强流D-D中子发生器氘钛靶损伤机理的研究

Neutron generator is electrostatic accelerator incorporating a deuterium ion source, ion optics and a target in a compact vacuum envelope.To yield 2.5MeV or 14MeV neutrons through D-D/D-T nuclear reactions, deuterium ions derived from a plasma source are accelerated by electric field to impact deuterium/tritium atoms within a target.With the development of neutron application technology and the gradually improvement of neutron generator commercialization, the service lifetime of neutron generator has become a key restrictive factor of sustainable development.In this project,regarding the radioactive property of tritium and the complicated work in dealing with tritium contamination in experimental instruments, radiation damage characterization of titanium deuteride target irradiated by deuterium ion beam will be studied by means of slow positron annihilation lifetime technique, slow positron annihilation Doppler broadening technique and Monte Carlo numerical simulation. Thermal damage characterization of titanium deuteride target irrdatied by deuterium ion beam will be studied by scanning electron microscopy, X-ray diffraction analysis and finite element analysis. In the meantime, the effect of deuterium ion beam on the service lifetime of titanium deuteride target and the way to enhance the service lifetime will be investigated. Not only does the study of this project deal with the fundamental problems concerning how to extend the service lifetime of high-intensity D-D neutron generator, but also meets the urgent need for the optimal design and sustainable development for high-intensity D-D neutron generator. Meanwhile, it serves as a complementary study for the inadequate researches on damage characterization of titanium deuteride target irradiated by deuterium ion beam in domestic and abroad.In general, the study of this project is first aimed to lay the theoretical foundation for the optimal design and sustainable utilization of neutron generator, and then provide the basic prediction for the effects of deuterium ion beam on the service lifetime of titanium deuteride target, which may serve as basic guidelines for the improvement of high-intensity D-D/D-T neutron generator.

随着基于D+离子束与固体氘/氚靶相互作用发生聚变反应产生中子的D-D/D-T中子发生器逐渐工业化，强流中子发生器的使用寿命成为制约中子发生器可持续发展的关键因素，研究D+离子束致氘钛靶损伤特性是提高强流中子发生器使用寿命的基本物理问题；是中子发生器优化设计的迫切需要。本项目拟采用慢正电子湮没寿命测量技术、慢正电子湮没多谱勒展宽技术和蒙特卡罗数值模拟方法研究D+离子束致氘钛靶的辐射损伤特性；采用扫描电镜、X射线衍射分析和有限元分析方法研究D+离子束致氘钛靶的热损伤特性，探索微观辐射损伤特性与宏观热损伤特性之间的关联性，探索强流D-D中子发生器氘钛靶使用寿命的影响因素及影响程度，探索提高强流中子发生器使用寿命的途径和方法。本项目的研究有效补充国内外在强流D-D中子发生器氘钛靶损伤机理研究方面的不足；为强流D-D/D-T中子发生器的优化设计和工程化的可持续发展奠定理论基础。

研究D+离子束致氘钛靶损伤特性是提高强流中子发生器使用寿命的基本物理问题；是中子发生器优化设计的迫切需要。本项目采用慢正电子湮没多谱勒展宽技术和蒙特卡罗数值模拟方法研究D+离子束致氘钛靶的辐射损伤特性；采用扫描电镜、X 射线衍射分析和有限元分析方法研究D+离子束致氘钛靶的热损伤特性；探索微观辐射损伤特性与宏观热损伤特性之间的关联性以及其对强流D-D中子发生器氘钛靶性能变化的影响程度。. 本项目主要获得了以下研究结论：1、有水冷条件下，氘钛靶表面预留的各种不规则形貌的消失主要由离子溅射效应造成；无水冷条件下，氘钛靶表面预留的各种不规则形貌在束流辐照下往往存在剧烈温升造成的“择优熔化”现象。2、中子发生器靶后的水冷却系统能有效的降低束流作用下氘钛靶内的温升，并能有效的抑制氘钛靶中氘的释放，减缓氘化钛向纯钛相变的程度。3、氘离子束辐照能导致氘钛靶内缺陷浓度的大幅上升，靶后的水冷却系统不但能减缓辐照缺陷向靶内扩散，而且能在一定程度上降低靶内辐照缺陷的浓度。4、D+ 离子束辐照氘钛靶过程中所产生的热效应是导致氘钛靶发生相变、内部辐照缺陷扩散加剧的主要因素。结论表明，D+ 离子束辐照氘钛靶过程中的热效应是导致氘钛靶分解，表面形貌改变，使用寿命下降的最主要因素，揭示在工程应用上要尽可能降低靶面的温升才能有效延长其使用寿命。