[论文解读] STAR_Lite: A stellarator designed to experimentally validate non-resonant divertors

Georg Friedrich Harrer, Andrew Giuliani+4 more|arXiv (Cornell University)|Mar 18, 2026

Magnetic confinement fusion research被引用 0

一句话总结

STAR_Lite 引入了一种大学尺度、双场周期、准轴对称型星形螺线器设计（STAR_Lite-A），用于实验验证非共振偏截器并评估其对线圈电流与制造扰动的鲁棒性。

ABSTRACT

The non-resonant divertor (NRD) offers a promising exhaust solution for stellarators, combining topological simplicity with resilience to magnetic field perturbations. To experimentally validate the robustness of non-resonant divertors in a quasi-axisymmetric (QA) configuration, we introduce STAR_Lite, a new stellarator experiment at Hampton University. This paper details the design and analysis of the first STAR_Lite coil configuration, STAR_Lite-A. The two field-period configuration manifests an NRD through X-points with zero rotational transform, at the top and bottom of the device. The divertor legs extruding from the X-points are topologically similar to the poloidal divertors of tokamaks. To expand the experimental range, STAR_Lite-A is optimized for experimental flexibility, producing a wide range of distinct QA configurations by only varying the currents in the modular coils. The NRDs not only persist across these configurations, but numerical strike-line simulations confirm that heat exhaust remains resilient to changes in coil currents, with plasma following the divertor legs and creating a toroidal, discontinuous, strike pattern. We further examine the resilience of the NRD to magnetic perturbations caused by manufacturing errors in the modular coils. We find that quasisymmetry and the existence of X-points is well-preserved under these magnetic field changes, but the rotational transform may vary substantially and displacements of the divertor X-points may lead to one X-point having a dominant effect on edge transport. Overall, our analysis indicates a compact, modular design can likely generate a resilient NRD structure while satisfying the practical constraints of a university-scale experiment.

研究动机与目标

• 确定一种可实现的具有非共振偏截器（NRD）的磁配置，使等离子体在强健偏转的同时对平衡变化保持稳定。
• 验证构建的 STAR_Lite 线圈几何形状能再现 NRD 特征和偏截行为。
• 通过在多个 QA 配置中改变线圈电流和几何形状，测试 NRD 对磁扰动的鲁棒性。

提出的方法

• 优化一个双场周期的 QA 线圈组以在顶部和底部产生 X 点（iota = 0）并实现对 NA 的友好偏截器腿部。
• 应用受偏微分方程约束的优化来设计两种线圈几何（L 线圈与 T 线圈）和三组电流，具有精确的曲面体积和目标准对称性度量。
• 使用 Boozer 表面技术来计算优化曲面并在应用二次罚项法以处理不等式约束的同时强制精确的 PDE 约束。
• 在低、中、高 iota 配置下评估准对称性、转动变换和主半径的一致性。
• 进行粒子追踪模拟以估算电子（20 eV）和快电子（约 2.86 keV）的束缚与损失分数，以绘制边缘传输灵敏性。

Figure 1: (a-d) Design A viewed from different perspectives; the stable and unstable manifolds emanating from the X-point are shown in red, and the toroidal surface on which quasisymmetry is optimized is shown in purple. The four $L$ -coils, and two $T$ -coils in black and blue, respectively. In (e)

实验结果

研究问题

• RQ1 一个紧凑的大学尺度星形螺线器设计是否能在 QA 配置中产生稳健的 NRD？
• RQ2 NRD 结构对线圈电流变化和线圈制造扰动的鲁棒性如何？
• RQ3 在 STAR_Lite-A 配置中改变转动变换时会出现哪些拓扑变化（如 X 点、守恒流形等）？
• RQ4 NRD 偏截器特征是否在不同 iota 值的 QA 平衡范围内持续存在？

主要发现

• 设计 A 在装置顶部与底部实现零转动变换的 NRD 与 X 点，形成类似偏截器腿部的拓扑。
• 数值冲击线模拟表明热排放在 QA 配置下对线圈电流变化具有鲁棒性。
• 相对于对称化基线，准对称性有所提升，在大多数配置中达到小于 5% 的 QA 误差（大约 3.5%–5%）。
• STAR_Lite-A 通过在 L 与 T 线圈之间调整电流比，在单一装置内实现三种不同的平衡，主半径固定在 R0≈0.5 m，磁场中心场强 B0≈87.5 mT。
• 设计对制造/放置误差和中等等离子体电流增大保持鲁棒，保留 X 点和 NRD 结构，同时 iota 值可能显著变化。

Figure 2: (Left) Visualization of the copper cable (orange, blue, purple) wrapped around the stainless steel central spine (silver), demonstrating “spine-based” coil winding. (Right) A cross-section of the winding pack showing three layers of copper cable (orange, blue, purple) forming a hexagonal l