大量气体注入破裂缓解中热辐射环向不对称性的研究

The method of massive gas injection (MGI) has been included in the main proposal for the disruption mitigation in ITER, but there still exists some key problems to be solved in the application. Many experiments found that MGI mitigation can lead to the obvious toroidal asymmetry of thermal radiation, and the Toroidal Peak Factor (TPF) of radiation can be larger than above 5 in some experiments, it will do serious damage to the first wall, therefore the reduction of the radiated power TPF is regarded as an open issue for IPTA. However, recent studies indicated that the radiated power TPF is closely related to the hydromagnetic instability triggered by MGI. By the applying of resonant magnetic perturbation field, the characteristics of the instability mode produced by MGI can be modulated, and then the toroidal asymmetry of thermal radiation can be changed. It is considered to be a possible solution to cut down TPF, but the physical mechanism need to be further studied. In this project, we will study the effect of plasma cooling, the efficiency of impurity gas mixture and the radiated power TPF in J-TEXT by the simulation and experimental methods; study the mechanism of action of the hydromagnetic instability triggered by MGI; explore the mechanism of the effects of externally applied resonant magnetic perturbations on the radiated power TPF of MGI disruption mitigation. And all of these will lay a solid foundation for this application in ITER.

大量气体注入（MGI）已被列入国际热核反应堆（ITER）破裂缓解的主选方案，然而MGI应用到ITER仍有一些关键问题有待解决。实验研究发现MGI会导致热辐射环向不对称性，环向峰化因子甚至高达5以上，这对ITER第一壁材料会造成局域严重损害，因此降低热辐射环向峰化因子是目前ITPA的研究重点。最近研究表明，热辐射环向不对称性与MGI触发的磁流体不稳定性密切相关。通过外加共振扰动场影响MGI过程中的不稳定性模特性，从而改变MGI破裂缓解过程中热辐射环向不对称性，是目前降低环向峰化因子一种可能的解决方案，但其物理机制需进一步研究。本课题拟采用数值模拟与实验相结合的方法，研究J-TEXT上大量气体注入时等离子体的冷却效果、杂质气体的混合效率以及热辐射的环向不对称性；研究MGI触发宏观磁流体不稳定性的作用机制；探索外加共振扰动场对热辐射环向不对称性的影响机制，从而为MGI在ITER上的应用提供参考。

本项目首先开展了J-TEXT装置实验参数的平衡重建和基本参数的设定研究， 在NIMROD计算平台上嵌入J-TEXT MGI以及SMBI杂质注入模型；在此基础上开展J-TEXT上MGI破裂缓解数值模拟，通过实验与数值模拟相结合研究方式得到MGI注入过程中MHD不稳定性模式、MGI触发破裂的环向辐射以及总辐射功率以及杂质混合效率的时空演化，破解了破裂缓解TQ阶段多阶段温度崩塌向大破裂演化中不稳定性模式结构以及类型的演化物理机制；. 在MGI模拟基础上，进行了外加共振扰动场对大量杂质注入破裂缓解影响的数值模拟研究，分别扫描等离子体参数和共振扰动场幅值和相位,获取等离子体的响应情况以及杂质扩散与共振扰动场参数的关系，得到扰动场对杂质注入径向输运大于环向输运影响的理论与实验结果，开展了J-TEXT装置环向辐射不对称性的相关实验研究；..此外还利用NIMROD的多弹丸注入模块还开展了SPI的MHD演化与热辐射分布的研究，为J-TEXT即将开展的SPI实验研究提供理论依据。..本项目在完成上述研究内容同时，共计发表了有项目标注论文共15篇（包括已接受论文一篇），毕业研究6人（1名博士，硕士5人）。