In this paper, experimental investigations of the discharge characteristics of magnetically enhanced corona discharges, for the purpose of capturing ne aerosol particles, are presented. The discharge mechanism during such a process is analyzed as well. The effects of magnetic enhancement under different magnet ux densities, and in positive- or negative-corona discharges, were experimentally compared. The magnetically enhanced effects in different inter-electrode regions were studied. Experimental results demonstrated that the magnetic eld could efciently increase the concentrations of both the negative ions and the free electrons during negative-corona discharge. The dominant mechanism of magnetic enhancement in a corona discharge involves the Larmor precessions of free electrons which enhance ionization of the gas molecules near the discharge electrode. A convenient conguration for enhancing corona discharge was formed by placing permanent magnets with a local strong magnetic eld near the discharge electrode. A magnetically enhanced negative-corona (MNC) pre-charger was assembled in front of an electrostatic enhancement lter. The inuence of the MNC pre-charger on the efciencies of an electrostatic enhancement lter was measured and compared with that of a conventional corona pre-charger. The free-electron-charging mechanism of the MNC pre-charger was preliminarily analyzed. Our results show that the new pre-charging technique is promising for capturing ne aerosol particles in electrostatic enhancement lters or electrostatic precipitators.

Experiments of charging particles by positive short-pulse corona discharges have been carried out. The experimental results show that the number of negatively charged particles was more than that of positively charged ones. The number ratio of the negatively charged particles to the positively charged ones can reach 2 : 1. The theoretical analysis demonstrates that the positive short-pulse corona discharges include both streamer and corona discharges. The positive streamer discharges consist of many nonthermal plasma leads (streamers) of the branch type, which have high ionizability and propagate rapidly from anode to cathode with the aid of ionization by light. The streamer discharges are at the prebreakdown stage. The positive corona discharges have a thin ionization layer around the anode and most of the interelectrode space is a positive-ion-charging region. The process of charging particles in positive short-pulse corona discharge can be divided into four stages. The free electron charging, which is produced by positive pulsed streamer discharges, is a signicant process for charging particles in positive short-pulse corona discharges. [DOI: 10.1143/JJAP.42.dummy]

Some new electrode congurations and high-voltage insulation methods have been employed in order to force the water sprays to pass across the near corona region. In these ways, the efciencies of charging and collecting aerosol particles are increased. At the same time, the sprays ejected from the discharge electrodes can overcome some difculties of electrostatic precipitation, such as the back ionization of dusts with high resistivity, the reentrainment of ne dusts and the fouling of discharge electrodes. In recent years, there are increasing demands for the researches of the theory and the application on this type of corona discharge. In this paper, we introduced the discharge characteristics and some examples of the applications of the direct current corona with spraying discharge electrodes.(c)2002 Elsevier Science B.V. All rights reserved.

Effective removal of adhesive and fine dusts from flue gas is very difficult. In this paper we introduce a new method of electrostatic precipitation of the Corona Discharges with Spraying Water (CDSW). A new electrode configuration and the circulation spraying of water were employed in the method. The efficient electrostatic precipitation for adhesive and fine dusts can be accomplished without any drain water during a long operating period. The fundamental structure, discharge characteristics, mechanism of spraying and precipitation principle of the electrostatic precipitation using CDSW were described and analyzed in detail. The V-I characteristics, spraying state, supplying water quantity, influence of temperature and clean of the electrodes were researched in series experiments. The treating effects of circulating spraying using the corona plasma at the same time of electrostatic precipitation were preliminary investigated. The fundamental theories and experimental data were proposed, in order to effectively remove the adhesive dusts from flue gas using CDSW in practice.

采用模拟除尘装置，研究比较了雾化电晕放电和干式电晕放电的电晕起始状态、伏-安特性和除尘效率。实验表明，在相同电压和较高烟气流量条件下，雾化负电晕放电比干式负电晕放电的除尘效率提高28%(从78.2%提高到84.2%） 对雾化电晕放电中新的放电特性和除尘机制进行了分析和讨论。对雾化负电晕放电和雾化正电晕放电的实验比较表明，雾化负电晕放电更适合应用于烟气中颗粒污染物的去除，而雾化正电晕放电中扩大的低温等离子区对雾化循环水的净化起到重要作用。