Dielectric Barrier Discharge Type Research Articles

Experimental study on repetitive unipolar nanosecond-pulse dielectric barrier discharge in air at atmospheric pressure

Dielectric barrier discharge (DBD) is a typical approach for producing non-thermal plasma at atmospheric pressure. In this experimental study, the DBD is excited by repetitive unipolar nanosecond pulses with a rise time of ∼15 ns and a full-width at half-maximum of ∼30 ns. With a unipolar pulse voltage of 35 kV, the measured discharge current across the DBD circuit has a positive and negative pulse, and the pulse peak value can be hundreds of amperes. The low-speed camera images of the discharge show that both diffuse ‘glow-like’ and filamentary discharges can be observed, and the air gap length, barrier variety and applied repetition rate are the important factors influencing the transition of the two discharge modes. According to a known equivalent circuit and measured data of a typical DBD, electrical parameters including voltage, current and instantaneous power across the air gap and dielectric layer are calculated. The calculated results indicate that there are two consecutive discharges in the air gap, and the secondary discharge fires immediately after the primary discharge extinguishes. The power consumption of the secondary discharge is provided by the dielectric layer and deposited during the primary discharge. With the increase in the repetition rate, the energy deposition in the air gap per second is greatly enhanced and can exceed one joule for a repetition rate up to 100 Hz, and the corresponding charge transfer is also increased. The electron temperature and density are estimated to be approximately 5.1 eV and 1.6 × 1012 cm−3, respectively.

Spatial and temporal evolution of a dielectric barrier discharge

Experimental study of spatial and temporal evolution of a dielectric barrier discharge (DBD) during a single current pulse is reported. The discharge light emission has been imaged using a high-speed intensified charge-coupled device camera. The time-resolved light emission data have been combined with the discharge current and applied voltage waveforms measurements. The discharge behavior has been found to be dependent on the external circuit impedance and bandwidth. Being nonstationary in principle, the DBD can exhibit both time evolution and development over the electrode area. For a typical DBD setup with flat parallel electrodes, the discharge breakdown occurs in the electrode’s central part; then, the plasma column expands to the electrode’s peripheries and gradually fills up the entire electrode area. The powering system should be able to provide enough current value during the discharge glow to achieve a simultaneous breakdown over the whole electrode area. In this case, the discharge appears over the entire electrode’s area and the plasma column exhibits temporal evolution only. The measured discharge characteristics for different power supply architectures had shown the evidence of a “normal current density” effect in DBD glow.

플라즈마를 결합한 바이오 트리클링 시스템에 의한 휘발성 유기물질의 제거

In this study, a newly developed biotrickling system, combined with a non-thermal plasma reactor, was investigated to effectively treat gaseous contaminants such as VOCs (Volatile Organic Compounds). Three kinds of non-thermal plasmas (NTPs) such as a rod type dielectric barrier discharge (DBD) plasma, a packed bead type DBD plasma and a gliding arc (GA) plasma, were tested and compared in terms of power consumption. The rod type DBD plasma was selected as one for integration with biotrickling system due to its relatively high VOC removal efficiency, low power consumption and low pressure drop. Toluene and xylene as representatives of VOCs were used as test gases. The experiment results showed that the efficiency of biotrickling system was especially very low at the high gas concentration and high flow rate and the removal efficiencies of VOCs were considerably enhanced in the biotrickling system, when the DBD plasma was worked in front of that even at the high gas concentration and high flow rate.

Influence of Penning Ionization on Glowlike Dielectric Barrier Discharge Formation in Medium-Pressure Ar

We experimentally investigated the influence of Penning ionization on glowlike discharge formation in Ar/C2H4 mixtures. The discharge was generated in a typical dielectric barrier discharge reactor with parallel-plate electrodes driven by sinusoidal voltage with a frequency of 100 kHz. The addition of a small amount of C2H4 caused the decrease of breakdown voltage. Excess C2H4 again increased the breakdown voltage since electron energy was reduced by the inelastic collision of C2H4. In the present case, the optimum amount of C2H4 addition was 0.07%. With increasing gas pressure, filamentary discharge appeared simultaneously in glowlike homogeneous discharge. The upper pressure limit to obtain the glowlike homogeneous discharge was improved from 220 Torr in Ar to 310 Torr in Ar/C2H4 (0.07%) because of the Penning effect. The temporal variation of Ar(1s5) density was observed by laser absorption spectroscopy. The density of Ar(1s5) coincided with the current waveform. C2H4 addition decreased the Ar(1s5) density because Ar(1s5) was consumed by Penning ionization. The reaction rate coefficient between Ar(1s5) and C2H4 was roughly estimated to be 10-9–10-10 cm3 s-1.

Impedance matching for an asymmetric dielectric barrier discharge plasma actuator

A typical dielectric barrier discharge plasma actuator requires a power supply capable of delivering power at a frequency range of several kilohertz and a rms voltage up to 20kV. An impedance mismatch resulting from the absence of a matching network causes a large reflected power from the plasma actuator back to the power supply. This does not contribute to plasma formation and requires an expensive over-rated power supply. The authors suggest an impedance matching network for a realistic asymmetric dielectric barrier discharge plasma actuator with a virtual electrode.

Study of photo-resistance and polyimide strip by atmospheric plasma technology

In this study, parallel-tube (PT) and plasma jet (PJ) dielectric barrier discharge (DBD) electrodes and alternating voltage (AC) generators with sinusoidal and pulsed types AC generators at voltage of 10 kV and frequency of 20 kHz, respectively, were selected for the investigation of the influences of these hardware combinations on the removal differences of photo-resistances (PRs) and polyimide (PI). Plasma ignition occurred with the flowing of clean dry air (CDA) for these self-designed PT– and PJ–DBD systems. The atmospheric plasma system consisting of PJ–DBD and pulsed type AC generator exhibited reasonable PR removal ability with no discharging phenomena and with more polar functional groups, and is recommended for these polymers removal.

Atmospheric-pressure diffuse coplanar surface discharge for surface treatments

We report results from a plasma source; a diffuse coplanar surface discharge (DCSD), which is capable of generating macroscopically uniform thin layers of diffuse plasmas in air and other reactive gases at atmospheric pressure. DCSD is a type of dielectric barrier discharge generated on the surface of a dielectric barrier with embedded electrodes, which appears to be advantageous to surface treatment and deposition processes. Preliminary results on hydrophilization of polypropylene nonwoven fabric are also presented.

Comparison of a regenerative thermal oxidizer to a rotary concentrator

The positive effect of plasma mediated treatment of powder fraction in water-based dispersion is a rather well documented fact. Despite its importance for ceramic processing, the applicability of plasma treatment of ceramic particles in a non-aqueous dispersions remains unexplored. In the presented article, a specific planar type of dielectric barrier discharge - Diffuse Coplanar Surface Barrier Discharge (DCSBD), operated in atmospheric pressure air was used for the surface activation of sub-micron alumina particles. These were consequently dispersed in organic solvent of 2-propanol and evaluated for the performance during the process of electrophoretic deposition (EPD). The surface of ceramic particles and the dispersion behaviour were investigated using thermogravimetric analysis, XPS, measurement of zeta potential and particle size distribution. Plasma treatment of ceramic particles had a substantial effect on the deposition rate, which caused a significant reduction of surface roughness and slight improvement of the density and mean grain size of the fabricated coatings. Moreover, the plasma treatment resulted in a simultaneous anodic and cathodic EPD.