Spectroscopic investigations of back-corona discharge on fly-ash layer

Results of spectroscopic investigations of back discharge generated in point-plane electrode geometry in ambient air at atmospheric pressure are presented in the paper. The back discharge was generated for the plate electrode covered with fly ash layer. To characterize the discharge process, the emission spectra were measured for the back discharges and compared with those obtained for corona discharge generated in the same electrode configuration but with dielectric layer removed. The measurements have shown that spectral lines emitted by the back discharge depend on the forms of discharge and the discharge current. From comparison of spectral lines of back and normal discharges an effect of the dust layer on discharge morphology can be determined. In normal conditions, the emission spectra are dominated by atmospheric components (molecular nitrogen, atomic oxygen and nitrogen) but for back-discharges, additional lines due to elements and compounds in fly ash were also identified. The studies of back discharge were undertaken because this type of discharge decreases the collection efficiency in electrostatic precipitators.