Development of Charging Device for Superfine Particles Using UV/Photoelectron Method

我们开发的UV/光电子法是在弱电场作用下，利用UV照射从光电子发射器发射出光电子/负离子的独特充电技术。本工作研制了新型254nm紫外灯镀膜圆柱形光电子发射器充电器；使用由Au（10nm）和掺锡In_2O_3（ITO）（5nm）组成的光电子发射器的圆柱形杀菌灯作为紫外光源来产生光电子/负离子。在我们的充电实验中，使用单分散的 NaCl 颗粒（颗粒直径：24 和 56 nm）作为样品气溶胶。使用先前开发的盒式充电器和应用该充电技术的上述新型充电器对超细氯化钠颗粒进行充电，并根据凝核计数器测量的数浓度检查其有效性。通过比较直流电场作用下不带电超细颗粒的充电率和穿透率以及带电颗粒的穿透率（充电穿透率），发现新型充电器相对于盒式充电器具有相当大的优势。尽管由于在充电区域施加交变电场而降低了充电率，但在计算带电粒子数时最重要的充电穿透率却增加了。

UV/photoelectron method developed by us is a unique charging technique using the photoelectrons/negative ions emitted from a photoelectron emitter by UV irradiation under an application of weak electric field. In this work, the new type charger of cylindrical photoelectron emitter coated on 254nm of UV-lamp was developed ; cylindrical germicidal lamp with photoelectron emitter composed of Au (10nm) and tin-doped In_2O_3 (ITO) (5nm) was used as UV-light source to generate the photoelectrons/negative ions. Mono-dispersed NaCl particles (particle diameter : 24 and 56nm) were used as sample aerosols in our charging experiments. Superfine NaCl particles were charged with a box type charger developed previously and the above new type charger applying this charging technique and, the validity was examined based on the number concentration measured by a condensation nuclei counter. The considerable predominance of the new type charger over the box type charger was found in comparison of charging ratio and penetration ratio of uncharged superfine particles and, penetration ratio of charged particles (charging-penetration ratio) under the application of direct electric field. Although charging ratio was decreased by the application of alternating electric field in the charging region, charging-penetration ratio, the most important thing in counting the number of charged particles, was increased.