Equivalent Capacitance Between Electrodes Of Dielectric Barrier Columnar Discharge In Atmospheric Pressure Helium

Dielectric barrier discharge(DBD)has various promising applications in industry in virtue of a large volume of non-equilibrium cold plasmas with moderate energy and density of active particles.However,theoretical understanding is still limited.In this thesis,using electrical parameters measurements,and the fast photography,discharge characteristics and evolution of dielectric barrier columnar discharge in atmospheric pressure helium were studied.Variation law of equivalent capacitance under different discharge behaviors,and the simplified electrical equivalent circuit of the gas gap and the dielectrics were also investigated.Waveforms of the applied voltage and loop current were measured and short exposure time discharge photos were taken with ICCD to investigate the characteristics of columnar discharges in 3 mm gap,one atmospheric pressure helium with a background air pressure of 40 Pa,frequency 11.41 k Hz.The results showed that glow discharges occurred when the applied voltage was high enough,a single-pulse columnar discharge by the same discharge physics as glow discharge could be achieved when the applied voltage was adjusted to a lower voltage,the pulse current amplitude increased gradually and showed a negative characteristic relation with applied voltage;Lissajous figures of each discharge state were polygons with multiple lines crossing each other;There was a sudden change of discharge power in a single discharge column,and then it increased linearly with the decrease of maintaining voltage.Based on the Lissajous figures,the equivalent capacitances between electrodes and the transferred charge were calculated under non-discharge,diffuse glow discharge,columnar pattern discharge,and discharge quenching in 3 mm gap,one atmospheric pressure helium with a background air pressure of 40 Pa,frequency 11.41 k Hz.The results showed that the equivalent capacitance(C)calculated by the Lissajous figure was constant(9.6p F)below the incipient discharge voltage,and does not change with the increase of applied voltage;In the discharge process,the equivalent capacitance was linearly correlated with the transferred charge,illustrating that the transferred charge during discharges caused the change of the equivalent capacitance between electrodes.From this understanding,an amendment was proposed for previously simplified electrical equivalent circuit.