Transient phenomena during dust formation in a N2–CH4 capacitively coupled plasma
Résumé
A capacitively coupled radio-frequency discharge in a nitrogen–methane (N2–CH4) gas mixture is used to simulate the formation of solid aerosols in Titan's atmosphere. The present work is focused on the time evolution of the plasma parameters, such as self-bias potential, Vdc, and electron density. The time evolution of the electron temperature is evaluated from the correlation of the optical emission spectroscopy and the electron density. In situ mass spectrometry is used to monitor the neutral composition of the gas phase. After a few seconds, a drastic change is observed for all of the parameters, which is related to the formation of solid particles in the discharge. The electron density decreases simultaneously with an increase of the electron temperature, which induces an increase of the methane consumption.