In this paper, we measure broadband terahertz spectra from a single 744-nm filament produced in tight, medium, and loose geometrical focusing conditions. Terahertz spectra are measured using interferometer coupled to a helium-cooled bolometer avoiding any cutoff frequencies. Based on THz spectrum maximum position and spectral width, we estimate electron-heavy particle (neutrals and ions) collision rate. Numerical simulations are performed using the state-of-the-art model of unidirectional femtosecond pulse propagation and convergence/divergence of optical radiation at large angles.

中文翻译：

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从单色灯丝太赫兹光谱跟踪空气击穿等离子体特性

在本文中，我们测量了在紧密，中等和宽松的几何聚焦条件下产生的单个744 nm灯丝的宽带太赫兹光谱。太赫兹光谱是使用与氦冷却辐射热计耦合的干涉仪测量的，避免了任何截止频率。基于太赫兹光谱的最大位置和光谱宽度，我们估计了重电子粒子（中性和离子）的碰撞速率。使用单向飞秒脉冲传播和大角度光辐射的会聚/发散的最新模型执行数值模拟。