Effect of Gas Pressure on Decomposition of Indigo Carmine in Water Subjected to Reciprocal Traveling Wave Voltage Pulse

This paper describes experimental results of decomposition of an organic material in water using repetitive surface discharges produced by reciprocal traveling wave voltage pulse. A point electrode with a CR high-pass-filter at one end of a long coaxial cable was faced on a surface of 3 mm thick water layer on the grounded-plate in a low-pressure chamber. When the cable and a coupling condenser in the filter were charged and then directly grounded at the other end of the cable, repetitive discharges propagated from the point electrode along the water surface with a very high frequency. In the test of an optical study, transient discharge light was observed using a gated image intensifier under gas pressures of 0.1 MPa and 0.02 MPa in air. Several discharge channels with branches propagated from the point electrode in 0.1 MPa, whereas glow-like discharges rapidly spread along the water surface in 0.02 MPa with a very high propagation speed. However, reaction speed of indigo carmine molecules in water in 0.1 MPa became higher than that in 0.02 MPa in a decolorization test. We concluded that active species produced by the surface discharge under atmospheric pressure had an important role for the decomposition of the indigo carmine molecules in water