This work starts an in situ processing capability to study a certain diffusion process in magnetic confinement fusion. This diffusion process involves plasma particles that are likely to escape confinement. Such particles carry a significant amount of energy from the burning plasma inside the tokamak to the diverter and damaging the diverter plate. This study requires in situ processing because of the fast changing nature of the particle diffusion process. However, the in situ processing approach is challenging because the amount of data to be retained for the diffusion calculations increases over time, unlike in other in situ processing cases where the amount of data to be processed is constant over time. Here we report our preliminary efforts to control the memory usage while ensuring the necessary analysis tasks are completed in a timely manner. Compared with an earlier naive attempt to directly computing the same diffusion displacements in the simulation code, this in situ version reduces the memory usage from particle information by nearly 60% and computation time by about 20%.

翻译：本研究启动了一项原位处理能力，用于研究磁约束聚变中的特定扩散过程。该扩散过程涉及可能逃逸约束的等离子体粒子，这些粒子将托卡马克内部燃烧等离子体中的大量能量携带至偏滤器，并对偏滤器板造成损伤。由于粒子扩散过程具有快速变化的特性，本研究需采用原位处理方法。然而，这种原位处理面临挑战：扩散计算所需保留的数据量随时间递增——这与多数原位处理场景中待处理数据量随时间保持恒定的情况不同。本文报告了我们在控制内存使用量同时确保必要分析任务及时完成的初步工作。相较于早期直接在仿真代码中计算相同扩散位移的粗放尝试，本原位方案将粒子信息的内存使用量降低近60%，计算时间减少约20%。