Electron dynamics of three distinct discharge modes of a cross-field atmospheric pressure plasma jet

TL;DR

This study uses simulations and experiments to analyze electron dynamics across three discharge modes in a cross-field atmospheric pressure plasma jet, revealing mode transitions with increasing power.

Contribution

It systematically characterizes the three distinct discharge modes of the COST-Jet and their transitions under varying operational conditions using combined simulation and experimental methods.

Findings

Low power operation results in a non-neutral, near-extinction mode.

Increased power leads to a quasi-neutral, bullet-like mode.

High power induces a constricted, dense plasma mode.

Abstract

This paper investigates the electron dynamics in three distinct discharge modes of a cross-field atmospheric pressure plasma jet, the COST-Jet. Thereby, the discharge modes are the non-neutral, the quasi-neutral, and the constricted mode. Using a hybrid Particle-In-Cell/Monte-Carlo Collisions (PIC/MCC) simulation, the study systematically varies the applied voltage and driving frequency to explore the operation modes and their relations. The results reveal that at low input power, the COST-Jet operates in a non-neutral mode, characterized by a discharge close to extinction, analogous to the chaotic mode observed in other plasma devices. As power increases, the jet transitions to a quasi-neutral mode, which aligns with the well-known {\Omega}- and Penning modes, comparable to the bullet mode in parallel-field jets. At the highest power levels, the COST-Jet enters a constricted mode, where the plasma significantly densifies and constricts towards the electrodes along the entire discharge channel. Experimental validation using phase-resolved optical emission spectroscopy (PROES) supports the simulation findings, particularly identifying the constricted mode as a distinct operational regime. These insights into the mode transitions of the COST-Jet under varying operational conditions help optimize plasma applications in various fields.