Discharge Process Of Atmospheric Pulsed Discharge And Radio Frequency Glow Discharge

Recently,much attention has been paid on the fundamental and application studies of atmospheric glow discharges due to their potential employments in surface modification,this film deposition and bio-sterilization and environmental treatment.Currently,investigation on atmospheric glow discharge is focused on the atmospheric dielectric barrier discharge,atmospheric pulsed glow discharge and atmospheric radio frequency glow discharge by means of numerical simulation and experimental studies.In experimental studies,the plasma images are normally taken between two electrodes to obtain the spatio-temporal evolution of discharge,which is used for the discussion of discharge dynamics,besides the experimental diagnostics of discharge current and voltage waveforms and optical emission spectrograph to obtain the discharge characteristics and plasma species generated in the discharge.As required on the uniformity in the application of plasmas,the appearance of discharge on the electrode is suggested to studied,which is also important for the discussion of discharge stability.Here,the time resolved plasma images on electrodes are measured and studied in atmospheric pulsed glow discharge,atmospheric pulsed modulated radio frequency glow discharge and atmospheric pulsed glow discharge assisted radio frequency glow discharge.The discharge process,especially the assistance of pulsed discharge on radio frequency glow discharge,is investigated with additional diagnostics of discharge current and voltage waveforms,discharge spatio-temporal evolution between two electrodes.In atmospheric pulsed glow discharge,the first discharge occurs at the rising phase of voltage pulse,which produces the discharge ring on the transparent glass electrode.The discharge ring shrinks to the bare metal electrode as the second discharge occurs at the falling phase of voltage pulse.In atmospheric radio frequency glow discharge,the discharge ignition happens at the middle region between two electrodes with the bell shape of spatial profile,which evolves into the double-hump spatial profile with stable operation of discharge,in which,the discharge at the edge of electrode is enhanced.By introducing pulsed discharge into radio frequency glow discharge,the first discharge of pulsed discharge is enhanced,as shown the discharge ring on the glass electrode is stronger than that in pulsed discharge.During the coexistence of pulsed discharge and radio frequency glow discharge,the discharge on the electrode surface shows that the discharge ring produced by pulsed discharge expands and shrinks and the intensity of discharge disc produced by radio frequency glow discharge improves and reduces alternatively with time.In addition,the interaction between the pulsed discharge and radio frequency glow discharge is studied.With the assistance of pulsed discharge,the radio frequency glow discharge achieves the stable operation much quickly,which is demonstrated by the double-hump spatial profile is formed as the ignition radio frequency glow discharge.Furtherly,the assistance of pulsed discharge on radio frequency glow discharge is investigated with the time interval between the pulse discharge and radio frequency glow discharge are set to be 12?s?5?s ? 0?s.It shows that the discharge image intensity of radio frequency glow discharge achieves the stable magnitude more quickly with lower time interval,which suggests that the assistance of pulsed discharge on radio frequency glow discharge can be enhanced by reducing their time interval.It is due to the more residual plasmas species,especially the electrons,generated by the pulsed discharge in the discharge gap as the radio frequency glow discharge is ignited.By investigating the processes of discharge on electrode and between two electrodes in the atmospheric pulsed discharge and radio frequency glow discharge,more information of discharge characteristics and discharge mechanism of atmospheric glow discharges is obtained,which provides the experimental evidence for achieving uniform and stable atmospheric glow discharge plasma source and the technical support on the application of atmospheric glow discharge plasmas.