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首页> 外文期刊>Journal of Nuclear Materials: Materials Aspects of Fission and Fusion >Evolution of vacancy defects in heavy ion irradiated tungsten exposed to helium plasma
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Evolution of vacancy defects in heavy ion irradiated tungsten exposed to helium plasma

机译：氦血浆中重离子辐照钨空间缺陷的演变

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Evolution of vacancy-type defects has been investigated in undamaged and copper ion pre-damaged tungsten exposed to low-energy and high-flux helium plasma (60 eV, 1 x 10(22) He/m(2)s). The results measured by Doppler broadening positron annihilation spectroscopy (DB-PAS) indicate that helium-vacancy complexes generate due to intense self-trapping in the undamaged tungsten after helium plasma exposure. In contrast, the occupation of pre-existing vacancies and vacancy clusters, caused by the presence helium atoms, plays a dominant role in the pre-damaged tungsten, but the density of vacancy-type defects in the pre-damaged case is still higher than that in the undamaged case. This means that the dominating process of helium-vacancy complexes formation in tungsten changes from self-trapping to vacancy-trapping in the case of high vacancy density. Meanwhile, the elastic recoil detection analysis (ERDA) and transmission electron microscopy (TEM) results reveal that these pre-existing defects can increase helium retention and helium nano-bubble size. However, it is surprising that in the case of pre-damaged sample, the density/volume of vacancy-type defects also decreased even outside of the helium distribution depth. We attribute this phenomenon to the interstitial dislocation loops punched by helium clusters preferentially diffusing into the pre-damage regions of tungsten far beyond the helium distribution depth, resulting in the significant recombination with vacancies or vacancy clusters. This intrinsic mechanism is further verified by TEM observations and molecular dynamics (MD) simulations. (C) 2020 Elsevier B.V. All rights reserved.
机译：在暴露于低能量和高通量氦等离子体（60eV，1×10（22）HE / M（2）S）中，已经研究了空置和铜离子预损伤钨中的空位型缺陷的演变。通过多普勒展现正电子湮没光谱（DB-PAS）测量的结果表明氦气空位复合物由于在氦血浆暴露后的未损坏钨中的强烈自捕集而产生。相比之下，由存在氦原子引起的预先存在的空位和空位簇的占用在预损伤的钨中起显性作用，但预损坏的情况下的空位型缺陷的密度仍然高于在未损坏的情况下。这意味着在钨中形成氦气空位复合物的主导过程从自捕获到空位密度高的情况下变化。同时，弹性反冲检测分析（ERDA）和透射电子显微镜（TEM）结果表明，这些预先存在的缺陷可以增加氦保持和氦纳米泡尺寸。然而，令人惊讶的是，在预损坏样品的情况下，即使在氦分布深度之外，空位型缺陷的密度/体积也降低。我们将这种现象归因于优先扩散到远远超出氦分布深度的钨的预损伤区域的氦簇中的间隙位错环，导致具有空位或空位簇的显着重组。通过TEM观察和分子动力学（MD）模拟进一步验证了这种内在机制。 （c）2020 Elsevier B.v.保留所有权利。

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