拉瓦尔喷嘴的气流线质量及密度分析

喷气负载是高功率Z箍缩的主要负载之一。应用一维等熵压缩气体动力学，分析了“强光一号”加速器拉瓦尔喷嘴的基本物理过程，获得了拉瓦尔喷嘴出口处气流的马赫数，Ma=4.6，并对其进行了修正，修正值为3.5。利用由雪耙模型导出的Z箍缩聚爆时间表达式，并结合“强光一号”Z箍缩实验结果，修正了由一维等熵气体动力学得到的喷嘴气流线质量表达式。最后根据已知气流的线质量40 μg/cm ，利用B-T模型初步估算了喷嘴的气流密度分布。估算结果为:在轴向2.5~40 mm，径向0~15 mm的区域内，气体分子密度基本在1016～1017/cm3，且在轴向2 cm内基本形成空心的气体壳层结构。

Study of the gas-puff line mass and density from Laval nozzle

The gas puff is one of the main loads used in Z pinch research. In this paper the basic physics process of the Laval nozzle on Qiangguang I generator is analyzed using one dimension isentropic gas dynamics equation.The Mach number 4.6 of the gas flow is calculated and corrected as 3.5 considering the effect of boundary. Combining the data of gas puff Z pinch experiments on Qiangguang I generator, the expression of the line mass is obtained using the implosion time expression which is deduced from snow-plow model. In the end of the paper the distribution of the gas density is given by the Bollistic-Transport (B-T) model and the gas density is between 10~(16)/cm~3 and 10~(17)/cm~3. Along the axis within 2 cm, a hollow gas shell structure is formed.