3D mapping of the concentration of OH radicals generated by surface barrier discharge emerging from liquid water using laser-induced fluorescence

The concentration of OH radicals has been mapped in three-dimensions by scanning planar laser-induced fluorescence (LIF) in the vicinity of surface barrier discharge emerging from liquid water and propagating along a fused silica dielectric tube in argon. The concentration peaked in the region of active discharges near the water level at the value of 1.5 × 1021 m−3 and decreased with the distance on a characteristic length of ~0.4 mm, which suggests that the OH transport is dominated by diffusion. The OH production increases with power input (P) until it saturates for P > 0.75 W. It has been observed that the repetitive discharge appearance at preferred locations can be changed to stochastic (i.e. macroscopically homogeneous) by increasing the thickness of deionized water covering the earthed electrode.