3D Helical Magnetic Perturbation Coils

Suppress Runaway Electron Generation

In tokamaks, these coils excite specific helical magnetic perturbations that enhance radial loss and lower the density threshold for runaway electron suppression, offering a mitigation tool for future large devices.

Yan, Wei · Guinan, Zou · Chen, Zhongyong Yongd · Li, You · Fang, Jiangang · Lin, Zhifang · Jiang, Zhonghe · Wang, Nengchao · Rao, Bo · Li, Yangbo · Ren, Zhengkang · Zhao, Chuanxu · Zhong, Yu · Fanxi, Liu · Yin-Long, Yu · Zi-Sen, Nie · Xun, Zhou · Yuan, Sheng · Yuwei, Sun · Zhou, Song · Zhang, Xiaoqing · Yang, Zhoujun · Chen, Zhipeng · Ding, Yonghua · Team, The W7 X.

Plasma Science and Technology 2025

Specifications

Magnetic perturbation mode

{'zh': '−2/2', 'en': '−2/2'}

Advantages

Lower threshold density

−2/2 magnetic perturbations can increase magnetic fluctuations to the same level at lower electron densities, thereby decreasing the threshold density for runaway electron suppression.

Enhanced radial loss

The −2/2 perturbations direct plasma toward the high-field side and enhance magnetic fluctuations, enhancing the radial loss of runaway electrons and even preventing their generation.

Reduced cooling time

−2/2 magnetic perturbations can reduce the cooling time during the disruption phase and generate a population of high-energy runaway electrons that interact with high-frequency fluctuations, suppressing runaway generation.

Applications

• Tokamak Runaway Electron Suppression：Lowers the density threshold for runaway electron suppression, providing a critical mitigation method for future large tokamaks.
• Plasma Disruption Mitigation：Enhances radial loss and reduces cooling time during disruptions, directly mitigating plasma disruption hazards.
• Magnetic Confinement Fusion Device Safety：Prevents runaway electron damage to device walls, ensuring safe operation of magnetic confinement fusion devices.