Establishment of Modeling of Hydrogen Isotopes Recycling in Plasma Facing Material for Control of the D-T Burning Experiments

本项目旨在阐明面向等离子体材料中氢同位素的保留和再发射的基本过程，建立描述氢同位素在材料中的动态输运的模型，用于预测和评价H^+和D^+双重辐照下的氢再循环速率。1993年和1994年，本项目对石墨材料的任务如下：1)建立了单氢离子辐照过程中石墨中氢同位素输运的质量平衡方程，并对所涉及的基本过程的速率常数进行了评述。提出了H^+和D^+辐照的质量平衡方程。2)利用弹性反冲探测器（ERD）技术测量了能量为0.2 ~ 5.0 kev的H_2 +离子束注入石墨后，深度剖面和石墨中氢峰浓度的能量依赖性。用所提出的质量平衡方程的解可以很好地解释稳态深度剖面和峰值浓度。3)用ERD技术测量了5 KeV H_2^+或D_2^+离子束注入石墨直至饱和的MeV He^+离子诱导氢同位素（H，D）在室温下的再发射，确定了He^+离子诱导脱捕截面和局部分子重组率与俘获率之比。发现后一种值的H与D的同位素比值约为2，这在扩散限制反应模型中得到了合理的解释。4)测量了室温下h_2 ^+和D_2^+离子束同时辐照石墨中H和D的保留曲线，两者的投影范围相同。用H^+和D^+双辐照质量平衡方程的解和基于扩散极限反应模型的基本过程速率常数很好地解释了D / H饱和浓度的同位素比值为1.7。少

Goal of this project is to clarify the elementary processes in the retention and reemission of hydrogen isotopes for plasma facing materials and to establish the model describing their dynamic transport in the materials for prediction and evaluation of hydrogen recycling rates during H^+ and D^+ dual irradiations.In 1993 and 1994, we have following tasks for graphite materials concerning this project.1) The mass balance equations describing the transport of hydrogen isotopes in graphite during single hydrogen ion irradiation have been proposed and the rate constants of the elementary process involved are reviewed. The mass balance quations for dial H^+ and D^+ irradiations have been proposed.2) The energy dependence of the depth profiles and the peak concentrations of hydrogen refained in graphite by implantation with H_2^+ ion beams at energies 0.2-5.0keV has been measured by means of the elastic recoil detector (ERD) technique. The steady state depth profile and peak concentrations a … More re found to be well explained in terms of the solution of the mass balance equations proposed.3) The MeV He^+ ion-induced re-emission of hydrogen isotopes (H,D) from graphite implanted with 5 KeV H_2^+ or D_2^+ ion beams upto saturation at room temperature were measured by means of the ERD technique and the He^+ ion induced detrapping crosssection and the ratio of the local molecular recombination rate to the trapping rate were defermined. It is found that the isotope ratio of the latter values for H to D is about 2 which was reasonably well explained in terms of the diffusion-limited reaction model.4) The retention curves of H and D in graphite irradiated simultaneously withH_2^+ and D_2^+ ion beams at room temperature were measured under the condition that both projected range are the same. The isotope ration of the saturation concentrations of D to H was found to be 1.7 which was excellently well explained by the solution of the mass balance equations for the H^+ and D^+ dual irradiations proposed and the rate constants of elementary processes based on the diffusion-limites reaction model. Less