抄録
An airless nozzle equipped with induction charging electrode is useful to produce the space charge cloud consisting of highly-charged droplets. To estimate and to increase the charge density of the space charge cloud, a model of the space charge cloud in a cylindrical grounded electrode is proposed including the effect of not only drift of charged droplet in radial direction due to the electric field but also the deceleration in axis direction due to air resistance. The distribution of the charge density both inside and outside the droplets jet is deduced by the method of characteristics, solving Poisson's equation. In order to confirm the characteristics evaluated from this model, a space charge cloud was formed experimentally using the charged-droplet jet ejected from straight type airless nozzle and the electric field intensity and the charged droplet current were measured at the surface of the cylindrical electrode of 4m long and 1m in diameter. Experimental results agree with calculated ones. It was found that increase in the rate of deceleration of the droplets jet and decrease in their mobility were quite effective to increase the charge density of the charged droplet cloud.
