Measurement of electron temperature in a non-equilibrium discharge of atmospheric pressure supported by focused microwave radiation from a 24 GHz gyrotron

TL;DR

This study measures the electron temperature in a non-equilibrium atmospheric pressure plasma generated by focused 24 GHz microwave radiation, using Langmuir probes and emission spectra, revealing high electron temperatures compared to gas temperature.

Contribution

It provides a dual-method approach to accurately determine electron temperature in microwave-supported atmospheric pressure plasma, confirming non-equilibrium conditions.

Findings

Electron temperature is much higher than gas temperature.

Values from Langmuir probe and emission spectra agree within measurement accuracy.

The plasma exhibits significant non-equilibrium characteristics.

Abstract

A microwave discharge of atmospheric pressure, maintained by focused CW radiation of a 24-GHz gyrotron in an argon flow in an external air atmosphere, was investigated. The electron temperature was determined by the current-voltage curve of a dual Langmuir probe placed in a plasma torch. The electron temperature was also estimated from plasma emission spectra within the framework of a coronal plasma model. The obtained values of the electron temperature coincide within the measurement accuracy. Also, the electron temperature is many times higher than the gas temperature. This fact allows us to stand of a significantly non-equilibrium atmospheric pressure plasma.