Experiments and interpretive modeling to identify the physics controlling material migration in the boundary of DIII-D, JET and EAST fusion energy tokamaks

聚变能源研究的目的是创造一颗“瓶子里的星”。磁聚变研究已经发展到了“瓶子”问题的地步。墙面装甲被热等离子体强烈侵蚀。一些被侵蚀的物质在原来的位置从等离子体中沉积出来，不会造成任何问题。然而，许多物质在再次沉积出来之前在等离子体中迁移了一段距离。后者造成了严重的问题：(1)装甲寿命损失，(2)堆积可能停止反应堆运行的沉淀物，(3)由于共沉积捕获而损失的氚燃料，(4)产生具有安全(化学爆炸)影响的粉尘，等等。 控制托卡马克等磁约束设备边界的物理机制还只有一部分得到了确认。特别是，人们对材料的迁移知之甚少。沿边界磁力线的非常快的等离子体流动已经被广泛地记录下来，但其原因只有很弱的理论基础。物质迁移研究的关键工具之一是注入碳-13甲烷等同位素示踪剂，自2003年以来，我们的多伦多小组一直在DIII-D托卡马克实验中发挥主导作用。 在拟议的工作中将采取的科学方法：I.创建OEDGE-UPGRADE，这是我们多伦多大学解释性OEDGE代码的重大升级。应用OEDGE-U解释DIII-D(美国)、JET(欧盟)和EAST(中国)托卡马克的专用材料迁移实验，以提取材料迁移的控制物理，特别适用于热核实验堆托卡马克(国际联合)。在DIII-D壁上安装多个弹出式探头，以提供关于边界等离子体流场和电场的更完整的空间诊断输入，以便充分约束OEDGE-U以能够识别控制托卡马克边界的物理因素。然后，将执行重复的、相同的、尽可能简单的等离子体放电，包括13CH4注射，其中充分利用所有边界诊断，以提供尽可能完整的边界等离子体图，以便输入到OEDGE-U。

The aim of fusion energy research is to create a 'star in a bottle'. Magnetic fusion research has advanced to the point where the 'bottle' is now the problem. The wall armour is strongly eroded by the hot plasma. Some eroded material deposits back out of the plasma at the original location, causing no problem. However, much of the material migrates some distance within the plasma before depositing out again. The latter creates serious problems: (i) loss of armour lifetime, (ii) pile-up of deposits which can stop reactor operation, (iii) loss of tritium fuel due to co-deposition trapping, (iv) dust creation with safety (chemical explosion) implications, etc. The physics controlling the boundary of magnetic confinement devices such as tokamaks has only been partly identified. In particular material migration is poorly understood. Very fast plasma flows along the magnetic field lines in the boundary have been widely recorded but their cause has only a weak theoretical basis. One of the key tools for material migration research is the injection of isotope tracers such as carbon-13 methane, which experiments our Toronto Group has played the lead role on in the DIII-D tokamak since 2003. The scientific approach that will be taken in the proposed work: I. Create OEDGE-Upgrade, a major upgrade of our University of Toronto interpretive OEDGE code. II. Apply OEDGE-U to interpret dedicated material migration experiments in the DIII-D (US), JET (EU) and EAST (China) tokamaks in order to extract the controlling physics of material migration, specifically for application to the ITER tokamak (joint international). III. Install multiple pop-up probes in the DIII-D wall to provide the more spatially complete diagnostic input on boundary plasma flow fields and electric fields required in order to sufficiently constrain OEDGE-U to be able to identify the physics controlling the tokamak boundary. IV Then sets of repeat, identical, simple-as-possible-plasma, discharges, including 13CH4 injection, will be performed where all the boundary diagnostics are fully exploited to provide as complete a mapping of the boundary plasma as possible for input to OEDGE-U.