Half Cycle Of Voltage Research Articles

An atmospheric pressure quasiuniform planar plasma jet generated by using a dielectric barrier configuration

A stable nonthermal quasiuniform planar plasma jet, originating from a planar dielectric duct with a rectangular exit and issuing into ambient air at atmospheric pressure, is reported in the present work. Current-voltage characteristics, one discharge current pulse per sinusoidal half voltage cycle, show that the discharge is not filamentary. Its spatial uniformity in the transverse direction is shown to be excellent by monitoring optical emission spectra in the jet core region except jet boundaries. This is possibly resulted from high preionization in the upstream region, and it is a challenge to the traditional single streamer explanation for nonthermal plasma jets.

Experimental and modelling investigations of a dielectric barrier discharge in low-pressure argon

The discharge behaviour of a dielectric barrier discharge (DBD) in low-pressure argon gas was investigated by experiments and modelling. The electrical characteristics and light emission dynamics of the discharge were measured and compared with the results of a two-dimensional fluid model. Our investigations showed that the discharge consisted of a single, diffuse discharge per voltage half-cycle. The breakdown phase of the low-pressure DBD (LPDBD) was investigated to be similar to the ignition phase of a low-pressure glow discharge without dielectrics, described by Townsend breakdown theory. The stable discharge phase of the LPDBD also showed a plasma structure with features similar to those of a classical glow discharge. The presence of the dielectric in the discharge gap led to the discharge quenching and thus the decay of the plasma. Additionally, the argon metastable density was monitored by measuring light emission from nitrogen impurities. A metastable density of about 5 × 1017 m−3 was present during the entire voltage cycle, with only a small (∼10%) increase during the discharge. Finally, a reduction of the applied voltage to the minimum required to sustain the discharge led to a further reduction of the role of the dielectric. The discharge was no longer quenched by the dielectrics only but also by a reduction of the applied voltage.

Spontaneous pattern formation in an effectively one-dimensional dielectric-barrier discharge system

In a dielectric-barrier discharge between diametrically opposite sides of a narrow tube, discharge filaments stabilize at regular intervals along the tube's length. Three types of periodic patterns are observed, as is a disordered state in which filaments fire at apparently random positions and times. Time-resolved current measurements indicate that for each spatial pattern, a particular number of discharge stages occur during the voltage half-cycle. A preliminary model of the pattern-formation dynamics is described, motivating further work on time-resolved imaging and investigations of surface charge distributions.

Calculation of High-Frequency Breakdown Voltages of Point-to-Plane Air Gaps

The performance of point-to-plane air gaps under a high- frequency voltage is studied theoretically. The electric field distribution along the gap axis is represented as a function of gap dimensions and applied voltage. This derived function yields accurate field values throughout the ionization zone which correspond to the peak value of the applied voltage. The condition for positive-ion space charge accumulation in the ionization zone is considered to be criterion for breakdown. An equation describing the temporal motion of positive ions under the alternating voltage wave is derived. For any given wave frequency and gap dimensions, the peak value of the breakdown voltage is obtained by equating the distance traveled by the positive ions during the positive half voltage cycle to the corresponding length of the ionization zone. An expression for the peak value of breakdown voltage corresponding to a particular frequency is analytically obtained as a function of the point-to- plane air gap dimensions. Comparison of calculated results with corresponding measurements reported in the literature indicated a reasonable agreement.