Experimental investigations of emission spectrum of a discharge with two liquid non-metallic (tap-water) electrodes in air at atmospheric pressure

Experimental investigations of the emission spectrum in the wavelength range 240 nm ⩽ λ ⩽ 850 nm of a discharge burning in open air between two flows of tap water (a discharge with two liquid electrodes) with direct current supply are carried out. The axial and radial distributions of spectral characteristics at different currentsiand discharge lengthsL(i= 40–80 mA;L= 4–8 mm) are investigated. From spectral distributions of plasma emissivity, the obtained results show that the discharge radiates mainly in the ultraviolet region of the spectrum. The main contribution to the radiation power is made by N2, OH and NO molecules. The near-electrode regions radiate most intensively. A comparison of the previously published results of the investigations of such a discharge with the present results allows us to give qualitative explanations of the regularities in the axial distributions of spectral characteristics and their dependences on current and discharge length. An estimation of the dose of irradiation of the electrode liquid (tap water) by discharge radiation, having bactericidal effect (λ ⩽ 310 nm) is made. The estimation shows that when water flows through the electrode attachment, the dose received by it is, by an order of magnitude, comparable to the dose which is necessary for sterilization.