AI 中文总结
研究托卡马克破裂中逃逸电子雪崩源，通过在三维非线性 MHD 代码 JOREK 中实现能量和动量守恒碰撞算子及重采样技术，精确模拟其相空间动力学，验证模型并应用于类似 JET 场景，为研究破裂提供新方法。
AI 中文摘要
破裂不仅因大的容器内作用力和热热负荷，还因一些电子被加速到相对论能量而威胁托卡马克运行。这些所谓的逃逸电子（REs）可通过与热电子的碰撞指数级倍增。对 RE 束形成和粒子相空间分布的详细理解需要对 RE 雪崩和 MHD 活性等离子体随机场中的竞争损失进行自洽处理。三维非线性 MHD 代码 JOREK 包含一个混合流体动力学模型，用全 f 相对论粒子模拟（PiC）方法描述 REs。本文实现了一个能量和动量守恒的碰撞算子以精确模拟 RE 在三维电磁场中的相空间动力学，还实施了重采样技术以限制标记数量。用文献中的解析表达式验证了雪崩模型并应用于类似 JET 的终止场景，证明其对实际三维 MHD 活性场景的适用性。未来需要将其移植到加速的高性能计算系统上以跨越长时间尺度，如在大型装置 ITER 中可能出现的周期性终止和再雪崩。
英文摘要
Tokamak disruptions may lead to the acceleration of some electrons to relativistic energies. These so-called runaway electrons (REs) can multiply exponentially via knock-on collisions with thermal electrons. As the resulting RE avalanche is exponentially sensitive to the pre-disruption plasma current, multi-MA RE beams may form in large future devices, risking severe localized wall damage. In this work, an energy and momentum conserving knock-on collision operator is implemented in the 3D nonlinear MHD code JOREK for the full-f relativistic hybrid fluid-kinetic model that describes the REs using the particle-in-cell (PiC) approach both for full-orbit and drift-kinetic markers, which will enable accurate modeling of the RE phase-space dynamics in realistic 3D electromagnetic fields. Such a self-consistent treatment of the RE avalanche and competing losses in the stochastic fields of MHD-active plasmas is required to further the understanding of RE transport and phase-space dynamics in self-consistent interaction with the 3D plasma evolution, which is needed for developing reliable predictions as well as reliable mitigation methods. To make such novel high-fidelity simulations computationally viable, a resampling technique was also implemented to restrict the number of markers. The avalanche model is verified using analytical expressions from literature and applied to a JET-like termination scenario, demonstrating its applicability to realistic 3D MHD active scenarios. Future work on porting to accelerated high-performance computing systems will be needed to cross the long time scales involved, e.g., in periodic termination and re-avalanching that could occur in large devices like ITER.
Comments19 pages, 12 figures, first revision
