Dielectric barrier discharges (DBDs) are widely used in applications such as ozone generation
and volatile organic compound treatment, where performance can be enhanced through catalyst
integration. A fundamental understanding of reactive species generation is essential for
advancing these technologies. However, temporally resolving reactive species production
especially during the initial discharges remains a challenge, despite its importance for
controlling production rates and energy efficiency. This study examines atomic oxygen
production as a model system for reactive species production in a micro-cavity plasma array, a
custom surface DBD confined to micrometer-sized cavities. Optical emission spectroscopy was
employed to investigate plasma-chemical processes in helium with 0.1%–0.25% molecular
oxygen admixture at atmospheric pressure. The discharge, powered by a 15 kHz, 600 V
amplitude triangular voltage, achieved near-complete oxygen dissociation (up to 100%), as
determined via helium state-enhanced actinometry. A novel multi-photomultiplier system
enabled precise temporal tracking of atomic oxygen density and dissociation dynamics. To
ensure measurement accuracy, a basic 0D chemical model was developed, reinforcing the
reliability of the experimental results.