长脉冲GW级HPM大气击穿时间分析

Analysis on atmospheric breakdown time for GW level HPM long pulse

结合电子流体方程与Maxwell方程组,对单脉冲高功率微波(HPM)大气击穿过程进行仿真,采用时域有限差分方法(FDTD)并结合HPM自生等离子体的特征参数,仿真了不同压强和场强下单脉冲HPM自生等离子体的参量变化,分析了HPM频率为6.4 GHz时,不同场强、压强下的大气击穿时间,并开展了大气击穿实验加以验证。理论分析与实验结果表明,实验与理论分析结果一致,压强与场强的变化对大气击穿时间均有显著影响,原因在于场强和压强对大气击穿种子电子浓度的变化起决定性作用,进而影响大气击穿时间。场强为k V/cm量级时,大气击穿时间在10 ns量级,在相同的场强下,随着压强的增大,击穿时间会先减小再增加。相同的大气压强条件下,场强越高,大气击穿时间越短。

The process of high power microwave atmospheric breakdown is simulated with the combination of electron fluid equation and Maxwell equation.Using the characteristic parameters of plasma,the Finite Difference Time Domain(FDTD)method is adopted to analyze the atmospheric breakdown of the single pulse High Power Microwave(HPM)under different pressures and electric field intensities,then the time of the atmospheric breakdown is obtained under different pressures and electric fields when the microwave frequency is6.4GHz.Theoretical analysis and simulative results show that the change of the pressure and the electric field has a significant effect on the atmospheric breakdown time,because the electron concentration in the atmosphere is dominated by the electric field intensity andpressure.The atmospheric breakdown time is at10ns order of magnitude when the field strength is at theorder of kV/cm.When the electric field strength is constant,it can be found that the atmospheric breakdown time will be reduced with the increase of pressure.Then the atmospheric breakdown time will increase again when the pressure drops to a certain value.Through the contrast analysis of different field strengths,it also can be found that the higher the electric field intensity,the shorter the atmospheric breakdown time.