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

采用量子化学计算和实验(红外吸收光谱、光电子能谱、热脱附谱和飞行时间技术)对包层繁殖材料和管道材料氧化表面的氢同位素行为进行了研究。在金属氧化表面上，通过辐照含能粒子观察到了吸附物种的脱附。脱附率和脱附物种的化学形态反映了表面电子结构和入射能量之间的关系。当入射能量引起价带和导带的精细重叠时，脱附率显著提高，相当于电子激发脱附。在Li2O的块体中，氢同位素似乎是通过F中心捕获而稳定的。退陷所需的能量受F心的带电状态的影响，F^0比F^0具有更大的捕获力2 eV。在与Li空位的相互作用中，通过形成定向于Li空位的-OH，增加了氢同位素的扩散势垒。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去氚的效率和评估包层育种材料中的氚库存提供可靠的方法。

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.