AI 中文总结
研究氘 - 氚燃料自旋状态对聚变影响，提出自旋极化燃料增强α粒子输运的两种方式，通过速度空间计算等方法得出其能提高输运效率及聚变功率，还能快速输送氦到偏滤器，为聚变研究提供新思路。
AI 中文摘要
氘 - 氚（D - T）燃料的核自旋状态决定了D - T聚变截面以及聚变产生的α粒子和中子的发射方向。我们展示了自旋极化燃料（SPF）增强α粒子输运的两种方式，α粒子输运是指波介导的α粒子能量耗散到燃料离子而非电子上，预计这会显著增加聚变功率。首先，增强的SPF截面产生更多α粒子；其次，α粒子动能的垂直（于磁场）偏置更有效地耦合到垂直共振输运波。出生时的各向异性在减速过程中得以保留，并在速度空间的广泛区域表现为体α分布的粒子数反转，因此共振α粒子可驱动适当调谐的输运波而非使其衰减。在没有输运的情况下，SPF通过截面提升及其对反应性的温度反馈使聚变功率密度大致翻倍。我们的速度空间计算发现，矢量对齐燃料的输运效率比非极化燃料高约1.5倍，并且随着输运效率提高，输运会将聚变功率增强提高到三倍或四倍，前提是波不会使燃料去极化。一个具有刚性临界梯度输运的ARC类平衡的输运模型给出的增强因子为2.2，对于较软的输运，增强因子升至3.4，在零维模型中，当临界梯度随较热离子升高时，增强因子为4.7。输运还能快速将氦输送到偏滤器：在固定抽气情况下，堆芯氦份额几乎减半，对氦选择性低几倍的偏滤器泵可支持相同的堆芯氦稀释。因此，自旋极化燃料通过各向异性α分布增强聚变功率，超出其对反应性的增加。
英文摘要
The nuclear spin state of deuterium-tritium (D-T) fuel sets both the D-T fusion cross section and the emission direction of the fusion-born alphas and neutrons. We show two ways that spin-polarized fuel (SPF) could enhance alpha channeling, the wave-mediated damping of alpha power onto fuel ions rather than electrons, which is predicted to increase fusion power significantly. First, the enhanced SPF cross section produces more alphas, and second, the perpendicular (to the magnetic field) bias of the alphas' kinetic energy couples more efficiently to the perpendicular-resonant channeling waves. The birth anisotropy survives slowing-down and appears as a population inversion of the bulk alpha distribution over a broad region of velocity space, so resonant alphas can drive a suitably tuned channeling wave rather than damp it. Without channeling, SPF roughly doubles the fusion power density through the cross-section boost and its temperature feedback on the reactivity, a well-known result. Our velocity-space calculations find the channeling efficiency about 1.5 times higher for vector-aligned fuel than for unpolarized fuel, and channeling raises the fusion power enhancement to three or four times as the channeling efficiency improves, provided the waves do not depolarize the fuel. A transport model of an ARC-class equilibrium with stiff critical-gradient transport gives an enhancement of 2.2, rising to 3.4 for less stiff transport and to 4.7 in the zero-dimensional model when the critical gradients rise with the hotter ions. Channeling also transports helium quickly to the divertor: at fixed pumping the core helium fraction nearly halves, and a divertor pump several times less selective for helium supports the same core helium dilution. Spin-polarized fuel thus enhances fusion power through the anisotropic alpha distribution, beyond its increase of the reactivity.
Comments36 pages, 29 figures
