Harilal S S, Yeak J, Phillips M C
Opt Express. 2015 Oct 19;23(21):27113-22. doi: 10.1364/OE.23.027113.
Ultrafast laser filament induced breakdown spectroscopy is a very promising method for remote material detection. We present characteristics of plasmas generated in a metal target by laser filaments in air. Our measurements show that the temperature of the ablation plasma is clamped along the filament channel due to intensity clamping in a filament. Nevertheless, significant changes in radiation intensity are noticeable, and this is essentially due to variation in the number density of emitting atoms. The present results also explain the near absence of ion emission but strong atomic neutral emission from plumes produced during fs LIBS in air.
超快激光丝诱导击穿光谱法是一种非常有前景的远程材料检测方法。我们展示了空气中激光丝在金属靶中产生的等离子体的特性。我们的测量表明，由于激光丝中的强度钳制，烧蚀等离子体的温度沿丝通道被钳制。然而，辐射强度有明显变化，这主要是由于发射原子数密度的变化。目前的结果也解释了在空气中飞秒激光诱导击穿光谱法（fs LIBS）产生的羽流中几乎没有离子发射但有强烈的原子中性发射的原因。
