Effect of process parameters on the EHD airflow

In this paper, the effects of the applied voltage modes on the positive corona discharge morphology and NO removal characteristics from air streams are experimentally investigated. By using a DC superimposed high frequency AC power supply (10-60 kHz), a uniform streamer corona can be generated, which is also less sensitive to electrode mis-arrangements. Hermstein glow can he transferred to streamer corona if the peak-to-peak voltage is larger than 1.0 kV at the voltage change rate of 0.2 kV//spl mu/s. A significant amount of NO removal is observed under streamer corona. For the Hermstein glow, the removal is negligible. Moreover, the basic principle for designing AC/DC energized streamer corona is also presented in this paper.

/pdf/no-removal-characteristics-of-a-corona-radical-shower-system-exp05dpko8.pdf

NO removal characteristics of a corona radical shower system under DC and AC/DC superimposed operations

Laser based lightning control holds a promising way to solve the problem of the long standing disaster of lightning strikes. But it is a challenging project due to insufficient understanding of the interaction between laser plasma channel and high voltage electric filed. In this work, a direct observation of laser guided corona discharge is reported. The high voltage corona discharge can be guided along laser plasma filament, and enhanced through the interaction with laser filaments. The fluorescence lifetime of laser filament guided corona discharge was measured to be several microseconds, which is 3 orders of magnitude longer than the fluorescence lifetime of laser filaments. This could be advantageous towards laser assisted leader development in the atmosphere.

/pdf/direct-observation-of-laser-guided-corona-discharges-4d25j2du5i.pdf

Direct observation of laser guided corona discharges

Functional surfaces have great significance for improving the performance of bio-devices. The selection of appropriate ways to functionalise the surfaces of the polymers used for bio-devices are in great demand. In particular, cyclic olefin copolymer (COC) and cyclic olefin polymers (COP) are emerging substrates for bio-devices and possess superior chemical resistance than other polymeric substrates such as polycarbonate (PC). These polymer substrates often require surface modification to provide the functionality required. Here, we present a means to functionalise the surfaces of these polymers by a corona discharge treatment method. The water contact angle (WCA) of as received PC, COC and COP was found to be around 80°, 96° and 93°, respectively. The WCA of PC, COC and COP is reduced by 40%, 46% and 44%, respectively when treated with corona dose of 95 W min/m2. The WCA of PC, COC and COP was further reduced by increasing the corona dosage. The reduction of WCA is found mainly due to the incorporation of oxygen-related functionalities (such as carboxylic, carbonyl or aldehyde groups) as confirmed by high-resolution X-ray photoelectron spectroscopy (XPS) and Time-of-flight secondary mass spectrometry (ToF-SIMS). The oxygen to carbon (O/C) ratio is clearly increased after the corona treatment confirming the depletion of carbon on the functional surfaces. The functionality of surfaces obtained by corona treatment could be useful in the development of new bio-devices.

/pdf/corona-discharge-induced-functional-surfaces-of-3igkv153ag.pdf

Corona Discharge-Induced Functional Surfaces of Polycarbonate and Cyclic Olefins Substrates

We investigate in this paper the radiated electromagnetic waves together with the discharge characteristics of Trichel pulse of negative DC corona discharge in air in pin-to-plate and wire-to-plate configurations. The feature of the current pulse and the frequency spectrum of the electromagnetic radiations were measured under various pressures and gas gaps. The results show that the repetition frequency and the amplitude of Trichel pulse current depend on the discharge conditions, but the rising time of the pulse relates only to the radius of needle or wire and keeps constant even if the other conditions (including the discharge current, the gas gap and the gas pressure) change. There exists the characterized spectrum of electromagnetic waves from negative corona discharge in Trichel pulse regime. These characterized radiations do not change their frequency at a given cathode geometry even if the averaged current, the gas gap or the air pressure changes, but the amplitude of radiations changes accordingly. The characterized electromagnetic radiations from Trichel pulse corona relate to the formation or the rising edge of current pulse. It confirms that the characterized radiations from Trichel pulse supply information of discharge system and provide a potential method for detecting charged targets.

https://www.koreascience.or.kr:443/article/JAKO201518058240961.pdf

金一郎加藤

Papers

On the corona discharge : 光漏難放電に就いて

金一郎 加藤

Papers

On the corona discharge : 光漏難放電に就いて

金一郎加藤