三七炮弹的碘化银成核率检测

The Experiment of Ice Nucleus Generating Efficiency by Model 37 Silver Iodide Shell

三七炮弹是进行人工增雨和防雹作业所需碘化银催化剂的主要载体之一.炮弹中碘化银催化剂的成核率数据是人工影响天气作业设计和指挥中进行催化剂作业剂量测算的重要参考,因此,对人工影响天气业务中使用的三七炮弹的碘化银成核率进行检测非常重要。2013年11—12月中国气象局人工影响天气中心利用新建的1200L等温云室和钢板式20 m^3专用爆炸室等设备,对目前人工影响天气业务中使用的两个厂家三七炮弹(样品1、样品2)的碘化银成核率进行国内首次统一检测。检测结果表明:两厂家炮弹成核率检测结果的拟合值量级均为10"~10^(12)/(g·AgI)(检测温度-6℃至-20℃),样品2成核率明显高于样品1。将本次检测结果与国内历次三七炮弹检测结果相比发现,两样品在负温高温段的成核率值均高于以往检测结果,其中,在具有指示意义的-10℃下的成核率,两样品均比以往检测结果要高2~3个量级。不同检测实验中成核率检测结果存在较大差异的现状说明,采用同一平台开展成核率统一检测十分必要。

Model 37 shell is one of the main carrier of silver iodide catalytic agent usedin rainfall enhancement and hail suppression operations.Nucleating effectiveness values of silver iodide filled in shell are important reference to measure the amount of silver iodide catalytic agent using in weather modification operation.Using a 1200 L isothermal cloud chamber and a 20 m^3 steel plate explosion chamber,the first uniform test of ice nucleus generating efficiency of model 37 silver iodide shells isimplemented by Weather Modification Center of CM A（WMC） from November to December of 2013,and samples chosen randomly from 2 manufacture factories is examined.Uucleation rates of two kinds of sample are detected at eight temperature between — 3℃ to —20℃.Results show that fitting values of nucleating effectiveness of two kinds of samples are all in the range of 10~9 — 10^（12）/（g·AgI） with the temperature from —6 ℃ to — 20℃,and the threshold temperature is —4＇C.The nucleating effectiveness of sample 2 is higher than that of sample 1 obviously,and the maximum difference of fitting values between them is 8.4 times at —14℃.The comparison between this experiment and past results given by domestic different experiments is carried out.Results indicate the nucleation rates of sample 1 and sample 2 are higher than the past results at —14 ℃ above,and they are both 2 to 3 orders of magnitude more effective than the detection values of past experiments at—10℃.To seek cause for this significant difference,a detailed comparative analysis onexperiment condition is carried out.Some techniques applied to the 1200 L isothermal cloud chamber such as temperature controlling,fog making and ice crystals counting are improved,and impacts of those operations are reduced.Meanwhile,larger volume of cloud chamber results in less border effect,and longer time of holding fog in cloud chamber,so it simulates actual atmospheric condition better.Based on above discussions,the testing results of model 37 silver iodide shell nucleation rate are reliable.Furthermore,in view of the great deviation in different experiments,it is very necessary to uniformly test nucleation rate of seeding agent on the same experiment platform.