基于流体-磁流体-粒子混合方法的高空核爆炸碎片云模拟  

Hydro-Magneto-PIC hybrid model for description of debris motion in high altitude nuclear explosions

作　　者：彭国良 张俊杰[2] Peng Guo-Liang;Zhang Jun-Jie(College of Mechanical and Electrical Engineering,Beijing Institute of Technology,Beijing 100081,China;Northwest Institute of Nuclear Technology,Xi’an 710024,China)

机构地区：[1]北京理工大学机电学院,北京100081 [2]西北核技术研究所,西安710024

出　　处：《物理学报》2021年第18期107-113,共7页Acta Physica Sinica

摘　　要：提出了描述高空核爆炸碎片云运动的流体-磁流体-粒子(particle-in-cell,PIC)混合模型,相较目前的主流模型,该模型能够计算更加广泛的空间尺度.根据碎片云运动涉及的高温离子、低温离子和中性大气的不同性质,采用三种模型进行联合求解:高温离子用PIC粒子模型计算,低温离子用磁流体模型计算,中性大气用流体模型计算,并将三者之间的相互作用作为源项加入相应的控制方程.最后,计算了美国Starfish试验中碎片云的扩展情况,与试验结果进行了比对,并验证了求解方案的可靠性.此外,还给出了不同投影角度下碎片云形状随时间的变化,并分析了影响碎片云运动的主要因素,包括大气阻力、磁压、槽型不稳定性和霍尔电流等.A Hydro-Magneto-PIC(particle-in-cell)hybrid model is proposed to describe the motion of the fission debris in high altitude nuclear explosions(HANEs).Compared with the state-of-art numerical models,our model is able to stably compute the motion of the fission debris in a broader spatial region.In a real HANE,the physical process contains many spatial scales.The upward moving debris particles manifest kinetic properties due to the fact that the dilute ambient atmosphere and the downward expanding particles manifest a fluid-like pattern and can be approximated by the usual hydro-dynamical models.Meanwhile,the debris particles receive electromagnetic forces from both the geomagnetic fields and the charged particles at all frequencies.This broad scale of frequencies can induce large-and small-scale instabilities,which cannot be solved by the usual hydrodynamic equations.Considering the motions of the debris and the different properties of the high temperature ions,the low temperature ions and the neutral atmosphere,we consistently combine three models for completely describing the debris expansion.The high temperature ions are described by the PIC model for their intrinsic kinetic behaviors,the low temperature ions are described by the magneto-hydrodynamic model for their fluid property,and fluid equations are applied to the neutral particles with no electromagnetic force.The corresponding interactions among the three components are added into the equations as the source terms.With the combination of the three models,our algorithm can stably calculate the regions that are a few thousand kilometers in altitude.Our proposed model contains both the kinetic and fluid properties,and is stable in numerical implementations.Finally,we calculate the debris motion in the Starfish experiment.The results confirm a consistency of our proposed model with the observations.The spatial scale of our simulation results is consistent with the result in the Starfish experiment.In addition,we also plot the distribution of the debris with

关 键 词：高空核爆炸 流体-磁流体-粒子混合模型 碎片云 

分 类 号：TL91[核科学技术—核技术及应用] P426.5[天文地球—大气科学及气象学]