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Tritium Migration Process on the Surface and near Defects Studied by In-situ Observation and Ab-Initio Calculation

原位观测和从头计算研究表面及近缺陷处氚的迁移过程

基本信息

批准号：
14208050
负责人：
TANAKA Satoru
金额：
$ 32.45万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

项目摘要

Hydrogen isotope behavior in blanket breeding materials and on an oxidized surface of piping materials was studied with focusing on interactions with defects or energetic particles, thorough comparison of results by quantum chemical calculation and experiments (infrared absorption spectroscopy, photoelectron spectroscopy, thermal desorption spectroscopy, and time-of-flight technique).On the oxidized surface of metals, desorption of adsorbed-species was observed by irradiation of energetic particles. The desorption yield and the chemical form of desorbed-species reflected a correlation of surface electronic structures and an incident energy. When the incident energy can induce a fine overlap of the valence band and the conducting band, the desorption yield was meaningfully heightened, corresponding to the electron stimulated desorption.In the bulk of Li_2O, it appeared that hydrogen isotopes is stabilized through trapping by F centers. The energy necessary for detrapping was influenced by the charged state of F centers, and F^0 held the higher trapping force than F^+ by 2 eV. Regarding an interaction with Li vacancy, increase of the diffusion barrier of hydrogen isotopes was found via formation of -OH oriented to the Li vacancy. Moreover, an additional stabilization was attained by mutual aggregation of the -OH.In terms of nuclear fusion engineering, the information obtained in the present study can provide reliable ways to optimize the efficiency of the tritium decontamination by the irradiation of energetic particles, and to assess the tritium inventory in blanket breeding materials.

通过量子化学计算和实验（红外吸收光谱、光电子能谱、热解吸光谱和飞行时间技术）对氢同位素在毯状繁殖材料和管道材料氧化表面的行为进行了研究，重点研究了氢与缺陷或高能粒子的相互作用，并对结果进行了比较。在金属的氧化表面，用高能粒子照射观察到吸附物的解吸。解吸收率和解吸物质的化学形态反映了表面电子结构和入射能量的相关性。当入射能量能诱导价带和导带有较细的重叠时，解吸产率显著提高，对应于电子激发解吸。在大部分Li_2O中，氢同位素似乎通过F中心的捕获而稳定下来。脱除所需的能量受F中心带电状态的影响，F^0比F^+的捕获力高2 eV。在与Li空位的相互作用中，发现氢同位素的扩散势垒增加，形成了面向Li空位的-OH。此外，通过-OH的相互聚集获得了额外的稳定性。在核聚变工程方面，本研究获得的信息可以为优化高能粒子辐照氚去污效率，以及评估毯层育种材料中的氚库存提供可靠的方法。