Characteristics Of Excited O Atoms In Multi-needle-to-plate Corona By OES

DC corona discharge in the configuration of needle-plate electrode has been widely used in decomposing contaminants. It has advantages of low energy consumption and high removal efficiency. However, there is no sufficient study on active species in this type corona discharge. There are some researches on OH radicals, but there is little study on O active atoms whose oxidizability is very strong.In this study, optical emission spectroscopy (OES) is used. OES has good selectivity, sensitivity and accuracy. Moreover, it does not interfere with plasma itself. However, the chemical activity of O active atoms is high and the concentration is low. Therefore, it is very difficult to extract weak signal of O active atoms from strong background interference.In this thesis, the O active atoms produced by multi-needle-to-plate DC corona discharge in air were detected using OES at atmospheric pressure. The effects of relative electrical properties in the negative corona discharge (including applied voltage U, discharge current I, discharge power P and space between electrodes d) on O active atoms were investigated experimentally, and some important rules of the characteristics of active O atoms were obtained. The distribution of active O atoms in streamer discharge was drawn according to the detected data, and the distribution characteristics of O active atoms were summarized.In corona discharge, the alternation of background gases affects the production of radicals. The O active atoms produced by multi-needle-to-plate DC corona discharge in N2/O2 system were detected using OES too. Because positive discharge is not very steady, only O active atoms are studied in negative corona discharge.The main conclusions are as follows:1 With the increases of U and I, the number of O active atoms increases in negative glow discharge. With the space between electrodes increasing, the density of O active atoms reduces, and the size of the ionization region becomes smaller.2 In streamer discharge at atmospheric pressure, the emission spectrum of excited O atoms can be detected almost in whole discharge gap and the back of the tips. It firstly increases and then reduces along the axis direction.3 The number of O active atoms firstly increases and then reduces with increase of the flow of N2.