FDTD结合DFT分析宽频高功率微波大气传播

FDTD Combined with DFT for Analysis of BroadbandHigh-power Microwave Propagation in Air

联立麦克斯韦方程与电子流体方程,用时域有限差分法(FDTD)模拟高斯型和阻尼正弦型等宽频高功率微波(HPM)的大气传播.在每个时间网格上,根据窄带脉冲的电子速度,通过离散傅立叶变换(DFT)方法求解出宽频脉冲的等效电场,将等效电场和压强代入电离参数公式,使电离参数随空间网格不断更新,提高计算准确性.结果表明,宽频HPM脉冲幅值、脉宽以及海拔高度等参数对大气击穿有明显的影响;大气击穿导致尾蚀效应;随着传播距离的增加,宽频HPM脉冲的尾部衰减加剧,脉宽缩短,引起宽频脉冲的频谱出现展宽、分裂及中心频率移动等现象.

With Maxwell equations and electron fluid equations Gaussian,damped sinusoidal broadband high-power microwave（HPM） propagation in air is analyzed by using finite difference time domain（FDTD） method.At each time grid,according to electronic velocity of narrow-band pulse,effective electric field of broadband pulse is solved with discrete Fourier transform（DFT） method.Ionization parameters at each spatial grid are updated by substituting effective electric field and pressure into corresponding formulas.Calculation accuracy is improved.It shows that broadband HPM pulse amplitude,pulse width,height above sea level have significant effect on air breakdown.Tail loss is resulted from air breakdown.As propagation distance increases,HPM pulse tail decay increases and spectrum of pulse is broadened,splited,and center frequency shifts.