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

研究了毯状育种材料和管道材料氧化表面上的氢同位素行为，重点关注与缺陷或高能粒子的相互作用，对量子化学计算和实验（红外吸收光谱、光电子能谱、热脱附光谱和飞行时间技术）结果进行了彻底比较。在金属的氧化表面上，通过高能粒子照射观察了吸附物质的脱附。解吸率和解吸物质的化学形式反映了表面电子结构和入射能量的相关性。当入射能量可以引起价带和导带的精细重叠时，解吸产率显着提高，对应于电子刺激解吸。在Li_2O块体中，氢同位素通过F中心的捕获而稳定。去俘获所需的能量受F中心带电状态的影响，F^0比F^具有更高2 eV的俘获力。关于与Li空位的相互作用，发现通过形成朝向Li空位的-OH来增加氢同位素的扩散势垒。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提供可靠的方法来优化高能粒子辐照氚净化的效率，并评估总体育种材料中的氚库存。

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.