稀薄空气、等离子体环境外系统电磁脉冲的数值模拟

Simulation study of external system generated electromagneticpulse in low pressure air or plasma

为研究大气环境对系统电磁脉冲(SGEMP)的影响,针对海拔50~100 km的X射线能量沉积区,分别应用3维PIC程序及3维PIC-MCC程序各自开展预电离等离子体和稀薄空气条件下外SGEMP的建模与模拟研究,针对3种不同的X射线注量(4×10^(−3) J/cm^(2)、4×10^(−2) J/cm^(2)、0.4 J/cm^(2)),分别取对应两种不同海拔高度(70 km和80~90 km)的本底等离子体及海拔56 km的稀薄空气条件进行模拟计算,并和真空中的计算结果进行对比,得出预电离等离子体及稀薄空气对外SGEMP的影响规律:当X射线注量较低时,等离子体使得磁场增大,电场减小,而稀薄空气对外SGEMP效应影响不明显;随着X射线注量增大,空间电荷非线性效应越来越明显,等离子体及稀薄空气都使得电场、磁场同时增大,且稀薄空气的增大效应更显著。

For examining effects of atmosphere on system generated electromagnetic pulse(SGEMP),theexternal SGEMP are simulated by the 3D PIC code in pre-ionized plasma and by the PIC-MCC code in low pressureair respectively in the X-ray energy deposition region(50 km to 100 km).For three fluences of X-ray(4×10^(−3)J/cm^(2)、4×10^(−2)J/cm^(2)、0.4 J/cm^(2)),the simulations are done in pre-ionized plasma corresponding to two different altitudes(70 km and 80−90 km)and low pressure air corresponding to 56 km altitude each other,and the results are comparedwith those in vacuum.The variation laws of external SGEMP in pre-ionized plasma and low pressure air are received:the effects have relation to fluence of X-ray,when the fluence of X-ray is low,the magnetic field increases and theelectric field decreases in the plasma environment,while the variations of external SGEMP are not obvious in lowpressure air;with the fluence of X-ray increasing,the space charge nonlinear effects become more and more obvious,the electric field and magnetic field are enhanced together in both pre-ionized plasma and low pressure air,and theenhancement effects are more significant in low pressure air.