AI 中文总结
本研究针对DIII-D托卡马克的实验与建模表明，等离子体电流上升期间误差场穿透阈值标度仍适用，模式触发由外加三维线圈电流控制，计入原位误差场对预测关键。
AI 中文摘要
本研究提供证据表明，已建立的误差场穿透阈值标度在等离子体电流上升（ramp-up）期间仍然适用。在DIII-D装置开展的专用实验中，于延长的等离子体电流（$I_p$）上升阶段施加$n=1$的扰动，发现表观经验阈值介于2至3千安（kA）的外加三维线圈电流之间，超过该阈值会触发磁流体动力学（MHD）模式。施加的扰动与上升过程中存在的有理面耦合，在$q=4$面附近触发，并在扰动阶段结束时以$m/n=3/1$模式穿透。为解释这些观测结果，将多装置穿透阈值标度与GPEC代码（基于平衡的重叠度量，包含装置的原位误差场）相结合，该建模重现了幅度扫描中的观测起始现象，并对涵盖不同等离子体电流和密度范围的12次上升放电数据库中的模式触发情况进行分类。在该数据库中，模式触发主要由外加三维线圈电流控制，而非等离子体电流或其上升速率。研究发现，计入原位误差场对可靠预测至关重要。这些结果表明，在瞬态上升条件下，基于标度的穿透度量与详细三维场建模结合时具有稳健性，且强调在评估其他外部诱导扰动时需考虑原位误差场。本研究的动机来自未来托卡马克装置，其在启动阶段可能出现瞬态非轴对称误差场，例如来自 runaway电子抑制线圈。
英文摘要
This work provides evidence that established error field penetration threshold scalings remain applicable during plasma current ramp-up. In dedicated DIII-D experiments with imposed $n=1$ perturbations during extended $I_p$ ramps, an apparent empirical threshold is found between $2$ and $3$~kA of applied 3D coil current, above which MHD modes are seeded. The imposed perturbation couples to the rational surfaces present during the ramp, seeding near the $q=4$ surface and penetrating as an $m/n=3/1$ mode by the end of the perturbation phase. To interpret these observations, multi-machine penetration threshold scalings are combined with equilibrium-based overlap metrics from the GPEC code, including the in-situ error fields of the device. This modeling reproduces the observed onset in the amplitude scan and classifies mode seeding across a database of 12 ramp-up discharges spanning a range of plasma currents and densities. Across this database, the seeding appears to be controlled primarily by the applied 3D coil current rather than by the plasma current or its ramp rate. Accounting for the in-situ error fields is found to be important for reliable prediction. These results are consistent with the robustness of scaling-based penetration metrics when coupled to detailed 3D field modeling under transient ramp-up conditions, and suggest the importance of accounting for in-situ error fields when assessing additional externally induced perturbations. This work is motivated by future tokamaks in which transient, non-axisymmetric error fields can arise during startup, for example from runaway electron mitigation coils.
