组合激光诱导熔石英等离子体及燃烧波演化机制研究

Study of Combined Laser-Induced Fused Silica Plasma and Combustion Wave Evolution Mechanism

摘要: 本研究旨在探讨磁场对毫秒–纳秒组合激光诱导熔石英产生等离子体及燃烧波动力学行为的影响。通过构建磁场环境下组合激光辐照熔石英的数值模型，并基于磁流体动力学(MHD)理论建立多物理场耦合模型，我们进行了系统的理论分析与仿真研究。研究重点分析了等离子体及燃烧波的温度演化和速度分布特性。结果表明，磁场显著改变了等离子体的热力学特性与膨胀动力学。具体而言，在磁场作用下，等离子体峰值温度提升至2611 K，且峰值温度出现时间提前至0.59 ms；同时，等离子体膨胀速度显著降低，峰值速度为162 m/s，并在0.85 ms达到峰值。这些现象主要归因于磁场通过洛伦兹力约束带电粒子运动，抑制等离子体横向扩散，增强能量局域化，并通过焦耳加热效应提升温度，从而限制了燃烧波速度的增长。本研究揭示了磁场与组合脉冲激光的协同作用机制，阐明了磁场调控下等离子体及燃烧波的演化规律，为高抗损伤光学元件设计、激光加工工艺优化以及等离子体控制与应用提供了重要的理论依据。

Abstract: This study investigates the influence of magnetic fields on the dynamics of plasma and combustion waves induced by millisecond-nanosecond combined laser irradiation in fused silica. By constructing a numerical model of combined laser irradiation on fused silica under a magnetic field environment and establishing a multi-physics coupling model based on magnetohydrodynamics (MHD) theory, we conducted systematic theoretical analysis and simulation research. The study focuses on the temperature evolution and velocity distribution characteristics of plasma and combustion waves. The results indicate that the magnetic field significantly alters the thermodynamic properties and expansion dynamics of the plasma. Specifically, under the influence of the magnetic field, the peak plasma temperature increases to 2611 K, and the time to reach the peak temperature is advanced to 0.59 ms. Simultaneously, the plasma expansion velocity is significantly reduced, with a peak velocity of 162 m/s occurring at 0.85 ms. These phenomena are primarily attributed to the magnetic field’s constraint on charged particle motion through the Lorentz force, which suppresses transverse plasma diffusion, enhances energy localization, and increases temperature through Joule heating effects, thereby limiting the growth of combustion wave velocity. This research reveals the synergistic mechanism between magnetic fields and combined pulsed lasers, clarifies the evolution mechanisms of plasma and combustion waves under magnetic field regulation, and provides critical theoretical support for the design of high-damage-threshold optical components, optimization of laser processing techniques, and future plasma control and applications.