Research on Formation of High Density Space Charge consisting with Charged Droplets and Air Discharge

在没有电极的空间电荷云中发生放电，形成了由带电液滴组成的空间电荷云。带电液滴是由一个在喷嘴尖端附近装有感应充电电极的无气喷嘴产生的。液滴的电荷量取决于充电电极的质量和几何形状。研究了插入带电液滴云中的接地针电极尖端的电晕点放电。云被限制在直径1米、高2米的圆柱形接地电极内，以定义云的大小。测得云的最大电荷密度为2.6muC/m~3。当接地针电极插入带电云中心时，发生电晕放电。在负电荷云中，当使用小半径的针状电极时，会出现正辉光电晕。当使用大半径针状电极时，可以观察到正的流光电晕。讨论了感应充电方式下无空气喷嘴喷出的带电液滴云内气隙的闪络特性。液滴在-200~+200muC/kg的范围内充电，形成约13muC/m^3的空间电荷。在带电云内的杆-球间隙上施加1.2×50亩的S脉冲电压，测量了闪络电压和闪络时间。随着荷质比的增大，正极棒的闪络电压在正电荷云中显著增加。与未带电液滴内的闪络电压相比，闪络电压最高可提高80%。阴极棒的闪络电压在两极的云中都降低了约20%。结果表明，间隙中带电液滴对放电过程有显著影响。

To occur electrical discharge in a space charge cloud without electrode, space charge cloud consisted with charged droplets was formed. The charged droplets were produced by an airless nozzle equipped with an induction charging electrode near the tip of the nozzle. The charge quantity of the droplets depends on the mass quantity and the geometry of the charging electrode.Corona point discharge at the tip of a grounded needle electrode inserted into a charged droplet cloud has been investigated. The cloud is confined within a cylindrical grounded electrode 1m in diameter and 2m in height to define the size of the cloud. The maximum charge density of the cloud obtained was 2.6muC/m^3. Corona discharge occurred when the grounded needle electrode was inserted into the center of the charged cloud. In a negative charged cloud, positive glow corona occurred when small radius of needle electrode was used. However, positive streamer corona was observed when a large radius of needle electrode was used.Flashover characteristics of air gap within charged droplet cloud ejected from an airless nozzle using induction charging method are discussed. The droplets are charged in the range-200 to +200muC/kg forming the the space charge of approximately 13muC/m^3. The flashover voltage and the time lag to flashover were measured when 1.2X50mu s impulse voltage applied to a rod-sphere gap within the charged cloud. Flashover voltage for positive rod markedly increased within positive charged cloud by increasing the charge-to-mass ratio. The increase of flashover voltage was up to 80% in comparison with flashover voltage within uncharged droplets. Flashover voltage for negative rod decreased about 20% in the cloud of either polarity. The results show that charged droplets in the gaps affect discharge process significantly.