PLASMA CONVERSION OF CO2 IN RF CAPACITIVE DISCHARGE WITH DISTRIBUTED GAS INJECTION AND EXTRACTION

In this paper, the process of plasma conversion of carbon dioxide in a discharge chamber with gas inlet and outlet distributed over the electrode surface is investigated. The experiments were carried out in a radio frequency capacitive discharge (13.56 MHz) in the carbon dioxide pressure range of 0.015…5 Torr. Mass spectrometry and optical emission spectroscopy were used to analyze the process of plasma conversion of CO2. With the proper correction of readings, both methods give close results. It is shown that the conversion coefficient can reach 70% and decreases with increasing gas pressure. The energy efficiency of conversion is 1…2% at low RF discharge voltages, but with a further increase in RF voltage, it decreases. The reason for this is the elevated losses of the power dissipated in the discharge due to the acceleration of positive ions in the near-electrode sheaths, heating the gas and electrodes, as well as power losses for excitation and ionization of the conversion products (CO and O), which worsens the energy efficiency of conversion.