Bak Junhwi, Urdaneta Gerardo, Pokharel Sagar, Miles Richard B, Tropina Albina
Department of Aerospace Engineering, Texas A&M University, College Station, TX, 77845, USA.
Sci Rep. 2024 Feb 14;14(1):3703. doi: 10.1038/s41598-024-52868-w.
This work reports the measurement of two-dimensional electron properties over a nanosecond scale integration time across a femtosecond laser-induced plasma filament in atmospheric pressure argon. Radial electron properties across the [Formula: see text] [Formula: see text]m diameter filament are obtained at discrete axial locations at 2.5 mm steps by one-dimensional high-resolution laser Thomson scattering with a spatial resolution of 10 [Formula: see text]m. These measurements reveal plasma structural information in the filament. The Thomson spectral lineshapes exhibit clear spectral sidebands with an [Formula: see text] parameter [Formula: see text], enabling the measurement of both electron temperature and density profiles. These measurements yield electron densities on the order of [Formula: see text]/m[Formula: see text] and electron temperatures of [Formula: see text] eV. Heating from the probe laser due to inverse bremsstrahlung is taken into account to correct the Thomson scattering electron temperature measurements. Under these conditions, electron-neutral collision induced bremsstrahlung becomes the dominant laser-induced plasma heating process associated with the probe laser. The measurements reveal structural features of the filament, including an asymmetrically skewed density structure in the axial direction and reversed radial distributions of electron density and temperature.
这项工作报告了在大气压氩气中，通过飞秒激光诱导的等离子体细丝，在纳秒尺度积分时间内对二维电子特性的测量。通过一维高分辨率激光汤姆逊散射，以10微米的空间分辨率，在直径为[公式：见原文]微米的细丝上，以2.5毫米的步长在离散轴向位置获得径向电子特性。这些测量揭示了细丝中的等离子体结构信息。汤姆逊光谱线形呈现出清晰的光谱边带，[公式：见原文]参数[公式：见原文]，从而能够测量电子温度和密度分布。这些测量得出电子密度约为[公式：见原文]/立方米，电子温度为[公式：见原文]电子伏特。考虑到由于逆轫致辐射导致的探测激光加热，对汤姆逊散射电子温度测量进行校正。在这些条件下，电子-中性碰撞诱导的轫致辐射成为与探测激光相关的主要激光诱导等离子体加热过程。测量揭示了细丝的结构特征，包括轴向不对称倾斜的密度结构以及电子密度和温度的径向分布反转。
