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首页> 外文期刊>The Journal of Chemical Physics >Understanding and predicting the temporal response of laser-induced incandescence from carbonaceous particles [Review]
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Understanding and predicting the temporal response of laser-induced incandescence from carbonaceous particles [Review]

机译：了解和预测碳质颗粒激光诱导的白炽灯的时间响应[综述]

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This paper describes a model for analyzing and predicting the temporal behavior of laser-induced incandescence (LII) from combustion-generated soot, carbon black, and other carbonaceous particles on a nanosecond time scale. The model accounts for particle heating by absorption of light from a pulsed laser and cooling by sublimation, conduction, and radiation. The model also includes mechanisms for oxidation, melting, and annealing of the particles and nonthermal photodesorption of carbon clusters from the particle surface. At fluences above 0.1 J/cm(2), particle temperatures during the laser pulse are determined by the balance between absorption and sublimation, whereas at lower fluences particle temperatures do not reach the sublimation temperature, and temperatures are predominantly controlled by absorption and conduction. After the laser pulse, temperatures are predominantly controlled by conductive cooling rates. Oxidative heating may compete with conductive cooling on these time scales. Annealing of the particles to a more ordered phase of carbon is predicted to occur at fluences as low as 0.02 J/cm(2). Annealing may strongly influence sublimation rates, and changes in emissivity during annealing are predicted to increase signal decay rates. Supersonic expansion of the carbon clusters sublimed from the surface is calculated to occur at fluences above 0.12 J/cm(2). When compared with LII measurements recorded in a flame at atmospheric pressure, the model reproduces the shapes and relative magnitudes of LII temporal profiles over a wide range of laser fluences. Comparisons between model predictions and experimental observations suggest that the particles do not melt at laser fluences that lead to melting of bulk graphite. These comparisons also indicate that the energy released during particle annealing is much smaller than that released during annealing of neutron- or electron-irradiated graphite. Despite good agreement between model and experimental results, large uncertainties exist for input parameters used to calculate annealing rates and rates of oxidation, conduction, absorption, emission, and photolytic desorption of carbon clusters for both the initial and annealed particles. (C) 2003 American Institute of Physics. [References: 203]
机译：本文描述了一个模型，用于在纳秒级尺度上分析和预测由燃烧产生的烟灰，炭黑和其他碳质颗粒产生的激光诱导白炽灯（LII）的时间行为。该模型考虑了通过吸收脉冲激光的光并通过升华，传导和辐射进行冷却来加热颗粒。该模型还包括颗粒的氧化，熔化和退火机制以及碳团从颗粒表面的非热解吸机理。在注量高于0.1 J / cm（2）时，激光脉冲期间的粒子温度由吸收和升华之间的平衡决定，而在注量较低时，粒子温度未达到升华温度，并且温度主要由吸收和传导控制。在激光脉冲之后，温度主要由传导冷却速率控制。在这些时间范围内，氧化加热可能与传导冷却竞争。预计将以0.02 J / cm（2）的能量密度将粒子退火至碳的更有序相。退火可能会严重影响升华率，并且预测退火过程中发射率的变化会增加信号衰减率。从表面升华的碳簇的超音速膨胀计算为在注量大于0.12 J / cm（2）时发生。当与在大气压下火焰中记录的LII测量值进行比较时，该模型可在很宽的激光注量范围内再现LII时间轮廓的形状和相对大小。模型预测值和实验观察值之间的比较表明，粒子不会在导致大块石墨熔化的激光注量下熔化。这些比较还表明，粒子退火过程中释放的能量远小于中子或电子辐照石墨退火过程中释放的能量。尽管模型和实验结果之间有很好的一致性，但是用于计算退火速率以及初始颗粒和退火颗粒的碳簇的氧化，传导，吸收，发射和光解吸速率的输入参数仍然存在很大的不确定性。 （C）2003美国物理研究所。 [参考：203]

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