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Molecular dynamics study of thermal stress and heat propagation in tungsten under thermal shock 下载免费PDF全文
Using molecular dynamics (MD) simulation, we study the thermal shock behavior of tungsten (W), which has been used for the plasma facing material (PFM) of tokamaks. The thermo-elastic stress wave, corresponding to the collective displacement of atoms, is analyzed with the Lagrangian atomic stress method, of which the reliability is also analyzed. The stress wave velocity corresponds to the speed of sound in the material, which is not dependent on the thermal shock energy. The peak pressure of a normal stress wave increases with the increase of thermal shock energy. We analyze the temperature evolution of the thermal shock region according to the Fourier transformation. It can be seen that the “obvious” velocity of heat propagation is less than the velocity of the stress wave; further, that the thermo-elastic stress wave may contribute little to the transport of kinetic energy. The heat propagation can be described properly by the heat conduction equation. These results may be useful for understanding the process of the thermal shock of tungsten. 相似文献
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本文采用基于速率理论的模拟方法研究钨材料中氢同位素氘的热脱附谱. 热脱附数据来源于520 K下受等离子体辐照的多晶钨, 入射离子能量为40 eV, 剂量为1× 1026 D/m2. 通过调节速率理论中的俘获能、俘获率等参数, 最终获得与实验相符合的热脱附拟合谱. 拟合结果表明, 钨中俘获的氘存在于三种俘获态, 俘获能分别为1.14 eV, 1.40 eV和1.70 eV, 相应脱附温度峰值为500 K, 600 K和730 K. 这三个俘获能分别应对应于第一原理计算得到的空位俘获第3–5个氢原子的俘获能(含零点振动能修正)、空位俘获第1–2个氢原子的俘获能, 空位团簇对氢原子的俘获能. 模拟结果表明, 在本辐照实验条件下, 钨中空位及空位团簇是氘在钨中的主要俘获态. 相似文献
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介孔碳CMK-3对苯酚的吸附动力学和热力学研究 总被引:14,自引:0,他引:14
研究了介孔碳CMK-3对苯酚的吸附性能, 与传统商用活性碳(CAC)进行了比较, 结果表明, CMK-3比CAC的吸附量大、吸附速率快、达到平衡时间短, 是一种较好的吸附剂. 同时探讨了介孔碳CMK-3对苯酚的吸附热力学和动力学特征. CMK-3对苯酚的吸附行为可用Langmuir和Freundlich等温式进行描述, 相关性都较好, 但更符合Freundlich经验公式. 分别采用模拟一阶反应和二阶反应模型考察了吸附动力学, 并计算了这些动力学模型的速率常数. 模拟二级反应模型和实验数据之间有较好的相关性. 分别计算了热力学参数ΔG0, ΔS0和ΔH0, 结果表明, CMK-3对苯酚的吸附过程是吸热和自发的. 相似文献
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