论文标题
密集气介质中细丝唤醒通道中的电离和激发动力学的延迟电离和激发动力学
Delayed ionization and excitation dynamics in a filament wake channel in dense gas medium
论文作者
论文摘要
如在高压氩气的示例中所示，为在密集气体培养基中形成了一个统一的理论描述，用于在密集气体培养基中形成一个电离灯丝通道以及该通道中电子自由度的演变。在激光脉冲期间，新出现的自由电子通过中性原子上的逆BREMSSTRAHLUNG获得能量，从而实现了撞击电离和原子的广泛碰撞激发。这些过程的动力学模型会在激光脉冲立即产生径向密度分布。脉冲后，热化电子气体通过冲击电离（来自地面和激发态）和残留中性原子的碰撞激发驱动系统的进化，而激发原子则参与了笔球电离。这三个过程的相互作用决定了电子气冷却动力学。自由电子和离子密度的局部不平衡引起了瞬态径向电场，这取决于电子温度。通过以数值求解扩散反应方程的系统，获得了电子，离子和激发原子密度以及电子温度和诱导电场的曲线的不断发展的径向。所有这些特征都以两个特征时间尺度进化，并允许通过线性和非线性光散射实验测量唤醒通道演化的电子阶段。
A unified theoretical description is developed for the formation of an ionized filament channel in a dense-gas medium and the evolution of electronic degrees of freedom in this channel in the laser pulse wake, as illustrated on an example of high-pressure argon. During the laser pulse, the emerging free electrons gain energy via inverse Bremsstrahlung on neutral atoms, enabling impact ionization and extensive collisional excitation of the atoms. A kinetic model of these processes produces the radial density distributions in the immediate wake of the laser pulse. After the pulse, the thermalized electron gas drives the system evolution via impact ionization (from the ground and excited states) and collisional excitation of the residual neutral atoms, while the excited atoms are engaged in Penning ionization. The interplay of these three processes determines the electron gas cooling dynamics. The local imbalance of the free-electron and ion densities induces a transient radial electric field, which depends critically on the electron temperature. The evolving radial profiles of the electron, ion, and excited-atom densities, as well as the profiles of electron temperature and induced electric field are obtained by solving the system of diffusion-reaction equations numerically. All these characteristics evolve with two characteristic timescales, and allow for measuring the electronic stage of the wake channel evolution via linear and nonlinear light-scattering experiments.
