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Plasma washer atmospheric pressure pulsed DC discharge plasma

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Published on:

04 Nov,2020

Plasma washer atmospheric pressure pulsed DC discharge plasma:

 

Atmospheric pressure plasma refers to the discharge plasma generated near atmospheric pressure. It does not need to use expensive and cumbersome vacuum system, and its process design is more flexible, showing a broad application prospect in energy gas conversion, material preparation and surface modification, environmental protection and other aspects. In addition, plasma washer atmospheric pressure plasma can discharge directly in the surrounding atmosphere, making it possible to realize plasma medicine.

 

The common ways of producing atmospheric pressure plasma include DC discharge, dielectric barrier discharge, radio frequency discharge, microwave discharge and pulse discharge. Various forms of atmospheric pressure plasma can be realized through different electrode designs and mode selection. The following is the introduction of plasma cleaner atmospheric pressure pulsed DC discharge plasma.

 

The pulse voltage parameter of atmospheric pressure pulsed DC discharge plasma has an important influence on the discharge effect. These parameters include the rising edge, falling edge and pulse repetition frequency of the pulse voltage. Compared with traditional AC drive, pulsed DC drive has the advantages of higher electron density, higher average electron energy of plasma and higher energy efficiency.

 

Atmospheric pressure pulsed DC power supply USES energy storage capacitor, and generates pulse high voltage by rotating spark clearance RSG to discharge load, which has the characteristics of steep rising edge and narrow pulse width, so that energy can be effectively injected into the reactor, and the power supply itself consumes less energy.

 

The voltage is output by the auto-voltage regulator, which is boosted by the high-voltage transformer and rectified by the full-wave rectifier. Then the energy storage capacitor C1 is charged. When the spark gap RSG1 is switched on, C1 is charged to the pulse capacitor C2 through the current limiting resistor R. At the moment of RSG2 conduction in the rotating spark gap, the energy on C2 is released to the reactor through RSG2, thus obtaining a high voltage pulse in the reactor. Because RSG1 and RSG2 spark-gap are placed on the same rotation axis, they cannot conduct at the same time. This ensures that C1 charging C2 and C2 discharging to the reactor are two independent processes.

 

By adjusting the output of the auto-voltage regulator, the voltage value on C2 can be changed, thus changing the peak pulse voltage. The pulse width is mainly determined by the volume of C2. The pulse repetition frequency is determined by the rotational speed of the RSG shaft, which can be adjusted by the speed-regulating DC motor. The motor speed regulating part and the pulse high voltage part are electrically isolated by 1:1 isolating transformer. The conversion of positive and negative pulse voltages can be obtained by interchanging the two wires charging C. The low-voltage control part of the power supply (220V) includes voltage regulation and motor speed regulation. The high voltage part and pulse forming part of the plasma cleaner pulse power supply should be placed in the shielding net to prevent electromagnetic radiation from interfering instruments and equipment and harmful to human body. If the mode of cusp discharge is adopted, according to the mode of discharge, the atmospheric pressure pulsed DC discharge can occur between corona discharge and spark discharge.

 

When the voltage of the charged body at the tip reaches a certain value, local ionization and excitation of the surrounding gas media occur to form a discharge channel. The discharge process is accompanied by a weak glow and sound, and corona discharge occurs when no breakdown or conduction of the electrode occurs. When a breakdown or conduction occurs between the plasma washer electrodes, a spark discharge occurs, accompanied by a strong light and sound. Wang Kangjun studied the effect of pulsed spark discharge and pulsed corona discharge on methane conversion under atmospheric pressure. The results show that the conversion rate of methane and the selectivity of C2 hydrocarbon (mainly including ethane, ethylene and acetylene) in spark discharge are superior to that in corona discharge, and the main C2 hydrocarbon product in spark discharge is acetylene, while the main C2 hydrocarbon product in corona discharge is ethane.

Plasma washer atmospheric pressure pulsed DC discharge plasma

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