磁增强负电晕放电特性和荷电方式研究

Discharge characteristics and charging modes of magnetically enhanced negative corona discharges with wide inter-electrode spacing and applications

研究了磁增强负电晕放电特征,分析了这一过程的放电特性和磁场对极间不同区域的影响,比较了磁增强预荷电器和传统的预荷电器对静电增强过滤器效率的影响.结果表明:在磁增强负电晕放电中,磁场能有效地提高负离子和自由电子的浓度;磁增强负电晕放电自由电子的拉莫运动提高了放电电极附近的电离程度,使放电电流明显增长,使更多的正离子在电晕区积累,形成了和原电场方向一致的正离子电场,进一步增强电离,电晕区中积累的正离子形成的电场削弱了荷电区原电场强度;磁场的应用对扩散荷电机制有增强作用,对电场荷电机制不利.

Experimental investigations on discharge characteristics of magnetically enhanced negative corona discharges are presented,both the discharge characteristics and the influences of the magnetic field on the different inter-electrode regions also were studied.The results show the densities of the ions and the free electrons could be enhanced by the magnetic field in the magnetically enhanced negative corona discharges.The mechanism of magnetically enhanced negative corona discharges are that the corona discharge currents are enhanced because of Larmor movement of free electrons near discharge electrode,which lead to more positive ions accumulate in the corona region.So a combined electric field was formed by the original electric field and the electric field of the positive ions whose direction was accordant with the original electric field.So the ionizations were enhanced again.In the charging region,the original electric field was weakened by the electric field of the accumulated positive ions.A magnetically enhanced negative corona pre-charger was assembled in the front of an electrostatic enhancement filter.The influence of the pre-charger on the efficiencies of an electrostatic enhancement filter was measured and compared with that of a conventional corona pre-charger.The results show that the diffusion charging was enhanced by the magnetic field,but it was disadvantageous for the field charging in the magnetic field.