AI 中文总结
研究通过 S 波段波导测量超短脉冲激光大气细丝电导率，利用相关模型推断其参数，通过自发射信号测量 Q，对比理论与实际微波辐射模式，考虑辐射后得出更低ν上限，给出不同气压下 30cm 长细丝结果。
AI 中文摘要
超短脉冲激光（USPL）光脉冲经克尔效应在空气中几何聚焦后再自聚焦，通过细丝穿过的 S 波段波导内 3.2GHz TE₁₀模式的衰减测量等离子体细丝的电导率σ，结合细丝特征半径 R。利用主要空气成分电离率 Wi 与局部激光强度 I 等模型推断假设稳态细丝的相关参数，通过细丝自发射信号独立测量 Q 进行比较。将因 Q(z)实际轴向变化产生的理论远场微波辐射模式与已发表测量结果对比，考虑辐射后推断出更低的ν上限，并给出了不同大气压力下 30cm 长细丝的结果。
英文摘要
The electrical conductivity $σ$ of the plasma filament left behind by an ultrashort pulsed laser (USPL) optical pulse after it is geometrically then self-focused in air via the Kerr effect is measured by attenuation of a 3.2 GHz TE$_{10}$ mode within an S-band waveguide through which the filament passes, taking into account the characteristic radius $R$ of the filament, as determined by fast camera visible light imaging. Models of the major air constituents' ionization rate $W_{i}$ vs. local laser intensity $I$, and of temperature $T$ and mean axial electron momentum $\left\langle p_{z}\right\rangle $ vs. peak laser intensity $I_{0}$ are then used to infer a hypothetical steady state filament's $I_{0}$, $T$, major species particle densities, and assumed axially invariant current time integral $Q$ and current decay rate $ν$ after pulse passage. $Q$ is independently measured via the filament's self-emission signal in the waveguide for comparison. The theoretical far field microwave radiation pattern due to the actual axial variation in $Q=Q\left( z\right)$ is compared favorably to published measurements. A much lower upper bound on $ν$ is inferred once such radiation is taken into account. Results are presented along a $30$ cm long filament at a broad range of atmospheric pressures.
Comments19 pages, 30 figures/subfigures. Journal submission pending
