Abstract
The effects of sound-wave irradiation were investigated on the decomposition of carbon dioxide in a discharge plasma. Discharge plasma supplies high local energy levels, as charged medium particles, so chemical reactions ungoverned by thermodynamics can occur. However, the discharge space is extremely confined, which restricts the conversion rate. This study investigated the combination of plasma and sound-wave irradiation, which increases the vibration motion of the medium. A streamer was observed to expand into a fan shape on irradiation of sound waves. The expansion of the discharge space was positively correlated with the magnitude of the sound. Accordingly, the effects of sound-wave irradiation on the direct decomposition of carbon dioxide were evaluated. The decomposition rate of carbon dioxide (rCO2) increased with sound pressure at the closed end of the sound tube, and rCO2 at 1.8 kPa approximately increased to approximately twice that for no sound-wave irradiation. This increase in rCO2 resulted from the improvement in the reaction probability due to expansion of the discharge space and increased vibration of the charged particles.
