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arXiv · 2605.15485

Re-acceleration of Energetic Ions via Small-Scale Reconnection in Magnetic Fusion Plasmas

Cong Zhang·Shaodong Song·Di Luo·Kai Huang·Linge Zang·Huibo Tang·Yanchao Li·Yihang Zhao·Ao Wang·Hanqing Wang·Zhenxing Wang·Lei Han·Xuxu Zhang·Jia Li·Dong Guo·Yunfeng Liang·Minsheng Liu·Yuejiang Shi
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Abstract

We report the first observation on the EXL-50U spherical torus that energetic particles injected by neutral beam injection (NBI) can be stably accelerated to significantly higher energies - reaching up to 2.5 times the injection energy, occurring without significant large-scale magnetohydrodynamic (MHD) bursts. Simulations based on EXL-50U parameters indicate that small-scale magnetic reconnection, mediated by multiple magnetic islands, fails to accelerate bulk thermal ions but efficiently energizes seed fast ions. Unlike global MHD events, such small-scale reconnection is ubiquitous in magnetic confinement devices and does not degrade core confinement. This mechanism offers a novel and potentially universal channel for auxiliary ion heating in future fusion reactors.

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Cong Zhang, Shaodong Song, Di Luo, Kai Huang, Linge Zang, Huibo Tang, Yanchao Li, Yihang Zhao, Ao Wang, Hanqing Wang, Zhenxing Wang, Lei Han, Xuxu Zhang, Jia Li, Dong Guo, Yunfeng Liang, Minsheng Liu, Yuejiang Shi. 2026-05-15. Re-acceleration of Energetic Ions via Small-Scale Reconnection in Magnetic Fusion Plasmas. https://arxiv.org/abs/2605.15485

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