发表机构
University of Toronto（多伦多大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
通过测量钠等离子体中斯塔克展宽发射，首次获得自由电子密度空间分布，并验证了LIBORS三维模型预测激光电离特性的能力。
AI 中文摘要
在激光共振饱和产生的钠等离子体中，$4^2D$--$3^2P$ 多重态跃迁的电子斯塔克展宽提供了一种手段，得以首次对在密度为 $10^{15}$--$5\ imes10^{16}$~cm$^{-3}$ 的钠蒸气中形成的等离子体通道进行横向和纵向的自由电子密度空间测量。基于这些测量以及热夹层炉内中性钠密度的测量，我们能够推导出相应的电子温度。这些温度与通过谱线强度的玻尔兹曼分析估算的电子温度吻合良好，并表明在激光激发后100~ns内，使用中等辐照度（$10^6$--$10^7$~Wcm$^{-2}$）的激光即可产生高度电离（$>$10%）、电子温度低于6000K的等离子体。实验结果与最近开发的三维模型合理吻合，该模型预测由于激光能量的显著耗竭，电离度沿激光束路径会降低。这些实验结果证明，该LIBORS代码能够以合理的精度预测这种新型激光电离模式的三维特性，并可能解释其他研究团队观测到的低电子温度和低自由电子密度。
英文摘要
Electron Stark broadening of the $4^2D$--$3^2P$ multiplet transition in a sodium plasma produced by laser resonance saturation has provided a means of undertaking the first spatial measurements of the free electron density across and along the plasma channel created in sodium vapor of density $10^{15}$--$5\times10^{16}$~cm$^{-3}$. From these measurements and measurements of the neutral sodium density within a heat sandwich oven, we are able to deduce the corresponding electron temperature. These temperatures compare favourably with the electron temperature estimated from a Boltzmann analysis of line intensities and suggest that a highly ionized ($>$10\%) plasma of electron temperature $<$6000K can be produced within 100~ns of laser excitation from a laser of modest irradiance ($10^6$--$10^7$~Wcm$^{-2}$). The experimental results are in reasonable agreement with a recently developed 3-dimensional model which predicts a decrease in the degree of ionization along the path of the laser beam as a result of significant depletion of laser energy. These experimental results demonstrate that this LIBORS code is capable of predicting the 3-dimensional nature of this new mode of laser ionization with reasonable accuracy, and may also explain the low electron temperatures and free electron densities observed by other research teams.
