Investigation Of Micro-discharge Channel In Dielectric Barrier Discharge With Different Configurations

Plasma parameters such as electron density, electron excited temperature and molecular vibration temperature in two different dielectric barrier discharge (DBD) systems in argon or argon/air have been investigated by using optical emission spectrum and optical methods.A stable micro-discharge channel (filament) in air discharge is obtained by cleaning discharge method in a dielectric barrier discharge system with two water electrodes. The distributions of intensity of luminescence and the vibrational temperature of a single micro-discharge filament are measured from instantaneous anode to instantaneous cathode. It is found that the emission intensity of discharge filament presents a distribution like a goblet with base locating at instantaneous cathode in each half period of the applied voltage. The intensity of the spectrum distributing is symmetrical. The vibrational temperature reaches the maximum at the middle of gap of the two parallel electrodes and presents the minimum at the instantaneous anode.A needle-plate dielectric barrier discharge device with a transparent plate electrode is designed for studying on characteristics of different types of discharge modes in atmospheric discharge in argon/air mixture. Three types of discharge modes, which are corona discharge, monofilament discharge, and spark discharge are realized by changing the applied voltage. The discharge currents in positive half-cycle of the applied voltage are different from that in negative half-cycle. The optical emission spectra are collected in three types of discharges and the molecular vibrational temperatures are calculated. It is shown that the vibrational temperature in corona discharge is the highest and that in monofilament discharge is larger than that in spark discharge. The distributions of electron density, electron excited temperature and molecular vibration temperature of a single micro-discharge filament in needle-plate dielectric barrier discharge are measured from glass plate to metal needle. It is found that the electron excited temperature and molecular vibration temperature is the lowest near the plate, while the highest at the end of metal needle. The electron density decreases gradually from glass plate to metal needle electrode.