Metal magnesium (Mg) fuels have been widely used in rocket propellants. The combustion study on individual Mg microparticles is crucial to the in-depth unveiling of the combustion mechanism of Mg-based propellants. In this paper, a new experimental setup was proposed to directly observe the combustion of individual micron-sized Mg particles, based on laser ignition and microscopic high-speed cinematography. The combustion process of individual Mg microparticles could be directly and clearly observed by the apparatus at high temporal and spatial resolutions. Individual Mg microparticles took gas phase combustion, and mainly underwent four stages: expansion, melting, gasification, ignition, and combustion. The ignition delay time and total combustion time had an exponential decay on the particle diameter, and they had a linear decay on the ignition power density. The melting took a dominant role in the whole burnout time. The gas-phase combustion flame seemed thick, inhomogeneous, and ring-like structure. The combustion model of individual Mg microparticles was built through combining the experimental results with the SEM, XRD, XPS, and EDS analysis of original samples and combustion residues. This study will be beneficial to understand the combustion process and reveal the combustion mechanism of metal microparticles besides Mg.

中文翻译：

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自然对流下激光诱导单个镁微粒的燃烧

金属镁（Mg）燃料已广泛用于火箭推进剂。单个镁微粒的燃烧研究对于深入揭示镁基推进剂的燃烧机理至关重要。在本文中，基于激光点火和显微高速摄影，提出了一种新的实验装置来直接观察单个微米级镁颗粒的燃烧。该装置可以在高时空分辨率下直接、清晰地观察单个镁微粒的燃烧过程。单个Mg微粒进行气相燃烧，主要经历膨胀、熔化、气化、着火和燃烧四个阶段。点火延迟时间和总燃烧时间对粒径呈指数衰减，并且它们的点火功率密度呈线性衰减。熔化在整个燃尽时间中起主导作用。气相燃烧火焰呈粗大、不均匀、环状结构。通过将实验结果与原始样品和燃烧残留物的SEM、XRD、XPS和EDS分析相结合，建立了单个Mg微粒的燃烧模型。该研究将有利于理解燃烧过程，揭示除镁以外的金属微粒的燃烧机理。原始样品和燃烧残留物的 EDS 分析。该研究将有利于理解燃烧过程，揭示除镁以外的金属微粒的燃烧机理。原始样品和燃烧残留物的 EDS 分析。该研究将有利于理解燃烧过程，揭示除镁以外的金属微粒的燃烧机理。