  In this experimental study, a flowing dielectric barrier discharge operating
at atmospheric pressure is used for the splitting of CO2 into O2 and CO. The
influence of the applied frequency and plasma power on the microdischarge
properties is investigated to understand their role on the CO2 conversion.
Electrical measurements are carried out to explain the conversion trends and to
characterize the microdischarges through their number, their lifetime, their
intensity and the induced electrical charge. Their influence on the gas and
electrode temperatures is also evidenced through optical emission spectroscopy
and infrared imaging. It is shown that, in our configuration, the conversion
depends mostly on the charge delivered in the plasma and not on the effective
plasma voltage when the applied power is modified. Similarly, at constant total
current, a better conversion is observed at low frequencies, where a less
filamentary discharge regime with a higher effective plasma voltage than that
at a higher frequency is obtained.
