Control of fusion reactor fuel particles utilizing anomalous behavior of hydrogen in surface atomic layr -transition metal complex system

一些过渡金属由于表面存在几个单层厚度的杂质原子层而表现出“超渗透”现象。本项目旨在通过检查存在表面杂质的氢-材料相互作用，展示控制表面杂质成分的方法，以有效控制聚变装置中的燃料颗粒。首先，对实验装置进行了改进。因此，由于采用了差动泵送系统，在100 eV到数keV的能量范围内，可以照射具有足够通量密度（>0 ^<17>m^<-2>s^<-1>）的质量分离离子束，并同时测量再发射（上游侧）和透射（下游侧）。利用上述实验系统，对Nb、Ti-6Al-4V和Mo进行了氘离子辐照实验。结果表明，对于已知具有超渗透特性的Nb，稳态渗透通量占入射通量的比例为0.1，但当下游受到Ar离子束辐照时，渗透通量显著增加。对于低活化材料Ti合金，得到了相似的渗透分数（<约等于>0.2）。在150 ~ 1500eV/D的能量范围内，利用辐照后热解吸光谱法测定了入射氘的粒子反射系数R_N。而在Mo中，Ar束对下游侧表面的照射没有改变氘的渗透通量，说明Mo中渗透的速率决定步骤与Nb中不同。计算了氘在Mo上的R_N，并与计算机模拟结果进行了比较；实验值小于计算值，而Nb和Ti合金的实验值一般大于计算值。表面杂质对R_N的影响尚不清楚，部分原因是实验散射大。少

Some transition metals exhibit "superpermeation" due to presence of surface impurity atomic layr with several monolayr thickness. The present project is aimed at demonstrating means to control surface impurity compositions for effective control of fuel particles in fusion devices, through examination of hydrogen-material interactions in the presence of surface impurities. To begin with, the experimental device was modified. As a result, irradiation of a mass-separated ion beam with sufficient flux density (>10^<17>m^<-2>s^<-1>) became possible in the energy range of 100 eV to several keV,together with simultaneous measurement of reemission (upstream-side) and permeation (downstream-side), due to an employment of differential pumpimg system. Using the experimental system described above, deuterium ion irradiation experiments were performed for Nb, Ti-6Al-4V and Mo. The results revealed that for Nb, which is known to exhibit superpermeation, the fraction of steady state permeation flux t … More o incident flux was 0.1, but when the downstream-side was irradiated by an Ar ion beam, significant increase of permeation flux was observed. For Ti alloy, which is known as low-activation material, similar permeation fraction (<approximately equal>0.2) was obtained. For these metals, the particle reflection coefficient, R_N, of incident deuterium was evaluated in the energy range of 150 to 1500eV/D,through post-irradiation thermal desorption spectroscopy. In the case of Mo, on the other hand, irradiation of Ar beam to the downstream-side surface did not change the permeation flux of deuterium, indicating that rate-determining step of permeation in Mo is different from that in Nb. The R_N of deuterium onto Mo was also evaluated and was compared with the result of computer simulation ; the experimental evaluation was smaller than the calculation result, whereas it was generally larger in the cases of Nb and Ti alloy. The effect of surface impurity on R_N is yet to be clarified, partly due to large experimental scatter. Less