pulse modulated RF (2 kHz modulation frequency (fp)) and propagates downstream into the ambient air. The geometrical characteristics of the observed structure are explored using optical imaging. Moreover, the influence of various input parameters viz., duty cycle (D), gas flow rate (Q), and RF power (P) of the modulated pulse on the formation of helical structure are studied. These helical structures have an implication on the plasma jet chemical features (enhancement of reactive oxygen and nitrogen species (RONS)) as these are involved in increase in air entrainment into the ionization region desired for various plasma applications.