Helical Shaped Plasma Jet: Introducing An Exclusive Behavior Of Atmospheric Pressure Plasma

A novel helical shape argon plasma jet is excited using a pulse modulated 13.56 MHz radiofrequency (RF) power source in atmospheric pressure. Very different from the conventional smooth conical shape, the first ever, helical structure is observed in open ambient air. This unique structure originated due to the pressure pulsation in the discharge region caused by pulse modulation of the RF at a 2 kHz modulation frequency. The geometrical features of the observed structure are explored using optical imaging. The experiments are performed with the aim of determining the optimal conditions (RF power, duty cycle, flow rate, etc.) for production of the helical structures as well as their geometrical characteristics. Moreover, there is a possibility that the helical structure modifies the plasma chemistry and promotes the enhancement of chemical reactive species by efficient mixing of the air into the ionized plasma, which is a critical requirement in various applications. 1,2 The study of the phenomenon reported here can also help to understand similar observations of helical dynamics in diverse fields such as lasers, communications, solar atmosphere, turbulent flows, biophysics, and other areas 3 . The details of the inception and evolution of the helical plasma structure and the influence of the input parameters will be presented.